Buy a new washing machine
Today's efficient washing machines use less energy and about half the energy of standard older models, 20 gallons per load vs. 40 gallons. While there are a few very efficient top-loading machines, most of the efficient models are front-loaders.
An efficient washing machine leads to sizable savings, and are also easier on clothes. Efficient washers spin more water out of your clothes than older models, so your dryer doesn't have to run as long -- saving even more energy.