IT’S one thing to favor clean energy and to want to reduce your carbon footprint. It may be quite another to put together enough cash to buy energy-efficient products like hybrid cars or electricity-efficient refrigerators  or to pay for an all-out home energy upgrade.

But help is at hand. Thanks to new and expanded tax credits included in the federal stimulus package, certain energy-saving purchases may be more affordable for some taxpayers.

In his State of the Union address last month, President Obama said that these incentives were meant to spur demand for energy-saving products, to help expand green industries, to create jobs and to keep the United States competitive. While perhaps appreciating these loftier goals, many taxpayers are also likely to find the potential reduction of their tax bill very appealing.

Not only do these tax breaks offer bigger savings when compared with those of previous years, but some people can use them to offset the alternative minimum tax for 2009. Still, the 2010 rules for the A.M.T. are not yet clear, and it may still be hard to calculate when, or if, an energy-efficient purchase is paying for itself.