ALGAE have been touted as a solution to environmental worries over biofuels, but they may be a long way from providing a truly green option.
Unlike maize, soya beans and oilseed rape (canola), algal farms don't take up valuable farmland, so algae-based biofuels don't threaten food supplies. However, Andres Clarens at the University of Virginia in Charlottesville has modelled the environmental impacts of algal farms and concludes that they require six times as much energy as growing land plants - and emit significantly more greenhouse gases (Environmental Science and Technology, DOI: 10.1021/es902838n).
"You have to add a whole lot more fertilisers, and the environmental cost of producing these is the primary drawback," Clarens says.
Using waste water instead of fertilisers helps, but not enough, he says. The only trick that tipped the balance in favour of algae in his models was to use nutrient-rich household waste like concentrated urine to fertilise the algae, but this would require new infrastructure and so is no short-term fix.
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Algal Power Not So Green After All
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Algal power not so green after all, yet
New Scientist, January 28, 2010
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