By: Jane Marsh
Algae biofuels are, quite literally, a green energy source. The early 2000s saw a lot of hype around the promise of algae as an alternative to fossil fuels, but 20 years later, the bubble seems to have burst. Does this naturally occurring resource have a place in the renewable energy discussion?
Bloom and Bust: The Pros and Cons of Algae Biofuel
Why did the hype around algae die so suddenly, and what are scientists doing to revive the excitement around biofuels?
First, large-scale algae cultivation doesn’t have to compete with crop growth, ranching or energy farms because algae grows in large concentrations in ponds. It can even grow in wastewater tanks already set aside for treating water.
Algae contains valuable oils manufacturers can convert into biofuels. It can serve as the base for various fuels, including butanol, ethanol, jet fuel and biodiesel. This versatility makes algae biofuel applicable to a wide range of industries. Biofuel is much better for the environment than gasoline and diesel. Every year, highway vehicles emit around 1.4 billion tons of greenhouse gases, so algae-based biofuel could serve a critical role in fighting climate change.
However, there are several challenges to its adoption. First, wild algae strains don’t produce enough lipids to produce large amounts of fuel. Scientists are working on bioengineering a high-yield strain, but that raises questions about the dangers of growing genetically modified algae in outdoor ponds. What if it alters the surrounding ecosystem?
The global algae market generates an estimated $1 billion annually, but most of these sales come from turning the substance into food additives, supplements and cosmetics. That’s because, as it turns out, it’s expensive to manufacture biofuels from algae.
Algae has a low energy return on investment, and competing with subsidized and readily available fossil fuels is a challenge. It takes around $3,500 to $4,000 in plant costs to produce a kilowatt of energy from biofuel, compared to just $2,000 to $2,300 for coal.
Additionally, growing enough algae can be difficult. It requires a lot of water, and many parts of the world are experiencing record droughts. Growing algae on a commercial scale also requires intensive fertilizer input, which can pose an ecological threat if used in outdoor ponds. Growing algae in tanks would, theoretically, be a better option, but producing even a single liter of algae biofuel requires up to 3,650 liters of water.
Finally, it’s expensive to harvest algae and extract its oil. Current manufacturing techniques require technicians to dry the algae completely so the lipids can be separated. As a consequence, it can take more energy to power the manufacturing process than the biofuel produces.
However, scientists may be close to a solution, with chemical engineers at the University of Utah developing a technique for extracting lipids from wet algae. Implementing this process would reduce the time and energy required to produce algae biofuel.
Nipped in the Bud
Algae biofuel seems promising on the surface, but most energy startups have redirected their research toward using algae for other purposes or dropped out of the race altogether. If scientists can overcome the problems of high water and fertilizer requirements, low lipid production and processing woes, algae could become a viable source of green energy. For now, however, it’s simply growing quietly in the background.
