Synthetic trees & other ways to keep emitting

Finally got around to reading this short but interesting piece in Newsweek on carbon sequestration.

Carbon sequestration is–as of yet–an untested means of capturing carbon dioxide emissions, either before the CO2 is even emitted (as in the case of coal gasification) or out of the ambient air and then storing it in oceans or deep underground.

A number of groups, including Al Gore and the Department of Energy are investing in sequestration technology. Newsweek highlights one concept I never heard about:

Lackner, a professor of geophysics at Columbia University, is helping to design a synthetic tree. It would stand roughly 1,000 feet tall with a footprint a little bigger than a football field, and be crisscrossed with scaffolding holding liquid sodium hydroxide, which is best known as lye. For in addition to cleaning drains, sodium hydroxide has a chemical property that promises to be in great demand if, as seems likely, the nations of the world fall short of stabilizing the atmosphere’s load of greenhouse gases: it sucks carbon dioxide out of the air…

It is only conceptual, but he calculates that an area of sodium hydroxide the size of asynthetic trees television screen (not a 103-inch plasma behemoth but the 20-inch diagonal that people found just fine once upon a time) would soak up an amount of carbon equivalent to what one American is responsible for emitting. Or, to use another comparison, one tree could absorb about as much as 15,000 cars emit. Paired with a windmill, the carbon-capture tree would generate about 3 megawatts of power, Lackner calculates, making the operation self-sufficient in energy. “The carbon-capture efficiency is better than a [living] tree,” he says. “We can, with such a system, collect a significant fraction of the carbon from the air.” Carbon capture from the air has the advantage of removing this pollutant no matter where it came from—cars, planes, factories, power plants. No other carbon-capture technology now on the drawing boards would work on moving sources, such as cars and planes.

The fact that Al Gore paired up with Richard Branson to offer a $25 million prize for the best plan to remove carbon from the air should not be ignored. Though Gore is focusing most of his energy on educating people about the crisis and now, more and more, advocating policy solutions for reducing emissions, he is clearly concerned that we won’t have enough time for reduction policies and technologies to work. The writer, Sharon Begley, does a very good job explaining why:

The growing interest in carbon capture also reflects the fact that the climate we have at 380ppm of CO2 is dire enough that even the inevitable 450ppm—perhaps 40 years away—looks scarier than it once did. Hurricane Katrina happened at 380. Glaciers are melting and coral reefs are dying at 380. The 2003 heat wave in Europe, which killed an estimated 35,000 people, happened at 380. The seas are rising at 380. Arctic sea ice is vanishing at 380; according to an analysis in the journal Science last month, by 2040 the Arctic may have zero summer sea ice. However you feel about polar bears not having floating platforms from which to hunt seals, the vanishing ice will shift wind patterns in a way that intensifies midlatitude storms, increasing wintertime precipitation over Western and Southern Europe, but reduces rainfall in the American West. Since 1998 that region has been mired in a historic drought. According to a study led by Lamont-Doherty’s Richard Seager to be published in Science, the Dust Bowl drought of the 1930s “will become the new climatology of the American Southwest.”

And yet, how much impact could capture & storage really have? According to Begley, earth sinks (oceans and depleted oil and natural gas fields) are large enough to store about 70 years’ worth, at current emission levels. There are two huge problems with this:

  1. Emission levels are increasing. CO2 emissions have more than tripled since the 1950s and are predicted to double from current levels by 2054 if we proceed on our current path. That means we would be able to store far less than 70 years worth. Try more like 35. I’m almost 35, so please don’t tell me that 1972 was eons ago.
  2. We aren’t even close to being able to broadly implement sequestration initiatives. The Department of Energy has raised its annual funding of sequestration R&D to $100 million, but that’s about how much money we spend to fund the Iraq War every nine hours! We’re probably further away from massively deploying sequestration than hundreds of alternative energy technologies.

So tell me this, why are we seriously entertaining this as a legitimate option for mitigating climate change?


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