HOUSTON, June 23 (Xinhua) -- U.S. renewable energy company Greenhunter Energy said Tuesday it is exploring a possible sale of its biodiesel plant in Houston, the largest in the nation, as it strives to improve its balance sheet and struggles with a tough market for alternative fuel.

    The firm said in a statement that it has hired an investment banking firm to search for a potential buyer for its massive Houston plant. The firm will also help find domestic or international partners, alternative financing, potential new equity capital and enough working capital to get the plant back into operation.

    Greenhunter Energy also said it has reached an agreement with lenders to delay some loan payments until November and cancel any events that may put the company in default before then, according to local newspaper Houston Chronicle.

    The 70-million-U.S. dollar Houston plant with a capacity of 105 million gallon per year opened in June 2008. It was touted for its ability to make biodiesel from a variety of vegetable oils and animal fats, rather than being tied exclusively to expensive soybean oil, like many of its rivals.

    However, the plant has been idle since February since weak domestic demand for the fuel, new trade barriers on U.S. biodiesel exports to Europe and low oil prices have made renewable less competitive with petroleum fuels, said Jack Zedlitz, spokesman for the company.

    Many U.S. new energy producers have struggled to remain profitable amid higher prices for soybean oil, the chief feedstock used to make biodiesel in this country. Some have cut production, while others have temporarily shut down, according to Houston Chronicle.

    Texas has 30 biodiesel plants with a total production capacity of 691 million gallons per year, according to the Biodiesel Coalition of Texas. But much of that capacity has been idle in recent months due to a bleak market.