Filed Pursuant to Rule 424(b)(5)
Registration No. 333-163301

PROSPECTUS SUPPLEMENT TO PROSPECTUS DATED DECEMBER 21, 2009

 

Active Power, Inc.
 
14,336,912 Shares
Common Stock
$0.68 per share

Active Power, Inc. is selling 14,336,912 shares of its common stock in this offering to two investors pursuant to this prospectus supplement and the accompanying prospectus.  We are offering to sell the securities being offered pursuant to this prospectus directly to such investors without the use of an underwriter, dealer or agent, and therefore no discounts, concessions or commissions will be paid.

Our common stock is listed on The Nasdaq Global Market under the symbol “ACPW.”  On March 6, 2012, the last reported sale price of our common stock on The Nasdaq Global Market was $0.70 per share.
 
As of March 7, 2012, the aggregate value of our outstanding common stock held by non-affiliates was approximately $39,288,020, based on 81,090,323 shares of outstanding common stock, of which 56,125,743 are held by non-affiliates, and a price of $0.70 per share based on the closing sale price of our common stock on March 6, 2012 as reported by The Nasdaq Global Market. We have not offered any securities pursuant to General Instruction I.B.6 of Form S-3 during the prior 12-month period that ends on and includes the date of this prospectus supplement.

INVESTING IN OUR COMMON STOCK INVOLVES A HIGH DEGREE OF RISK.  SEE "RISK FACTORS" BEGINNING ON PAGE S-4 OF THIS PROSPECTUS SUPPLEMENT.  YOU SHOULD READ THIS PROSPECTUS SUPPLEMENT, THE ACCOMPANYING PROSPECTUS, AND THE DOCUMENTS INCORPORATED BY REFERENCE INTO THIS PROSPECTUS SUPPLEMENT AND THE ACCOMPANYING PROSPECTUS CAREFULLY BEFORE YOU MAKE YOUR INVESTMENT DECISION.  

 
 	 	Per Share	 	Total	 	
Offering price	 	$	0.68	 	 	$	9,749,100.16	 	
Proceeds, before expenses, to us	 	$	0.68	 	 	$	9,749,100.16	 	
 
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.

 
The date of this prospectus supplement is March 7, 2012

 

 
 
TABLE OF CONTENTS
 
PROSPECTUS SUPPLEMENT
 
 	Page	
Where You Can Find More Information	S-i	
About this Prospectus	S-ii	
Prospectus Supplement Summary	S-iii	
Note Regarding Forward-Looking Statements	S-1	
Securities We May Offer	S-3	
Risk Factors	S-4 	
Use of Proceeds	S-14	
Dilution	S-15	
Plan of Distribution	S-16	
Legal Matters	S-17	
Experts	S-17	
 
ACCOMPANYING PROSPECTUS

 	Page	
Where You Can Find More Information	2	
About this Prospectus	3	
Note Regarding Forward-Looking Statements	5	
Risk Factors	5	
Securities We May Offer	5	
Use of Proceeds	6	
Description of Common Stock	6	
Description of the Warrants	9	
Plan of Distribution	11	
Legal Matters	12	
Experts	13	

 
You should rely only on the information contained in this prospectus supplement, the accompanying prospectus and the documents we incorporate by reference in this prospectus supplement and the accompanying prospectus.  We have not authorized anyone to provide you with information different from that contained or incorporated by reference in this prospectus supplement and the accompanying prospectus.  If anyone provides you with different or additional information, you should not rely on it.  You should assume that the information contained in this prospectus supplement and the accompanying prospectus, as well as the information that we have filed with the Securities and Exchange Commission, or the SEC, and incorporated by reference herein and therein, is accurate only as of the date of the applicable document.  This prospectus supplement and the accompanying prospectus do not constitute an offer or solicitation by anyone in any jurisdiction in which an offer or solicitation is not authorized or in which the person making an offer or solicitation is not qualified to do so, or to anyone to whom it is unlawful to make an offer or solicitation.

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WHERE YOU CAN FIND MORE INFORMATION

We file reports, proxy statements and other information with the SEC in accordance with the Securities Exchange Act of 1934, or the Exchange Act.  You may read and copy our reports, proxy statements and other information filed by us at the Public Reference Room of the SEC at 100 F Street, N.E., Washington, D.C. 20549.  Please call the SEC at 1-800-SEC-0330 for further information about the Public Reference Room.  Our reports, proxy statements and other information filed with the SEC are available to the public over the Internet at the SEC’s website at www.sec.gov and on our Internet website at http://www.activepower.com.  Information contained on our website does not constitute part of this prospectus supplement or the accompanying prospectus.

The SEC allows us to “incorporate by reference” information that we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus supplement and the accompanying prospectus, and information that we file later with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings we will make with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, after the date of this prospectus supplement but before the end of any offering made under this prospectus supplement and the accompanying prospectus (other than current reports or portions thereof furnished under Item 2.02 or 7.01 of Form 8-K, unless such current reports or portions thereof specifically reference their contents as being filed):

 	●	Description of our common stock contained in our registration statement on Form S-1 (File No. 333-36946), filed with the SEC on May 12, 2000, including any amendment or report filed for the purpose of updating such description;	
 
 	●	Our annual report on Form 10-K for our fiscal year ended December 31, 2011, filed with the SEC on March 1, 2012; and	
 
 	●	Our current reports on Form 8-K, filed with the SEC on January 18, 2012, February 23, 2012, and February 24, 2012.	
 
Copies of documents incorporated by reference, excluding exhibits except to the extent such exhibits are specifically incorporated by reference, are available from us without charge, upon oral or written request to:
 
Active Power, Inc.
2128 W. Braker Lane, BK12
Austin, Texas 78758
Attn: John K. Penver, Chief Financial Officer
(512) 836-6464

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document is in two parts.  The first part is the prospectus supplement, which describes the specific terms of the securities we are offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into the accompanying prospectus.  The second part, the accompanying prospectus, including the documents incorporated by reference, provides more general information, some of which may not apply to this offering.  Generally, when we refer to this prospectus, we are referring to both parts of this document combined.  To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference that was filed with the SEC before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement.  If any statement in one of these documents is inconsistent with a statement in another document having a later date — for example, a document incorporated by reference in the accompanying prospectus — the statement in the document having the later date modifies or supersedes the earlier statement.
 
We own the registered trademarks ACTIVE POWER, CLEANSOURCE, COOLAIR, and POWERHOUSE in the United States and abroad. The ACTIVE POWER logo is a trademark of Active Power. All other trademarks, service marks or trade names referred to in this prospectus supplement and the accompanying prospectus are the property of their respective owners.

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PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights information contained in this prospectus supplement, the accompanying prospectus or incorporated by reference. While we have included what we believe to be the most important information about the company and this offering, the following summary may not contain all the information that may be important to you. Before you decide to make an investment, you should read this entire prospectus supplement and accompanying prospectus carefully, including the risks of investing discussed under “Risk Factors” beginning on page S-4 of this prospectus supplement, and the information to which we refer you and the information incorporated into this prospectus supplement by reference, for a complete understanding of our business, this offering and the investment you are contemplating.  Unless the context otherwise requires, the terms “Active Power,” “we,” “us,” “the Company” and “our” refer to Active Power, Inc., a Delaware corporation.

Active Power, Inc.

Active Power designs and manufactures continuous power and infrastructure solutions. These solutions ensure continuity for data centers and other mission critical operations in the event of power disturbances.

Our products and solutions are designed to deliver continuous conditioned (“clean”) power during power disturbances and outages, voltage sags and surges, and provide ride-through power in the event of utility failure, supporting operations until utility power is restored or a longer term alternative power source, such as a diesel generator is started.  We believe our products offer an advantage over those of our competitors in the areas of power density (less space) and energy efficiency, total cost of ownership, system reliability, modular design, and the economically green benefits of our solutions.

We have sold our patented flywheel-based uninterruptible power supply (“UPS”) systems since 1999. As of December 31, 2011, we have shipped more than 3,200 flywheels in UPS system installations, delivering more than 800 megawatts of power to customers in 42 countries around the world with more than 110 million runtime hours of operation.

In addition to selling stand alone UPS systems, we also manufacture and sell continuous power systems (“CPS”) that integrate our UPS products with other related equipment such as switchgear and backup diesel generators, and that are sold as a complete power solution for customers. Our CPS systems can be sold in a containerized format, or as individual components.

We have leveraged our success with containerized CPS solutions to work with our partners to develop and manufacture containerized  infrastructure solutions. These solutions serve as the infrastructure for containerized data center products, which are self-contained fully-functional data centers.  We design and build enclosures that have a fully built out interior – including electrical, cooling, monitoring and other elements – ready for the customer to add their IT racks and servers. These products can be deployed rapidly and at a lower cost than traditional brick-and-mortar solutions and are optimally suited for hyper-scale IT and cloud applications.

In 2011, 42% of our product revenue came from the sale of UPS systems, 36% from the sale of CPS solutions and 22% from the sale of infrastructure solutions.

We are headquartered in Austin, Texas, with international offices in the United Kingdom, Germany, and China.

We believe a number of underlying macroeconomic trends place Active Power in a strong position to be one of the leading providers of critical power protection. These trends include:

 	●	increasing business costs of downtime;	

 	●	a rapidly expanding need for data center infrastructure;	

 	●	ever-increasing demands placed on the public utility infrastructure;	

 	●	an inadequate investment in global utility infrastructure;	

 	●	rising costs of energy worldwide driven by volume of energy used; and	

 	●	an increasing demand for economically green solutions.	

