Algal Biofuel: The Long Road to Commercial Viability

by Chris Lo (Power Technology) The green technology sector has fallen out of love with algae as a feedstock for biofuel production, but there is hope yet for algae-derived fuel in the long-term. What are the recent advances that are refining the production processes that could see algal biofuel compete with petroleum in the decades to come?

These algal advantages include higher biofuel yields compared to previous systems, a diverse list of possible fuel types including biodiesel, butanol, ethanol and even jet fuel, as well as the fact that large-scale algae cultivation – whether in open ponds or more advanced closed-loop systems – can be done on land unsuitable for food crops, removing a key concern that biofuel feedstock crops would compete with food producers.

For more than five years from around 2005, algae-based biofuel companies, including the likes of Algenol, Sapphire Energy and Solazyme, raised hundreds of millions of dollars in private sector investment on the promise that chemically engineering algae could scale up to produce tens of millions of gallons of fuel in a matter of years, at prices competitive with fossil fuels. Fuel conversion from algae is broadly based on the feedstock’s high concentrations of lipids: fatty, oil-containing acid molecules that can be extracted to create biofuels.

Nearly 15 years later, the green tech world has fallen out of love with algal biofuel. Despite the large sums spent on developing the conversion process, the industry’s ambitious production goals – not to mention cost-competitiveness with fossil fuels – remain a distant dream. In terms of cost, major oil price declines in 2008 and 2014 certainly didn’t help biofuel competitiveness, but technical issues have also proven a major sticking point. Intractable problems have been encountered in terms of the energy balance of lipid extraction, maintaining suitable growing conditions in open ponds, and the immense volumes of water, CO₂ and fertiliser required to allow the algae to photosynthesise fast enough at large scales.

As a result, most of the companies touting algal biofuel in 2005-2012 have been driven out of business or shifted their business models to algal production of higher-value products such as dietary supplements, food additives, animal feed and cosmetics.

However, a new method invented by researchers at the University of Utah may have a solution to the energy parity conundrum. A team of chemical engineers have developed a new jet mixer technology that precludes the need for energy-intensive drying processes. The new mixing reactor shoots jets of solvent into jets of algae in liquid suspension, creating the turbulence needed to prompt the lipids to transfer into the solvent stream. Not only does this process require much less energy, the researchers say it is also faster, with lipids extracted in mere seconds.

Further thoughts on how to optimise the algal biofuel process have been offered by the US National Renewable Energy Laboratory’s (NREL) National Bioenergy Center. In a June 2018 article published by R&D, National Bioenergy Center strategic project lead Philip Pienkos laid out NREL’s research into the economics and practicality of producing algal biomass in large open ponds.

According to the team’s techno-economic analyses, once certain economies of scale are reached and improvements are made in strain characteristics and cultivation methods, it would be possible in the future to produce algal biomass at a cost of $300 per dry ton. This would still not be enough to compete with crude oil, however.

In response, NREL has been investigating the viability of a ‘combined algal processing’ (CAP) concept, which involves a plant capable of simultaneously producing algal biofuels along with a number of useful co-products, including surfactants, polyurethanes and plastic composites.

Synthetic Genomics is one of the few companies founded during the ‘gold rush’ period of algal biofuel development that still has a focus on fuel, having partnered with ExxonMobil to work towards producing biofuel from algae at an unprecedented scale. After years of biological research into optimising algae oil production, the partners are now progressing on an outdoor field study growing naturally-occurring algae in several contained ponds in California. READ MORE