Energizing Ideas

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"Power Revolution" [November 5] was very interesting, especially the "Deep geothermal" section.

My business has been using what we call "low-grade geothermal" for more than 30 years in two projects. In most areas of the United States, the ground temperature at a depth of 8 feet is over 50 degrees. We extract this earth heat using 1,100 feet of 6-inch tubes. With only a three-quarter horsepower blower, we keep the temperature of an 85-foot-by-16-foot greenhouse above freezing. We have 15-year-old citrus trees in the ground that produce more than 120 pounds of top-quality fruit each year. For less than $500 a year, we heat and cool an area that would cost thousands in conventional greenhouses. Our other system uses the underground air to flow through a room that houses the outdoor unit of a standard heat pump. In this way, we fool the heat pump into thinking it is in a warmer climate, and it never switches to the more expensive resistance heat mode. When we started this project, energy conservation was all the rage. Imagine our surprise when we found that no one is interested in it.


Russ Finch
Oranges in the Snow Greenhouse
Alliance, Neb.  

"Power Revolution" infers that Silicon Valley venture capital brought about concentrated solar-thermal power plants. Silicon Valley is now rushing to deploy and improve them, but the original demonstration plants were created by the Department of Energy and the National Renewable Energy Lab. In 2000, the National Research Council concluded that solar-thermal worked as planned, but commercial power-generating companies didn't seem interested. A doe-funded cost analysis by a commercial consulting firm confirmed that, produced in quantity, solar-thermal plants would be profitable at about 6 cents per kilowatt-hour. In 2002, the NRC concluded that with further government funding, solar-thermal could be brought to market. California, Nevada, and other states set goals for renewable energy, and commercial power producers finally began to understand. This safe breakthrough makes nuclear power plants unnecessary.


David Wright
Emerald Hills, Calif.  

If we are to put a dent in the problems associated with climate change, Silicon Valley needs to bring us personal power. These technologies would help us build houses and offices that minimize the need for routing power from miles away. If every home and office building was designed to supply most of its own energy, the power grid would serve as a supplemental source and as a place to store power that couldn't be used immediately.


Lindsay Reed
Lubbock, Texas  

Both solar and wind energy projects have footprints that almost always result in unfavorable local reaction because of the perceived visual blight the projects will cause. Pushing these projects into the deserts of California or Texas is as disrespectful to the people who live there as it is to people living in urban areas. People should accept the benefits of these clean energy sources rather than opposing them because of how they look.


Steven Smith
Orange, Calif.