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We have evolved significantly since the company was founded in 1992.  Our early focus was on research and development of the core products that continue to enable the business today.  Over the past several years, we have focused our efforts on brand, markets, and channels of distribution.  The technological foundation of Active Power has yielded more than 100 worldwide patents and a highly differentiated, cost-efficient product platform that we have evolved into an expanding suite of infrastructure solutions.  As we go forward, it’s critical for us to focus on both technology development to maintain and grow our leadership position and build channels of distribution to have more avenues into the market.

Corporate Information
 
We were founded as a Texas corporation in 1992 and reincorporated in Delaware in 2000 prior to our initial public offering. Our principal executive offices are located at 2128 W. Braker Lane, BK12, Austin, Texas 78758 and our telephone number at that address is (512) 836-6464.  Our website address is www.activepower.com and we make our periodic and current reports that are filed with the SEC available, free of charge, on our website as soon as reasonably practicable after such material is electronically filed with, or furnished to, the Securities and Exchange Commission.  Information contained on our website does not constitute part of this prospectus supplement or the accompanying prospectus.
 
Our common stock trades on The Nasdaq Global Market under the symbol “ACPW.”

The Offering
 
Shares of common stock we are offering	 	14,336,912 shares	
Shares of common stock to be outstanding immediately after this offering	 	94,894,735 shares	
Use of Proceeds	 	We currently intend to use the net proceeds from this offering to fund working capital requirements and general corporate purposes and as further described in this prospectus supplement under the heading “Use of Proceeds.”	
Risk Factors	 	See the “Risk Factors” beginning on page S-4 of this prospectus supplement and the accompanying prospectus, as well as the documents we file with the SEC that are incorporated by reference in this prospectus, for a discussion of the risk factors to be considered before deciding to purchase our securities.	
Nasdaq Global Market symbol	 	ACPW	
 
The number of shares of common stock outstanding immediately after this offering in the table above is based on 80,557,823 shares of our common stock outstanding as of December 31, 2011 and excludes the following, each stated as of December 31, 2011:
 
 	·	9,718,241 shares of our common stock issuable upon the exercise of stock options at a weighted average exercise price of $1.79 per share; and	

 	·	 2,364,578 shares of common stock reserved for future issuance under our stock plans.	

Unless otherwise stated, all information contained in this prospectus supplement reflects an offering price of $0.68 per share.

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NOTE REGARDING FORWARD-LOOKING STATEMENTS
 
This prospectus supplement, the accompanying prospectus and the documents incorporated by reference into these documents contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Forward-looking statements deal with our current plans, intentions, beliefs and expectations and statements of future economic performance. Statements containing terms such as “believe,” “do not believe,” “plan,” “expect,” “intend,” “estimate,” “anticipate” and other phrases of similar meaning are considered to contain uncertainty and are forward-looking statements.   In addition, from time to time we or our representatives have made or will make forward-looking statements orally or in writing.  Furthermore, such forward-looking statements may be included in various filings that we make with the SEC, or press releases or oral statements made by or with the approval of one of our authorized executive officers. These forward-looking statements are subject to certain known and unknown risks and uncertainties, as well as assumptions that could cause actual results to differ materially from those reflected in these forward-looking statements.  Factors that might cause actual results to differ include, but are not limited to, those set forth under “Risk Factors,” in our most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q and in our future filings made with the SEC.  Readers are cautioned not to place undue reliance on any forward-looking statements contained herein, which reflect management’s opinions only as of the date hereof.  Except as required by law, Active Power undertakes no obligation to revise or publicly release the results of any revisions to any forward-looking statements.  You are advised, however, to consult any additional disclosures we have made or will make in our reports to the SEC on Forms 10-K, 10-Q and 8-K.  All subsequent written and oral forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the cautionary statements contained in this prospectus supplement and the accompanying prospectus.

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RISK FACTORS

An investment in our securities involves a high degree of risk.  You should carefully consider the following risk factors related to the securities offered in this prospectus supplement and to our business and operations.  You should also carefully consider the other information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus before you decide to purchase our securities.  Some of these factors have affected our financial condition and operating results in the past or are currently affecting us.  All of these factors could affect our future financial condition and operating results.  The risks and uncertainties described below are not the only risks and uncertainties we face.  Additional risks and uncertainties not presently known to us or that we currently deem immaterial also may impair our business operations.  If any of the following risks actually occur, our business, results of operations and financial condition could be harmed, the trading price of our securities could decline and you may lose all or part of your investment.  The risks set forth below replace and supersede in their entirety the risks set forth beginning on page 5 of the accompanying prospectus.  The risks discussed below also include forward-looking statements and our actual results may differ substantially from those discussed in these forward-looking statements.
 
Risks Related to our Business

We have a history of significant operating losses.

We have incurred operating losses since our inception in 1992. Although we have achieved operating profitability on a quarterly basis, we have not yet sustained this and achieved annual operating profitability. As of December 31, 2011, we had an accumulated deficit of $260.9 million. To date, we have funded our operations principally through the public and private sales of our stock, from our credit facility, from product and service revenue and from development funding. We will need to generate significant additional revenue while maintaining our current margins in order to achieve annual profitability, and we cannot assure you that we will ever realize such revenue levels or achieve profitability on a consistent basis.

Our increased emphasis on larger and more complex system solutions and customer concentration may affect our ability to accurately predict the timing of revenues and to meet short-term expectations of operating results.

Our increased emphasis on larger and more complex system solutions has increased the effort and time required by us to complete sales to customers. Further, a larger portion of our quarterly revenue is derived from relatively few large transactions with relatively few customers. For example, in 2011, our three largest customers contributed 55% of our revenue. Any delay in completing these large sales transactions or reduction in the number of customers or large transactions, may result in significant fluctuations in our quarterly revenue. Further, we use anticipated revenues to establish our operating budgets and a large portion of our expenses, particularly rent and salaries are fixed in the short term. As a result, any shortfall or delay in revenue could result in increased losses and would likely cause our operating results to be below public expectations. The occurrence of any of these events would likely materially adversely affect our results of operations and likely cause the market price of our common stock to decline.

Our business may be affected by general economic conditions and uncertainty that may cause customers to defer or cancel sales commitments previously made to us.

Continuing economic difficulties in the Unites States and certain international markets have led to an economic recession and lower capital spending and credit availability in some or all of the markets in which we operate. A recession or even the risk of a potential recession or uneven economic growth conditions may be sufficient reason for customers to delay, defer or cancel purchase decisions, including decisions previously made. This risk is magnified for capital goods purchases such as the UPS products and CPS solutions that we supply. Although we believe that our competitive advantage and our efforts to broaden the number of different markets in which we sell will help mitigate the economic risk associated with any one country or market vertical, any customer delays or cancellation in sales orders could materially adversely affect our level of revenues and operating results. Should our financial results not meet the expectations of public market analysts or investors, the market price of our stock would most likely decline.

Our financial results may vary significantly from quarter to quarter.

Our product revenue, operating expenses and quarterly operating results have varied in the past and may fluctuate significantly from quarter to quarter in the future due to a variety of factors, many of which are outside of our control. As a result you should not rely on our operating results during any particular quarter as an indication of our future performance in any quarterly period or fiscal year. These factors include, among others:

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 	●	timing of orders from our customers and the possibility that customers may change their order requirements with little or no notice to us;	

 	●	rate of adoption of our flywheel-based energy storage system as an alternative to lead-acid batteries and our continuous power and infrastructure solutions;	

 	●	ongoing need for short-term power outage protection in traditional UPS systems;	

 	●	deferral of customer orders in anticipation of new products from us or other providers of power quality systems;	

 	●	limited visibility into customer spending plans;	

 	●	timing of deferred revenue components associated with large orders;	

 	●	ability to manage capital requirements associated with large orders;	

 	●	timing and execution of new product introductions;	

 	●	new product releases, licensing or pricing decisions by our competitors;	
 
 	●	commodity and raw material component prices;	
 
 	●	lack of order backlog;	

 	●	ability to adjust our cost structure in response to reductions in income;	

 	●	loss of a significant customer or distributor;	

 	●	impact of changes to our product distribution strategy and pricing policies;	
 
 	●	failure to achieve our anticipated revenue growth rate;	

 	●	impact of changes to the product distribution strategy and pricing policies of our distributors;	

 	●	changes in product mix;	

 	●	changes in the mix of domestic and international sales;	

 	●	rate of growth of the markets for our products; and	

 	●	other risks described below.	

The market for power quality products is evolving and it is difficult to predict its potential size or future growth rate. Most of the organizations that may purchase our products have invested substantial resources in their existing power systems and, as a result, have been reluctant or slow to adopt a new technological approach, particularly during a period of reduced capital expenditures. Moreover, our current products are alternatives to existing UPS and battery-based systems and may never be accepted by our customers or may be made obsolete by other advances in power quality technologies.

Significant portions of our expenses are not variable in the short term and cannot be quickly reduced to respond to decreases in revenue. Therefore, if our revenue is below our expectations, our operating results are likely to be adversely and disproportionately affected. In addition, we may change our prices, modify our distribution strategy and policies, accelerate our investment in research and development, sales or marketing efforts in response to competitive pressures or to pursue new market opportunities. Any one of these activities may further limit our ability to adjust spending in response to revenue fluctuations. We use forecasted revenue to establish our expense budget. Because most of our expenses are fixed in the short term or incurred in advance of anticipated revenue, any shortfall in revenue may result in significant losses.

