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Forget the days of searching for black gold. Scientists are setting their sights on something greener.

Researchers in Arizona and New Mexico are improving processes to derive fuels from algae.
Credit: U.S Environmental Protection Agency

Algae—the slimy stuff that plagues pool owners and coats fish tanks—may soon become the perfect biofuel source.

Biofuels generally burn cleaner than petroleum products and are seen as a way to reduce the greenhouse gas emissions that contribute to global warming.

Using algae—instead of food crops—for biofuel production has major advantages, said Joel Cuello, associate professor of agriculture and biosystems engineering at The University of Arizona.

“It’s become obvious that the use of food crops for biofuels helps reduce the amount of food available globally, causing food prices to go up,” Cuello said.

In the U.S., more than 90 percent of the biofuel produced comes from corn and soybean crops.

Algae farms would not compete with those crops. Algae aren’t a dietary staple and don’t need to be grown on fertile land. And with millions of people at risk of dropping to poverty level as a result of food price hikes, using algae is a much better option, he said.

Algae also have the potential to generate a lot more fuel than the corn and soybeans currently used. Conservative estimates put algae production at about 4,000 gallons of fuel per acre per year, with some researchers claiming that number is closer to 10,000 gallons.

Even sticking with the low estimate, one acre of algae could potentially produce about 13 times more fuel than an acre of corn, which makes about 300 gallons of ethanol, and nearly 67 times more fuel than an acre of soybeans, which produces about 60 gallons of biodiesel.

Because algae are so diverse, there’s a species to do just about anything. Some accumulate oil that’s ideal for biodiesel production. Others build up starch to be used for ethanol, and some even produce hydrogen gas, Cuello said.

One of the most attractive things about growing algae is that the process can be highly controlled, he said. Every aspect of algae growth can be managed using photobioreactors—closed vessels that provide algae with an optimum growing environment.

Bubble column (left) and air-lift photobioreactors (right) provide optimal growing environments for algae. At the time this article was written this technology had not been scaled up to an entire biofuel facility.
Credit: Joel Cuello, The University of Arizona

This closed system allows algae to be kept at specific temperatures, to be given exact amounts of nutrients, and to receive the right amount of light. Though the method produces excellent algae yields, there isn’t one operational biofuel plant based on photobioreactor technology yet.

“The economics are still preventing it,” Cuello said. The technology is very expensive, especially on a commercial-scale.

The cheapest way to produce algae is with an open pond system. The biggest drawback to the open pond is it doesn’t allow for any control over the algae’s environment. Weather changes and open air can adversely affect the algae’s growth. Even bird droppings present a problem, as they cause different strains of algae to form in the pond water.

So, Cuello is working to find a middle ground—inside a greenhouse. “By growing the algae in inexpensive vessels in a greenhouse setting, it’s more controlled than an open pond and cheaper than using photobioreactors,” he said.

A potential low-cost alternative design of an algae production system located inside a greenhouse structure. Advantages over the open-raceway design include lower evaporation rates, greater land utilization efficiency, and greater productivity.
Credit: Joel Cuello, The University of Arizona

Still, the industry is probably five years away from producing biofuel from algae on a commercial-scale, Cuello said.

An algae plant in Carlsbad, New Mexico, is working to beat that projection.

Researchers harvested their first commercial-scale quantity of algae from two saltwater ponds in early July, said Doug Lynn, executive director for the Center of Excellence for Hazardous Waste Material Management.

About 12,000 gallons of algae-concentrated pond water was harvested to produce an algae paste with the consistency of peanut butter, Lynn said.

The center, in conjunction with New Mexico State University, is refining that harvesting technique, working toward the day when a commercial quantity of oil can be extracted from the algae and processed into fuel.

That day is still about two years away. “You have to crawl before you can walk,” Lynn said.

Fortunately, algae seem to be worth the crawl. They double in size about every day and can be grown and harvested all year long in the Southwest.

“If a natural disaster strikes a canola or soybean field, you have to wait an entire year to grow it back. If a natural disaster hits an algae farm, it recovers in 24 hours,” he said.

Algae aren’t picky about their living conditions, growing well in salty groundwater and even in wastewater.

There couldn’t be a more perfect crop for the Southwest, Lynn said. In a place where desert land is available and sunshine is endless, he said, “the advantages of algae are limitless.”