**EXHIBIT 31.2**

 

CERTIFICATIONS

 

I,James M. Spiezio, certify that:

 
| 1.     | I  have reviewed this Quarterly Report on Form 10-Q of Beacon Power  Corporation;                                                                                                                                                                                                                                                                                                                                     |
|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
| 2.     | Based  on my knowledge, this report does not contain any untrue statement of a  material fact or omit to state a material fact necessary to make the  statements made, in light of the circumstances under which such statements  were made, not misleading with respect to the period covered by this report;                                                                                                             |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
| 3.     | Based  on my knowledge, the financial statements, and other financial information  included in this report, fairly present in all material respects the  financial condition, results of operations and cash flows of the registrant  as of, and for, the periods presented in this report;                                                                                                                                |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
| 4.     | The  registrant’s other certifying officer and I are responsible for establishing  and maintaining disclosure controls and procedures (as defined in Exchange  Act Rules 13a-15(e) and 15d-15(e)) and internal control over  financial reporting (as defined in Exchange Act rules 13a-15(f) and  15d-15(f)) for the registrant and have:                                                         |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
|   | (a)   Designed such disclosure controls and procedures, or caused such disclosure  controls and procedures to be designed under our supervision, to ensure that  material information relating to the registrant, including its consolidated  subsidiaries, is made known to us by others within those entities,  particularly during the period in which this report is being prepared;                              |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
|   | (b)   Designed such internal control over financial reporting, or caused such internal  control over financial reporting to be designed under our supervision, to  provide reasonable assurance regarding the reliability of financial reporting  and the preparation of financial statements for external purposes in  accordance with generally accepted accounting principles;                                     |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
|   | (c)   Evaluated the effectiveness of the registrant’s disclosure controls and  procedures and presented in this report our conclusions about the  effectiveness of the disclosure controls and procedures, as of the end of the  period covered by this report based on such evaluation; and                                                                                                                     |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
|   | (d)   Disclosed in this report any change in the registrant’s internal control over  financial reporting that occurred during the registrant’s most recent fiscal  quarter (the registrant’s fourth fiscal quarter in the case of an annual  report) that has materially affected, or is reasonably likely to materially  affect, the registrant’s internal control over financial reporting; and |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
| 5.     | The  registrant’s other certifying officer and I have disclosed, based on our most  recent evaluation of internal control over financial reporting, to the  registrant’s auditors and the audit committee of the registrant’s board of  directors (or persons performing the equivalent functions):                                                                                                         |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
|   | (a)   All significant deficiencies and material weaknesses in the design or  operation of internal control over financial reporting which are reasonably  likely to adversely affect the registrant’s ability to record, process,  summarize and report financial information; and                                                                                                                               |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
|   | (b)   Any fraud, whether or not material, that involves management or other  employees who have a significant role in the registrant’s internal control  over financial reporting.                                                                                                                                                                                                                               |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |   |
|   | May 11,  2009                                                                                                                                                                                                                                                                                                                                                                                                         |   |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                       |   |
|   | /s/  James M. Spiezio                                                                                                                                                                                                                                                                                                                                                                                                      |   |
|   | James  M. Spiezio                                                                                                                                                                                                                                                                                                                                                                                                          |   |
|   | Chief  Financial Officer                                                                                                                                                                                                                                                                                                                                                                                                   |   |

 

----