Biodiversity boosts algal biofuel yields

Pioneering research has confirmed that a diverse mix of algal species in biofuel systems will significantly improve production.

Scientists from the University of Michigan (UM) grew various combinations of freshwater algal species in 80 artificial ponds to test the effects of biodiversity on biofuel production. According to a press release, it was the ‘first’ large scale, controlled experiment of its kind.

It was found that diverse mixes of algal species, known as polycultures, performed more key functions at higher levels than any single species. However, somewhat surprisingly, it was also discovered that polycultures did not produce more algal mass, known as biomass, than the most productive single species, or monoculture.

"The results are key for the design of sustainable biofuel systems because they show that while a monoculture may be the optimal choice for maximising short-term algae production, polycultures offer a more stable crop over longer periods of time," said study lead author Casey Godwin, a postdoctoral research fellow at UM's School for Environment and Sustainability, in a press release.

The team’s results have just been published in the journal Global Change Biology-Bioenergy. 

Technical challenges associated with algae cultivation have so far hindered its progress towards commercial scale implementation. One major issue is that outside, away from controlled laboratory conditions, an algal cultivation system would have to maintain constant and regular growth of fuel algae in the face of fluctuating weather, population crashes caused by disease and pests, and invasion by nuisance species of algae.

Ecological research has demonstrated that plant and animal communities containing a rich mix of species are, on average, more productive than less-diverse communities, more stable in the face of environmental fluctuations, and more resistant to pests and diseases. However, the new study marks the first time the idea that algal polycultures can outperform algal monocultures for biofuels production has been tested.

"Our findings suggest there is a fundamental tradeoff when growing algal biofuel," said U-M ecologist Bradley Cardinale, a contributor to the study.

"You can grow single-species crops that produce large amounts of biomass but are unstable and produce less biocrude. Or, if you are willing to give up some yield, you can use mixtures of species to produce a biofuel system that is more stable through time, more resistant to pest species, and which yields more biocrude oil."

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