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A significant increase in sales of our PowerHouse product and infrastructure solutions may materially increase the amount of liquidity required to fund the Company’s operations.

Because of the significant up-front investment required, and a longer period between order and delivery relative to our UPS products a significant increase in sales of our PowerHouse product and infrastructure solutions may materially increase the amount of liquidity required to fund our operations. The amount of time between the receipt of payment from our customers and our expenditures for raw materials, manufacturing and shipment of products (the cash cycle) for sales of our standard UPS product can be as short as 45 days, and is typically 60 days. However, this cash cycle on a PowerHouse or infrastructure solution sale can be as much as 210 days, depending on customer payment terms. We intend to mitigate the financial impact of this longer cash cycle by requiring customer deposits and periodic payments where possible from our customers. This is not always commercially feasible, and in order to increase our PowerHouse or infrastructure solution sales, we may be required to make larger investments in inventory and receivables to fund these sales opportunities. During 2010 we obtained a bank line of credit with borrowing capabilities tailored to help us finance growth of our PowerHouse or infrastructure solutions business. However, if we experience a substantial increase in the size or number of PowerHouse or infrastructure solutions orders, we may need  to obtain additional sources of working capital, debt or equity financing in order to fund this business. If we are unsuccessful at obtaining additional sources of working capital, we may be required to curtail our level of PowerHouse and infrastructure solutions sales or we may lose potential customers, both of which may cause our financial results not to meet the expectations of public market analysts or investors and adversely impact our results of operations.

We derive a substantial portion of our revenues from international markets and plan to continue to expand such efforts, which subjects us to additional business risks including increased logistical and financial complexity, managing internal controls and processes, political instability and currency fluctuations.

The percentage of our product revenue derived from customers located outside of the United States was 31%, 29% and 38% in 2009, 2010 and 2011, respectively. Our international operations are subject to a number of risks, including:

 	●	foreign laws and business practices that favor local competition;	

 	●	dependence on local channel partners;	

 	●	compliance with multiple, conflicting and changing government laws and regulations;	

 	●	longer cash cycles;	

 	●	difficulties in managing and staffing foreign operations;	

 	●	foreign currency exchange rate fluctuations and the associated effects on product demand and timing of payment;	

 	●	political and economic stability, particularly in the Middle East and North Africa;	

 	●	greater difficulty in the contracting and shipping process and in accounts receivable collection including longer collection periods;	

 	●	ability to fund working capital requirements;	

 	●	greater difficulty in hiring qualified technical sales and application engineers; and	

 	●	difficulties with financial reporting in foreign countries.	

To date, the majority of our sales to international customers and purchases of components from international suppliers have been denominated in U.S. dollars, Euros and British Pounds. All of our UPS systems are manufactured in the United States and then sold to our foreign subsidiaries and customers, normally in U.S. dollars. We have generally benefited from the decline in value of the U.S. dollar relative to foreign currencies over the last several years, which has made our UPS systems more price competitive in foreign markets. However, the value of the dollar will likely fluctuate, and an increase in the value of the U.S. dollar relative to foreign currencies could make our UPS systems more expensive for our international customers to purchase, thus rendering our products less competitive. We also source the non-UPS components for our CPS products locally where possible and pay for these components in local currencies as a way to mitigate the impact of fluctuations in foreign currencies and lessen the impact of any unfavorable fluctuations with the U.S. dollar. Because the UPS system is a small part of the total cost of a CPS solution, this strategy will minimize the effect of currency fluctuations on the pricing of our CPS solutions.  As our business expands internationally, many of our subsidiaries are selling products outside of their country of incorporation, and often in foreign currencies. To the extent that we record sales in other than our local currency, this can result in translation gains and losses. Currently, we do not engage in hedging activities for our international operations to offset this currency risk. However, we may engage in hedging activities in the future.

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We are subject to risks relating to product concentration and lack of revenue diversification.

We derive a substantial portion of our revenue from a limited number of products, particularly our 250-900 kVA UPS product family. These UPS products are also an integral component part of many of our newer products such as PowerHouse and our infrastructure solutions. We expect these products to continue to account for a large percentage of our revenues in the near term. Continued market acceptance of these products is therefore critical to our future success. Our future success will also depend in part on our ability to reduce our dependence on these few products by developing and introducing new products and product or feature enhancements in a timely manner. Specifically, our ability to capture significant market share depends on our ability to develop and market extensions to our existing product lines at higher and lower power range offerings and as containerized solutions. We are currently investing significant amounts to finalize development of our next-generation UPS product and to broaden our product portfolio. Even if we are able to develop and commercially introduce new products and enhancements, they may not achieve market acceptance and the revenue generated from these new products and enhancements may not offset the costs, which would substantially impair our revenue, profitability and overall financial prospects. Successful product development and market acceptance of our existing and future products depend on a number of factors, including:

 	●	changing requirements of customers;	
 
 	●	accurate prediction of market and technical requirements;	

 	●	timely completion and introduction of new designs;	

 	●	quality, price and performance of our products;	

 	●	availability, quality, price and performance of competing products and technologies;	

 	●	our customer service and support capabilities and responsiveness;	

 	●	successful development of our relationships with existing and potential customers; and	

 	●	changes in technology, industry standards or end-user preferences.	
 
We must expand our distribution channels and manage our existing and new product distribution relationships to continue to grow our business.

The future growth of our business will depend in part on our ability to expand our existing relationships with distributors, to identify and develop additional channels for the distribution and sale of our products and to manage these relationships. As part of our growth strategy, we may expand our relationships with distributors and develop relationships with new distributors. We will also look to identify and develop new relationships with additional parties that could serve as outlets for our products, or that could provide additional opportunities for our existing sales channels, such as the relationships that we have developed with IT hardware manufacturers such as HP. Our inability to execute this strategy successfully and to integrate and manage our existing OEM channel partners and our new distributors and manufacturer’s representatives could impede our future growth.

The transition to a new Chief Executive Officer may limit our ability to effectively execute on our business plan.

Effective March 1, 2012, Douglas Milner will become our President and Chief Executive Officer.  Because he is new to Active Power, his experience with our management team  and knowledge of our operations is limited.  While Jan Lindelow, who has been serving as our Interim Chief Executive Officer, will assist Mr. Milner as he transitions into the position, this leadership change may result in disruptions to our business or operations or otherwise limit the ability of our management team to effectively execute on our business plan, which could have an adverse effect on our results of operations and financial condition.

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We must continue to hire and retain skilled personnel.

We believe our future success will depend in large part upon our ability to attract, motivate and retain highly skilled managerial, engineering and sales and product marketing personnel. There is a limited supply of skilled employees in the power quality marketplace particularly. Our small size relative to our competitors and lack of brand equity, particularly in foreign markets, makes it very difficult for us to attract personnel in foreign markets. Our failure to attract and retain the highly trained technical personnel who are essential to our product development, marketing, sales, service and support teams may limit the rate at which we can develop new products or generate revenue, particularly in foreign markets. If we are unable to attract the new personnel we desire, retain the personnel we currently employ, or if we are unable to replace departing employees quickly, our operations and new product development may suffer.

We are significantly dependent on our relationships with Hewlett Packard and Caterpillar. If these relationships are unsuccessful, for whatever reason, our business and financial prospects would likely suffer.

Caterpillar including its dealer network is our primary OEM customer and our largest single customer for our flywheel-based products. Caterpillar and its dealer network accounted for 24%, 19% and 16% of our revenue in 2009, 2010 and 2011, respectively. HP is our largest IT channel partner and accounted for 12%, 25% and 36% of our revenue in 2009, 2010 and 2011, respectively. A number of factors could cause these customers to cancel or defer orders, including interruptions to their operations due to a downturn in their industries, delays or changes in their product offerings or securing other sources for the products that we manufacture, or developing such products internally.  If our relationships with HP or with Caterpillar are not successful or suffers a material adverse change, such as a material reduction in the level of orders or their failure to timely pay us, our business and operating results would likely suffer.

We have underutilized manufacturing capacity and have no experience manufacturing our products in large quantities.

In 2001, we leased and equipped a 127,000 square foot facility used for manufacturing and testing of our three-phase product line, including our DC and UPS products. To be financially successful, and to utilize fully the capacity of this facility and allocate its associated overhead, we must achieve significantly higher sales volumes. We must accomplish this while also preserving the quality levels we achieved when manufacturing these products in more limited quantities. To date, we have not been successful at increasing our sales volume to a level that fully utilizes the capacity of the facility and we may never increase our sales volume to necessary levels. During 2007, we subleased approximately 31,000 feet of our manufacturing facility to help lower our operating costs and to take advantage of surplus space that we leased but were not using. If we do not reach these necessary sales volume levels, or if we cannot sell our products at our suggested prices, our ability to reach profitability on an annual basis will be materially limited.

Achieving the necessary production levels to absorb the capacity of our manufacturing facility efficiently presents a number of technological and engineering challenges for us. We have not previously manufactured our products in high volume. We do not know whether or when we will be able to develop efficient, low-cost manufacturing capability and processes that will enable us to meet the quality, price, engineering, design and product standards or production volumes required to manufacture large quantities of our products successfully. Even if we are successful in developing our manufacturing capability and processes, we do not know whether we will do so in time to meet our product commercialization schedule or to satisfy the requirements of our customers.

