The U.S. Secretary of Energy—channeling former Soviet leader Nikita Khrushchev perhaps?—has one thing to say in this week's Science to the greenhouse gases emitted by coal-fired power plants: We will bury you. Nobel laureate Steven Chu's department has funneled $3.4 billion in stimulus dollars to research and develop the technology known as carbon capture and storage (CCS).
But to give you a sense of the challenge, here are his estimates of the scale of the challenge: six billion metric tons of coal burned every year, producing 18 billion metric tons of carbon dioxide and requiring an underground storage volume of 30,000 cubic kilometers per year with untold consequences on subsurface pressure, mineral composition and the like. And we are nowhere near that scale: "We now sequester a few million metric tons of CO2 per year," he wrote, largely from cleaning natural gas or so-called "enhanced oil recovery" efforts, in which CO2 is pumped down to flush out more of the valuable petroleum (and therefore not as useful, from a climate perspective, as sequestration for its own sake).
But there is hope. This week the world's first carbon capture and storage at an actual power plant burning coal fired up near New Haven, W. Va. China is following suit, according to a news story in the same issue of Science, launching the Erdos coal-to-liquid plant in Inner Mongolia that will capture some of its 3.6 million metric tons of CO2 emissions and use it to flush out oil from nearby fields.
That's good because such carbon capture and storage "may be the single most effective and direct climate action available," geoscientist R. Stuart Haszeldine wrote in the same issue of Science. Technologies, like amine scrubbers and chilled ammonia or oxyfuel, continue to be improved in the lab and at demonstration projects. And new storage options may be opening up, ranging from offshore sediments to basalt, briny aquifers to porous sandstone. Even capturing carbon dioxide from the air—it makes up 0.04 percent of the air we breathe—might prove possible, according to would-be geoengineer David Keith of the University of Calgary.
Haszeldine and his colleagues therefore call for a quick infusion of massive funds on a global scale, something Steven Chu appears to have at least started in the U.S. And the energy secretary hopes to see major results within a decade.
But is carbon capture and storage really necessary? After all, some studies have shown that major emitters like China or the U.S. could get all their energy from renewables, such as wind or solar.
Chu, for one, doesn't buy it. "It is highly unlikely that any of these countries will turn their back on coal any time soon, and for this reason, the capture and storage of CO2 emissions from fossil fuel power plants must be aggressively pursued," he wrote. "There are many hurdles to making CCS a reality, but none appear insurmountable…. The climate problem compels us to act with fierce urgency."
Image: Courtesy of University of Edinburgh. The largest natural CO2 seep in Italy, at Mefite in Campania, has a CO2 flux exceeding 100,000 tons per year. This has been a site of ritual offerings to the underworld for over 2,000 years, since pre-Roman times. Studies at such sites assist understanding the impacts of unplanned leakage from engineered CO2 storage sites.