Not long ago, people who wanted to generate their own green energy at home had to content themselves with rooftop solar panels.

But new technologies -- and hefty government subsidies -- are now allowing homeowners to tap the wind, the Earth and other renewable sources in their own backyards.

Call it the green evolution.

The cost of heating and cooling with fossil fuels has nowhere to go but up, thanks to rising global demand and increased regulation of carbon emissions. Turning one’s home into a clean mini-power plant is getting cheaper and easier all the time.

Here’s a look at three technologies that some California residents are using now to cut utility costs while turning their homes into truly green houses.

Small wind

Californians driving along gusty interstates near such places as Palm Springs are accustomed to seeing commercial wind farms, where turbines as tall as buildings spin lazily against a blue sky.

These days, a modest but growing number of people are using a downsized version of that technology inside their own fence lines.

Roughly 10,500 small turbines were sold to homes, farms and businesses nationwide in 2008, according to the American Wind Energy Assn. Though 2009 figures aren’t yet available, demand last year remained strong despite the recession, said Elizabeth Salerno, the association’s director of data and analysis. A survey of small-turbine manufacturers has projected a thirtyfold increase in the U.S. market by 2013.

Locally, some of the growth comes from companies eager to lower their electricity costs. In Palmdale, for instance, city officials are allowing businesses to install wind turbines up to 60 feet high. Among them is Wal-Mart Stores Inc., which has a 17-turbine project planned for its Sam’s Club store in Palmdale.

But interest is also surging among people such as Ernest Ramirez. He and his wife live in Oak Hills, an unincorporated, blustery section of western San Bernardino County dotted with spacious homes on multi-acre lots. The couple weren’t looking to install a wind turbine. Their 3,250-square-foot home, which they purchased in 2003, just happened to come with one.

Ramirez can’t imagine life without it now.

Perched on a slender tower about 80 feet high, the 10-kilowatt turbine has three 10-foot-long blades that whip often enough to keep his power bills from Southern California Edison at about $100 a month -- roughly a quarter of what he calculates he’d fork out otherwise.

Gusts are so fierce in this part of the Cajon Pass that they have been known to snap trees and jackknife semi-trucks. But Ramirez welcomes a bad hair day.

“When I get out of my car and it’s blowing 35 mph and I have to stay inside the house, at least I know I’m saving money,” said the 46-year-old grant writer. “Wind is such a precious resource.”

Ramirez said he could count seven neighbors with their own wind turbines. Still, what works in windblown, rural San Bernardino County won’t necessarily fit everywhere.

For a turbine to make economic sense, the AWEA said, a homeowner considering one should live in an area where 10-mph winds are frequent and be paying at least 10 cents a kilowatt-hour for electricity. Permitting is also a challenge in many communities; some neighbors consider the spinning contraptions ugly.

The technology certainly isn’t cheap, running about $3,000 to $6,000 per kilowatt installed, or about $40,000 for a system large enough to power a typical home, according to the AWEA.

Subsidies are helping to soften some of that sticker shock. Homeowners can get a hefty rebate from the state of California -- up to $12,500. They’re also eligible for a 30% investment tax credit from the federal government.

Geothermal

Solar panels and wind turbines are the rock stars of the renewable-energy world. But one of the most reliable performers is right under our feet.

Geothermal heat pumps harness the Earth’s constant, natural heat to warm and cool a home, regardless of whether the sun is shining or the wind is blowing. Around since at least World War II, the technology consumes 25% to 50% less electricity than conventional systems, according to the U.S. Energy Department.

These devices gather ground heat through buried pipes that form a loop. During winter, an antifreeze-type fluid circulates through the loop, grabs heat from the soil and transfers it to the home, where it is circulated by a fan through the ductwork or vents. In summer, the process is reversed: The pump draws heat from the home’s interior and dumps it back into the Earth.

Geothermal heat pumps are cousins of regular heat pumps, which extract heat from the outside air. The difference is that geothermal is more efficient because soil temperatures, even just a few feet underground, remain fairly stable year-round. Geothermal systems also have few moving parts, so they’re quiet and durable. They can be adapted to provide a home’s hot water.