We must build quality products to ensure acceptance of our products.

The market perception of our products and related acceptance of the products is highly dependent upon the quality and reliability of the products that we build. Any quality problems attributable to the CleanSource DC, CleanSource UPS, PowerHouse or containerized infrastructure solution product lines may substantially impair our revenue and operating results. Moreover, quality problems for our product lines could cause us to delay or cease shipments of products or have to recall or field upgrade products, thus adversely affecting our ability to meet revenue or cost targets. In addition, while we seek to limit our liability as a result of product failure or defects through warranty and other limitations, if one of our products fails, a customer could suffer a significant loss and seek to hold us responsible for that loss.

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We currently operate without a substantial backlog.

We generally operate our business, without sufficient backlog of orders from our customers. Normally our products are shipped and revenue is recognized shortly after the order is received, usually within two quarters of the date of the order. Because historically our backlog has not always been sufficient to provide all of the next quarter’s revenue, revenue in any quarter is often dependent on orders booked and shipped throughout that quarter. We are attempting to increase the size of our backlog to allow greater efficiency in production and to facilitate business planning and to improve revenue visibility. During periods of economic uncertainty, the rate of customer orders can quickly decrease, limiting our ability to build a substantial backlog. Therefore, there can be no guarantee that we can successfully build and maintain a meaningful level of backlog.

Seasonality may contribute to fluctuations in our quarterly operating results.

Our business has experienced seasonal customer buying patterns. In recent years, the UPS industry and our business have generally experienced relatively weaker demand in the first calendar quarter of the year, including a sequential decrease in revenue compared to the fourth quarter.   We believe this pattern, which we attribute to annual capital budgeting procedures, will continue. In addition, we anticipate that demand for our products in Europe and Africa may decline in the summer months, as compared to other regions, because of reduced corporate buying patterns during the vacation season.

We depend on sole and limited source suppliers, and outsource selected component manufacturing.

We purchase several component parts from sole source and limited source suppliers. As a result of our current production volumes, we lack significant leverage with these and other suppliers especially when compared to some of our larger competitors. If our suppliers receive excess demand for their products, we may receive a low priority for order fulfillment as large volume customers may receive priority that may result in delays in our acquiring components. If we are delayed in acquiring components for our products, the manufacture and shipment of our products could be delayed. We are, however, continuing to enter into long-term agreements with our sole suppliers and other key suppliers, when available, using a rolling sales volume forecast to stabilize component availability. Lead times for ordering materials and components vary significantly and depend on factors such as specific supplier requirements, contract terms, the extensive production time required and current market demand for such components. Some of these delays may be substantial. As a result, we purchase several critical, long lead time or single sourced components in large quantities to protect our ability to deliver finished products. If we overestimate our component requirements, we may have excess inventory, which will increase our costs. If we underestimate our component requirements, we will have inadequate inventory, which will delay our manufacturing and render us unable to deliver products to customers on scheduled delivery dates. If we are unable to obtain a component from a supplier or if the price of a component has increased substantially, we may be required to manufacture the component internally, which will also result in delays, or be required to absorb price increases. Manufacturing delays could negatively impact our ability to sell our products and could damage our customer relationships.

To assure the availability of our products to our customers, we outsource the manufacturing of selected components prior to the receipt of purchase orders from customers based on their forecasts of their product needs and internal product sales revenue forecasts. However, these forecasts do not represent binding purchase commitments from our customers. We do not recognize revenue for such products until we receive an order from the customer and the product is shipped to the customer. As a result, we incur inventory and manufacturing costs in advance of anticipated revenue. As demand for our products may not materialize, this product delivery method subjects us to increased risks of high inventory carrying costs, obsolescence and excess, and may increase our operating costs. In addition, we may from time to time make design changes to our products, which could lead to obsolescence of inventory.
 
Our manufacturing operations are concentrated in a small number of nearby facilities.
 
Our manufacturing, research and development and administrative activities are concentrated in a small number of nearby facilities, and all of our UPS systems are manufactured in our Austin, Texas facility. If, for any reason, including as a result of a natural disaster, act of terrorism or other similar event, any of these facilities should be damaged or destroyed or become inoperable or inaccessible, our ability to conduct our business could be adversely affected or interrupted entirely.

We face significant competition from other companies.

The markets for power quality and power reliability are intensely competitive. There are many companies engaged in all areas of traditional and alternative UPS and backup systems in the United States and abroad, including, among others, major electric and specialized electronics firms, as well as universities, research institutions and foreign government-sponsored companies. There are many companies that are developing flywheel-based energy storage systems and flywheel-based power quality systems. We may face future competition from companies that are developing other types of emerging power technologies, such as high-speed composite flywheels, ultra capacitors and superconducting magnetic energy storage.

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Many of our current and potential competitors have longer operating histories, significantly greater financial, technical, service, marketing and other resources, broader name and brand recognition and a larger installed base of customers. As a result, these competitors may have greater credibility with our existing and potential customers and greater service infrastructure than we do. They also may be able to adopt more aggressive pricing policies and devote greater resources to the development, promotion and sale of their products than we can to ours, which would allow them to respond more quickly than us to new or emerging technologies or changes in customer requirements. In addition, some of our current and potential competitors have established supplier or joint development relationships with our current or potential customers. These competitors may be able to leverage their existing relationships to discourage these customers from purchasing products from us or to persuade them to replace our products with their products. Increased competition could decrease our prices, reduce our sales, lower our margins, or decrease our market share. These and other competitive pressures could prevent us from competing successfully against current or future competitors and could materially harm our business.

We may be unable to protect our intellectual property and proprietary rights.

Our success depends to a significant degree upon our ability to protect our proprietary technology, and we expect that future technological advancements made by us will be critical to sustain market acceptance of our products. We rely on a combination of patent, copyright, trademark and trade secret laws and restrictions on disclosure to protect our intellectual property rights. We also enter into confidentiality or license agreements with our employees, consultants and business partners and control access to and distribution of our software, documentation and other proprietary information. Despite these efforts, unauthorized parties may attempt to copy or otherwise obtain and use our products or technology. Monitoring unauthorized use of our products is difficult, and we cannot be certain that the steps we have taken will prevent unauthorized use of our technology, particularly in foreign countries where applicable laws may not protect our proprietary rights as fully as in the United States. In addition, the measures we undertake may not be sufficient to protect our proprietary technology adequately and may not preclude competitors from independently developing products with functionality or features similar to those of our products.

We may be subject to claims by others that we infringe on their proprietary technology.

In recent years, there has been significant litigation in the United States involving patents, trademarks and other intellectual property rights. We may become involved in litigation in the future to protect our intellectual property or defend allegations of infringement asserted by others. Legal proceedings could subject us to significant liability for damages or invalidate our intellectual property rights. Any litigation, regardless of its merits or its outcome, would likely be time consuming and expensive to resolve and would divert management’s time and attention. Any potential intellectual property litigation also could force us to take specific actions, including:

 	●	cease selling our products that use the challenged intellectual property;	

 	●	obtain from the owner of the infringed intellectual property right a license to sell or use the relevant technology or trademark, which license may not be available on reasonable terms, or at all;	

 	●	redesign those products that use infringing intellectual property; or	

 	●	cease to use an infringing trademark.	

Our involvement in any such litigation will cause us to incur unexpected litigation costs, require modifications to or limit our ability to sell our products, and adversely impact our business and reputation.

Risks Related to our Common Stock

We have anti-takeover provisions that could discourage, delay or prevent our acquisition.

Provisions of our certificate of incorporation and bylaws could have the effect of discouraging, delaying or preventing a merger or acquisition that a stockholder may consider favorable. We also are subject to the anti-takeover laws of the State of Delaware, which may further discourage, delay or prevent someone from acquiring or merging with us. In addition, our agreement with Caterpillar for the distribution of CleanSource UPS provides that Caterpillar may terminate the agreement in the event we are acquired or undergo a change in control. The possible loss of our most significant customer could be a significant deterrent to possible acquirers and may substantially limit the number of possible acquirers. All of these factors may decrease the likelihood that we would be acquired, which may depress the market price of our common stock.

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The trading price of our common stock has been volatile and is likely to be volatile in the future.

Historically, the market price of our common stock has fluctuated significantly. In 2011, the sales price of our common stock ranged from $0.59 to $3.03. In addition to those risks described earlier in this section, the market price of our common stock can be expected to fluctuate significantly in response to numerous other factors, many of which are beyond our control, including the following:

 	●	actual or anticipated fluctuations in our operating results;	

 	●	changes in financial estimates by securities analysts or our failure to perform in line with such estimates;	

 	●	changes in market valuations of other technology companies, particularly those that sell products used in power quality systems;	

 	●	announcements by us or our competitors of significant sales, technical innovations, acquisitions, strategic partnerships, joint ventures or capital commitments;	

 	●	introduction of technologies or product enhancements that reduce the need for flywheel energy storage systems and CPS;	

 	●	the loss of one or more key OEM customers or channel partners;	

 	●	inability to expand our distribution channels successfully;	

 	●	departures of key personnel; and	

 	●	changing external capital market conditions.	

If the market for technology stocks or the stock market in general experiences loss of investor confidence, the trading price of our common stock could decline for reasons unrelated to our business, operating results or financial condition. The trading price of our common stock might also decline in reaction to events that affect other companies in our industry or the stock market generally even if these events do not directly affect us. Each of these factors, among others, could cause our stock price to decline. Some companies that have had volatile market prices for their securities have had securities class actions filed against them. If a suit were filed against us, regardless of its merits or outcome, it could result in substantial costs and divert management’s attention and resources.

