By Dr. Robert Thorson
There’s a change blowing in the wind of U.S. energy policy. It’s blowing up from below. Think steam.
On Jan. 22, the Massachusetts Institute of Technology released a blockbuster report titled “The Future of Geothermal Energy,” which I hope will change the way Americans think about energy independence. What they argue is so simple that a lizard could understand it and so certain that the only thing left will be hard work and prudent investment, rather than high-tech dreams.
The new generation of nuclear power plants certainly looks fancy enough to be of possible interest. But this technology is threatened by undesirable releases of radio-nuclides, whether by intent from bombing, or by accident from power-plant malfunction or waste-site leaks.
Solar power also stimulates the visual centers in our brains with dazzling arrays of photovoltaic cells or parabolic mirrors: Unfortunately, they don’t work that well on foggy days, especially during winter. Wind power looks great too, with its ultra-sleek, somewhat exotic turbine towers. But they, too, are subject to the vicissitudes of the weather and generate less power than their looks would suggest. Hydrogen fuel cells for our cars are exciting under- the-hood prospects, but like nuclear fusion they seem stuck in the experimental engineering phase.
Oldest and simplest of fossil fuel alternatives is geothermal energy, the subject of the MIT report. Two versions of this power have been around since Day One. The first is used by lizards to regulate their body temperatures — the use of rocks as heat exchangers.
Taking this idea further, many forward-thinking people are already using this idea for space heating and cooling in areas with a pronounced seasonal climate. Basically, pipes are drilled or inserted into shallow rock, water is circulated through them, and the heat is exchanged with that inside a building.
Water pumped up during winter is warmer than outside air, so it can be used to offset space heating from oil, gas, wood or electricity. Water pumped up during summer is cooler than the outside air, so it can offset electricity used for air conditioning. There’s nothing complex here. All that’s necessary is the financial investment and a government policy to encourage it.
But the real power of the MIT report involves using deep geothermal heat to produce steam-powered electricity, not just in volcanic places, but everywhere in the world, even below lands of steady tectonic habits. Such technology could eliminate the need for electric plants fueled by fossil fuels, thereby reining in greenhouses emissions, acid rain, sulfur aerosols and airborne toxic metals, especially mercury. It could also eliminate the need for nuclear power plants, thereby doing away with the chronic anxiety of radio-nuclides being in the wrong place.
The basic idea of steam-powered geothermal is as old as Old Faithful, the world famous geyser in Yellowstone National Park. Cool, shallow groundwater sinks downward through fractures to reach depths where it’s heated by hot dry rock.
Being less dense, the heated water migrates upward. At some critical depth the pressure falls low enough for the water to boil. This lifts the water column, lowers the pressure further and causes the remaining water to flash to steam. Once expelled on the ground, the water condenses, cools and sinks once more.
The MIT report suggests is that we mimic this process by creating artificial geysers that run continuously rather than intermittently. The idea is to drill an injection well to a depth of four to six miles, then pressurize the water to open up fractures. Collection wells are then drilled to tap the hot water. When raised, its steam can be used to drive turbines, condensed back to water, then re- injected as part of a closed loop.
Creating such a power plant does not involve a new invention. All it takes is a one-time substantial investment. There is no risk beyond that of equipment failure. Oil wells can come up dry. But if you drill straight down, nowhere on earth is too cold to make steam.