Is geothermal a viable source of N.H. electricity?

Although one of the recommendations of the Committee to Study Maximizing Incentives for Voluntary Use of Renewable Energy in New Hampshire — set up by the Legislature in 2005 – calls for the state to “establish a program to access the feasibility of using geothermal energy to produce electricity in New Hampshire,” it looks as if the state will have to wait a while longer to do so.

The House Science Energy and Technology Committee recently recommended to the full House deem inexpedient to legislate House Bill 1691, which would have appropriated $106,731 to hire a full-time hydrogeologist to complete a geothermal assessment project and pay for associated costs.

While the committee said the bill “may be a valuable tool towards alternate energy production,” it noted that the Department of Environmental Services “could apply for federal funds for implementation of the project or otherwise include the implementation of the assessment project in the upcoming budget for DES.”

The full House upheld the 13-0 vote of the committee and killed the bill.

Geothermal energy is the thermal energy contained in the rock and fluid that fills the fractures and pores within the rock in the earth’s crust. According to the Geothermal Resources Council, current production of geothermal energy from all uses places third among renewables, following hydroelectricity and biomass, and ahead of solar and wind.

Current U.S. geothermal electric power generation totals approximately 2,200 megawatts, or about the same as two large nuclear power plants.

Despite these statistics, the GRC says the level of geothermal use pales in comparison to its potential.

The 2005 Renewables Study Committee chaired by Rep. Sam Cataldo of Farmington also saw significant potential in geothermal energy, calling it “a resource that has been employed in other areas of the country and the world to generate electricity and to supply heat for various other purposes such as heating buildings.” It also noted that geothermal power production, which increased dramatically during the 1980s following the enactment of federal laws that required utilities to purchase electricity from independent power producers, has tapered off in recent years.

The panel also noted that, while geothermal energy is already being successfully captured in New Hampshire, it is not used to generate electricity, but instead to heat and cool homes and businesses.

Noting that the “potential of geothermal energy is significant and should not be ignored due to a lack of basic scientific information,” the study panel also recommended that the state “should establish a program to access the feasibility of using geothermal energy to produce electricity in New Hampshire.”

Time for an assessment?

The uses to which geothermal resources are applied also are influenced by temperature. The highest temperature resources, typically above 350 degrees, are generally used only for electric power generation.

So what about New Hampshire? How hot are our geothermal resources and could they support significant electric generation sites? According to Representative Cataldo, a test drilling was conducted by the state geologist in Redstone, a town located near Conway, in 1977 that showed a temperature of 249 degrees. If this drilling had been done in a slightly different location it could very well have produced an even higher temperature.

Electric generation, however, is not the only use for geothermal energy. Uses for low and moderate temperature resources can be divided into two categories: direct use and ground-source heat pumps. Direct use, as the name implies, involves using the heat in the water directly (without a heat pump or power plant) for such things as heating of buildings, industrial processes, greenhouses, aquaculture (growing of fish) and resorts.

Accurate data is not available on the current number of these systems, but the rate of installation is thought to be between 10,000 and 40,000 per year.

Public Service of New Hampshire has for a number of years administered a Geothermal Homes Program that provides incentives for its customers to install and operate geoexchange systems.

PSNH will pay up to $7,500 of the installation costs of a geoexchange system, provided the home is first certified as being energy-efficient in design. The customer also is given a reduced electric rate for participating in the program. The annual electric bill to heat, air-condition and provide hot water to the 81 homes in the program has averaged $760, the utility said.

But without the benefit of a formal assessment – which could determine the location of known and potential geothermal deep sites and their characteristics — it is difficult to answer the question of whether New Hampshire has sufficient geothermal resources to sustain an electric generation site.

Douglas L. Patch, a former chairman of the state Public Utilities Commission, is an attorney with the Concord law firm of Orr & Reno.