Securities or industry analysts may not publish research or may publish inaccurate or unfavorable research about our business.

The trading market for our common stock will continue to depend in part on the research and reports that securities or industry analysts publish about us or our business. If we do not continue to maintain adequate research coverage or if one or more of the analysts who covers us downgrades our stock or publishes inaccurate or unfavorable research about our business, our stock price would likely decline. Although we were able to secure three additional analysts to provide research coverage on our company during 2011, there can be no guarantee that these research analysts will continue to provide coverage of our company. If one or more of these analysts ceases coverage of our company or fails to publish reports on us regularly, demand for our stock could decrease, which could cause our stock price and trading volume to decline.
 
Our common stock could be delisted from the NASDAQ Global Market if our stock price continues to trade below $1.00 per share.
 
On December 19, 2011, we received a Staff Deficiency Letter from The Nasdaq Global Market LLC, or Nasdaq, notifying us that we were not in compliance with Nasdaq’s Marketplace Rule 5450(a) (1), or the Rule, because the closing bid price for our common stock had, for the preceding 30 consecutive business days, closed below the minimum $1.00 per share requirement for continued listing. In accordance with Marketplace Rule 5810(c) (3) (A) we were provided a period of 180 calendar days, or until June 18, 2012, to regain compliance. If at any time before June 18, 2012, the bid price of our common stock closes at or above $1.00 per share for a minimum of 10 consecutive business days, Nasdaq will provide written confirmation that we have achieved compliance with the Rule. If compliance with the Rule cannot be demonstrated by June 18, 2012, our common stock will be subject to delisting from The Nasdaq Global Market.

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In the event that we receive notice that our common stock is being delisted from The Nasdaq Global Market, Nasdaq rules permit us to appeal any delisting determination by the Nasdaq staff to a Nasdaq Hearings Panel. Alternatively, Nasdaq may permit us to transfer the listing of our common stock to The Nasdaq Capital Market if we satisfy the requirements for initial inclusion set forth in Marketplace Rule 5505(a), except for the bid price requirement. Currently, we believe we satisfy these requirements. If our application for transfer is approved, we would have an additional 180 calendar days to comply with the Rule in order to remain on The Nasdaq Capital Market.
 
We will continue to monitor the bid price for our common stock and consider various options available to us if our common stock does not trade at a level that is likely to regain compliance.
 
Delisting from The Nasdaq Global Market could have an adverse effect on our business and on the trading of our common stock. If a delisting of our common stock from The Nasdaq Stock Market were to occur, our common stock would trade on the OTC Bulletin Board or on the “pink sheets” maintained by the National Quotation Bureau, Inc. Such alternatives are generally considered to be less efficient markets, and our stock price, as well as the liquidity of our common stock, may be adversely impacted as a result.

Our internal control over financial reporting may not prevent or detect misstatements because of its inherent limitations.

Pursuant to the Sarbanes-Oxley Act of 2002, we are required to provide a report by management on internal control over financial reporting, including management’s assessment of the effectiveness of such control. Internal control over financial reporting may not prevent or detect misstatements because of its inherent limitations, including the possibility of human error, the circumvention or overriding of controls, or fraud. Therefore, even effective internal controls can provide only reasonable assurance with respect to the preparation and fair presentation of financial statements. In addition, projections of any evaluation of effectiveness of internal control over financial reporting to future periods are subject to the risk that the control may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. If we fail to maintain the adequacy of our internal controls, including any failure to implement required new or improved controls, or if we experience difficulties in their implementation, our business and operating results could be harmed, we could fail to meet our reporting obligations, and there could be a material adverse effect on our stock price.

If we need additional capital in the future, it may not be available to us on favorable terms, or at all.

We have historically relied on outside financing and cash flow from operations to fund our operations, capital expenditures and expansion. We may require additional capital from equity or debt financing in the future to fund our operations or respond to competitive pressures or strategic opportunities. We may not be able to secure timely additional financing on favorable terms, or at all. The terms of any additional financing may place limits on our financial and operating flexibility. If we raise additional funds through further issuances of equity, convertible debt securities or other securities convertible into equity, our existing stockholders could suffer significant dilution in their percentage ownership of our company, and any new securities we issue could have rights, preferences and privileges senior to those of holders of our common stock. If we are unable to obtain adequate financing or financing on terms satisfactory to us, if and when we require it, our ability to grow or support our business and to respond to business challenges could be significantly limited. Should additional funding be required, we may need to raise the required funds through borrowings or public or private sales of debt or equity securities. If we raise additional funds through the issuance of debt or equity securities, the percentage ownership of our stockholders could be significantly diluted. If we obtain additional debt financing, a substantial portion of our operating cash flow may be dedicated to the payment of principal and interest on such indebtedness, and the terms of the debt securities issued could impose significant restrictions on our operations. We do not know whether we will be able to secure additional funding, or funding on terms acceptable to us, to continue our operations as planned. If financing is not available, we may be required to reduce, delay or eliminate certain activities or to license or sell to others some of our proprietary technology.

Because we do not expect to pay dividends on our common stock, stockholders will benefit from an investment in our common stock only if it appreciates in value.

We have never paid cash dividends on our common stock and have no present intention to pay any dividends in the future. Any future determination about the payment of dividends will be made at the discretion of our board of directors and will depend upon our earnings, if any, our capital requirements, our operating and financial conditions and on such other factors as our board of directors may deem relevant. As a result, the success of an investment in our common stock will depend upon any future appreciation in its value. There is no guarantee that our common stock will appreciate in value or even maintain the price at which stockholders have purchased their shares.

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Future sales of a substantial number of shares of our common stock in the public market, including the shares offered pursuant to this prospectus supplement, could adversely affect the trading price of our common stock and impair our ability to raise funds in future stock offerings.

Future sales of a substantial number of shares of our common stock in the public market, including the shares to be offered pursuant to this prospectus and other resale prospectuses and shares available for resale under Rule 144 under the Securities Act, or the perception that such sales could occur, could adversely affect the prevailing market price of our common stock and could make it more difficult for us to raise additional capital through the sale of equity securities.

Risks Related to this Offering

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

Our management will have broad discretion in the application of the net proceeds from this offering and could spend the proceeds in ways with which you may not agree.  Accordingly, you will be relying on the judgment of our management with regard to the use of these net proceeds, and you will not have the opportunity, as part of your investment decision, to assess whether the proceeds are being used appropriately.  It is possible that the proceeds will be invested or otherwise used in a way that does not yield a favorable, or any, return for our company.
 
You will experience immediate dilution in the book value per share of the common stock you purchase.

You will suffer immediate dilution in the net tangible book value of the common stock you purchase in this offering because the price per share of our common stock being offered hereby is substantially higher than the book value per share of our common stock.  Based on the offering price of $0.68 per share in this offering, if you purchase shares of common stock in this offering, you will suffer immediate and substantial dilution of $0.406 per share in the net tangible book value of the common stock determined based on the net tangible book value and number of outstanding shares of common stock, in each case as of December 31, 2011.  See “Dilution” on page S-15 for a more detailed discussion of the dilution you will incur in this offering.

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USE OF PROCEEDS

We estimate that the net proceeds to us from the sale of our common stock in this offering will be approximately $9,649,100, after deducting the estimated offering expenses payable by us.
 
We currently intend to use the net proceeds we receive from the sale of our common stock in this offering for working capital requirements and general corporate purposes.
 
At this time, we have not determined the approximate amount of net proceeds that will be allocated to each of the uses of proceeds stated above.  We may also use a portion of the net proceeds to fund possible partnerships, minority investments, products or technologies. Currently, there are no commitments or agreements regarding such acquisitions or investments that are material.  Our management will retain broad discretion as to the allocation of the net proceeds from this offering.  Pending application of the net proceeds as described above, we intend to invest the proceeds in highly liquid, investment-grade securities and money market funds.

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DILUTION
 
If you invest in our common stock, your interest will be diluted to the extent of the difference between the offering price per share you pay in this offering and the net tangible book value per share of our common stock immediately after this offering.  Our net tangible book value of our common stock as of December 31, 2011 was approximately $16.3 million, or approximately $0.202 per share of common stock based upon 80,557,823 shares outstanding.  Net tangible book value per share is equal to our total tangible assets, less our total liabilities, divided by the total number of shares of our common stock outstanding, in each case as of December 31, 2011.  After giving effect to the sale by us of the 14,336,912 shares of our common stock we are offering, our as-adjusted net tangible book value would have been approximately $26.0 million as of December 31, 2011 or approximately $0.274 per share of common stock based upon 94,894,735 shares outstanding.  This represents an immediate increase in net tangible book value of $0.072 per share to our existing stockholders and an immediate dilution in net tangible book value of $0.406 per share to new investors.  The following table illustrates this calculation on a per share basis:
 
Offering price per share	 	 	 	 	$	0.68	 	
 	 	 	 	 	 	 	 	
Net tangible book value per share as of December 31, 2011	 	$	0.202	 	 	 	 	 	
 	 	 	 	 	 	 	 	 	
Increase in net tangible book value per share attributable to the offering	 	$	0.072	 	 	 	 	 	
 	 	 	 	 	 	 	 	 	
As-adjusted net tangible book value per share after giving effect to the offering	 	$	0.274	 	 	 	 	 	
 	 	 	 	 	 	 	 	 	
Dilution in net tangible book value per share to new investors	 	 	 	 	 	$	0.406	 	

The foregoing table excludes the following, each stated as of December 31, 2011:
 
 	·	9,718,241 shares of our common stock issuable upon the exercise of stock options at a weighted average exercise price of $1.79 per share; and	

 	·	2,364,578 shares of common stock reserved for future issuance under our stock plan.	

