Old frog, new tricks: The rise of magnetic biofuels

July 17, 2012 |

Can the harnessing of the powers of magnetism overcome cost challenges in algal biofuels?

Researchers across the globe pursue the answers.

Of all the many contributions that the English have made to the study and advancement of biofuels, it may be that one day that the appearance of an unusual bacterium back in the last days of the dinosaurs – amongst the organisms that eventually formed the White Cliffs of Dover – that we may remember best.

That location – the northern downs of England – is home to the oldest known magnetotactic bacteria, which is to say bacteria that respond to electromagnetic forces.

Engineering magnetic algae

The bacterium was first observed in the 1960s, but their role in the future of energy took a significant step forward last year, when a group of Los Alamos National Laboratory researchers genetically engineered “magnetic” algae to investigate alternative, more efficient harvesting and lipid extraction methods for biofuels.

At LANL, the researchers took a gene that is known to form magnetic nanoparticles in magnetotactic bacteria and expressed it in green algae, where a permanent magnet can be used to separate the transformed algae from a solution.

Other approaches to magnetism and biofuels

It’s not the first attempt to harness the powers of the electromagnetic force in the service of biofuels. Back in 2009, Siemens researcher Manfred Ruehrig proved, at lab scale, that it was possible to add magnetic iron oxides into water, have them snatched up by algae, and then use external permanent magnets to separate the suddenly-magnetic algae from the water and, presto!, a low-cost means of concentrating algae out of all the water that it grows in.

In 2010, a team of researches led by Wankei Wan, at the University of Western Ontario, reported that they had successfully used the introduction of electromagnetic fields to speed up the reproduction rate of a single-celled alga, Chlorella kessleri, in a small-scale raceway pond.

But the Los Alamos approach is perhaps the most intriguing – the introduction of magnetic properties into microalgae. For the challenge of algal biofuels these days, is to shake the cost out of the systems. Two key challenges in that quest: first, keeping algal production, over the long term, at healthy rates by ensuring that the selected strain can outcompete predators and competitors; second, by finding the lowest-cost path to getting the water out of the algae or the algae out of the water.

Algal biofuels and the defense against the dark arts

As Tony Haymet, Director of Scripps Institution of Oceanography, Vice Chancellor for Marine Sciences, and Dean of the Graduate School of Marine Sciences at UCSD, pointed out recently, the science of algae in open pond systems has proceeded to the point where 25 grams per square meter per day of biomass, with a 25 percent lipid content, is no longer a stretch goal for algal scientists. In fact, he said, it has become table stakes.

In layman’s terms, what does that productivity translate to? That’s right around 2700 gallons of renewable oil per acre of production. Compared to around 800 gallons of ethanol per acre for sugarcane and around 400 gallons per acre of ethanol for corn. Not to mention the far higher BTUs, or heating value, of algal oils, gallon for gallon, compared to ethanol.

So the challenge with algae has been less in the productivity of the system and more with its sustainability and the overall system cost.

To date, Sapphire Energy and Aurora Algae have proceeded the farthest towards large-scale open pond algal systems that they believe have a reliable degree of sustainability. In other words, they have studied up sufficiently in their Defense against the Dark Arts studies that they can defend their ponds and their prized algae against all comers.

Getting the algae out of the water

Leaving the problem of getting the algae out of the water – and for some time there has been increasing focus on natural systems by which biomass can aggregate itself. There’s bioflocculation, for example, a process by which algae clump together and, in so clumping, settle quickly out of the water. A 2008 project at the School of Marine Science and Technology and the School of Chemical Engineering and Advanced Materials at Newcastle University was one of the pioneering efforts at harnessing this process into an applied technology for algal biofuels.

Which brings us to magnetism. It’s a powerful force, as is commonly known, acts across large distances. In fact, a subclass known as diamagnetic material can be successfully floated in a magnetic field, without the use of power consumption. Back in 2006, a group of researchers at Radboud University in the Netherlands, managed to successfully levitate a live frog in a magnetic field.

So, there is paramagnetism, which describes the attractive force – and diamagentism, which describes a repelling force.

To use a commonplace image, consider the effect which a serving of ice cream has upon an otherwise uniformly distributed roomful of diners – generally, an attractive force. Then there the effect which, say, the impact which a noseful of hot, freshly-made Scottish haggis has upon the uninitiated – the repellent force in action, requiring not of energy but simply the distribution of a force across a field.

For now, the work remains to take the work out of the lab and into the field. But it reminds us why so many thoughtful people are betting that advances in biology and genetic engineering will cause bio-based materials and fuels to be produced more cost-effectively than from fossil-based molecules.

A Molecule that learns

For the fossil molecule, its time within a living system is complete and its development is finished – it is simply a matter of finding the best way to retrieve it. But for the bio-based molecule, it is still a living thing and, ultimately, can be helped to acquire traits that make it spectacularly successful as a platform for fuels and materials.

The old dog, as it turns out, is highly capable of learning new tricks, if we simply master the means of looking beyond traits . That is, assembling traits – like magnetism of magnetotactic bacteria and the lipid production rates of green algae – into aggregated groups that we might refer to not only as organisms, but as organisms with talents.

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