Marine microalgae: a sustainable saviour?

It resides at the bottom of the marine food chain, but researchers studying microalgae cultivation believe it could become a top-tier contender to combat global warming, climate change and food insecurity.

“We may have stumbled onto the next green revolution,” said Charles H Greene, professor of earth and atmospheric sciences at Cornell University, and lead author of the paper ‘Marine Microalgae: Climate, Energy and Food Security From the Sea’, published in the journal Oceanography. The study presents an overview of the concept of large-scale industrial cultivation of marine microalgae (ICMM).

ICMM has the potential to reduce fossil fuel use by supplying liquid hydrocarbon biofuels for the aviation and cargo shipping industries.

To produce the biofuel, freshly grown microalgae is harvested, most of the water is removed and then lipids are extracted for the fuel. The remaining defatted biomass is a protein-rich and highly nutritious by-product — one that can be added to feeds for domesticated farm animals, like chickens and pigs, or aquacultured animals, like salmon and shrimp. It also has the potential to be consumed by humans.

Growing enough algae to meet the current global liquid fuel demand would require an area of around 2 million km² — just over a quarter of the size of Australia. At the same time, 2.4 billion tons of protein co-product would be generated, which is roughly 10 times the amount of soy protein produced globally each year.

Marine microalgae do not compete with terrestrial agriculture for arable land, nor does growing it require fresh water. Many arid, subtropical regions — such as Australia, Mexico, North Africa and the Middle East — would provide suitable locations.

“I think of algae as providing food security for the world,” said Greene. “It will also provide our liquid fuels needs, not to mention its benefits in terms of land use. We can grow algae for food and fuels in only one-tenth to one one-hundredth the amount of land we currently use to grow food and energy crops.

“We can relieve the pressure to convert rainforests to palm plantations in Indonesia and soy plantations in Brazil,” Greene said. “We got into this looking to produce fuels, and in the process, we found an integrated solution to so many of society’s greatest challenges.”