With electricity and natural gas prices soaring, chances are you’ve been scrutinizing your home energy use and you may be considering renewable energy. Residential-scale options—solar, wind, geothermal, biodiesel, microhydro—are plentiful, but it’s not always easy to figure out their cost-effectiveness. Retrofitting an existing home for alternative power can be challenging and pricey, but many systems pay for themselves in savings after a few (or several) years. And, of course, there’s the satisfaction of cutting your biggest ties to coal and nuclear power.
Coal accounts for about half of U.S. electricity, and burning coal emits carbon dioxide (a global warming gas), additional pollution and heavy metals. Nuclear plants make up another 19 percent through radioactive uranium isotopes, which lead to tons of nuclear waste. The United States imports natural gas from Canada (through pipelines) and from other countries as liquefied natural gas (LNG). In 2004, the United States imported 19 percent of its natural gas from foreign sources, and the demand is rising. The natural gas industry says the United States has enough natural gas embedded in its shale deposits to last 118 years and new drilling technology should be able to get natural gas from the shale.
The good news is that more renewables are showing up in the utility mix. Wind could provide 20 percent of U.S. electricity by 2030, according to the U.S. Department of Energy, and many cities are promoting alternative energy. Chicago, for instance, recently amended its building code to allow rooftop wind turbines. In addition, solar thermal electric plants, sometimes called concentrating solar power (CSP), are popping up in the Southwest. A large plant was just completed outside Las Vegas, and many new plants are on the drawing boards. CSP is the second most cost-effective renewable energy source after wind. A 100-by-100-mile area in the desert could supply all of the nation’s electricity needs.
Your energy choices
“Before looking at renewable components, evaluate your home’s energy efficiency,” says Ron Judkoff, director of the Buildings and Thermal Systems Center at the National Renewable Energy Laboratory (NREL). “That’s the most cost-effective place to start.” You can save energy by upgrading attic and wall insulation; installing a programmable thermostat, high-efficiency furnace and energy-efficient appliances; and replacing incandescent lights with compact fluorescents.
You also can reduce the need for air conditioning by restricting the amount of sunlight that enters through windows. An energy audit can help show you how. “Once you’ve installed the most costeffective energy-efficiency measures, then consider renewables,” Judkoff says. “In some locations you can purchase wind power directly from your utility company for little or no additional cost.” Cutting back now could also save you money when you’re ready to invest in an alternative energy system—fewer watts consumed means fewer solar panels required.
What is it? A small portion of a river or stream’s water is diverted through a channel or pipeline to a turbine. The water rotates the turbine, which spins a shaft to generate electricity. To determine how big a system you need, you should measure the stream’s water pressure and flow rate throughout the year and calculate how much water you can remove from the stream without harming the aquatic ecosystem. Consult with a stream biologist, and consider hiring a microhydro consultant to install the system (check www.microhydropower.net or www.energybible.com to find a specialist).
■ Proximity to year-round flowing water where you can obtain a permit to build a microhydro system.
■ Produces power 24 hours a day
■ Can be tied to grid or stand alone with storage batteries
■ Usually least expensive system to install
■ Requires no fuel or electricity
■ Payback on investment (if tied to grid):10 years or less
■ Systems damage ecosystems if too much water is diverted.
■ Expertise and permits are needed to plan and implement microhydro.
■ Suitable sites are rare, and steep terrain can make installing the pipeline difficult and costly.
■ No federal tax credits. Check for local incentives at www.dsireusa.org.
Average cost: $2,000 to $10,000 Prices vary according to terrain. Payback time for investment, if tied to grid, is 10 years or less
■ Microhydro: Clean Power from Water by Scott Davis (New Society, 2003)
■ The Homeowner’s Guide to Renewable Energy by Dan Chiras (New Society, 2006)
■ Home Power magazine
What is it? The sun provides natural daylighting and passive heating (if you have large, south-facing windows). In addition, there are three ways to mechanically convert the sun’s energy into home power:
1. Solar electricity. When the sun strikes the solar cells in a photovoltaic (PV) panel, electron movement creates DC current. An inverter converts that into AC current, the type homes use. If your system is tied to the utility grid, a meter tracks electrical consumption and feeds any excess power back to the grid. Off-grid systems require large batteries to store energy for use at night and on cloudy days. PV systems can be installed on unshaded, south-facing parts of your roof or ground-mounted.
