The annual health and environmental benefits to the United States from geothermal energy have been estimated to be $278 million a year, according to the Geothermal Energy Association. Binary geothermal energy plants produce almost no fossil fuel emissions, and other types only trace amounts of pollutants. Argonne National Laboratories found that hydrothermal binary plants have some of the lowest emissions of any energy technology, in their 2010 life-cycle emissions study. Most new geothermal plants that have recently come online in the US are this type.
Their analysis is titled Promoting Geothermal Energy: Air Emissions Comparison and Externality Analysis (21 pages, PDF) One of the more fascinating comments made in their report was one comparing geothermal emissions to coal’s, ‘Flash and dry steam plants emit about 5% of the carbon dioxide, 1% of the sulfur dioxide, and less than 1% of the nitrous oxide emitted by a coal-fired plant of equal energy capacity, and binarygeothermal plants produce near-zero emissions.’ (Source: Promoting Geothermal)
This comparison is especially noteworthy because coal’s air pollution has been estimated to cost the US $500 billion a year, by a Harvard study. While geothermal currently produces far less energy than coal in America, the benefits it is associated with for public health and reducing climate change might have actually been underestimated.
At this extremely low adoption rate, geothermal seems to very overlooked and yet it has great potential to provide reliable, clean energy. As more plants are built and more research is conducted, costs and efficiencies should become even more favorable. Current energy outputs could be increased while emissions remain low, so the value of geothermal to society would likely increase. The same could not be said of coal.