CURBING EMISSIONS WON’T BE ENOUGH

We˜re great at spewing CO2 into the air. Visionaries are devising ways to suck it out

Like many people who are scrambling for ways to stave off climate disaster, Klaus Lackner is thinking trees. But not the kind with green leaves and roots, and certainly not the sweet little specimens that “carbon offset” purveyors hawk as a way to balance out the carbon dioxide emitted when you tool around town in a Hummer. 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.

A new phrase has emerged in the debate over climate change: managing the unavoidable. To grasp “unavoidable”, consider a few simple numbers. Before the Industrial Revolution, the atmosphere held 280 parts per million of carbon dioxide (CO2). We are now at 380 and climbing. Combine that pathetic record with another number: molecules of carbon dioxide stay in the atmosphere as long as 200 years; yes, carbon dioxide molecules belched out by Model Ts are still up there. As a result, “incremental reductions in CO2 emissions” as called for by the 1997 Kyoto Treaty and legislation pending in Congress “will not stabilise atmospheric CO2 levels,” argues climate researcher Wallace Broecker of Lamont-Doherty Earth Observatory, part of Columbia. “They only slow the rate of increase.”

Environmental leaders are, therefore, getting serious about carbon capture and storage. The idea is to suck carbon out of the ambient air or out of power plants where it’s produced, and store it in the deep ocean or in depleted oil and natural-gas fields. The US Department of Energy is spending $100 million this year for R&D on carbon storage, up from $1 million in 1997. Just before his death in 2006, Gary Comer, founder of Lands’ End, funded a start-up company in Arizona, called Global Research Technologies to develop ways to pull CO2 out of the air. In February, Sir Richard Branson, chairman of the Virgin Group, and Al Gore announced the creation of a $25 million prize for devising a way of, as Branson put it, “removing the lethal amount of CO2 from the Earth’s atmosphere.”

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Enter Lackner’s synthetic, carbon-sucking tree. It is only conceptual, but he calculates that an area of sodium hydroxide the size of a television screen 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.”

Even cheaper than drawing carbon dioxide out of the atmosphere is capturing it from power plants before it heads for the sky. GreenFuel Technologies Corp., in Massachussets, has invented a process for treating power-plant exhaust to remove a large fraction of the CO2. The basic technology is 3.5 billion years old — that’s when organisms first began photosynthesising — and all it takes is a greenhouse and a trough filled with algae. A prototype is under construction at a 1,000-megawatt natural-gas-fueled power plant outside Phoenix run by Arizona Public Service. Built to full capacity — which would require about 8,000 acres — it could absorb as much as 80 percent of CO2 emissions during daylight hours. With ethanol or biodiesel as byproducts, an algae installation could actually be a profit centre, says GreenFuel CEO Cary Bullock.

The US Department of Energy is working on ways to grab CO2 from coal burned for electricity. Existing technology can reduce CO2 emissions from coal-fired or natural-gas power plants by 80 to 90 percent, estimates the IPCC.

Earth has no shortage of places to stow the stuff, starting with depleted oil and natural-gas fields as well as the deep ocean. By one estimate, the storage capacity exceeds 545 billion tons of carbon, or 70 years’ worth at current emissions levels.
SHARON BEGLEY (Newsweek)

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Some Earth TErms
Carbon Footprint: The effect human activities have on the climate in terms of the total amount of greenhouse gases produced. This quantity is usually measured in units of CO2 emitted per year.

Net Metering: A method of measuring the energy produced and consumed at a home or business. If a customer generates more than is used, the surplus electricity will run the meter backward.

Carbon Offset: The process of balancing a unit of carbon dioxide emissions with a product that saves or stores an equivalent amount of CO2. Carbon credits are typically bought and sold through a number of online retailers and trading platforms.