Oct 13, 2010
Marine algae offer sustainable fuel hope
Biofuels from algae grown in seawater are the only fossil fuel alternative that doesn't compromise food and freshwater supplies, believes Yusuf Chisti. Algae are an increasingly popular potential feedstock for biofuels, but the Massey University, New Zealand, scientist says that currently used techniques won't provide fuel in the quantities needed.
"Most companies appear to be using freshwater to grow the algae, but this may not be the way forward as supply is limited," Chisti told environmentalresearchweb.
Consequently, while Chisti has reviewed algae's attraction in the journal Biofuels, his approach differs from the mainstream. "My focus is on using marine algae for making biofuels," he explained. He sees no technological restrictions against selecting seawater species, but suggests that the freshwater choice is down to the inland locations of many experimenters.
"Another likely reason is that many of the companies have little direct experience of culturing algae and have selected production systems without careful thought to the freshwater resource requirements," Chisti said. He notes that growing algae in seawater is comparatively straightforward, and can use waste carbon dioxide and standard agricultural fertilizers.
However, producing these fertilizers requires large amounts of fossil fuels and energy, heading a list of energy inputs into making algal biofuels. These inputs have led Lucas Reijnders of the University of Amsterdam in the Netherlands to claim that algal fuels effectively output just fossil fuel energy, but Chisti disagrees.
"It would be stupid to try to produce fuels from algae if it took as much fossil fuel to do so as the energy contained in the biofuel produced," he said. "The net energy gain from sunlight in production of algal fuels certainly needs to be improved, but it is definitely neither zero nor negative as is sometimes suggested."
Currently algal biofuel is too expensive and fertilizer use must be curbed, Chisti concedes. So, while he has no commercialization plans, the New Zealand scientist is focused on growing oil-rich algae that can produce liquid transport fuels economically.
"How algae are grown has a tremendous influence on their oil content and I am trying to identify the conditions that favour oil accumulation," Chisti explained. Also, to reduce the use of fertilizers, the Massey researchers are looking at exploiting nitrogen-fixing algae. "In the long run, the cost will come down significantly," Chisti added.
Although much current experimental biofuel production employs pond-grown algae, Chisti's team is investigating photobioreactors, engineered production systems removed from all external environmental influences except light. "Compared to ponds, photobioreactors have a strong potential for cost reduction and scope for improved design to reduce energy consumption," he explained.
Chisti sees the chances of commercial algal biofuel developers achieving success as slim in the near term. Nevertheless, he believes these biofuels will ultimately penetrate the market, especially if fossil fuels are restricted. "We may have to give up on the fossil fuels because of their adverse impact on the environment and their finite supply," he said. "Algae fuels will certainly have their day."
About the author
Andy Extance is a contributing editor to environmentalresearchweb.