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Making Energy With Salt and Thorium

from KHouse
Mount Storm Power Station in Grant County, West Virginia, generates almost 1600 megawatts of electricity from burning West Virginia’s famous coal. The power plant is not the only source of energy on the mountain, though. From the shores of Mount Storm Lake—the reservoir used to cool the power station—at least thirty large wind turbines can be seen turning in the high mountaintop winds. The NedPower Mount Storm wind farm employs a total of 132 wind turbines running along 12 miles of mountaintop, each with a 2 megawatt capacity.
One mountain ridge offers two methods of producing energy, one renewable and one not-so-much, but at 1600 MW, the coal-fired power station offers six times the energy production of those 132 wind turbines. Replacing fossil fuels with renewable energy isn’t as simple as one would hope.
One of the greatest challenges of our times is to find sources of inexpensive energy that don’t leave us dependent on foreign nations for fuel, don’t create environmental hazards that poison our water or give our dogs extra eyes, and won’t run dry on us during the next few generations. The human race has plenty of ideas, from molten salt to liquid thorium reactors. The question is… will alternative energies be nipped before they can bloom or will expenses, inherent cons, and the ubiquitous red tape choke the life out of them?
Energy Consistency
The quest for renewable energy has caused wind farms with their multitude of turbines to poke up across America like porcupine quills. Solar plants abound in Germany and the rest of the world is watching. The problem with solar and wind, however, is that they offer little consistency. The sun goes down. The wind stops blowing. The technology is improving and the costs are dropping, but wind and solar still do not produce enough efficient, consistent energy to begin to replace the likes of Mount Storm’s coal-fired power plant.
Even Germany’s vast solar success may not be as sunny as it’s been sold to the world. In October, a scathing analysis of Germany’s use of solar power appeared on the Forbes website. Ryan Carlyle pointed to the high costs of solar and the country’s increasing dependence on coal power during the times the sun doesn’t shine. Germany suffers from too much power they don’t need in the summer, putting all non-solar power suppliers in financial straits and resulting in exceptionally expensive power in the winter. Carlyle stated that Germans pay $0.34 per kWh, one of the highest rates in the world, and that 300,000 German households lose their electricity every year because they can’t pay their high energy bills. (Most Americans still pay less than $0.12/kWh, according to the U.S. Energy Information Administration.)
The Light Switch
It wouldn’t hurt the members of the human race to turn off the lights more often, to ride their bikes, to put on a sweater when the house feels cool. At the same time, the members of the human race are filled to the brim with bright ideas. The production of clean, safe, readily available energy is a problem, but not because human ingenuity hasn’t developed a wide range of potential ideas:
Molten Salt
Generally when we think of solar power, we think of photovoltaic cells, which convert the photons from the sun into electrons and harness them into an electric current. Solar thermal plants use a different means to grasp the sun. They employ big, curved, mirror-lined troughs to focus the light from the sun to create heat that turns turbines. Think of starting a fire with a magnifying glass—row after row over almost 2000 acres.
The Solana solar farm recently opened 70 miles southwest of Phoenix, Arizona—1920 acres of parabolic trough mirrors that can generate 280 MW of electricity. Solana is the first solar farm to store its thermal energy in molten salt, offering a detour around the problem that solar farms consistently face: the sun hides at night.
Systems that depend on photovoltaics have to use expensive, somewhat inefficient batteries if they are to store unused energy created during the day. Solana’s use of molten salt—a mixture of sodium nitrate, potassium nitrate, and calcium nitrate—provides a way of prolonging the plant’s energy production long after sundown. After the sun heats the liquid salt to 566°C (1,051°F), it is stored in well-insulated heat tanks where it can remain for hours until needed to create the steam that turns the turbines that generate energy.
Still, the setup is expensive. The technology works, but at 1 MW per 6.9 acres, it will be a long time before Solana pays off its $2 billion price tag.
Energy Consistency
