WILMINGTON, Del, Feb 12 (Reuters) - Optim Energy LLC, a Texas electric company owned by a Bill Gates investment fund, filed for Chapter 11 bankruptcy on Wednesday after piling up losses in a depressed power market.

The company, which owns three power plants in eastern Texas, said in court documents it has been unable to reduce costs far enough to stem financial losses.

“The current depressed economic environment of the electric power industry - particularly with respect to coal-fired plants- and the Debtors’ liquidity constraints have resulted in continuing losses that, simply put, have left the Debtors without alternatives,” Optim Chief Executive Officer Nick Rahn said in a court papers.

Two of Optim’s plants are natural-gas fired. The company may seek to sell its coal-fired Twin Oaks plant during the course of its bankruptcy, according to papers filed with the U.S. Bankruptcy Court in Wilmington, Delaware.

Optim said it had $713 million outstanding under a credit agreement with Wells Fargo. It estimated its assets were worth less than $500 million.

The Wells Fargo agreement dates from 2007, when Optim was created by an affiliate of Cascade Investments LLC and energy holding company PNM Resources Inc.

Cascade is an investment vehicle controlled by Gates. PNM’s initial 50 percent stake in Optim was later cut to 1 percent through a restructuring and eventually written off, leaving Optim solely under the control of Cascade.

Power companies such as Optim that sell on deregulated markets have been stung by plummeting natural gas prices, which in turn depress prices for power. Dynegy Inc and Edison Mission Energy both filed for bankruptcy in recent years, and Energy Future Holdings, formerly TXU, is negotiating with creditors to restructure $40 billion in debt.

Optim generated revenues of $236 million last year, according to filings with the U.S. Bankruptcy Court.

To fund Optim’s operations while it restructures in bankruptcy, Cascade has proposed a $115 million debtor-in-possession loan.

Optim has retained Bracewell & Giuliani as legal adviser, Protiviti Inc as restructuring adviser and Barclays Capital Inc as financial adviser.

The case is Optim Energy LLC, U.S. Bankruptcy Court, District of Delaware, No. 14-10262