With European backing, scientists in Scotland are out to prove that seaweeds and microalgae can become the sustainable fuels of the future

Seaweeds, or macroalgae, and their smaller cousins microalgae produce half the biomass on Earth. But despite the fact they grow in a wide variety of ocean environments, algae remain largely unexploited for energy generation.

This may be set to change. Scientists at the Scottish Association for Marine Science (SAMS), near Oban on the west coast of Scotland, have gathered one of the world’s largest collections of microalgae, and are now considering how to set up large scale sustainable algae production in the UK.

Within the next few weeks, the facility hopes to get confirmation of €6 million funding from INTERREG, an EU programme, to fund more research into the algae growth. The Carbon Trust also plans to invest several million pounds over the next four to six years to develop commercially viable algal bio-energy systems, both in the UK and further afield.

Macroalgae, or seaweed, is already harvested or cultivated in at least 40 countries as a source of food, fertiliser, and pharmaceutical and cosmetic ingredients

Whilst macroalgae is a proven source of biomass for ethanol and methane production, microalgae is also considered by scientists to be a promising source of biodiesel.

Micro on a macro scale?

Microalgae comprise a vast group of organisms that grow wild and can also be cultivated. They develop much faster than terrestrial crops, without the need for precious freshwater. Some multiply every seven hours and double in size in a day, potentially enabling “constant harvesting”.

The yield of oil from microalgae is estimated at between 5,000 and 20,000 gallons per acre per year. This is seven to 30 times greater than the next best energy crop, Chinese tallow.

As with cellulosic ethanol, the environmental impact of large-scale microalgae cultivation would be limited by the fact that no arable land is required. Instead, pond or reactor systems are used. Algae require sunlight, carbon dioxide, nutrients (such as nitrogen, phosphorous and potassium) and water.

The challenge is to grow and harvest suitable algae in a controlled and efficient way in a large-scale commercial facility.

However, work on cultivating microalgae has been going on for 30 years and SAMS hasn’t yet found a strain that can cope with the Scottish winter. Progress in the US has also stalled after a large US microalgae programme was halted in 1996 because the price of oil was then so cheap.

SAMS is researching both open-pond systems and photobioreactors in its search for the best method of growing microalgae in the UK. “The latter are very expensive because you have to provide light, a certain amount of heat, to keep conditions constant,” says research fellow Michele Stanley. “The open-pond system seems more attractive, but then you’ve got problems with predators.”

Seaweed powering ahead

The picture is rosier for seaweed production. Macroalgae, or seaweed, is already harvested or cultivated in at least 40 countries as a source of food, fertiliser, and pharmaceutical and cosmetic ingredients.

China is by far the biggest producer. The world’s total annual harvest is 8.4 million tonnes of green seaweed, 2.8 million tonnes of brown and 1.2 million tonnes of red, of which China accounts for some 90%. Most of it is cultivated in large nets off the coast.

SAMS researchers have cultivated seaweeds in Scotland for more than five years, raising sporeling plants in labs and transferring them to sea when they reach 0.5cm to 1cm. Within months they span 2m to 3m.

And while SAMS estimates that microalgae biofuel could take up to 20 years to reach commercial production in the UK, for macroalgae the payoff may be only five years away.

Author: Sam Phipps, climate Change corp