2. Solar hot water. Roof- or ground-mounted solar collectors contain fluidfilled tubes. The sun heats the fluid, then the warm liquid circulates to a storage tank, which supplies the home’s hot-water taps.
3. Solar hot air. Air circulates through roof-, wall-, window- or ground-mounted solar collectors. The sun heats the air, which then circulates through the home’s air ducts.
■ Unobstructed, south-facing areas
■ Panels should not receive shadows (from tree branches, electrical poles, neighbors’ roofs) during midday.
■ Can be tied to grid or stand alone with a storage battery
■ Increases home value
■ Has no movable parts
■ Emits no waste
■ Experienced installers available nationwide
■ Tax incentives widely available
■ Retrofitting your house with solar panels can be difficult if you or your neighbors have mature trees that shade your roof.
■ Not all roofs can bear the extra weight of solar panels, especially thermal water heaters. (But ground-mounting can work, too.)
■ Panels must be cleared of dirt, bird droppings and snow.
Average cost: For PV, about $30,000 to $50,000 for a 3- to 6-kW system (without incentives). For a rough estimate of the system size you need, divide the number of kWh you use per month by 150. For a solar hot water system, prices without incentives will vary from about $1,800 to $8,000 for systems that will reduce hot water energy use by 50 to 70 percent. The least expensive systems are designed for mild climates. Severe climates require more complex, expensive systems. Payback should take five to 20 years depending on your area’s utility rates and incentives.
■ Solar Calculator determines price, savings and system size and helps you find local installers
■ A Consumer’s Guide to Energy Efficiency and Renewable Energy
■ American Solar Energy Society
■ Solar Water Heating by Bob Ramlow (New Society, 2006)
■ The Solar House by Dan Chiras (Chelsea Green, 2002)
What is it? Geothermal systems—also called ground-source heat pumps (GHP) or GeoExchange—use the earth’s constant temperature to heat and cool a home. Geothermal systems consist of closed loops of pipe laid underground, either horizontally in 5- to 10-foot trenches, or vertically in 100- to 400-foot holes. Pipes also can be submerged in a nearby pond or lake. An electrically powered system, or “pump,” circulates water or an antifreeze solution through tubes. In winter, the fluid collects heat from the earth and carries it through the system and into your home. There, it’s compressed to a higher temperature and released as warm air into the ductwork. In summer, the system reverses, pulling heat from the house, carrying it through the system and returning it to the ground.
■ Enough yard space to accommodate heavy digging equipment. If ground area is limited, deep vertical holes can be drilled. Installations can be designed to minimize tree clearing.
■ Can be installed in most ground conditions except where there are underground voids, such as in areas previously mined
■ Eliminates gas use and requires 25 to 50 percent less electricity than conventional heating or cooling systems
■ Can be installed in new homes or retrofitted for existing homes
■ Mechanical systems are underground or inside the house, so there’s no sound or machinery.
■ Durable; require little maintenance (Though any necessary maintenance can be difficult and costly.)
■ Can be equipped to supply hot water
■ Must be professionally installed; experienced contractors can be difficult to locate.
■ Systems require electricity to run compressor, water pump and fan. They do not generate their own electricity.
■ Systems in northern states require antifreeze, which may be toxic and nonbiodegradable. Ask your installer if less-toxic antifreeze, such as propylene glycol, is appropriate.
■ There are no federal tax credits, and only a few states have GHP programs. Check for local incentives.
Average cost: For a 2,000-square-foot home, $18,000 to $40,000 installed (prices vary according to size and region). Payback time for investment is five to 10 years.
■ A Consumer’s Guide to Energy Efficiency and Renewable Energy. Click on “Heat Pumps,” then choose “Geothermal.”
■ Geothermal Heat Pump Consortium
■ International Ground Source Heat Pump Association
What is it? Clean-burning biodiesel, made from soybean oil or recycled restaurant grease, can be used in oil-burning furnaces for home heating. Biodiesel blends, called Bioheat, mix conventional heating oil with 5, 10 or 20 percent biodiesel. (They’re known as B5, B10 or B20.)
