A carbon-neutral fuel alternative

[USA] As early as the 1950s, researchers were looking at algae for methane gas production. The algae was grown on rooftops of Massachusetts Institute Technology (MIT). Drawings and illustrations of open pond raceways on the roof of Harvard Univ. were also recovered from the 1950s. The reason for this research was algae naturally make oil, and this intrigued researchers as a feedstock for biodiesel.

In the 1970s, algae for use as an alternative fuel had another push, this time related to gas-related fuels. And this push came when the U.S. Dept. of Energy (DOE)’s National Renewable Energy Laboratory (NREL) started a program called the Aquatic Species Program. The program was originally meant to evaluate photosynthetic organisms that grew in or near water—including algae, seaweed, swamp-type plants and more. The program was looking for ways to supplement the amount of terrestrial biomass that could be grown, looking at different aquatic species. And very quickly into this process, NREL settled on algae, more specifically microalgae, due to their ability to produce lipids, which were known as a potential source of biofuels. The project lasted from 1978 to 1996, at which point the price of oil had gone down to about $10 to $20/barrel. And the price was thought to stay at that price for a long time.

Since the interest dried up due to the decreasing price of gasoline/oil, the DOE could no longer hold funding across the board on biofuels, so they terminated the algae part of the program to continue focusing on cellulosic biofuels. From 1996 to 2006, little work was done on algal biofuels. Then, starting in 2007, interest was, yet again, sparked when the price of oil rose to $40 to $50/barrel; and companies started to form the Algae Biomass Organization in 2008. From there, algal research started up again with a vengeance.

Despite the ups and downs, this alternative fuel source has seen its renaissance today, with similar funding (over $18 million spread across national labs, universities and industrial companies from the DOE and more from private sources) and more interest from companies in its potential.

The trouble of commercialization stunts benefits

The onset of the rise in algal biofuels research in 2006 and 2007 was the publication of the first billion ton study, which was a joint effort between the USDA and the DOE. The study posed the question of how much terrestrial biomass or lignocellulosic biomass could be sustainably produced in the U.S? And the answer, according to the study, was about a billion tons per year.

“Looking at the different conversion properties and processes to turn cellulosic biomass into fuel, you can basically assume a billion tons a year could be used to produce about 60 billion gallons of gasoline equivalent a year—whether that is ethanol or some other fuel molecule,” says Philip Pienkos, Group Manager of the Bioprocess R&D Group at NREL in an interview with R&D Magazine.

As a nation, we burn about 140 billion gallons of gasoline a year. We also burn 40 billion gallons of diesel, and 20 billion gallons of jet fuel. “Cellulosic biomass can only cover a small fraction of this,” says Pienkos. “Our calculations show algae could easily match cellulosic biofuels in terms of overall production. It could actually exceed the cellulosic biofuels we produce because of the lipids, sugars and other components found in algae. There is enough free space in the U.S. that isn’t being used that can cultivate algae; so, easily, 60 billion gallons of biofuels could be produced in the U.S.”

However, the DOE has set a more conservative target, and is looking to establish 5 billion gallons of algal biofuels a year, with a notion it could be an order-of-magnitude higher.

Yet, the commercialization of algal biofuels has proved much harder than expected. And some view algal biofuels as more hype than a reality.

“The joke is algal fuels are 10 years off, and they always will be,” says Pienkos.

However, the main reason why algal biofuels haven’t exploded yet is the reason why most are getting their funding: Algal biofuels aren’t quite economically viable to compete with gasoline. “They are getting there,” says Rhona Stuart, Postdoctoral Researcher at Lawrence Livermore National Laboratory in an interview with R&D Magazine. “And there’s research being conducted in all different pipelines, not just in the growth of algae, but also the production and conversion of algal biofuels to get it to the point where it competes with gasoline at a cost per gallon.”

To help alleviate this issue, there has been much effort from the national labs and DOE-funded projects that look at techno-economic analysis and lifecycle analyses of algal biofuels. And these projects have identified two key barriers to getting these biofuels within the cost per gallon range of gasoline: low yields of algae biofuels and high costs of producing algal biomass. “The goal for the funding provided by the DOE is getting the gasoline gallon dollar equivalent of biofuel product down to less than $5/gallon,” says Stuart. “And right now, by some estimates, it’s at around $8/gallon.”

“If you look at the petroleum industry, worldwide it’s a trillion dollars a year industry,” says Pienkos. “And that’s the magnitude of the opportunity for biofuels and bio-based chemicals. We are talking about an algae industry that could be on the same order of magnitude, or thereabouts, as the petroleum industry. And it’s going to take a lot of money.” The industry is starting small, and it will take success at the higher-value, smaller-market products to establish commercial revenue streams. In response, high-value products will be the main focus for near-term commercial success. And it is hoped that those revenue streams will lead to further R&D progress, eventually ushering large-scale algal biofuel production (and some companies are well on their way, such as Sapphire, Cellana and Algenol).

Yet, despite the cost issue, there are many benefits to using algae instead of gasoline. How algae compares to gasoline is highly determined on the strain of algae used and chemically what oil that strain makes. Currently, some companies are engineering algae to produce oil very similar to a gasoline equivalent biodiesel that could be dropped into a car. Other downstream processes harvest the biomass, not just the oil, and convert it into ethanol.

“In general why algae is a good alternative is because it’s carbon neutral,” says Stuart. “Algae is grown on non-potable water, maybe even wastewater, so you’re not using water and you’re not using arable land, because you are growing this algae in ponds. This means the cultivating of algae isn’t interfering with our food source. The algal biofuels, once produced, will take up carbon dioxide and burn that carbon dioxide immediately in a car, showing a carbon neutral process.” Essentially, the algae is taking up the same amount of carbon that’s released. In addition, algae can produce mass quantities of lipids and fats, making them easily convertible into liquid fuels, such as biodiesel or jet fuel.

The barrier of pond crashes

A large barrier to the commercialization of algal biofuels is pond crashes, where algae will begin to grow and then suddenly die off. The reason ponds crash is because they are open to the atmosphere and many deleterious species come into the pond and either eat or infect the algae. These pond crashes are unpredictable and must be understood to minimize their devastating impacts—basically losing whole algae harvests and starting over again.

 

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