Residential Geothermal Explained
If you’re searching for energy alternatives but need a quick primer on geothermal production for your home or small business, Scientific American has a good explanation of the currently available options.
Geothermal isn’t just for utilities. Homeowners looking to go green and lower their utility bills can install a residential system, essentially a scaled-down version of the binary-cycle system. A series of pipes is installed underground. Water circulating in the loop is heated naturally underground and then transferred to a heat exchanger which concentrate the energy and releases it inside the home as heat. In summer and in warmer climates, the process is reversed to fill the home with geothermal-cooled air.
The binary-cycle technology extracts close-to-the surface warm (not necessarily hot) water and combines it with a second (“binary”) fluid, like butane or pentane, which has a low boiling point. This fluid is then pumped through a heat exchanger, where it is vaporized and sent through a turbine before being recycled back into the system. Binary-cycle geothermal plants already pump out dozens of megawatts of electricity in California, Nevada and Hawaii, among other places.
Residential geothermal systems are expensive to install, but there is a 30 percent tax credit currently available. The Geothermal Energy Association has even more info. And The Christian Science Monitor’s Bright Green Blog has a personal-experience story, too.
