Coal is making a comeback as a home heating fuel in the Northeast, Midwest, and Alaska, because it is cheap, plentiful, and locally-mined.

According to the New York Times:

Burning coal at home was once commonplace, of course, but the practice had been declining for decades. Coal consumption for residential use hit a low of 258,000 tons in 2006 — then started to rise. It jumped 9 percent in 2007, according to the Energy Information Administration, and 10 percent more in the first eight months of 2008.

Retailers of home indoor coal stoves have seen the greatest sales increase in 30 years, and many models are on backorder until March.

Image:  Jen SFO-BCN on Flickr under a Creative Commons License

Although they sound like they are different terms for the same thing, geothermal energy and ground source heat pumps are two different systems, with little in common other than that they are making use of what lies below the surface of the Earth. They do it in very different ways, however.

A geothermal energy system uses heat from below the surface of the earth as an energy source, much like solar panels capture sunlight and convert it into useful energy (electricity or hot water). A geoexchange system with a ground source heat pump (GSHP) is more akin to a hybrid automobile. It is not a method for generating energy, but a method for more efficiently using energy. It still takes energy input to operate a GSHP system, but a GSHP can be as much as 300% to 400% more efficient when compared to highly efficient furnaces, which are typically in the high 90s for efficiency percentage.

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