Micro-algae could provide clean energy

An Australian scientist is leading an international consortium to develop solar-powered bio-reactors and micro-algae as possible sources of energy, which could see some of our future fuel and possibly water needs being generated while absorbing CO₂.

Associate Prof Ben Hankamer, from the Institute for Molecular Bioscience (IMB) at The University of Queensland, has established the Solar Bio-fuels Consortium which is engineering green algal cells and advanced bio-reactor systems to produce bio-fuels, such as hydrogen, in a CO₂-neutral process.

"The development of clean fuels to combat climate change and protect against oil price shocks is an urgent challenge facing our society," said Hankamer, who co-directs the Consortium with Prof Olaf Kruse from the University of Bielefeld in Germany.

"Many countries are already aiming to replace 10-20% of their existing energy production capacity with CO₂-neutral energy systems by 2020. But this is very likely not nearly enough.

"Some reports indicate that 50-66% of current energy production capacity may have to be CO₂-free by 2020 to avoid the worst effects of climate change. This will be very hard to achieve and we need new technologies to do so."

The solar bio-hydrogen process uses solar-powered bioreactors filled with single-celled algae to produce hydrogen from water.

Algae naturally capture sunlight and use its energy to split water into hydrogen and oxygen; however, this process is not efficient enough to make it commercially viable.

The consortium is developing ways of enhancing its efficiency to a level where the process will be economically viable. This will be done with the help of a $286,000 Australian Research Council grant received last week.

"We have conducted detailed feasibility studies that show that once key technical milestones are overcome, this technology could achieve economic viability, which will increase further with the introduction of carbon trading schemes and the predicted rise in the oil price," Associate Prof Hankamer said.

"We have focused on micro-algae as a source of hydrogen because they have several advantages over traditional bio-fuel crops."

One major advantage, especially in drought-stricken countries like Australia, is that hydrogen can be produced from salt water. Marine and salt-tolerant algae can extract hydrogen and oxygen from seawater and on combustion these gases produce fresh water and electricity, which can be fed into the national grid.

So, theoretically, clean energy production can be coupled with desalination.

Algal bioreactors can also be placed on non-arable land and use much less water than conventional bio-fuel crops.

"This opens up new economic opportunities for arid regions and eliminates competition with agricultural crops or rainforest regions which are increasingly being used to plant oil palms for bio-diesel production," Hankamer said.

"Algae also have a very short life cycle and can be harvested every 1-10 days rather than once or twice a year, increasing yield."

The hydrogen production process also absorbs CO₂.

"We are therefore starting to investigate whether our hydrogen-producing systems can be linked to conventional power stations to sequester CO₂ which would otherwise be released into the atmosphere," said Hankamer.