What are your renewable energy options?

There is no cookie-cutter solution for what type of renewable energy system will be most effective and economical in any given application. Many factors must be balanced to develop a good design, including proper siting, environmental resources, financial incentives, social considerations, and environmental effects. Here is some real-world advice concerning each of the major technologies.

Solar Hot Water. Solar thermal systems include a rather large category of energy collection and distribution devices for pool heating, domestic water heating, and space heating via radiant floor heating or water-to-air heat exchangers. You should consider all these options during the design phase of your project. Installing a solar domestic hot water (SDHW) system is one of the best investments homeowners can make to reduce their electric or natural gas water heating bills, with typical financial paybacks at less than eight years. Depending on the size of the system you install, your local climate, and your hot water use, SDHW systems can cut your water heating bills by 40 to 80 percent. Systems have been designed for all types of applications. Whether you live in the farthest reaches of Alaska, in cloudy Seattle, or by the beach in Jamaica—an SDHW system can work for you.

Solar Electricity. The use of residential solar-electric systems began decades ago in rural locations where utility electricity was not available. While the number of off-grid PV systems continues to grow, grid-tied PV systems are an increasingly popular urban and suburban option for generating clean, sustainable electricity. Not to be confused with solar heating (which uses the sun’s heat to warm air or water), PV modules use photons in sunlight to excite electrons and generate electricity. PVs have no moving parts, are virtually indestructible, and typically carry a 25-year warranty. You’ll face a major choice when planning a grid-tied PV system (and increasingly with wind and microhydro systems)—will you have batteries or not? If your primary motivation is environmental, a batteryless grid- tied system is probably the best choice. Batteryless systems are simple, economical, maintenance free, and highly efficient. If your home experiences frequent or extended utility outages that are an inconvenience to you and your family, then you may want to consider a system with battery backup.

Wind Electricity. Wind energy can be quite economical if your site has an adequate wind resource. Optimal, consistent wind resources are not located near buildings or down among the trees. Rather, they are found at least 30 feet above all nearby obstructions. Tapping wind energy involves tall towers, which need to be engineered specifically for the turbine you are installing. Wind turbines come in a variety of shapes and sizes, with many different specifications.

Microhydro Electricity. If you have a stream running through your property that drops along its course, tapping its energy potential may be economical. With microhydro, as with all renewable energy technologies, you must weigh the economics at each site based on the resources at hand. Opportunities for installing a microhydro system are often few and far between, but if your stream has significant water flow or a large vertical drop (head), you’re in luck. Even streams that only flow seasonally can be good candidates for generating electricity. Unlike PV or wind systems, hydro systems generate electricity continuously, as long as the water is flowing, and will typically be the most cost-effective renewable energy approach. -Home Power, april/may 2007

Tagged as: microhydro, solar electricity, solar hot water, wind electricity