Aug 27 2009

Retrofit Your Home with . . . Algae?

Posted by: Jonathan Marshall

Just how far are you prepared to go to fight global warming? Would you cover your home with algae?

That, essentially, is the intriguing proposal advanced this week by the Institution of Mechanical Engineers, a 160-year-old professional organization, based in London, devoted to sustainable energy and cleaner and safer transportation.

In a major new report, Geo-Engineering - Giving us time to act?, the organization argues that in addition to the usual climate-change proposals, governments need to consider geoengineering schemes to cool the planet before we experience "dramatic changes to our climate . . . which could jeopardise modern civilisation."

Unlike some science-fiction-sounding proposals, like firing millions of solar reflectors into orbit, the group's three favorites include making building roofs more reflective (a favorite of Energy Secretary Steven Chu), building millions of "artificial trees" to chemically absorb CO2 out of the atmosphere (an idea championed by Columbia University physicist Klaus Lackner), and--most intriguingly--"algae-coated buildings."

This latter approach may seem a tad unappealing, but hear them out.

The idea is to install sealed containers of algae--photobioreactors--on the side of new or existing buildings. As the algae grows inside, it absorbs CO2 from the surrounding air, reducing greenhouse gases.

The carbon in the algae can then be "sequestered," or stored, by turning it into biofuel or into biochar, a soil additive used by farmers since prehistoric times, as discussed previously in NEXT100.

The algae-filled panels could use waste water or salt water, avoiding the need to tap scarce fresh water supplies. And by insulating buildings, they would reduce energy usage by  occupants.

The institute concedes that the proposal is "very much at a conceptual stage," its technical feasibility remains unknown, and the cost of photobioreactors is at present "too expensive to be commercially viable." (And here's a question they don't answer: why would you install an algae photoreactor, with a photosynthetic efficiency of less than 5 percent, instead of photovoltaic building materials with twice that efficiency? ) But the group insists that many of the underlying processes are proven and the idea "is worthy of further research."

Any volunteers?

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