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Introduction

Using Geothermal Energy

Using Geothermal Energy
Geothermal Technologies

Conclusion

Is geothermal energy practical?

References

Bibliography of Sources

U.S. Department of Energy

Geothermal technology is a rapidly evolving field, improvements often made with regards to the efficiency, environmental cleanliness, or cost of harnessing geothermal energy. The following paragraphs illustrate some of the developments in geothermal technologies.

Enhancing Natural Systems
The efficiency of geothermal systems may be improved by enhancing the potential of natural geothermal sites. Some geothermal sites may contain extremely hot rocks, yet may lack enough water to reach their full potential. Likewise, some geothermal sites may contain hot rock, yet may lack the fissures and chambers in which water must collect to be heated. Fortunately, advancements in geothermal technology provide solutions to both problems.

Water may be forced into a geothermal site, by using a high-pressure well called an injection well, and thus providing a geothermal site with an adequate supply of water. Some geothermal plants pumped treated municipal wastewater into their geothermal reservoirs, thus both improving a geothermal plant’s reservoir and recycling water. (Geothermal Education Office)

The permeability of geothermal reservoirs may also be improved though advances in geothermal technology. A geothermal plant may inject high-pressure water into its reservoir; the pressure erodes the rocks of the reservoir, expanding it and increasing the efficiency of the geothermal site.

Heat Mining
Recently, advances in geothermal technology have permitted geothermal energy a greater geographical scope. Traditional methods of using geothermal energy have required the presence of geothermal sites, where reservoirs of superheated water exist naturally. Yet such sites are limited, and – in the United States – are confined to the West of the country.

Yet “heat mining,” a relatively new technology, promises to provide geothermal energy, without natural geothermal sites, by using heated rock layers. These rock layers, “2-6 miles below the earth’s surface,” are hot enough to boil water. “Heat-mining” plants drill wells to reach the heated rock layers, then inject pressurized water above the layer, breaking apart rocks and creating an artificial reservoir. The artificial reservoir then acts in much the same way as a natural geothermal one – water is heated by the rock layers, converted to steam and used to generate electricity, then condensed and re-injected into the reservoir. The system is thus largely closed, although it would require a supply of water to create and maintain the reservoir.

“Heat mining” geothermal plants hold a significant advantage over conventional means of using geothermal energy, yet, as an emerging technology, it is difficult to implement. Although current technology can allow “heat mining” at the required depths of up to 6 miles, such drilling techniques are expensive and difficult to implement. “Heat mining” therefore remains a developing technology, yet one which may significantly alter the ways in which geothermal energy is used.