About three dozen states will soon offer you a rebate of as much as $250 if you trade in your clunky old clothes washer, refrigerator or water heater for a more efficient model. Besides the money back, you'll welcome the savings on your electric bill.

Here is a primer on the program.

WHEN: Nearly three dozen states will roll out appliance rebate programs over the next two and a half months, according to the Department of Energy. You can find the schedule for your state, as well as a link to the state's program Web site, at http://www.energysavers.gov/financial/70022.html.

WHY: The Obama administration is trying to stimulate economic activity while also encouraging consumers to be more efficient in their energy use. Under the federal stimulus act (formally the American Recovery and Reinvestment Act of 2009), the government has allocated $300 million to the states and seven U.S. territories for appliance rebates.

WHAT: Eligible trade-ins will vary by state. In California, for instance, the program will give rebates for three types of appliances: clothes washers ($100), refrigerators ($75) and air conditioners ($50). States such as Ohio and South Dakota exclude air conditioners but include rebates for water heaters. You must purchase an Energy Star-qualified appliance. An Energy Star clothes washer, for example, uses about 30 percent less energy and more than 50 percent less water than a regular washer.

WHERE: Programs start next week in Alaska, Arkansas and Washington. All others should be in place by May (although North Carolina could possibly kick off a phase 2 to its program in June). A dozen states, among them Michigan and New York, have programs already underway. Programs in three states - Iowa, Kansas and Minnesota - have already closed.

HOW: Generally, people are required to contact the state agency running the program through a Web site or a telephone number to reserve their rebate before they buy an appliance. The amount of time allotted to submit your proof of purchase varies by state, so check the program's Web site. The program will last as long as the states and territories have money to support it. For instance, Iowa's program was so well-received that it exhausted its funding of $2.8 million for about 9,000 rebates in six hours on March 1. Michigan's program, which started earlier, is still open.

HOW MUCH: Amounts could range from $50 to $250, depending on the product being purchased, the purchase price and "other market factors," the DOE says. Unfortunately, you can't get a rebate retroactively for an energy-efficient appliance you bought before your state's program started.

The Energy Department says replacing a clothes washer made before 2000 with a new Energy Star model can save $135 per year in water and electricity costs; replacing a refrigerator made before 1993 with a new Energy Star one can lower your electric bill $65 per year.