Algae absorbs carbon a lot more quickly than trees.
So the slimy green stuff has long been a top candidate for bio-based systems to trap and store CO2, the most abundant greenhouse gas, that is created by, among other things, burning coal -- which supplies close to a third of the world's energy consumption.
On a research campus in Langfang, about an hour out of Beijing, Chinese firm ENN is prototyping a carbon capture-and-storage (CSS) system that uses green algae to absorb CO2, reports the UK's Guardian newspaper:
"Coal is first gasified in a simulated underground environment. The carbon dioxide is extracted with the help of solar and wind power, then "fed" to algae, which can be then used to make biofuel, fertiliser or animal feed...Researchers at the algae greenhouse plan to scale up the trial to a 100 hectare (247 acre) site over the next three years. If it proves commercially feasible, coal plants around the world could one day be flanked by carbon-cleaning algae greenhouses or ponds."
The algae is grown in stacked tubes in a nearby "bio-reactor." It must be harvested every day. "ENN is experimenting with different algae to find a hybrid that has an ideal balance of oil content and growth speed. It is testing cultivation techniques using varying temperatures and acidity levels," reports The Guardian.
While oil from algae can be used as a biofuel, extracting it is both costly (over three times more expensive than palm oil extraction, according to a 2007 study) and energy-intensive. So algae-based CSS systems may ultimately be one of a suite of solutions to keeping industrially-generated CO2 out of the atmosphere.
China relies on coal for about 70% of its energy. As a developing economy that's still trying to pull millions of citizens out of poverty, it is not bound by the GHG targets agreed to under the Kyoto climate treaty.
But having surpassed the United States as the world's greatest greenhouse gas polluter 2007, China is under intensifying international pressure to curb the roughly 6.8 billion metric tons (and rising) of greenhouse gas pollution it produces per year.
Despite China's refusal so far to commit to carbon targets, it may have more to gain than lose in the long run from capping and lowering greenhouse gas pollution: A new report from Greenpeace and Oxfam has documented that some of China's most impoverished people are also enduring some of the worst manifestations so far of global warming. Shifting weather patterns are causing floods and droughts that damage farm fields, destroy homes, and leave thousands with reduced access to clean drinking water.
Image: "Pediastrum, a flat colony of green algae." Via Microscopy UK.
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