Supporters call it “clean diesel” to differentiate it from “biodiesel,” and indeed, there is a difference. Soybeans, the main feedstock for biodiesel, have only a 2-3 percent oil content. Some species of algae can have up to 60 percent oil content. This reduces the land requirements for growing a crop by a factor of 30.
So is algae biodiesel one of those great ideas that is always just over the horizon? Or has it germinated long enough that it may finally about to become a reality? The outcome still appears to be up for grabs.
The term “algae” actually cover a whole spectrum of organisms, from the 20-foot ribbon-like “seaweed” that grows in ponds and along littoral shores to the mid-ocean, microscopic “plankton” that is the diet of whales. All have one thing in common – they use carbon and sunlight to photosynthesize organic material. And they are good at it. Some species can double their mass within 24 hours. Thousands of species thrive in varying environments. Last summer, a red algae “tide” that feeds on farm runoff at the mouth of the Mississippi River “bloomed” to cover 5,000 square miles of the Gulf of Mexico, killing all manner of birds, fish and marine life, including hundreds of manatees. “If we can figure out how to make energy out of that,” President Obama told an audience at the University of Miami, “we’ll be doing alright.”
The idea of harvesting algae for energy was first suggested by Richard Harder and Hans von Witsch, two European scientists at the outbreak of World War II. Nothing much developed, however, and interest didn’t revive until the Energy Crisis of the 1970s, when the Department of Energy set up an Aquatic Species Program to pursue research.
Funded with $25 million over the next 18 years, the Aquatic Program investigated thousands of species, finding the Chlorella genus the most promising. It also made an important discovery. When Chlorella is deprived of nitrogen, it can increase its lipid (fat and oil) content to a remarkable 70 percent of mass! Remember, soybeans are only 2-3 percent lipids. But this created a conundrum. While depriving algae of nitrogen might may increase lipid content, it also severely inhibited growth. The Aquatic Program had not yet resolved this dilemma when it was disbanded in 1996.
Private companies picked up the research, however, and have tried to overcome it with genetic engineering. While pursuing this, they have developed two methods of cultivation. The easiest is to grow algae in open pools or “raceways” that devour large areas of land, since sunlight can only penetrate a few centimeters into the algal mat. The problem here is that most species are highly sensitive to variations in acidify, temperature and humidity. Their high lipid content also means they synthesize fewer proteins, which makes them extremely vulnerable to invasive species. This makes it very difficult to bring them up to commercial scale.
The more advanced technology is “photobioreactors,” conducted in large networks of glass or plastic tubes. The system overcomes environmental difficulties but is very expensive. In 2009 Exxon combined with J. Craig Venter, the decoder of the human genome, to try to develop a commercial method for developing algae-based fuels. After investing $600 million, however, Exxon pulled out of the enterprise in 2013, saying commercialization was 25 years away.
Nevertheless, several small companies say they are now making progress. Algenol, a Fort Myers, Fla. company, says it has developed a revolutionary “3rd generation” technology that can produce ethanol, jet and diesel fuel 8,000 gallons per acre, 18 times the output of corn-based ethanol, at $1.25 per gallon. Sapphire, a San Francisco company, has opened a 100-acre Green Crude Farm in New Mexico and hopes to be producing 100 barrels a day next year with full-scale commercialization by 2018. And Aurora Algae, a Hayward, Calif. firm which has operated a test facility in Western Australia for the last three years, has just announced an open-pond operation in Harlingen, Texas that it hopes to expand to 100 acres.
There is one great irony to all this. A full-blown algae industry already exists, providing feedstock for food additives, cattle silage and nutritional and pharmaceutical products. Some highly specialized fatty acids derived from exotic species can fetch $10,000 per gallon. In fact, the current industry sees algae-for-fuel as a rather low-grade use. “Until more federal funding is available, my members are going to continue growing for the higher-value products,” Barry Cohen, executive director of the National Algae Association, told Slate’s John Upton. “We have algae companies that are growing for the ingredients industry, the food industry and the nutraceutical industries. If they can grow the right species, those companies will buy every drop they can make.”
What makes these operations viable, of course, is their high-value end products, which cover the costs of growing algae in commercial quantities. An algae-for-fuel industry will either have to: a) develop new species that are much more efficient or b) perfect mass-production techniques that can bring prices down to an acceptable range. Only then will “clean diesel” become a competitor. For now, the industry seems headed in the right direction.