WASHINGTON, D.C. — The U.S. Department of Energy cannot afford to buy 15,000 barrels of home heating oil for the nation’s emergency reserve because of rising fuel prices, underscoring just how high prices have risen since last year.

Congress appropriated $3 million last year for the department to buy 35,000 barrels of home heating oil for the North East Home Heating Oil Reserve, but now that is enough money to buy roughly 20,000 barrels.

A Department of Energy official revealed the shortcoming at a hearing before the Senate Small Business and Entrepreneurship Committee on Wednesday.

Mainers could pay an average price of $4.60 a gallon for home heating oil during the upcoming winter.

“There are so many people who will not be able to afford this price,” Sen. Olympia Snowe, the top Republican on the Small Business panel, said. “It’s not an option not to have enough oil to heat your home.”

Heating prices in the northeast averaged $3.40 in the first quarter of 2008 and they are expected to rise to $4.46 a gallon between October 2008 and March 2009, according to the U.S. Energy Information Administration.

Snowe introduced legislation last week that would require the government release oil from the reserve if prices remain above $4 a gallon. Proceeds from the sales would be reinvested in weatherization programs.

Two Mainers also testified at the hearing.

Michael Stoddard, the deputy director of the Portland, Maine-based Environmental Northeast, told the panel that Congress should provide more funding to better protect low-income homes and buildings against the cold weather.

Jennifer Brooks of Brewer, Maine also testified. She is the community relations manager of Penquis, an anti-poverty program that serves several counties in northern Maine.