FOURTEENTH AMENDMENT TO LEASE AGREEMENT BETWEEN WINDSOR AT STONEHOLLOW, LP, AS SUCCESSOR-IN-INTEREST TO BRAKER-STONEHOLLOW, LTD. AS LANDLORD, AND ACTIVE POWER, INC., AS TENANT

Exhibit 10.21

FOURTEENTH AMENDMENT TO LEASE AGREEMENT BETWEEN

WINDSOR AT STONEHOLLOW, LP,

AS SUCCESSOR-IN-INTEREST TO

XXXXXX-STONEHOLLOW, LTD. AS LANDLORD,

AND

ACTIVE POWER, INC., AS TENANT

THIS FOURTEENTH AMENDMENT TO LEASE AGREEMENT (the "Fourteenth Amendment") is made and entered into as of the 6^th day of March 2007 by and between WINDSOR AT STONEHOLLOW, LP, a Delaware limited partnership, as Successor-in-Interest to XXXXXX-STONEHOLLOW, LTD., a Texas limited partnership, ("Landlord") and ACTIVE POWER, INC. ("Tenant").

WITNESSETH:

Landlord and Tenant entered into that certain Lease Agreement dated March 12, 1996 (the "Lease" for space in Stonehollow 1), amended by the First Amendment dated June 24, 1996 increasing the square footage to 8,100 square feet in Xxxxxxxxxxx 0, Xxxxx 000, amended by the Second Amendment dated September 4, 1996 notifying Landlord of a name change from "Magnetic Bearing Technologies" to "Active Power, Inc." amended by the Third Amendment dated October 10, 1997 expanding into STONEHOLLOW 2 for approximately an additional15,080 square feet of space located at 00000 Xxxxxxxxxxx Xxxxx, Xxxxx 000, Xxxxxx, Xxxxx for a total of 23,180 square feet of space, amended by the Fourth Amendment dated August 20, 1999 extending the term in Xxxxxxxxxxx 0, Xxxxx 000 for an additional twelve months, amended by the Fifth Amendment dated February 9, 2000 extending the lease term for Xxxxx 000 xxx Xxxxx 000 to expire on March 31, 2003 and expansion into Suites 120, 110 and 130 to expire March 31, 2003, amended by the Sixth Amendment dated September 22, 2000 where Tenant expanded into Suite 155, amended by the Seventh Amendment dated April10, 2001 where the commencement date for Suite 155 is confirmed as December 15, 2000, amended by the Eighth Amendment dated May 7, 2001 where Tenant expanded into Suite 130, amended by the Ninth Amendment dated June 27, 2002 where Tenant was released from Suite 155 and amended by the Tenth Amendment dated January 31, 2003 that extended the lease term of Suites 130 and 135 to expire on March 31, 2005, amended by the Eleventh Amendment dated July 31, 2003 that extended the lease term of Suite 120 to expire on March 31, 2005, amended by the Twelfth Amendment dated February 8, 2005 that extended the lease term of Suites 120, 130 and 135 to expire on March 31, 2006 and as amended by the Thirteenth Amendment dated December 7, 2005 which extended the term of the lease for Suites 120, 130 and 135 to expire on March 31, 2007.

Landlord and Tenant now desire to further amend the Lease Agreement and Amendments in certain respects as more fully hereinafter set forth. Landlord and Tenant agree as follows:

1. Tenant agrees to renew and extend the lease term for Suite 120 (7,466 square feet), Xxxxx 000 (4,050 square feet) and Suite 135 (8,100 square feet) containing a total of 19,616 square feet, for an additional term of thirty-six (36) months commencing April 1, 2007 and expiring March 31, 2010.

2. Beginning April1, 2007, the Monthly Base Rental Rate for Suites 120, 130 and 135 shall be as follows:

04/01/07-03/31108		$	0.84 psf			$	16,477.44 monthly
04/01108 03/31/09		$	0.88 psf			$	17,262.08 monthly
04/01109-03/31110		$	0.93 psf			$	18,242.88 monthly

3. Tenant accepts Suites 120, 130 and 135 in its current "as is" condition with no improvements by Landlord.

[Signatures on following page]

DATED AS OF XXX 0^xx XXX XX Xxxxx, 0000.

	LANDLORD:
	WINDSOR AT STONEHOLLOW, LP,
	a Delaware limited partnership
	By:	Stonehollow GP, LLC,
		a Delaware limited liability company, its general partner
	By:
	Name:	Xxxxxxx X. Xxxxxxxx
	Title:	Vice President

 

DATED AS OF THE DAY OF, 2007.

	TENANT:
	ACTIVE POWER, INC.
	By:
	Name:	XXXX X. XXXXXX
	Title:	CHIEF FINANCIAL OFFICER