Geothermal map of the U.S. mainland courtesy of SMU

(Click for larger image)

The earth's interior is almost entirely molten iron and rock. The thin layer of cool earth, upon which humankind builds their homes and follows their dreams, varies in its depth, bringing heat in a few locations close enough to the surface to form volcanoes, geysers and hot springs. Heat from the earth's interior, if it is close enough to the surface, can be directly tapped and used as a source of renewable, sustainable energy. Throughout history people have used heat from these surface level sources for everything from heating their homes to objects of worship.

However, if generation of electricity is the goal, then higher temperatures are necessary, which are available only at depths of several thousand feet in most locations. Although many of the techniques required for reaching those deep heat resources have been developed in the oil and natural gas industries, there remain a number of technologies specific to geothermal energy extraction that need further development. The solutions to these technical problems are necessary to improve geothermal engineering techniques to a point where the sizeable capital cost of building a new geothermal plant is acceptable to investors and developers.

So is it worth it to do the research necessary to develop geothermal energy as a source of power for the future? What are the rewards we might, as a society, achieve by collectively investing in that research? The advantages of geothermal energy are multiple:

• It emits very minor, manageable levels of pollution or greenhouse gases.
• It is renewable and sustainable for thousands of years into the future.
• Technically, it is available almost everywhere on the earth's surface, enhancing national energy security.
• The energy into which it taps (the earth's internal heat) is free.
• Once in place, a geothermal power plant provides consistent base load power.
• It can function as a consistent, sustainable supplement for the intermittant power available from wind and solar energy systems.

The specific engineering challenges to bringing geothermal energy to life as a resource for electrical power are discussed in the research and development (R & D) challenge.