Lime Energy (LMEC) 10-K 2010 FY Annual report

Exhibit 32.1

CERTIFICATION OF THE PRINCIPAL EXECUTIVE OFFICER

PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the annual report of Lime Energy Co. (the “Company”) on Form 10-K for the period ended December 31, 2010, as filed with the Securities and Exchange Commission on the date hereof (the “Report”) to which this Certification is attached, I, David R. Asplund, Chief Executive Officer of the Company, certify solely for the purposes of 18 U.S.C. § 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that to my knowledge:

1.The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2.The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: March 10, 2011

/s/ David R. Asplund

David R. Asplund

Chief Executive Officer

This certification is not deemed filed with the Securities and Exchange Commission and is not to be incorporated by reference into any filing of the Company under the Securities Act of 1933 or the Securities Act of 1934 (whether made before or after the date of the Report), irrespective of any general incorporation language contained in such filing.