Across the world, various means are used to store wind and solar energy so that a surplus of energy won’t be wasted, to squirrel it away until a later time when demand is high. Batteries. Molten salt. Pumping air into underground caverns and releasing it to turn turbines when it’s needed. Pumped Storage Hydroelectric plants generate electricity by directing water downhill through turbines. When demand is low, these plants pump water back uphill to store for use when demand increases again.
The ability to efficiently store energy is just as large an issue as producing it in the first place. As environmentally unfriendly as fossil fuels may be, their use in power plants is easy to control. Coal can always wait to be fired until everybody gets home from the beach.
Thorium Reactors
And then came nuclear. Nuclear power has offered another alternative to coal and petroleum products, one that is still highly controversial. Light-water nuclear reactors operate cleanly and inexpensively, producing plenty of energy without also producing much-maligned CO2 emissions. Of course, people get put off by the occasional meltdown that spews radiation into the air and water. There is also the huge issue of waste. The uranium-dioxide fuel rods must be changed out after only 3–5% of the uranium is used, forcing the disposal of highly radioactive material that will take multiple thousands of years to “cool.” The plutonium generated by light-water reactors also runs the risk of being swiped by disreputable groups for use in bombs destined for places like New York and Tel Aviv.
Blame it on the Cold War. We did not have to focus on light-water reactors with their associated problems. Back in the 1950s, though, producing plutonium as a bi-product sounded like a good idea. Admiral Hyman Rickover wanted the U.S.S. Nautilus, the world’s first nuclear submarine, to get into the water as soon as possible, and the LWR was the most convenient choice at the time. The Nautilus was launched in 1954, and the world followed down the uranium path.
It didn’t have to be thus; other fuel sources could have been used. A successful liquid-fluoride thorium reactor was developed at Oak Ridge National Laboratory in Tennessee between 1959 and 1973, until the Nixon Administration shut it down because the reactor didn’t produce plutonium. These days, plutonium production is a huge risk factor.
Thorium is common on the planet and contains vast amounts of energy. It’s as common as coal with exponentially greater energy potential—and without the pollution coal causes. It requires a kick-start because it won’t start reacting on its own, and stockpiles of existing waste can be used to do the kick-starting. Once it gets going, thorium decays through several steps into uranium–233, an excellent fuel source, without requiring the removal of partially used fuel rods.
The use of thorium as a liquid fuel avoids a number of the major problems that cause light-water nuclear reactors to be as dangerous as they are. Rather than the high-pressure toxic water that cools LWRs, thorium reactors are cooled with liquid fluoride salt under normal atmospheric pressure. The reactor won’t melt down because its normal state-of-being is molten salt at its core. If that salt leaked out, it would simply solidify. A thorium reactor produces a minute fraction of the waste that LWR reactors produce, and the waste breaks down in terms of hundreds of years rather than tens of thousands. There is some argument about whether the uranium–233 can be stolen for use in weapons, but proponents argue it would be highly difficult to do so.
Various forms of sticky tape promise to keep thorium reactors on the back burner for decades in the United States, where conventional nuclear and the oil industry can put up a deep-pocketed fight. Outside the U.S., a variety of countries are already pursuing the thorium dream. Thirty-two countries were represented at the Thorium Energy Conference in Geneva, Switzerland in November, with notable attendees who included CERN Director General Mr. Rolf-Dieter Heuer, former International Atomic Energy Agency director Hans Blix, and Nobel Prize Laureate Carlo Rubbia. Thor Energy in Norway is already working on using thorium in existing reactors, and the British nuclear scientists have been involved in developing research for use in thorium reactors in both Norway and India.
We have plenty of options for producing energy that doesn’t depend on finite oil resources in hostile foreign lands. We have options that don’t demand we pollute our watersheds or litter our horizons with windmills that depend on the inconsistent wind. The question is whether we’ll pursue the courses that will produce the most benefit, or whether we’ll get hung up in the bad politics of pushing solar panels on locations where the sun is absent half the year.

Notes
Mount Storm Power Station
— Dominion
NedPower Mount Storm
— Shell
Average Revenue per kWh by State
— Energy Information Administration
ThEC13 in Geneva at CERN—Success!
— Thorium Energy Conference
The Nuke That Might Have Been
— The Economist

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