Isramart : Turning Carbon Dioxide into a Resource

Isramart news:
Many people have carbon dioxide on the mind, and not just political leaders meeting in Copenhagen. Tom Levitt, in a post on the Ecologist, noted that any long-term plan to curb carbon dioxide emissions has to take into account the fact that, in the short term, carbon emissions will continue to rise. Skeptical of carbon capture and storage—which he equates to burying garbage in landfills—Levitt examines other possible means of turning this waste into a form of energy.

Carbon capture and storage—a process through which carbon polluted into the air from fossil-fuel burning power plants and the like is compressed and then buried deep within the Earth—is hailed as a potential breakthrough for reducing carbon emissions, but is worrisome to some scientists. Levitt points to an alarming statistic provided by authors Robert Kunzig and Wallace Broecker in Fixing Climate. The pair, who say carbon capture and storage will lead to landfills of a much more caustic and damaging nature than the garbage dumps we currently have, put the scenario in these sobering terms: “If the twenty-nine gigatons produced by the world’s fossil-fuel burning in a single year were liquefied and spread over Manhattan, they would bury the island to about the eighty-fifth floor of the Empire State Building.” Levitt also quotes Columbia University’s Frank Zeman, who works for the school’s Department of Earth and Environmental Engineering, saying that using carbon capture and storage will create significant friction over the challenges surrounding its disposal.

Among some of the most promising options of carbon dioxide recycling is reusing the captured emissions to feed algae, or growing algae in waste water that could potentially emit carbon dioxide. As Levitt explains, “through the process of photosynthesis algae is able to use sunlight to absorb carbon dioxide and provide an end product—oil or feedstock.” At the University of Minnesota sewage water has been used to grow algae, recycling the carbon dioxide that would emit from the waste water if it were left alone.

Levitt writes that yields for algae are, right now, more promising than other biofuels—10,000 to 15,000 liters of oil per hectare versus 5,000 to 6,000 liters for palm oil plantations. But production is still low and faces several challenges.

One difficulty in producing algae is collection, and another is harvesting it. The latter process requires large amounts of energy, which increases production costs. Some companies that have announced plans to turn sewage into biofuels, like New Hampshire’s Simply Green Biofuels, have not yet found an economical way to process algae into fuel.

Nonetheless, Levitt points to University of Minnesota’s Roger Ruan, a professor who believes commercial algae production could be at significantly higher levels in just five years. And Graciele Chichilnisky, an academic who helped outline the Kyoto protocol, sees potential for algae production in poorer, less-industrialized countries. (Some scientists think tropical climates will bring the best algae yields.) Chichilnisky said:

We need negative carbon technologies to bring most of the Clean Development Mechanism (CDM) investment to the regions that need it most: the low emitters in Africa, Latin America and the Small Island States that need energy to grow and to adapt and mitigate the catastrophic risks of climate change.

Green cement is another thing scientists are researching in the hunt to find ways to reuse carbon dioxide. Cement, as Levitt notes, accounts for 5 percent of greenhouse gas emissions. Green cement would, as Levitt writes, uses “non-carbonate materials that cut out most of the CO2 emitted during production.” He adds that green cement also absorbs carbon dioxide during production, which helps make it “carbon negative.”

Hydrocarbon fuels offer another hope for recycling carbon dioxide. By reacting hydrogen with CO2 you can produce hydrocarbon fuels. As Levitt notes, the “big hope for a renewable hydrocarbons sector is the ability to use solar energy to split water (H2O) to make hydrogen.” But this possible new energy sector also faces economic hurdles. As Columbia’s Dr. Frank Zenman notes: “The million-dollar question is solar-pv [photovoltaic] hydrogen. It’s too expensive at the moment but it is the panacea. This kind of closed loop system is the future if we are ever to reach zero carbon emissions.”