The economics are looking favorable for a 160 Mw geothermal power plant estimated to cost $760 million. Compare that to an estimate for a 47 Mw biomass plant planned for Greenfield, MA at $240 million. (3 x 47= 141 Mw and 3x 240= $720 million) The estimated cost for geothermal is about the same. With no cost for fuel, there are only maintenance, employee and construction finance expenses. The maintenance expense is estimated to be comparable to that of hydro electric.

The geography is flexible a road is good, a rail line would be ideal. The first one built should be in a low population area close to 160-1,400 Mw power lines.

Most important is geology and type of rock. Large granite formations like the Warwick, Pelham and Fitchburg domes have good potential. These domes are massive and extend across a number of towns. Rock type is important for thermal diffusivity and quartzite granite formations with large crystal structure (not uncommon in New England) can be some of the best types of rock for thermal diffusivity.

The geology of how the rock was formed is also important. Numerous granitic plutonic masses in New England are believed by many geologists to have been formed by melting through the early basalt granites when the continents were being formed. This gives them a direct connection to deeper and hotter rocks.

Here is a little side history about the development of geothermal that most people do not know: D.O.E. is supporting geothermal research called E.G.S. This concept is based on the idea of expanding geothermal geyser fields with hydro fracturing. It only works well if you have the right conditions for a geyser field. This concept is the preferred option if you have those rare conditions; however with increased depth this idea becomes increasingly problematic. 

The next generation of geothermal power plant we believe will be a quantum step forward for the geothermal industry. We call it C.L.E.M. (short for Closed Loop Energy Mine). This will come about when people start to understand that the thermal diffusivity of a rock formation and geological connection to deeper/larger heat supplies are more valuable. This quantum step is based on the idea of designing for an optimal recharge rate. The better the recharge rate is of a geothermal system, the less surface area the underground thermal exchange system would require. Smaller can also translates into lower cost to build per unit of power producing capacity.

It may be discovered that New England has some of the best granitic formations for this concept. East Coast geothermal economic potential may be greater than most people ever imagined, due to some of these granitic domes. In short, a closed loop geothermal system of interconnecting pipes could be built in almost any rock formation, but the amount of electricity it could produce is tied to the system's ability to recharge.  

Using the geothermal system called E.G.S., the rate of recharge is not important for most people. With E.G.S., porous hot rocks close to the surface are the prime determining factors in evaluating a geothermal resource. These systems are designed to use up a geothermal resource over 30 years and then be decommissioned, so it does not matter if the resource takes as much as 300 years to fully recharge.       

This 30 year plan works, but only serves one generation. There is nothing left for the next generation to build on, old systems have to be demolished. Every generation has the burden of building new power plants and or well fields. Large hydro electric power plants like the Hoover Dam have stimulated economic growth for generations and it is unlikely they would have been built if all we could do was a 30 year lifespan plan.

The proposed C.L.E.M 160 Mw geothermal project could be expanded to 1,400 Mw as demand increased, producing and selling electricity for around $.05/Kwhr. and doing that for generations. Not having to build new power plants saves massive amounts of resources. These savings and other products produced with a stable supply of electricity makes possible long-term stable economic growth.