Around 25,000 aircraft take to the skies every year. Together, they burn 1.5 billion barrels of jet fuel and pump out more than 780 million tonnes of CO2. While this accounts for only a fraction of the world’s CO2 emissions, there is a growing need for aviators to clean up their act.

One popular way to cut the CO2 from flights is to switch to alternative fuels. Sustainable biofuels are a promising candidate to shrink the industry’s huge carbon footprint.

Biofuels are regarded as any fuel produced from organic material. Wood, animal dung and charcoal are traditional examples, widely used in developing countries. Advanced technologies can convert these materials into even more efficient fuel sources. In more developed countries, wood, crops and waste materials are processed to produce burnable solids, liquids or gasses.

Algae are a commonly used biofuel plant. Some species already work as miniature factories to make a fuel known as biodiesel. Microalgae are small, aquatic plants that use the sun’s energy, CO2 and nutrients to grow. They are so efficient they can multiply many times in a day, producing large ‘crops’ very quickly. Some of these microalgae store their excess energy as oils called lipids. When produced in large enough quantities, these oils can be converted into biofuel.

These biofuels could even replace fossil fuels across the whole transportation industry. However, to do so, the process must become much more economically viable. In order to extract the oils for our use, the cell walls of the algae must be carefully broken down. This is a painstaking process that accounts for an enormous 20% of fuel production cost.

Chemical engineer Dr Antonio Del Rio, and his team at Imperial College London, are searching for a cheaper way to produce green fuels.

Their idea looks at a new type of biofuel using different strains of algae and bacteria. They hope to genetically programme the algae into ‘manufacturing’ tiny amounts of fuel. Instead of breaking the cells apart to get the fuels, the team instead plan to make the algae excrete it. This would make processing the fuel much less energy intensive and much cheaper.

Working with a research group led by Professor Klaus Hellgardt, Del Rio is looking at three particular strains of algae to produce three different biofuels. Biohydrogen is a clean transport fuel; biobutanol could replace petrol; and biohydrocarbon provides an alternative to diesel.

Alongside appealing to the energy industry, the study could also be of interest to companies using algae to produce animal feeds. In addition to their primary income, algae farmers could benefit from the co-production of biofuels.

While the idea of cheap and green energy is a hot topic, the team are still in the early stages of research. They are currently modelling the algae’s fuel production abilities and developing strategies to further improve it. With an ambitious EU goal to produce 10% of transport energy from biofuels by 2020 however, things are on the move. The latest projection from the European Algal Biomass Association suggests we could see lab experiments move up to industrial scale production in the next 10 years.

Photo credit: AgriLife Today