Today, algae fuels still are not close to being economically competitive with petroleum, according to NREL scientists. So what's changed?

Record high crude oil prices, instability in the Middle East and other oil exporting regions and global warming concerns connected to increasing levels of carbon dioxide (CO₂) have made algae an appealing potential fuel source - again.

Interest in algae fuel at an all-time high

And public interest is soaring after recent well-publicised algae fuel demonstrations, including airliner test flights using blends with conventional jet fuel - most recently in Houston by Continental Airlines. Some airlines and engine manufacturers hope to be using algae blends within a few years.

“I'm getting calls every day from people who want to get into algae fuels,” says Al Darzins, a Group Manager and Principal Researcher in NREL's National Bioenergy Center. “There are hundreds of companies looking into it now here, in Europe and the Middle East.”

So is pond scum ready to replace nearly 100 million gallons of petroleum diesel and jet fuel burned every year?

Not remotely, Darzins says. Biological questions about the organisms and engineering questions related to algae fuel production, distribution and quality standards must be answered for algae fuels to be competitive with oil currently priced at less than US$50 per barrel.

“All we've really seen are tests involving one engine of a jet running on a blend using a small percentage of algal fuel — and there were no passengers, of course,” Darzins says. “In my book, that's a long way from commercialization.”

Potential is enormous

That does not mean the prospect is not tantalising. Algae are like microscopic factories using photosynthesis to transform CO₂ and sunlight into lipids, or oil. Some strains can double their weight in a few hours under the right conditions.

Algae can grow in fresh, salty or even contaminated water, can generate 30 times more oil per acre than plants used for biodiesel and other biofuels, and algae do not compete with food crops.

Scientists think algae might grow fatter and faster if they were force-fed extra carbon dioxide, which could help alleviate the build-up of greenhouse gases. Smokestack emissions from power plants and other sources could be diverted directly into the ponds, feeding the algae while keeping greenhouse gases out of the atmosphere.

From 1978 to 1996, the laboratory was a pioneer in the field with the Aquatic Species Program. Researchers screened and characterised more than 3000 potential strains, shed light on the growth conditions that stimulate lipid production, demonstrated open ponds for mass production of biomass, and made significant breakthroughs in genetic engineering.

Back to the basics

Today, NREL has resumed that work, while putting a greater emphasis on understanding their basic biology. When these microalgae are starved of the nutrients they need, their lipid content can increase as much as 60%.

NREL and Chevron Corporation are working under a Cooperative Research and Development Agreement (CRADA) in which NREL is boosting microalgae's productivity. Chevron anticipates using the resulting oil as a feedstock for renewable transportation fuels.

But not every strain contains all the qualities required to produce algae fuel - growing fast, growing fat and tolerating a wide variety of conditions.

And, different strains have evolved under different conditions in different locales. It is unlikely, Darzins says, that one strain of algae would be used nationwide because of regional differences in climate and water.

"We've only begun to scratch the surface," Darzins says. "We need to understand the lipid pathways and what regulates their lipid production and growth."

Currently NREL's algae experiments are limited to 1l flasks under fluorescent light. When renovations to the greenhouse at the Field Test Laboratory Building are completed, algae strains can be tested in 75 gallon batches under natural light conditions, which can be 10 times more intensive than artificial lighting.

"Some strains that look good now may not maximise photosynthesis when we scale up or expose them to natural light," Darzins says.

Within a few years, Darzins hopes to complete construction of new outdoor ponds behind the FTLB that will test algae strains, production systems and harvesting methods at scales up to 100 acres.

Learn more about NREL research in biofuels from microalgae here.

This article was written by Joseph B. Verrengia at NREL, and has been reproduced with the permission of NREL.