The explosive growth of worldwide energy demand has made it painfully clear that that our traditional sources of electricity can no longer be expanded without creating a major environmental tragedy. Coal burning during the industrial revolution created localized disasters but the massive scale today is creating disaster on a global scale. Fuel costs are growing exponentially as we reach the limits of our planet's resources.
The failure of the Futuregen "clean coal" project is the nail in the coffin of the coal power boom. Oil and natural gas supplies are running short but coal supplies were thought to be plentiful and cheap. "Clean coal" was supposed to rescue us from global meltdown by capturing the CO2 and storing it underground. The problem is that every ton of coal burned produces 3.7 tons of CO2! The idea of transporting and hiding forever that much CO2 was ludicrous from the start. To make matters worse, coal prices have quadrupled since 2003.
Even if we ignore CO2, coal is an environmental nightmare: Mercury emissions make it dangerous to eat many fish today and may be responsible for our epidemic of autism. Acid rain has destroyed forests, lakes and coral reefs. Particulates from coal smoke gray our skies and cause asthma and lung disorders. There is little doubt that the coming elections in the U.S. will bring an end to the denial of coal's unsolvable problems. Already new laws are being considered to ban coal outright. But what is the alternative? Solar power works mainly during midday and wind power can stop almost completely from late night through morning. Weather conditions can completely disable both wind and solar. Geothermal power uses no fuel, produces no pollution and works reliably and steadily all day and every day.
While we were depending on the dream of "clean coal," research funds for alternative sources of baseload power were choked off. Now that that dream has died we have a choice between continuing to foul the planet with more coal plants or running short on power. A bill to ban conventional coal plants is now pending in congress but this could cause massive South Africa-like power shortages in the future unless we take dramatic action now to develop alternatives.
In January 2007, MIT released a report on the amazing potential of Enhanced Geothermal Systems. By injecting water into hot rocks underground to produce steam, power can be generated in areas never considered for geothermal. The U.S. Department of Energy responded by cutting its already inadequate $20 million geothermal research budget to zero. After a tough battle, (including a failed attempt to reallocate some of the US $13 billion in coal, oil and gas subsidies), congress finally came to the rescue with the 2007 energy bill, which appropriated US $90 million for EGS research. The DOE responded by ignoring the law and budgeting only US $30 million in their 2009 budget! (They still have US $407 million budgeted for coal!)
With the elections drawing near, there is hope that we can restore some sanity to our energy policy but precious years have been wasted. The MIT report suggested a US $900 million program to develop EGS geothermal technology. If the DOE director hadn't ignored that plea, we could be building large-scale EGS plants today instead of continuing to crank out coal plants.
Every time we commit to building a megawatt (MW) of coal power capacity we are also committing to produce hundreds of million tons of CO2 over the life of the plant. A typical coal plant emits 2.1 lbs of CO2 per kilowatt-hour (kWh).
Australia has vast coal resources, yet the new government has committed to a massive effort to develop EGS geothermal power plants. Drilling was just completed on the first wells for a 500 MW EGS powerplant in the desert. There are 33 companies with 277 exploration licenses working on projects all over the country. Germany has provided free connection to the grid for remote geothermal projects. This has triggered a gold-rush boom in geothermal projects with over 100 exploration licenses granted so far. Medco in Indonesia just signed a $600 million contract for a 340 MW geothermal plant that will sell power for only $.0468/kWh.
New price breakthroughs in modular geothermal generators have been made possible by adapting high-volume air conditioning chillers to run backwards as generators. UTCPower has a new 250 kW, truck-transportable unit called Purecycle that works with temperatures as low as 74°C. Another breakthrough, called the Kalina cycle, improves the efficiency of low temperature systems by as much as 30%.
Geothermal power stations have traditionally been built in thermal hot springs areas but Hot Dry Rocks technology taps the heat from dry rocks deep in the earth by using the same water-injection technology that has been used for decades to get more oil out of old wells. There are some 50,000 oil wells in the Gulf states that are already spewing hot water mixed with oil to extend the life of the well. This hot water can be used to generate power now. It is estimated that the geothermal energy produced could exceed the power in the oil already extracted!
Drilling and exploration costs make geothermal power plants expensive to build. However, cost/watt construction costs are a poor measure of true cost: Coal plants, for example, must be fed an endless stream of trainloads of coal. Coal prices have increased 140% since January 2007. Coal also has incalculable hidden costs from severe storms, acid rain, contamination of fisheries and increased healthcare costs. In spite of massive subsidies, the real cost of coal power is clearly more than geothermal.
Of course there are other clean renewable sources of electric power besides geothermal. The reason we use coal for over 50% of our power is that it provides predictable, base-load power. Weather is unpredictable. Sunshine and wind can sometimes drop to a tiny fraction of their long-term averages for months at a time. Base-load power is needed to provide a predictability base to be supplemented by wind and solar when available. Maintenance shutdowns reduce average availability (capacity factor) to 71% for coal and nuclear and 90% for geothermal.
Depending on location, the capacity factor of wind power averages only 30% and solar averages 18% in "normal" years. These capacity factor figures cannot be ignored. Your electric bill is for kilowatt-hours not kilowatts.
In a normal year, 1 MW of geothermal capacity will generate as many kWh as 6 MW of solar power in New York or 5 in California. Wind power averages 30% capacity factor so 3 MW will generate as much as 1 MW of geothermal. On bad weather years the differences are even greater. We have been injecting water into the earth to squeeze more oil out of depleted wells for decades. It works and doesn't cause earthquake problems any more than blasting the tops off of mountains to get coal does. Geothermal heat is continually replenished by atomic decay of isotopes in the rocks. It is renewable, reliable and clean and doesn't clutter the landscape.
The scientists at DOE have tried to support geothermal for years only to have it shot down by high-level politics. It makes no sense to be mining and hauling coal then trying to bury the mess when the free heat of the earth will boil all the water we need. The time has come to take bold action with a Manhattan Project-like crash program to develop and scale up EGS technology to free us from the bondage of coal.
Thomas R. Blakeslee is president of The Clearlight Foundation, a non-profit organization that invests in renewable energy and other socially useful companies and issues cash grants to individuals who are working effectively for change.