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Biofuels: Literally Green Energy

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With world officials attempting to come to agreements over future climate budgets, renewables energy are once again in the eye of the media. Undeterred by the global focus, a solution to providing clean, low carbon energy is still some way off. The argument for nuclear power rages on, - regardless of recent advances in wind and tidal energy - while our carbon footprint continues to expand exponentially. It seems clear to me that the global energy crisis can not be solved by complete reliance on one renewable energy source, and that a cumulative effort is the key to success.

One source of energy that could contribute to this effort, is biofuels. The idea of biofuels, such as biodiesel, is an interesting concept. Harnessing the power of nature has always be the aim of renewable energies, but this is a task that has not proved easy. Creating biofuels is no exception to this rule, but that has not deterred scientists to attempt to create energy from the byproducts of growing naturally occurring organisms, such as marine phytoplankton, in vast quantities.

Plankton

If you remember from a previous post, we discussed that plankton are in fact not evil geniuses as depicted by Spongebob Squarepants, but in fact are responsible for life as we know it. It seems only logical then, that growing phytoplankton can help mitigate the effects of climate change.

Biofuels are not the only compound that can be achieved through growing marine phytoplankton em masse. Production of other desirable compounds is key in identifying potential species for cultivation. This is due to the production of biofuels still being relatively inefficient, to make up costs other high value compounds need to either be reduced, or byproducts recycled into the cultivation process.

These high value compounds can be used in fuels, such as biodiesel, cosmetics, and even as food sources. Astaxanthin is one such compound used in cosmetics, and is currently worth around £350 per kg.

It’s not just plankton that produces high value compounds. Where they are highly desirable because of their lipid content (the combustion of which forms the fuel within biodiesel) there are other marine organisms which can produce useful compounds. Take magneotactic bacteria for example. These bacteria produce magnetic particles, that can be used for medicinal purposes. These particles can be used to display antibodies, enzymes and receptors within to body to make for better targeting of drugs.

Biodiesel

Lets focus on biodiesel, how does it work and how efficient is it as process?
The principle behind biodiesel hinges on a simple reaction:

Tricylglycerol + Methanol —Catalyst—> Fatty Acid Methyl Ester (biodiesel) + Glycerol



The tricylglycerols are produce in massive quantities in some species of marine algae. Take the diatom
Fistulifera solaris for example, when grown under stress conditions as high as 65% of their weight is comprised of lipids capable of fitting into this biodiesel reactions. These lipids are also of high quality. Perhaps the best way to explain this is to compare the current market fuels, unleaded and super unleaded. Super unleaded is deemed to be more fuel efficient, due to the combustion reaction.

This also applies to lipids. Lipids or fats, can be of different grades. Those produced by
F. solaris - currently being used by Tokyo University of Agriculture and Technology. The lipids produced by F. solaris are high quality, with high number of single bonds, which are more easily oxidised and therefore more easily combusted.

Easier combustion makes for a more efficient fuel, or energy profit ratio. The energy profit ratio can be calculated by divided energy output by energy input, which in lay terms means the amount of energy gained by the fuel by the amount required to make it. The energy output needs to outweigh energy input for the biofuel to be worth making.

There are a number of ways in which to make the energy profit ratio more favourable. These include also producing the aforementioned high value compounds for foods and cosmetics industries, but also recycling the byproducts of the biodiesel production reactions. Currently, a new technique of using the glycerol byproduct as a source of carbon for growth is under development.

For biodiesel to be a significant alternative to current fossil fuels, and to be a real player in the renewables industry, there need to be significant increases in the harvesting efficiency, to help further improve the energy profit ratio.

Many issues exist currently with using marine phytoplankton as a source of biodiesel. To begin with, growing them in quantities large enough and in a sustainable fashion is very difficult. By using lots of electrical lighting, which currently comes from fossil sources means that the ‘clean’ energy being produced is effectively fossil fuel energy just displaced. Furthermore, growing marine plankton in large quantities is very difficult. Getting the balance between light and nutrients to ensure viable growth is easier said than done.

In short, where biodiesel may present a logical alternative in the future, currently the process is too unrefined to be effective. To combat climate change on the renewable energy front, biodiesel could be used in conjunction with other sources, such as solar, wind and tidal. Shifts to renewable energy have been shown to be effective, although costly, with Uruguay
recently moving to 95% renewable energy.

Here’s to hoping that similar shifts come out of COP21…


Seth Author