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PLAN OF DISTRIBUTION

We are offering to sell the shares being offered pursuant to this prospectus directly to Kinderhook Partners, LP and Ardsley Partners, or their affiliates (collectively, the “Investors”), without the use of an underwriter, dealer or agent, and therefore no discounts, concessions or commissions will be paid.  We expect to enter into a stock purchase agreement with the Investors for the sale and purchase of the shares offered by this prospectus supplement and the total gross offering proceeds to us, before offering expenses, will be approximately $9,749,100.

Each of the Investors may, from time to time, and in its sole discretion, resell the securities into the open market at prevailing market prices.  Each of the Investors has advised us that no special selling efforts will be used in the resale of the securities, if any.
 
The Company intends to enter into a Resale Registration Rights Agreement with Kinderhook Partners, LP which will  require the Company to file a resale registration statement covering the shares they will acquire in the offering.
 
In connection with the offering, the Company has agreed to appoint one designee of Kinderhook Partners LP to its board of directors.

The transfer agent and registrar for our common stock is American Stock Transfer & Trust Company, LLC.

Our common stock is quoted on the Nasdaq Global Market under the symbol “ACPW.”

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LEGAL MATTERS

Wilson Sonsini Goodrich & Rosati, Professional Corporation, Austin, Texas, has passed upon the validity of the issuance of the securities offered by this prospectus.

EXPERTS
 
The financial statements, schedules, and management’s assessment of the effectiveness of internal control over financial reporting incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the report of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing in giving said report.

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PROSPECTUS

 
$25,000,000
 
ACTIVE POWER, INC.
 
By this prospectus, we may offer, from time to time —
 
 	●	Common stock	
 
 	●	Warrants	

 
See “Risk Factors” beginning on page 5 for information you should consider before buying our securities.
 
From time to time, we may offer and sell, in one or more offerings, in amounts, at prices and on terms determined at the time of any such offering, common stock, warrants, and any combination thereof, with a total value of up to $25,000,000.
 
As of December 15, 2009, the aggregate market value of our outstanding common stock held by non-affiliates was $65,709,295, based on 66,478,623 shares of outstanding common stock, of which 65,709,295 are held by non-affiliates, and a price of $1.00 per share, based on the closing sale price of our common stock on December 15, 2009 as reported by The Nasdaq Global Market. We have not offered any securities pursuant to General Instruction 1.B.6 of Form S-3 during the prior 12-month period that ends on and includes the date of this prospectus.
 
Our common stock is listed on The Nasdaq Global Market under the symbol “ACPW.” On December 15, 2009, the closing price of our common stock was $1.00 per share.

 
We will provide specific terms of these securities in supplements to this prospectus. You should read this prospectus and any supplement carefully before you purchase any of our securities.

 
This prospectus may not be used to offer and sell securities unless accompanied by a prospectus supplement.

 
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
 
We may offer the securities in amounts, at prices and on terms determined at the time of offering. We may sell the securities directly to you, through agents we select, or through underwriters and dealers we select. If we use agents, underwriters or dealers to sell the securities, we will name them and describe their compensation in a prospectus supplement.
 
This prospectus is dated December 21, 2009

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TABLE OF CONTENTS
 
 	Page	
 	 	
Where You Can Find More Information 	2	
About this Prospectus	 3	
Note Regarding Forward-Looking Statements	4	
Risk Factors	5	
Securities We May Offer	5	
Use of Proceeds	5	
Description of Common Stock	5	
Description of the Warrants	8	
Plan of Distribution	9	
Legal Matters	11	
Experts	11	

 
No person has been authorized to give any information or make any representations in connection with this offering other than those contained or incorporated by reference in this prospectus and any accompanying prospectus supplement in connection with the offering described in this prospectus and any accompanying prospectus supplement, and, if given or made, such information or representations must not be relied upon as having been authorized by us. Neither this prospectus nor any accompanying prospectus supplement shall constitute an offer to sell or a solicitation of an offer to buy offered securities in any jurisdiction in which it is unlawful for such person to make such an offering or solicitation. Neither the delivery of this prospectus or any accompanying prospectus supplement nor any sale made hereunder shall under any circumstances imply that the information contained or incorporated by reference in this prospectus or in any accompanying prospectus supplement is correct as of any date subsequent to the date of this prospectus or any accompanying prospectus supplement.

 
 
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WHERE YOU CAN FIND MORE INFORMATION
 
We file reports, proxy statements and other information with the Securities and Exchange Commission, or the Commission, in accordance with the Securities Exchange Act of 1934, or the Exchange Act. You may read and copy our reports, proxy statements and other information filed by us at the Public Reference Room of the Commission at 100 F Street, N.E., Washington, D.C. 20549. Please call the Commission at 1-800-SEC-0330 for further information about the Public Reference Room. Our reports, proxy statements and other information filed with the Commission are available to the public over the Internet at the Commission’s website at www.sec.gov and on our Internet website at http://www.activepower.com.
 
The Commission allows us to “incorporate by reference” information that we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus, and information that we file later with the Commission will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings we will make with the Commission under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, after the date of this prospectus but before the end of any offering made under this prospectus and accompanying prospectus supplement (other than current reports or portions thereof furnished under Item 2.02, 7.01 or 8.01 of Form 8-K, unless such current reports or portions thereof specifically reference their contents as being filed):
 
 	●	Description of our common stock contained in our registration statement on Form S-1 (File No. 333-36946), filed with the SEC on May 12, 2000, including any amendment or report filed for the purpose of updating such description;	
 
 	●	Our annual report on Form 10-K for our fiscal year ended December 31, 2008, filed with the SEC on March 3, 2009, as amended by that certain Amendment No. 1 to Form 10-K filed with the SEC on October 28, 2009;	
 
 	●	Our quarterly report on Form 10-Q for the quarter ended March 31, 2009, filed with the SEC on April 28, 2009;	
 
 	●	Our quarterly report on Form 10-Q for the quarter ended June 30, 2009, filed with the SEC on July 28, 2009;	
 
 	●	Our quarterly report on Form 10-Q for the quarter ended September 30, 2009, filed with the SEC on October 27, 2009;	
 
 	●	Our definitive proxy statement for our 2009 annual meeting of stockholders, filed with the SEC on April 10, 2009; and	
 
 	●	Our current reports on Form 8-K, filed with the SEC on March 17, 2009, May 14, 2009, June 1, 2009, July 6, 2009 and October 29, 2009.	
 
Copies of documents incorporated by reference, excluding exhibits except to the extent such exhibits are specifically incorporated by reference, are available from us without charge, upon oral or written request to:
 
Active Power, Inc.
2128 W. Braker Lane, BK12
Austin, Texas 78758
Attn: John K. Penver, Chief Financial Officer
(512) 836-6464

 

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ABOUT THIS PROSPECTUS
 
This prospectus is part of a registration statement that we filed on Form S-3 with the Commission, using a “shelf” registration process. Under this shelf process, we may, from time to time, sell any combination of the securities described in this prospectus in one or more offerings up to a total dollar amount of $25,000,000. This prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. This prospectus does not contain all of the information included in the registration statement. For a more complete understanding of the offering of the securities, you should refer to the registration statement, including its exhibits. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and any prospectus supplement, including the risk factors, together with the additional information described under the heading “Where You Can Find More Information.”
 
THIS PROSPECTUS MAY NOT BE USED TO OFFER AND SELL SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.
 
About Active Power, Inc.
 
The following summary highlights information contained in this prospectus or incorporated by reference. While we have included what we believe to be the most important information about the company and this offering, the following summary may not contain all the information that may be important to you. You should read this entire prospectus carefully, including the risks of investing discussed under “Risk Factors” beginning on page 5, and the information to which we refer you and the information incorporated into this prospectus by reference, for a complete understanding of our business and this offering.
 
We are a manufacturer and provider of critical power solutions incorporating uninterruptible power supply (UPS) systems that provide business continuity to enterprises requiring protection against electrical power disturbances. Our products are designed to deliver continuous clean power, protecting customers from voltage fluctuations, such as surges and sags, and frequency fluctuations, and also to provide ride-through, or temporary, power to bridge the gap between a power outage and the restoration of utility power. Our target customers are those global enterprises requiring “power insurance” because they have zero tolerance for downtime in their mission critical operations. The UPS products we manufacture utilize green technology to create a renewable energy source. These products are highly reliable, are energy and space efficient, and significantly reduce client electricity expenses. As of September 30, 2009, we have shipped more than 2,400 flywheels in UPS system installations, delivering more than 600 megawatts of power to customers in more than 40 countries around the world. We are headquartered in Austin, Texas, with international offices in the U.K., Germany and Japan.
 
