DURHAM – FlexGen Power Systems Inc. continues to ramp up its capital-raising efforts.

The energy storage and conversion company that develops technology to increase generator efficiency is looking to raise $34 million, according to a securities filing.

So far the firm has raised $7 million – all in debt – from two investors, the filing discloses.

In June, FlexGen said it had raised more than $900,000 of a $4.2 million equity offering.

The company, founded in 2009 in Houston, sells the FlexGen Solid State Generator, a hybrid power system used in the oil and gas industries. The company says the systems have shown fuel savings of 15 percent to 25 percent and maintenance savings of up to 45 percent. It uses energy storage and power conversion to improve the reliability of electric power generators.

The hybrid power systems were originally designed for the U.S. military and have been sold to the U.S. Marien Corps, U.S. Army, U.S. Navy Seals and the Joint Special Operations Forces in Afghanistan. FlexGen is veteran owned and operated. The company has said it moved to the Triangle because of the talent pool available here.

The company now also markets the technology, developed in North Carolina, to oil and gas drilling companies.

The company closed a $25.5 million Series A venture round led by Denver-based Altira Group with investments from General Electric Ventures and Caterpillar Ventures in 2015.