So your home is a good place to start if you want to help slow global warming. It’s basically a two-step process. First, you figure out how to use less energy. That means choosing energy-saving light bulbs and appliances, insulating and air sealing, and taking other low- or no-cost steps to make your home energy efficient. The second step involves considering “renewable” energy. The Earth can provide a finite amount of fossil fuels such as oil and coal–and then they are gone. But if your home can harness the inexhaustible energy of the sun or the wind, you can help the United States transform the way it produces electricity and create a brighter future. Solar electric systems, which are also called photovoltaic (PV) systems, convert the sun’s energy into electricity. PV systems are made up of semiconductor cells manufactured in thin layers and grouped into larger modules. They need to be installed in a south-facing location (typically on a roof) that’s not shaded by trees, buildings, or other structures. When light hits a PV cell, it generates direct current (DC) electricity. The DC current runs through an inverter–a small box that transforms the DC current into AC current used to power your home. Residential-scale wind turbines generate electricity from the wind’s kinetic energy–that’s the energy of motion. When wind moves the turbine’s blades, it turns a shaft connected to an electrical generator. The generator feeds electricity to your home. For a wind turbine to be cost effective, it needs to be in a location with ample, consistent wind. Most residential wind turbines don’t need a lot of space, but they are mounted on tall towers (typically 80 to 100 feet), so they’re best suited to properties of half an acre or more to avoid conflicts with neighbors. Depending on its size, a PV system or wind turbine can provide a portion or all of your home’s electricity needs. Most installations are grid-connected, so that when they are producing more electricity than you need, you get a credit for the excess from the utility company. And when the sun isn’t shining or the wind isn’t blowing, your home gets its power from the utility grid. Off-the-grid installations in rural areas rely on expensive banks of batteries to store electricity for use when the renewable energy system isn’t running.

Costs

The sun and wind are free, but harnessing their energy isn’t. After available state and federal incentives, the average cost of a solar electric installation is $15,000 to $30,000 for a typical 2 to 4 kilowatt system. A 3-kW wind turbine on a 60- to 80-foot tower would cost $15,000 to $21,000, including all components and installation. Unfortunately, even in areas with high electricity prices, it can take 15 years or more for a typical system to pay for itself. That’s still a 7% annual return on your investment–more than your bank pays you–but you must be willing to make the large up-front investment. As energy costs rise and the cost of renewables comes down, however, solar and wind power will become even more cost competitive. And in remote areas where it would be exorbitantly expensive to hook up to the electricity grid, a wind turbine or photovoltaic (PV) system may be the most economical choice. Taking out a loan for a renewable energy installation often makes good sense. Depending on the situation, a homeowner’s monthly loan payments for a solar or wind system may be lower than their old monthly electric bill. After the loan is paid off, the electricity generated by the system is free.

Purchasing Green Power

If you can’t afford to generate your own solar or wind power, consider purchasing it from someone else. To do that, first check with your local electric company. They may offer a green power option from sources like solar, wind, geothermal, biomass, biogas (such as methane), or low-impact hydro. When you buy green power you’re paying a small premium to support the utility’s renewable energy generation, but you’re not actually getting “green electrons” delivered to your home. Electrons are indistinguishable; those generated by renewable energy sources go into the grid and mix with electrons from all the utility’s other sources. If your utility company doesn’t offer green power, don’t despair. You can purchase “green tags” (they’re also called renewable energy certificates, RECs, or green energy certificates). It’s similar to buying green power from your local utility, except that when you buy a green tag, you may be supporting green power generation in other parts of the country, not necessarily in your region. When you buy a green tag, you’re rewarding power suppliers that offer green power, but you’re not necessarily funding the development of new renewable energy sources. To find out more about green power and green tags, check out the U.S. EPA’s green power website.

Other Renewable Energy Sources

Most people mean sun and wind when they talk about home-scale renewable energy sources. But two other renewables are worth mentioning:

• For home heating, wood is a renewable source of energy if it’s harvested responsibly to balance the need for wood with protection of forest health and soil and water quality. Unlike burning fossil fuels, burning wood is not a net contributor of CO2 to the atmosphere. That’s because more CO2 is absorbed by a growing tree than is emitted when the wood is burned. Wood burning creates hazardous pollutants, however, including fine particles that can harm people’s lungs and cause asthma attacks and bronchitis. To learn more about the pros and cons of heating with wood, see our hearth products page.
• Some day, hydrogen fuel cells may be used to power our homes. They work by converting the chemical energy in hydrogen into electricity, producing water and heat as the only byproducts. This technology, although limited, is already available for commercial and residence use. To learn more visit ClearEdge Power. One challenge is extracting the hydrogen for use in the fuel cell, since in nature hydrogen is almost always bound with another element, such as oxygen. If fossil fuels, such as coal or natural gas, are used to produce the hydrogen, then hydrogen wouldn’t be considered a form of renewable energy. But if solar or wind energy is used to split water into hydrogen and oxygen, then the electricity produced is renewable.

Ground-source heat pumps (also called geothermal heat pumps) are sometimes referred to as renewable energy, but they’re actually an energy-efficient way of heating and cooling with electricity.

Big Benefits

According to the U.S. Department of Energy, producing 20% of our nation’s electricity with renewable energy by 2020 is both possible and affordable. When combined with strong energy-efficiency programs, meeting such a goal would

• Spur innovation The United States, once a leader in renewable energy development, has fallen behind other nations in pursuing clean energy solutions. By reinvigorating our commitment to renewable energy and energy efficiency, we can develop the technologies of tomorrow and find solutions for today’s most pressing problems.
• Curb global warming Fossil-fuel power plants are a primary source of CO2 emissions in the United States. Boosting the country’s use of renewable energy and increasing energy efficiency could eliminate the need for nearly a thousand new fossil-fuel power plants over the next 20 years.
• Improve public health Pollution from existing power plants contributes to over 600,000 asthma attacks each year. Increasing energy efficiency and our use of renewable energy would take dangerous pollutants out of the air and let us all breathe a little easier.
• Cut energy bills Although it takes a while to recoup the initial cost, eventually the electricity generated by a solar or wind energy system saves you money. In addition, renewable energy systems give you a hedge against future energy price increases. They may even increase the value of your home by as much as $10 to $20 for every dollar in saved in annual energy costs.
• Enhance energy security Renewable energy allows communities and homes to generate their own decentralized power, which would make it difficult for terrorists to disrupt large portions of the electrical grid.
• Generate jobs, income, and revenue Renewable energy development can be a powerful economic support for rural areas. Some farmers and ranchers have received $2,000 a year in lease payments for each wind turbine operating on their land. Renewable energy projects also boost local tax revenues and generate local jobs.

]]>