A 10-kilowatt windmill, like the Guastis', can supply most residential homes with all the electricity they need. But there's a catch. Actually, there are two. The first is simple. It doesn't work if your home, and your windmill, are not in a windy area. Period.
The second challenge is more complex. Although the total amount of electricity generated in a year by their windmill exceeds what the Guastis need, sometimes it's not windy when they need electricity.
The solution lies in a deal with the local power company. The Guastis are connected to the same electrical grid of power lines that supply electricity the old-fashioned way, from power plants that emit greenhouse gases that exacerbate global warming.
When it's windy, the windmill supplies their home with clean green electricity. When it's not, the local power utility steps in and supplies the electricity they need.
But when it gets really windy, it gets really, really interesting. Then, their windmill creates more electricity than their home can use, and the excess electricity goes onto the local power grid. That pollution-free energy powers other homes in the community, reducing the load on the polluting power plants. And what's more, the Guastis' electric meter runs backward, literally.
"When it's making more power than our home can consume, our electric meter actually -- the little disk inside -- actually spins backward and the number clicks down," Beverly said.
In effect, they get credit for all the electricity their windmill contributes to the grid. So when the wind dies down, they have energy credit with the power utility that they cash in to light up their home. They say that they never use up all the extra energy they generate when it's very windy. Every year, they give away more electricity than they take.
Windmills are not cheap. Today, a windmill like the Guastis' costs between $50,000 and $60,000. California's incentive programs reduce that price tag to somewhere between $30,000 and $40,000.
So how long does it take for the free electricity to match the substantial cost of purchasing a windmill? Estimates range from six years to 12 years.
The cost/benefit analysis in terms of environmental health is even more imprecise. According to the Web site of Environmental Defense, a not-for-profit, bipartisan organization that seeks practical solutions to environmental problems, 80 percent of global carbon dioxide emissions come from power plants.
Switching one home from fossil fuel electricity to wind power won't make a dent, but in San Bernardino County, one home has turned into 100 homes, so far.