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Harnessing Entropy

In Solar, a novel by acclaimed author Ian McEwan, the protagonist, a physicist named Michael Beard, has been tasked to evaluate submissions from the public sent to a UK panel looking for new ideas for clean energy. He divides them into piles: those that violate the first law of thermodynamics, those that violate the second law, and those that violate both. This cleantech reporter could relate.

That’s why ideas that start with the laws of thermodynamics – rather than those that have to account for them later – are so attractive. Take entropy, for example. In our daily life we struggle against entropy – the iPod headphone wires that get totally knotted up in my handbag, the fact that the neatest person you know still has a junk drawer, and so on.

This week’s issue of C&EN explores research that tries to harness the universe’s arrow-like movement to disorder. When CO2 laden emissions from power plants are released into the atmosphere, the CO2 mixes into the ambient air mass. As Naomi Lubick explains, an electrochemical cell could harvest the energy that is released when these two gases mix. Researcher Bert Hamelers of the Dutch water treatment tech center Wetsus, has developed a lab scale device to do just that.

But Lubick points out that to implement such a solution would require overcoming at least two hurdles – one, the sulfur dioxide and nitrogen oxides may foul the system’s membranes. And two, it is no easy task to dissolve huge amounts of CO2 in liquid.

Dissolving gas in liquid requires toil and trouble. Credit: Wikimedia Commons

Dissolving gas in liquid requires toil and trouble. Credit: Wikimedia Commons

In fact, dissolving the gas uses quite a bit of energy. Which reminds me of another literary reference: the witches of Shakespeare’s MacBeth chant “Double, double, toil and trouble; Fire burn and cauldron bubble” – indeed, there is some toil and trouble involved.

I know that many other researchers and technology companies are working on these two problems. For example, there are programs working on carbon capture and storage that are using liquids, catalysts and membranes to grab components of power plant emission gases. And firms such as Calysta Energy and Lanzatech have plans to use microbes to make useful products out of gases such as methane and flue gas. For that, they need to dissolve the gas in water. It is not a trivial problem.

 

1 Comment

  • Sep 13th 201315:09
    by gerritjansen

    Some of these challenges are already met. One of the last sulfur mines in the world was shut down years ago since all the sulfur anyone would need could be obtained from the flue gases of fossil fuel plants. Noxout is the core business of a company called Fuel Tech (FTEK). Water treatment of cooling towers routinely deals with solubility of carbonates in water through “Cycles of Concentration”. I have some interest in growing micro algae from the CO2 from the stack and the blowdown water from the power plant cooling towers. If my math is correct, one percent conversion of CO2 from the stack of an average coal-fired plant into algae biomass yields 1 million gallons of biodiesel every 90 days.

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