■ Burns cleaner and more efficiently with less smell than regular oil
■ Is from a renewable, domestic source: soybeans and other agricultural products
■ Can be used in existing oil burners with few or no modifications
■ Currently not enough supply
■ Costs more per gallon than regular heating oil
■ Biodiesel blends are still primarily petroleum.
Average cost: 5 to 10 cents more per gallon than conventional oil
What is it?: Residential wind turbines with propeller-like blades (15 to 25 feet long) catch the wind’s energy and turn a rotor, which spins a generator to make electricity. Turbines can be mounted on rooftops or on 50- to 100-foot freestanding towers.
■ Home sits on at least an acre of property. The turbine must be at least 10 feet higher than anything within 300 feet (trees, roofs, power lines).
■ Consistent wind with an average wind speed of 10 miles per hour
■ Can lower electricity bills by 50 to 90 percent
■ Can be tied to grid or stand alone with a storage battery
■ Federal incentives are available. Check for additional state/local programs.
■ No federal tax credit for home wind systems; only a few states provide tax incentives.
■ Unpredictable wind conditions make rooftop turbines less viable than towers.
■ Zoning regulations may restrict turbine tower height and placement.
Average cost: For a 10-kW grid-connected home system, $35,000 to $40,000 (prices vary according to size and region). The payback time on the investment should be from five to 10 years.
■ American Wind Energy Association
■ A Consumer’s Guide to Energy Efficiency and Renewable Energy. Click on “Wind Turbines (small)”
Find Tax Incentives
Installation costs for home renewable energy systems are pricey, but federal, state and municipal tax credits can help defray the expense. For instance, San Francisco’s new Solar Energy Initiative offers homeowners a $3,000 to $6,000 rebate as an incentive.
Check what incentives you’re eligible for.
Good News For Tax Payers
Take advantage of the 2009 federal tax provisions for eco-friendly upgrades.
1. $500 for energy efficiency: Covers up to 10 percent of the cost of home efficiency projects.
2. $2,000 for geothermal: Recover $2,000 of installation costs.
3. $2,000 or more for solar power systems: A credit for 30 percent of the cost of new systems.
4. $500 or more for fuel cell or microturbine: Recover 30 percent of the cost, up to $500 per 0.5 kWh.
5. $7,500 for plug-in hybrid cars: The first 250,000 buyers will qualify.
6. Wildcard: The bill authorizes $800 million for new state tax incentives.
- Adapted with permission from The Daily Green
Considering your own renewable energy system? Ask yourself:
- Is my property ripe for making energy?
Some spots are more suited for renewable energy systems than others. If you have an unshaded, south-facing roof, solar could be for you. If you live near a mountain stream, consider microhydro. Steady winds? A small, backyard wind turbine can work well if you have unobstructed space to erect a wind tower.
- What if I'm not sure?
Hire an energy consultant, who can help evaluate your current energy use, suggest ways to reduce your consumption and help determine what type of alternative system would work best at your house.
- What if I can't invest in my own system right now?
You can still support clean energy. Many municipalities now offer renewable energy options. Find out what’s available in your area or, buy Green-e Renewable Energy Certificates (RECs), which support clean energy sources such as wind and solar.
Shorten Your Payback Time
If your home’s solar, wind or hydro system is tied to the electrical grid, you may be able to reduce the payback time on your investment—provided you minimize your energy use. You can return the excess electricity you generate to the local utility through a system called net metering.
■ You’ll need a reversible electricity meter that tracks energy in and out of your home. When your excess energy feeds back to the utility—which either purchases your excess kilowatts or credits them to your account—your meter will actually run backward.
■ Net metering eliminates the need for battery storage for supplying energy when the sun isn’t shining or the wind isn’t blowing. If you need more energy than you are making at any given time, you simply pull power from the grid.
■ Find out if net metering is available in your state by checking the Database of State Incentives for Renewables & Efficiency.
Interstate Renewable Energy Council
National Renewable Energy Laboratory
U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy
The Homeowner’s Guide to Renewable Energy by Dan Chiras (New Society, 2006)
Spruce Line PV panels
flat-plate solar water collectors
Abundant Renewable Energy
residential wind turbines
Wind Turbine Industries(952) 447-6064
Jacobs wind turbines
Energy Star heat pumps
Econar Energy Systems
Energy Star heat pumps