Technology:

Can Carbon Dioxide Replace Steam to Generate Power? (Scientific American)

Credit: Michael Spiller/Flickr

Much has changed in the modern electric power plant since Thomas Edison's era, but the parts that actually turn heat into electrons haven't changed since his eureka moments.

Whether burning coal, concentrating sunlight or splitting atoms, most thermal power plants use the energy for the same thing: heating water into steam to drive a turbine. Steam-based generation produces 80 percent of the world's electricity.

After more than a century of incremental improvements in the steam cycle, engineers have plucked most of the low-hanging fruit and are chasing diminishing returns, spending millions of dollars for every percentage point of efficiency improvement. These upgrades propagate to other steps in electricity production, allowing power plants to extract more work for a given unit of fuel.

Now engineers are looking into replacing steam with supercritical carbon dioxide, a technique that could unlock up to 50 percent greater thermal efficiency using a smaller, cheaper turbine.

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