Our patented flywheel-based UPS systems store kinetic energy by constantly spinning a compact steel wheel (“flywheel”) driven from utility power in a low friction environment. When the utility power used to spin the flywheel fluctuates or is interrupted, the flywheel’s inertia causes it to continue spinning. The resulting kinetic energy of the spinning flywheel generates electricity known as “bridging power” for short periods, until utility power is restored or a backup electricity generator starts and takes over generating longer-term power in the case of an extended electrical outage. We believe our flywheel products provide many competitive advantages over conventional battery-based UPS systems, including substantial space savings, higher power densities, “green” energy storage, and higher power efficiencies of up to 98%. This high energy efficiency reduces operating costs and provides customers a lower total cost of ownership. We offer our flywheel products with load capabilities from 150 kVA to 8,400 kVA. We typically target higher power applications of 200 kVA and above, largely because a majority of customers in this market segment have backup generators. Our flywheel products are marketed under the brand name CleanSource ® . Our continuous power systems are marketed under the name PowerHouse and combine our UPS system with switchgear and a generator to provide complete short- and long-term protection in the event of a power disturbance.
 
We believe a number of underlying macroeconomic trends place Active Power in a strong position to be one of the leading providers of critical power protection. These trends include:
 
 	●	the ever-increasing demands placed on the public utility infrastructure;	
 
 	●	an inadequate investment in global utility infrastructure;	
 
 	●	rising costs of energy worldwide;	
 
 	●	significant costs of downtime;	
 
 	●	a rapidly expanding need for data centers that require reliable, efficient power; and	
 
 	●	an increasing demand for economically green solutions.	

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We were founded as a Texas corporation in 1992 and reincorporated in Delaware in 2000 prior to our initial public offering. Our principal executive offices are located at 2128 W. Braker Lane, BK12, Austin, Texas 78758 and our telephone number at that address is (512) 836-6464.

 
We own the registered trademarks ACTIVE POWER, CLEANSOURCE and COOLAIR in the United States and abroad. The ACTIVE POWER logo is a trademark of Active Power. All other trademarks, service marks or trade names referred to in this report are the property of their respective owners.
 
NOTE REGARDING FORWARD-LOOKING STATEMENTS
 
This prospectus and the registration statement of which it forms a part, any prospectus supplement and the documents incorporated by reference into these documents contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Forward-looking statements deal with our current plans, intentions, beliefs and expectations and statements of future economic performance. Statements containing terms such as “believe,” “do not believe,” “plan,” “expect,” “intend,” “estimate,” “anticipate” and other phrases of similar meaning are considered to contain uncertainty and are forward-looking statements. In addition, from time to time we or our representatives have made or will make forward-looking statements orally or in writing. Furthermore, such forward-looking statements may be included in various filings that we make with the Commission, or press releases or oral statements made by or with the approval of one of our authorized executive officers. These forward-looking statements are subject to certain known and unknown risks and uncertainties, as well as assumptions that could cause actual results to differ materially from those reflected in these forward-looking statements. Factors that might cause actual results to differ include, but are not limited to, those set forth under Item 1A, “Risk Factors,” in our most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q and in our future filings made with the Commission. Readers are cautioned not to place undue reliance on any forward-looking statements contained herein, which reflect management’s opinions only as of the date hereof. Except as required by law, Active Power undertakes no obligation to revise or publicly release the results of any revisions to any forward-looking statements. You are advised, however, to consult any additional disclosures we have made or will make in our reports to the Commission on Forms 10-K, 10-Q and 8-K. All subsequent written and oral forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the cautionary statements contained in this prospectus.

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RISK FACTORS
 
An investment in our securities involves a high degree of risk. The prospectus supplement applicable to each offering of our securities will contain a discussion of the risks applicable to an investment in our securities. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the heading “Risk Factors” in the applicable prospectus supplement, together with all of the other information contained or incorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus. You should also consider the risks, uncertainties and assumptions discussed under Item 1A, “Risk Factors,” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2008, and our Quarterly Reports for the quarterly periods ended March 31, 2009, June 30, 2009 and September 30, 2009, all of which are incorporated herein by reference, and may be amended, supplemented or superseded from time to time by other reports we file with the Commission in the future. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our operations.
 
SECURITIES WE MAY OFFER
 
We may offer up to $25,000,000 of common stock and warrants in one or more offerings and in any combination thereof. A prospectus supplement, which we will provide each time we offer securities, will describe the specific amounts, prices and terms of these securities.
 
We may sell the securities to or through underwriters, dealers or agents or directly to purchasers. We, as well as any agents acting on our behalf, reserve the sole right to accept and to reject in whole or in part any proposed purchase of securities. Each prospectus supplement will set forth the names of any underwriters, dealers or agents involved in the sale of securities described in that prospectus supplement and any applicable fee, commission or discount arrangements with them.
 
USE OF PROCEEDS
 
Unless otherwise indicated in the prospectus supplement, the net proceeds from the sale of securities offered by this prospectus will be used for working capital requirements, general corporate purposes and investments in and acquisitions of complementary businesses. We may also use a portion of the net proceeds to fund possible partnerships, minority investments, products or technologies. Currently, there are no commitments or agreements regarding such acquisitions or investments that are material. Pending their ultimate use, we intend to invest the net proceeds in bank demand deposits, certificates of deposit, investments in debt securities with maturities of three months or less when purchased, and money market funds which invest primarily in U.S. government obligations and commercial paper.
 
DESCRIPTION OF COMMON STOCK
 
General
 
As of the date of this prospectus, our authorized capital stock consists of 160,000,000 shares. Those shares consist of 150,000,000 shares designated as common stock, $0.001 par value per share, and 10,000,000 shares designated as preferred stock, $0.001 par value per share. The only equity securities currently outstanding are shares of common stock. As of December 15, 2009, there were 66,478,623 shares of common stock issued and outstanding.
 
The following description summarizes the material terms of our common stock. This summary is, however, subject to the provisions of our restated certificate of incorporation and any applicable certificate of designation for a series of preferred stock, our amended bylaws, a rights agreement between us and EquiServe Trust N.A., and applicable law.
 
Common Stock
 
The holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders. Subject to preferences that may be applicable to any outstanding preferred stock, the holders of common stock are entitled to receive ratably any dividends or other distributions that may be declared from time to time by the board of directors out of funds legally available for that purpose. However, we are not currently paying any dividends. In the event of our liquidation, dissolution or winding up, the holders of common stock are entitled to share ratably in all assets remaining after payment of liabilities, subject to prior distribution rights of preferred stock then outstanding. The common stock has no preemptive or conversion rights or other subscription rights. There are no redemption or sinking fund provisions applicable to the common stock.

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All outstanding shares of common stock are fully paid and nonassessable, and any shares of common stock to be issued upon an offering pursuant to this prospectus and the related prospectus supplement will be fully paid and nonassessable upon issuance.
 
Our common stock is listed on The Nasdaq Global Market under the symbol “ACPW.” The transfer agent and registrar for the common stock is American Stock Transfer & Trust Company, LLC.
 
Anti-Takeover Effects of Some Provisions of Delaware Law
 
Provisions of Delaware law and our currently in effect restated certificate of incorporation and amended bylaws could make the acquisition of our company through a tender offer, a proxy contest or other means more difficult and could make the removal of incumbent officers and directors more difficult. We expect these provisions to discourage coercive takeover practices and inadequate takeover bids and to encourage persons seeking to acquire control of our company to first negotiate with our board of directors. We believe that the benefits provided by our ability to negotiate with the proponent of an unfriendly or unsolicited proposal outweigh the disadvantages of discouraging these proposals. We believe the negotiation of an unfriendly or unsolicited proposal could result in an improvement of its terms.
 
We are subject to Section 203 of the Delaware General Corporation Law, an anti-takeover law. In general, Section 203 prohibits a publicly held Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years following the date the person became an interested stockholder, unless:
 
 	●	Prior to the date of the transaction, the board of directors of the corporation approved either the business combination or the transaction which resulted in the stockholder becoming an interested stockholder;	
 
 	●	The stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the number of shares outstanding (a) shares owned by persons who are directors and also officers, and (b) shares owned by employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or	
 
 	●	On or subsequent to the date of the transaction, the business combination is approved by the board and authorized at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least two-thirds of the outstanding voting stock that is not owned by the interested stockholder.	
 
Generally, a “business combination” includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. An “interested stockholder” is a person who, together with affiliates and associates, owns or, within three years prior to the determination of interested stockholder status, did own 15% or more of a corporation’s outstanding voting securities. We expect the existence of this provision to have an anti-takeover effect with respect to transactions our board of directors does not approve in advance. We also anticipate that Section 203 may also discourage attempts that might result in a premium over the market price for the shares of common stock held by stockholders.
 
Anti-Takeover Effects of Provisions of Our Charter Documents
 
Our currently in effect restated certificate of incorporation provides for our board of directors to be divided into three classes serving staggered terms. Approximately one-third of the board of directors will be elected each year. The provision for a classified board could prevent a party who acquires control of a majority of the outstanding voting stock from obtaining control of the board of directors until the second annual stockholders meeting following the date the acquirer obtains the controlling stock interest. The classified board provision could discourage a potential acquirer from making a tender offer or otherwise attempting to obtain control of our company and could increase the likelihood that incumbent directors will retain their positions. In accordance with our currently in effect restated certificate of incorporation, directors may be removed by the affirmative vote of the holders of the outstanding shares of common stock only with cause.
 