Dennis Bushnell, a NASA scientist who studies renewable fuels, said that thousands of homeowners in the eastern U.S. already rely on geothermal heat pumps. People who live in warmer Sun Belt states could especially benefit from them, he said, because the loop works best when the soil temperature stays above 30 degrees.

The equipment is “not exotic at all,” Bushnell said. “You can go on the Web and buy one today.”

Now for the bad news: Upfront costs are hefty, sometimes twice as much as conventional heating and cooling units. But some satisfied customers say the quick payback time and minimal maintenance expenses make it worthwhile.

Among them is John Sergneri. California’s electricity crisis motivated him to install a geothermal heat pump on his 1,280-square-foot tract home in Petaluma. It cost $40,000, about $15,000 more than a traditional system. But it has slashed his utility bills dramatically.

Sergneri, an information technologist, plans eventually to install solar panels to further trim his power costs, because the ground pump and associated machinery, like many renewable systems, require some electricity to operate.

It’s all part of what he terms a low-cost, eco-friendly “retirement plan.” Sergneri, 58, jokes that it will yield a better return than his battered 401(k).

“My goal is to be as independent as possible,” he said. “I’ve always dreamed of getting as far from the grid as possible.”

Though California isn’t offering rebates for ground heat pumps, a 30% federal tax credit is available.

Solar hot water

California leads the nation in using photovoltaic panels to generate clean electricity. A cheaper and more practical way to harness the sun’s energy is for heating water.

Solar water heaters typically require just a few small rooftop panels; they work even in chilly Northern climates. Yet the technology is little used in California, despite its abundant sunshine.

Officials are hoping to change that with subsidies to coax consumers to swap their old energy-sucking water heaters for efficient solar-power systems.

Last month the California Public Utilities Commission approved a $350-million rebate program. Californians can get as much as $1,875 for swapping out their natural gas units and $1,250 for ditching their electrically heated tanks. The rebates phase out at the end of 2017, or when the ratepayer-subsidized funds dry up, whichever comes first.

The subsidies are aimed at customers of the state’s large investor-owned utilities: Southern California Edison, Southern California Gas Co., Pacific Gas & Electric and San Diego Gas & Electric. Some municipal utilities offer their own incentives, so check your provider’s website.

Buyers can also qualify for a 30% renewable-energy tax credit from Uncle Sam.

All told, that could amount to as much as a 55% subsidy for equipment that normally costs $6,000 to $8,000, depending on a home’s size and energy use.

Heating water represents the third-largest energy expense for most households, according to the Energy Department. If California’s solar water heater initiative succeeds, it could help reduce the need to build power plants and reduce greenhouse gas emissions.

Such systems are popular in Israel, China, Spain and other countries. Beginning this year, Hawaii is mandating that all new homes be equipped with them.

“Solar water heaters are the low-hanging fruit,” said Katrina Phruksukarn, solar water heating program manager with the California Center for Sustainable Energy. “They may not be as cheap as putting in a high-efficiency light bulb, but they’re about as cost-effective as you’re going to get.”

Technologies vary by manufacturer. One common arrangement involves a storage tank linked to a rooftop solar array, which converts the sun’s rays into electricity that heats the water. Backup gas or electrical heating kicks in if the temperature falls below a certain threshold.

Steve Glenn, whose company, LivingHomes, designs eco-friendly modular dwellings, has a system in his home that employs solar tubes filled with special oil. When sun rays strike the tubes, they produce steam that rises and transfers some of its heat to water, which is stored in an ordinary-looking 60-gallon tank. The water is then delivered to showers and sinks. Heat radiating from the system’s piping also keeps the floors toasty.

Glenn said the solar water heater, photovoltaic panels and other energy-miserly features in his Santa Monica home have reduced his electric bill to the cost of a nice lunch: about $15 to $20 a month.

“I don’t have to even think about it,” Glenn, 45, said. “The hot water feels like hot water. I’m not aware its it’s sun-baked and not natural-gas-baked.”

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