Another alternative energy company that received a loan guarantee from the U.S. government has filed for bankruptcy. Beacon Power, which makes energy storage devices used to help the power grid become more efficient, filed for bankruptcy protection Sunday, according to a filing with the Securities and Exchange Commission. The company received a $43 million loan guarantee from the Department of Energy last August. "This latest failure is a sharp reminder that DOE has fallen well short of delivering the stimulus jobs that were promised," Florida Republican Rep. Cliff Stearns said in a statement Sunday night. "Now taxpayers find themselves millions of more dollars in the hole." Stearns is leading an investigation into the bankruptcy of Solyndra, a solar panel maker that received a $535 million government loan guarantee last year. The Beacon bankruptcy will likely only make that investigation more urgent.