Our currently in effect amended bylaws establish an advance notice procedure for stockholder proposals to be brought before an annual meeting of our stockholders, including proposed nominations of persons for election to the board of directors. At an annual meeting, stockholders may only consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of the board of directors. Stockholders may also consider a proposal or nomination by a person who was a stockholder of record on the record date for the meeting, who is entitled to vote at the meeting and who has given to our Secretary timely written notice, in proper form, of his or her intention to bring that business before the meeting. The amended bylaws do not give the board of directors the power to approve or disapprove stockholder nominations of candidates or proposals regarding other business to be conducted at a special or annual meeting of the stockholders. However, our amended bylaws may have the effect of precluding the conduct of business at a meeting if the proper procedures are not followed. These provisions may also discourage or deter a potential acquirer from conducting a solicitation of proxies to elect the acquirer’s own slate of directors or otherwise attempting to obtain control of our company.

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Our amended bylaws provide that only our board of directors may call a special meeting of stockholders. Because our stockholders do not have the right to call a special meeting, a stockholder could not force stockholder consideration of a proposal over the opposition of the board of directors by calling a special meeting of stockholders prior to such time as a majority of the board of directors believed the matter should be considered or until the next annual meeting provided that the requestor met the notice requirements. The restriction on the ability of stockholders to call a special meeting means that a proposal to replace the board also could be delayed until the next annual meeting.
 
Our currently in effect restated certificate of incorporation does not allow stockholders to act by written consent without a meeting. Without the availability of stockholder’s actions by written consent, a holder controlling a majority of our capital stock would not be able to amend our amended bylaws or remove directors without holding a stockholders’ meeting. The holder would have to obtain the consent of a majority of the board of directors to call a stockholders’ meeting and satisfy the notice periods determined by the board of directors.
 
Transfer Agent and Registrar
 
Our transfer agent and registrar for our common stock is American Stock Transfer & Trust Company, LLC. Its address is 59 Maiden Lane, Plaza Level, New York, New York 10038.
 
Listing
 
Our common stock has been approved for listing on The Nasdaq Global Market under the trading symbol ACPW.

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DESCRIPTION OF THE WARRANTS
 
We may issue warrants for the purchase of our common stock. Warrants may be issued independently or together with our common stock and may be attached to or separate from any offered securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between us and a bank or trust company, as warrant agent. The warrant agent will act solely as our agent in connection with the warrants. The warrant agent will not have any obligation or relationship of agency or trust for or with any holders or beneficial owners of warrants. This summary of certain provisions of the warrants is not complete. For the terms of a particular series of warrants, you should refer to the prospectus supplement for that series of warrants and the warrant agreement for that particular series.
 
The prospectus supplement relating to a particular series of warrants to purchase our common stock will describe the terms of the warrants, including the following:
 
 	●	the title of the warrants;	
 
 	●	the offering price for the warrants, if any;	
 
 	●	the aggregate number of warrants;	
 
 	●	the terms of the common stock that may be purchased upon exercise of the warrants;	
 
 	●	if applicable, the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each security;	
 
 	●	if applicable, the date from and after which the warrants and any securities issued with the warrants will be separately transferable;	
 
 	●	the number of shares of common stock that may be purchased upon exercise of a warrant and the exercise price for the warrants;	
 
 	●	the dates on which the right to exercise the warrants shall commence and expire;	
 
 	●	if applicable, the minimum or maximum amount of the warrants that may be exercised at any one time;	
 
 	●	the currency or currency units in which the offering price, if any, and the exercise price are payable;	
 
 	●	if applicable, a discussion of material U.S. federal income tax considerations;	
 
 	●	the antidilution provisions of the warrants, if any;	
 
 	●	the redemption or call provisions, if any, applicable to the warrants;	
 
 	●	any provisions with respect to the holder’s right to require us to repurchase the warrants upon a change in control or similar event; and	
 
 	●	any additional terms of the warrants, including procedures and limitations relating to the exchange, exercise and settlement of the warrants.	
 
    Holders of equity warrants will not be entitled to:
 
 	●	vote, consent or receive dividends;	
 
 	●	receive notice as stockholders with respect to any meeting of stockholders for the election of our directors or any other matter; or	
 
 	●	exercise any rights as stockholders of Active Power.	

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PLAN OF DISTRIBUTION
 
We may sell the securities from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods. We may sell securities:
 
 	●	to or through one or more underwriters or dealers;	
 
 	●	directly to purchasers;	
 
 	●	through agents; and	
 
 	●	through a combination of any of these methods of sale.	
 
We may distribute the securities from time to time in one or more transactions:
 
 	●	at a fixed price or prices, which may be changed from time to time;	
 
 	●	at market prices prevailing at the time of sale;	
 
 	●	at prices related to prevailing market prices; and	
 
 	●	at negotiated prices.	
 
We will describe the method of distribution of each series of securities in the applicable prospectus supplement.
 
We may also make sales through the Internet or through other electronic means. Since we may from time to time elect to offer securities directly to the public, with our without the involvement of agents, underwriters or dealers, utilizing the Internet (sometimes referred to as the “world wide web”) or other forms of electronic bidding or ordering systems for the pricing and allocation of such securities, you will want to pay particular attention to the description of that system we will provide in a prospectus supplement.
 
Such electronic system may allow bidders to directly participate, through electronic access to an auction site, by submitting conditional offers to buy that are subject to acceptance by us, and which may directly affect the price or other terms and conditions at which such securities are sold. These bidding or ordering systems may present to each bidder, on a so-called “real-time” basis, relevant information to assist in making a bid, such as the clearing spread at which the offering would be sold, based on the bids submitted, and whether a bidder’s individual bids would be accepted, prorated or rejected.
 
Upon completion of such an electronic auction process, securities will be allocated based on prices bid, terms of bid or other factors. The final offering price at which securities would be sold and the allocation of securities among bidders would be based in whole or in part on the results of the Internet or other electronic bidding process or auction.
 
Many variations of Internet or other electronic auction or pricing and allocation systems are likely to be developed in the future as new technology evolves, and we may utilize such systems in connection with the sale of securities. The specific rules of such an auction would be described to potential bidders in a prospectus supplement. You should review carefully the auction and other rules we will describe in a prospectus supplement in order to understand and participate intelligently in the applicable offering.
 
Underwriters, dealers or agents may receive compensation in the form of discounts, concessions or commissions from us or our purchasers as their agents in connection with the sale of securities. These underwriters, dealers or agents may be considered to be underwriters under the Securities Act. As a result, discounts, commissions, or profits on resale received by the underwriters, dealers or agents may be treated as underwriting discounts and commissions. Each prospectus supplement will identify any such underwriter, dealer or agent, and describe any compensation received by them from us. Any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time.
 
Underwriters, dealers and agents may be entitled to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments made by the underwriters, dealers or agents, under agreements between us and the underwriters, dealers and agents.
 
In connection with underwritten offerings of securities, underwriters may over-allot or effect transactions that stabilize, maintain or otherwise affect the market price of the offered securities at levels above those that might otherwise prevail in the open market, including by entering stabilizing bids, effecting syndicate covering transactions or imposing penalty bids, each of which is described below.

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 	●	A stabilizing bid means the placing of any bid, or the effecting of any purchase, for the purpose of pegging, fixing or maintaining the price of a security.	
 
 	●	A syndicate covering transaction means the placing of any bid on behalf of the underwriting syndicate or the effecting of any purchase to reduce a short position created in connection with the offering.	
 
 	●	A penalty bid means an arrangement that permits the managing underwriter to reclaim a selling concession from a syndicate member in connection with the offering when offered securities originally sold by the syndicate member are purchased in syndicate covering transactions.	
 
These transactions may be effected on The Nasdaq Global Market, in the over-the-counter markets or otherwise. Underwriters are not required to engage in any of these activities, or to continue the activities if commenced.
 
We may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales or to close out any open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third parties in such sale transactions will be underwriters and, if not identified in this prospectus, will be identified in the applicable prospectus supplement, or a post-effective amendment.
 
We may grant underwriters who participate in the distribution of securities an option to purchase additional securities to cover over-allotments, if any, in connection with the distribution.
 
Some securities which we may issue under this prospectus may be new issues of securities with no established trading market. Underwriters involved in the public offering and sale of these series of securities may make a market in the securities. However, they are not obligated to make a market and may discontinue market making activity at any time. No assurance can be given as to the liquidity of the trading market for any securities.
 
Underwriters or agents and their associates may be customers of, engage in transactions with or perform services for us in the ordinary course of business.
 
To the extent required, this prospectus may be amended and supplemented from time to time to describe a specific plan of distribution.

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LEGAL MATTERS
 
The validity of the securities offered by this prospectus will be passed upon by Wilson Sonsini Goodrich & Rosati, Professional Corporation, Austin, Texas.
 
EXPERTS
 
Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2008 as set forth in their report, which is incorporated by reference in this prospectus and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP’s report, given on their authority as experts in accounting and auditing.

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Active Power, Inc.
 
14,336,912 Shares
Common Stock

PROSPECTUS SUPPLEMENT
 
March 7, 2012

 

Neither we nor the underwriter have authorized anyone to provide information different from that contained in this prospectus supplement and the accompanying prospectus. When you make a decision about whether to invest in our common stock, you should not rely upon any information other than the information in this prospectus supplement or the accompanying prospectus. Neither the delivery of this prospectus supplement or the accompanying prospectus nor the sale of our common stock means that information contained in this prospectus supplement and the accompanying prospectus is correct after their respective dates. This prospectus supplement and the accompanying prospectus is not an offer to sell or a solicitation of an offer to buy these shares of common stock in any circumstance under which the offer or solicitation is unlawful.

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