The Group of 8 may have failed to set specific goals for greenhouse gas reduction. T. Boone Pickens may have put his plans for the world s largest windmill farm on hold. But there are plenty of cost-effective ways for you to make the switch to renewable energy sources at home, without waiting for governments or billionaires to take the first step.

The largest source of industrial air pollution in the U.S. today is electricity generation, according to the Environmental Protection Agency. So reducing the amount of electricity you use has a big environmental impact. It can also be a wise investment: New renewable-energy projects require cash upfront for a utility or a homeowner, but sunshine and many of the world s other energy-producing resources will always be free.

For example, if you spend the money now to install solar panels on your roof, you ll be saving later. In a way, you re purchasing your energy now at a lower rate and protecting yourself from an increasing utility bill, says Dona Stankus, the building programs manager for the North Carolina Solar Center. If oil prices rise again as the global economy picks back up, the cost of electricity from conventional sources will rise, but those solar panels will still be generating free juice.

Your first step should be to make your home as energy efficient as possible, particularly if you re planning to invest in an energy-generating system. If you re not changing your consumption, the investment is going into the wrong place, says Bomee Jung, a spokeswoman for GreenHomeNYC, a volunteer organization that connects building owners with green building services and materials firms. The Department of Energy s Energy Savers web site provides information on how to reduce your electricity use the easiest and most cost-effective way to go green.

The next step is passive solar: strategically using your home s exposure to the sun to reduce heating and cooling costs. Consider insulated shades for your windows that would allow you to block out daytime heat during the summer or cold night air during the winter. A trellis to block a window facing south in the summer is another inexpensive way to cut air-conditioning costs, says Stankus. For eastern and western exposures, Stankus suggests applying low-E film to your windows an easy installation you could do yourself.

About 25% of the nation s utilities currently offer a green-pricing program for about $5 or $10 a month you can buy renewable energy certificates (or RECs) as part of your electric bill. If your utility doesn t offer such a program, you can buy the RECs directly online from a provider like Community Energy or Renewable Choice Energy.

Producers of renewable energy like wind farms sell the power they produce directly to utility companies. When this megawatt hour is produced from the wind farm, that wind farm can sell the megawatt hour one place and the REC to a totally different place, says Jeff Swenerton, the communications director for the Center for Resource Solutions, a nonprofit think tank that develops policy and market strategies to advance sustainable energy.

This system allows producers to recover the higher start-up costs of a new renewable-energy project. The Center for Resource Solutions runs a certification program for RECs called Green-e, which checks that these credits are supporting recently built operations. Consumers can consider their purchase a small investment in developing more alternative energy capacity in the U.S.

If you want to go a step further and have some extra cash on hand, now may be the time to invest in the technology to generate renewable electricity at home, particularly with federal and state tax credits currently cutting anywhere from 30% to 50% off the cost of installing some systems.

Check out these 5 cost-effective ways you can use renewable energy in your home.

If you have running water on your property, you could install a microhydropower system. You ll need to live near water that falls at least two feet to generate a useful amount of electricity. Find out how to evaluate a stream as a potential microhydropower site at EnergySavers.gov. A small system that generates electricity at a rate of 10 kilowatt hours of energy every hour could be enough to power a typical home.

Pro: Could potentially provide all the electricity you need to run your home.

Con: Without running water, you re out of luck; will require navigating some bureaucracy to get permits and water rights; water flow varies seasonally; not eligible for federal tax credit.

Cost upfront: Anywhere from $5,000 to $20,000, depending on the size of the system.

Time to recoup investment: 3 to 10 years.

If you live in a breezy enough area, a small wind electric system could provide all the electricity you need to power your home. The windiest areas of the U.S. are in central states like North or South Dakota, Nebraska or Kansas. Many areas in the West also have what s known as a good wind resource. Windmill systems are typically quiet enough to avoid upsetting the neighbors. When installing a system like this, you should expect to pay $3,000 to $6,000 per kilowatt of capacity, according to data from the American Wind Energy Association, a trade organization for the wind power industry. A five-kilowatt system should be enough to power a typical home.

Pro: Maintenance costs are usually low.

Con: Works best for rural homes far from utility lines with at least one acre of land.

Cost upfront: $15,000 to $30,000 for a five-kilowatt system

Time to recoup investment: 5 to 10 years, or 4 to 8 years with a 30% federal tax credit.

There is a wide variety of solar power options available for the residential consumer from small $20 to $50 devices that can recharge your iPod or cellphone to a roof covered in photovoltaic cells that can power your whole house. Home Depot (HD) offers free in-home consultations for homeowners looking to install a complete home solar power system, which will set you back at least $50,000. A more modest starting point could be a solar hot water heater. For about $5,000 (not including tax credits) you could eliminate the cost of heating water for a family of four. A system like that would pay for itself in about eight years.

If you want to take your home partially off the grid, Stankus suggests starting with a two-kilowatt system enough to provide you with emergency back-up power for outages now and recharge an electric car in the future.

Pro: Could provide about 15% of your household electricity; typically covered under warranty for 25 years.

Con: Efficiency limited by home s orientation. Works best with a southern exposure.

Cost: $30,000 for a top-of-the-line two-kilowatt system with battery back-up.

Time to recoup investment: 75 years, or about 55 years with a 30% federal tax credit.

Utilities can generate power from biological material like wood waste from trees or decaying trash in landfills. The easiest way to use biopower at home is also the most old-fashioned: Install a wood- or pellet-burning stove. Pellet stoves are more efficient than wood-burning stoves, and they burn the cleanest of any residential fuel-burning appliance. The fuel for these stoves is made out of compacted sawdust, wood chips, agricultural waste, waste paper and other materials.

Pro: A pellet stove could provide nearly all the heat you ll need for your home; you ll only need to refuel it once a day; it may be cheaper to install than a wood-burning stove because it usually doesn t require a chimney.

Con: Pellet fuel isn t available everywhere; pellet stoves are more complex than wood stoves and may require more careful maintenance.

Cost: $1,700 to $3,000 for the stove; $250 to $600 each winter for fuel.

Time to recoup investment: About 3 or 4 years if you re switching from gas heat, or 2 or 3 years with a federal tax credit.

Correction: A previous version of this story stated that pellet stoves were not eligible for a federal tax credit. Although pellet stoves are not eligible for a deduction under the renewable energy tax credit, they are eligible for a tax credit for energy-efficient home improvements, worth 30% of the cost, up to $1,500, as long as they have a thermal efficiency rating of at least 75% as measured using a lower heating value.

Geothermal heat pumps take advantage of the fact that the temperature stays relatively constant all year long just a few feet under the ground; it s cooler than the air above ground in summer and warmer in winter. Installing a pump isn t a do-it-yourself project, so be sure you carefully research the installer you hire.

Pro: Takes up less indoor space and makes less noise than a conventional system; particularly effective at controlling humidity; some systems may also provide hot water.

Con: You ll be able to install a cheaper type of system in new construction existing homes may need to go with a more expensive option that takes up less space underground.

Cost: About $7,500.

Time to recoup investment: 5 to 10 years, or 4 to 8 years with a 30% federal tax credit.