ENN, a Chinese firm, is developing a greenhouse that functions like a bioreactor. The bioreactor breeds micro-algae using carbon captured from gasified coal. Various strains of micro-algae are among the fastest growing species on earth.
According to the Guardian (UK), China is one of the world’s largest emitters of C02, largely because of its reliance on coal-generated power. Almost none of the C02 emitted by coal plants is captured because, to date, there has been no profitable way to use the CO2. Algae may provide a solution — “The organism can absorb carbon far more quickly than trees, a quality that has long attracted international scientists seeking a natural method of capturing the most abundant greenhouse gas.”
In ENN’s process, coal is first gasified in a simulated underground environment. C02 resulting from the extraction process is then ‘fed’ to algae, which can then be used to make biofuel, fertilizer, or animal feed. (To further cut down emissions, the C02 can be extracted from coal using wind or solar power). According to the Guardian, Deborah Seligsohn, China Director for the World Resources Institute, was positive on the technology: “Algae biofuels and sequestration are being tried in a bunch of places, but never with such an innovative energy mix. It is really interesting and ambitious.”
Researchers working on the algae greenhouse plan at ENN seek to scale up the trial to a 100 hectare (247 acre) site. “If it proves commercially feasible, coal plants around the world could one day be flanked by carbon-cleaning algae greenhouses or ponds.” Zhu Zhenqi, an advisor to the project, said to the Guardian: “Algae’s promise is that its population can double every few hours. It makes far more efficient use of sunlight than plants. The biology has been proven in the lab. The challenge now is an engineering one: We need to increase production and reduce cost. If we can solve this challenge, we can deal with carbon.”
However, there are a few potential pitfalls. Algae must be harvested daily. Additionally, extracting the oily components (which can be used in biofuels) is still an expensive process. Some researchers are exploring spraying or bubbling CO2 into algae ponds. Others, like ENN, are controlling the process in greenhouses, creating a reactor. In either case, land and water is needed, and algae facilities or ponds would need to be located near enough to coal power plants to be economically feasible.
Also, the New York Times recently wrote about a new demonstration project led by Dow Chemicals and Algenol Biofuels, which would feed CO2 to algae to produce biofuels. In this process: “algenol grows algae in “bioreactors,” troughs covered with flexible plastic and filled with saltwater. The water is saturated with carbon dioxide, to encourage growth of the algae. ‘It looks like a long hot dog balloon,’ Mr. Woods said. Dow, a maker of specialty plastics, will provide the ‘balloon’ material. The algae, through photosynthesis, convert the carbon dioxide and water into ethanol, which is a hydrocarbon, oxygen and fresh water.” Algenol is planning a demonstration project that could produce 100,000 gallons of algae-generated ethanol per year. Read the article
Image credit: Jonathan Watts / Guardian