Single-cell organisms living in oceans and ponds could provide a fresh new source of energyby Philip Hunter / June 21, 2010 / Leave a comment
Ocean bound: could harnessing the energy produced by algae cure the world of its oil dependency?
The environmental disaster caused by the Gulf of Mexico oil spill has underscored our urgent need for alternative energy sources. But existing ones—like wind, wave and solar—all have their drawbacks, while nuclear fusion remains stillborn despite its long-term promise of almost unlimited power. For a while there was hope that converting biomass from crops such as corn and sugarbeet would make a serious dent in fossil fuel consumption, but this is likely to remain a marginal solution since it would take too much land away from food crops. Now microalgae—single-cell organisms living in either sea or fresh water—have emerged as the most promising new biomass candidate.
There are some 500,000 species of microalgae living in our oceans, rivers and ponds. Because they are single-cell organisms, they are highly efficient at converting light into energy (photosynthesis), unlike more complex plants that comprise millions of cells. During photosynthesis microalgae also produce hydrogen, to protect themselves from excess light energy, and it’s this that has interested US researchers, because hydrogen can be used as fuel and also to generate electricity.
Experiments have already shown that microalgae cells can be engineered to yield much greater amounts of hydrogen than they do naturally, and that they can even generate electricity directly. The cells also naturally produce organic oils, or lipids, that can be converted into biodiesel which closely resembles the diesel used for heating and internal combustion engines.
There is also the longer-term possibility of going further, and engineering microalgae to produce biofuels (including biodiesel) directly, without having to convert from organic oils as an intermediate step. This may be achieved by re-engineering the photosynthesis process to yield hydrocarbons like petrol or diesel, by combining water and carbon dioxide, and removing the oxygen by reduction. This would make them a potentially effective source of biofuels, and perhaps even direct generators of electricity.
Refining these processes is a work in progress, but it is telling that some leading experts, such as the US National Renewable Energy Laboratory (NREL), the largest federal agency dedicated to sustainable energy research, declined to comment for this article because it is currently filing patents. Indeed, Craig Venter, who recently claimed to have created “artificial life,” has singled out production of biofuels from algae as an important future application of his work. He believes that emerging…