Thursday, February 7, 2013

Meet the tonic for a clean energy future: Molten salts

By  | January 30, 2013, 5:52 AM PST

Salting the highway. Molten salts can help produce hydrogen that would power cars such as this Mercedes Benz prototype.
So the world has an energy hangover from its centuries long binge on fossil fuels. Here’s the coming cure: molten salts.
These intriguing elixirs and their handy thermodynamic properties will soon stream and bathe their way into any number of power and industrial applications that will help the planet kick its addiction to hydrocarbons.
Want to produce hydrogen? Store solar energy? Remove CO2 from fossil fuels? Build a much safer and more effective nuclear reactor? Slash the carbon footprint of oil sand production?
Then try a molten salt.
As the name implies, these substances are salts that melt at a high temperature - hundreds of degrees C, depending on the particular salt. They’re stable, they’re good at absorbing heat, they don’t boil easily (convenient when you need a very hot liquid) and they flow like water.
Many of you will already know that molten salts could hold the key to turning solar electricity into a round-the-clock affair, rather than the intermittent “only when the sun shines” state that characterizes it today. A handful of “solar thermal” power plants - Gemasolar in Spain andCrescent Dunes in Nevada, for example - are or soon will start to warm up molten salts with special reflective mirrors in order to store heat that by night they can convert to steam and drive a generator.
Keeping the heat on. Mirrors reflect sunlight that warms molten salt in this Gemasolar plant in Spain. The salt releases heat to drive a turbine at night.
Regular readers of my blog will also know that alternative nuclear reactors that use molten salt fuel and coolants at high temperatures could trump today’s conventional reactors in many ways. They’d be safer, meltdown proof, would operate more efficiently, leave much less long-lived waste, and their waste would be less suitable for fashioning bombs. Use thorium instead of uranium in those reactors, as China is planning, and those advantages hold even truer.
Here’s another potential use, as I wrote recently on my blog for the Weinberg Foundation, a London-based non-profit group that advocates alternative forms of nuclear energy:
Molten salts can help extract hydrogen while at the same time removing CO2 from hydrocarbons like oil sands, according to Western Hydrogen Ltd., a Calgary-based company.
Deploying molten salt technology developed at the U.S. Department of Energy’s Idaho National Laboratory, Western Hydrogen thinks it can pull hydrogen out of “carbonaceous” materials such as the bitumen in the oil sands common in Canada, as well as from other petroleum residue and petroleum coke.

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