Photovoltaic solar cells capture the public imagination as a renewable energy source for homeowners, but nothing beats geothermal heating/cooling for proven efficiency and reliability. My dad installed a geothermal system when he built a house in Norfolk some two decades ago. As far as I know, it has worked trouble-free all those years, quietly racking up savings on his heating and air conditioning bills.
Geothermal units function as heat pumps: They run water through underground tubes, absorb the constant 57- to 58-degree temperature found underground, recirculate the water into the house, and exchange the heat again. Although circulating the water does requires electricity, the system is three to four times more cost-effective than electric resistance heat.
From an electric-grid perspective, geothermal offers advantages over solar. Solar generates electricity intermittently — during the daytime only, and when clouds aren’t blocking the sun. When homeowners are generating more electricity than they need, they can sell it into the electric grid. The inherent unpredictability poses problems for power companies whose job it is to manage a stable grid. That’s why Dominion and other electric utilities want to restrict the contribution of solar energy to one percent of system capacity.
By contrast, geothermal is totally predictable. It runs evenly round the clock, and by its nature, it makes the biggest contribution when outdoor temperatures — and the demands on the electric grid — are at their extremes of heat and cold. Geothermal systems create a more stable and easily managed grid.
Geothermal isn’t high-tech, cool or glamorous in any way. You don’t even know it’s there. Which is another one of its selling points — geothermal systems are unobtrusive. They don’t violate homeowner covenants for unsightliness. The neighbors won’t complain. As Virginia investigates strategies to promote conservation and renewable fuels, it should take a good, hard look at geothermal.
As a practical matter, what can Virginia do?
- Work out electric billing rates that reward homeowners for reducing peak electric loads. Right now, power companies charge the same for every kilowatt hour, regardless of the time of day. Charging higher rates during periods of peak load and lower rates for off-peak consumption will provide a strong financial incentive for homeowners to invest in systems, like geothermal, that moderate system demand.
- Get some clarity, reflected in local ordinances, on when less expensive “open loop” systems are permissible. Clarke County recently denied a homeowner request to install an open loop system, which draws water from one well and discharges it into another, on the grounds that “they use more water and cause what they called ‘ponding and excessive runoff’ when no body of water was available to receive discharge,” reports the Clarke Times-Courier.
Here’s what not to do: Give homeowners a tax credit for installing the systems, as the state has already done with energy-efficient appliances. The state tax code already looks like it’s been peppered with buckshot. Tax credits of various kinds cost the state well over $1 billion a year in lost income tax revenue alone. The goal of public policy should not be to encourage geothermal regardless of the cost — it should be to encourage geothermal where it makes rational economic sense. The best way to do that is to create a rational tariff for electricity consumption and to clear away encumbrances from local ordinances.
(Image credit: Renewable Energy UK.)