The US government has granted almost US$650 million (Dh2.38 billion) in loan guarantees to four biofuel companies for building refineries to produce transport fuels from plant and animal wastes.
The awards represent the US government's largest financial aid package for the so-called advanced biofuels industry, which is seeking to develop competitive fuels from biological sources other than maize and soybeans.
They closely followed Tuesday's state of the union address in which Barack Obama, the US president, again called for more federal support for clean-energy initiatives.
"With more research and incentives, we can break our dependence on oil with biofuels," Mr Obama said.
On Thursday, the US agriculture department gave the Illinois-based biofuel company Coskata a $250m loan guarantee to help it build a plant in Alabama to produce 55 million gallons a year of ethanol from wood waste.
Diamond Green Diesel, a joint venture between the oil refiner Valero and Darling International, a company that renders animal fat, received a $241m loan guarantee from the US energy department for a proposed renewable diesel plant in Louisiana that will use cooking oil and other waste grease to produce 137 million gallons a year.
Enerkem received $80m in loan aid from the energy department to build a Mississippi plant to produce 10 million gallons a year of biofuel from municipal trash.
The agriculture department awarded a $75m loan guarantee to INEOS New Planet BioEnergy to make biofuels from citrus waste in Florida.
"Our belief is the industry is here to stay," says Tom Vilsack, the US agriculture secretary.
The US government is seeking to encourage the development of new feedstocks for ethanol, which is blended with petrol in the fuel sold at many US petrol stations.
Nearly 40 per cent of the US maize crop is sold to ethanol producers, raising concerns that the widespread use of agricultural land to grow crops for fuel rather than food could raise prices of human food products and animal fodder.
At the same time, US government subsidies for ethanol that have primarily benefited maize farmers and tariffs on imported ethanol have caused a trade dispute between the US and Brazil, which wants to export cheaper sugar cane-derived ethanol to the US. The two countries are the world's leading ethanol producers.