Flora to fuel: could wind-powered algae make bioreactors competitive?

Algae-derived fuel was an exciting prospect for energy companies in the early 2010s, with a number of investments made into exploring the potential of algae fuels to combat the climate crisis and facilitate the development of renewable energy sources.

In 2010 the Algae Biomass Organisation (ABO) predicted that algae fuel would reach price parity with oil by 2018, with ABO head at the time Mary Rosenthal expecting “several billions of gallons” of algae to be produced as a fuel source by 2017.

The world’s first building powered entirely by algae was unveiled in Hamburg in March 2013, using 129 bioreactors to generate power and heat for a four-story residential building.

This optimistic approach to algal fuels also encouraged investment at scale from energy companies, with US-based Sapphire Energy and Spanish Aqualia starting development of algae-based biofuel facilities in August 2013.

However, the reality of algae-based fuel today is far from the green superfuel predicted by the energy industry, and although these algae projects demonstrate the utility of existing renewable energy infrastructures, the viability of algae as a fuel source itself is up for question.

Shellcock says: “If we are talking about algae-based fuel, production cost is the main limitation. For the moment it's around £10 per litre of biodiesel. The quantity of algae that needs to be produced to enter the market is huge compared to the current global production.

A major problem with algae as a fuel source is the high-maintenance growing conditions required to produce the required quantities of algae - the plants need large open ponds, and significant volumes of CO₂ and fertiliser to enable the algae to photosynthesise fast enough at large scales.

Swansea University marine biologist Professor Kevin Flynn wrote in 2017: “The dream has been broken not by failings in engineering, but by the inefficiency of biochemistry. Simulations of microalgal biofuel production show that to approach the 10% of EU transport fuels expected to be supplied by biofuels, ponds three times the area of Belgium would be needed.

“And for the algae in these ponds to produce biofuel, it would require fertiliser equivalent to 50% of the current total annual EU crop plant needs. 

“Ironically, such ponds would also need to be located near heavy industry which produces CO₂ to provide the level required by the microalgae for photosynthesis.”

Another issue with algal fuels is energy - with current methods, it takes more energy to produce algal fuels than it would provide as power. This, coupled with the costs needed to produce algae at scale, means that algal technologies in their current state are neither effective nor efficient enough to supplant oil as a renewable energy source.

In response to this disappointment, many companies that started on the idea of algae as an alternative to oil have shifted their business models to algal production of products such as feed and cosmetics. The ENBIO and ASLEE projects have similar goals, integrating renewable energy infrastructures into the manufacturing of bioproducts rather than relying on algae as a fuel source.

Explaining the current state of algal technology, Shellcock says: “At the moment algae-based fuel is not able to replace oil-based fuels due to the economics of production.

“It has potential to be used as a supplement in classical fuel. Algae-based products have potential to be integrated into the biobased feedstocks, perhaps as part of a biorefinery approach.”

While the energy industry as a whole has fallen out of love with algae-based fuels, and the technology is unlikely to become competitive or economically viable any time soon, projects like ENBIO and ASLEE show it should still be part of the conversation, especially as other small breakthroughs are still being made to refine biofuels.

In March 2019, a team of chemical engineers from the University of Utah developed a new biocrude production method to more efficiently extract the important lipids from algae. 

This method involves shooting jets of solvent at jets of algae, creating enough turbulence to transfer lipids from the algae to the solvent stream. This removes the energy-intensive drying process needed with current algal fuel production, vastly increasing the efficiency of the biofuels produced.

In a press release, co-author of the study Dr Leonard Pease said: “The key piece here is trying to get energy parity. We’re not there yet, but this is a really important step toward accomplishing it. 

“We have removed a significant development barrier to making algal biofuel production more efficient and smarter. Our method puts us much closer to creating biofuels energy parity than we were before.”

Researchers at the US National Renewable Energy Laboratory’s (NREL) National Bioenergy Centre have also attempted to improve the efficiency of algae-based biofuels, with strategic project lead Philip Pienkos explaining these efforts in a June 2018 article for R&D world. 

Pienkos suggests an alternative solution to the current biofuel production process, converting the leftover biomass from the drying process into biogas that would then go into the production of biofuel to ensure that no component of the algal biomass goes to waste.

The NREL also proposed a Combined Algal Processing scheme, which would use the by-products of biofuel production to produce a number of other important chemicals such as plastic composites, polyurethanes and surfactants.