Dim Scum


The solution to global warming may be floating in our ponds.

By Matt Williams May 19, 2009 Published in the January 2009 issue of Portland Monthly

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MORE THAN eight hundred thousand Portland and Salem area residents get their power from PGE—and about 15 percent of PGE’s electricity comes from a coal-fired plant in Boardman. But the juice comes at a cost: five million tons of globe-heating carbon dioxide per year. What’s a big power company to do? Think small. Algae, it turns out, is extremely adept at turning carbon dioxide into oxygen through photosynthesis. Better yet, it’s a two-fer: the byproduct of that process can be used to create biodiesel. Last July, PGE and Columbia Energy Partners began a pilot project at Boardman using algae to devour ?carbon dioxide. Right now, it’s a small-scale endeavor, but if it’s expanded, the pollution-chewing phytoplankton could eliminate up to 60 percent of PGE’s carbon dioxide, and may also be able to produce a million gallons of biodiesel a year—enough to turn the phrase “pond scum” into a compliment.


CO2 is diverted from Boardman’s smokestack into eight tubs filled with three strains of algae native to the Northwest (including one the researchers have nicknamed “El Gordo,” or “The Fat One”).


It takes the algae just a few microseconds to photosynthesize the CO2, emitting good, clean oxygen in the process. Generally speaking, those eight tubs of algae process a kilogram or so of CO2 each week. But that’s just a fraction of what might be achieved on a larger scale: one ton of algae can convert two tons of CO2.


Twice weekly, the algae is harvested, and once it’s removed from the water, lipid oils are extracted from it via centrifuge. (Other studies being carried out across the country use chemical removal to extract the lipid oils.)


Because the project is so small, little lipid oil is being extracted right now. If the project is expanded and larger amounts of the lipid oils are available, they could be processed into algal biodiesel, which researchers say is a quantum leap over today’s popular soy-based biodiesel. Algal oil stays liquid in lower temperatures than its soy cousin, and a one-acre pond could yield around 2,500 gallons of biodiesel per year; an acre of soy generates only 300 gallons.

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