Green power from algae?

Posted: Monday, March 30, 2009 6:08 PM by Alan Boyle

William A. Cotton / Colorado State University Click for video: Alpha cribs containing colonies of algae grow under artificial lights at Colorado State University's Engines and Energy Conversion Laboratory. Click on the image to watch an archived video about algae-based biofuels from NBC Nightly News.

In the past, Venetians have looked upon algae as their scumbag enemy, but now they're hoping to tame the plants to satisfy the historic Italian seaport's energy needs. Will algae provide the ultimate in green power, or is the scheme merely a green pipe dream?

The Venetian port authority's deal with Enalg, announced last week, represents one of the latest and highest-profile forays into algae-fueled energy production. As detailed in the port's news release, the plan calls for construction of a $273 million, 40-megawatt power plant by 2011, using technology pioneered by Washington-based Solena Group.

Like many other plants, algae produce an oil that can be converted for industrial use. Solena's process involves growing the algae in plastic cylinders that are supplied with water, carbon dioxide and sunshine. The resulting biomass is then turned into a synthetic natural gas to fire electricity-generating turbines. The carbon dioxide released by burning the gas is fed back into the system to help grow the next generation of algae.

"The lagoon surroundings are ideal for experimenting with this new technology," said Paolo Costa, president of Venice's port authority. "The objective is to guarantee the energy self-sufficiency of the port of Venice and, in the near future, to look for the possibility of supplying energy to the ships moored at the dock."

Lots of claims have been made over the years for algae energy efficiency: Some experts say each acre given over to algae cultivation could theoretically produce the equivalent of thousands of gallons of oil per year, compared with an estimated yield of 18 to 335 gallons of ethanol per acre for traditional biofuel crops. Others claim that algae-growing systems could be tweaked to yield as much as 100,000 gallons per acre annually.

"That's almost like having an oil well in your backyard!" said David Pimentel, a researcher at Cornell University who's known for taking a hard look at alternative-energy claims.

Pimentel is known for taking a skeptical view of the energy equation for ethanol - and he doesn't believe the most optimistic claims for algae, either. But he does think algae power is worth looking into. "It's a disappointment that DOE [the Department of Energy] is not investing in this one as much as we should," he told me today.

From slime to biofuel
Pimentel's research focuses on the benefit/cost ratio for extracting oil from algae and converting it into biodiesel. That's different from Solena's syngas process, but it's more in line with the mainstream approach for using algae oil.

His calculations, based on an analysis of the literature rather than lab studies, indicate that each gallon of oil (or its equivalent) that's invested in algae power would yield the energy equivalent of 1.4 gallons of oil. Researchers in New Zealand recently came up with a slightly higher return of 1.7-to-1, he said.

"This is somewhat optimistic, but you've got to have a little bit of optimism," he said.

The current algae-producing process requires lots of water, and getting the oil out of the algae is a "fairly energy-intensive" job, Pimental said. "It takes approximately a quarter of a gallon of oil to extract [the equivalent of a gallon of] that oil out of that squishy green mass," he said. There's also the problem of keeping impurities out of the algae culture, he added. 

Pimentel figures that algae oil would cost the equivalent of $4 a gallon - which means it's not quite competitive with current gasoline prices. However, he said, "this is much, much better than producing ethanol from corn, and it's much better than producing biodiesel from soybeans."

The idea of capturing the carbon dioxide emissions from, say, a coal-fired power plant and using that CO₂ to feed the algae adds to the technology's attraction - and that's a big reason why the coal industry is so eager to see algae power take hold.

Changing the cost equation
If the production process could be made more efficient, that would improve the prospects for slimy green power. And improving the process is exactly what Ben Wen, chief scientist at New York-based United Environment & Energy, is hoping to do.

At last week's meeting of the American Chemical Society, Wen reported that his company was testing an algae-to-biodiesel conversion process that could be 40 percent cheaper than today's standard. The process involves pumping the algae oil plus methanol through a solid catalyst at high pressure. Biodiesel comes out the other end.

"It's a continuous process," Wen told me. "You just pump the feedstock through the catalyst all the time, instead of the batch process used in the industry right now."

The process promises to provide "the first economical way to produce biodiesel from algae oil," Wen said in a news release. "It costs much less than conventional processes because you would need a much smaller factory, there are no water disposal costs, and the process is considerably faster."

However, the process not yet quite ready for prime time. Wen said that United Environment & Energy was working with a venture partner (which he declined to name) to set up a pilot plant capable of producing nearly 1 million gallons of algae biodiesel annually.

"This year we get the pilot plant into operation," he told me. "Next year, we optimize all the conditions. In late 2010, we should get an idea of how to put it into commercialization."

Is the buzz over algae power for real - or is it mostly, as one commentator said last week, "wild-eyed optimism and pure hype"? Feel free to join in with your comments below.

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