Biofuels have been hailed by the aviation industry as the best way for aircraft to become
carbon neutral, but does the argument fly?

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With more people taking to the skies around the world, environmental c a m p a i g n e r s must fear the only things rising faster than CO2 emissions from airliners are sea levels. After all, carbon produced by the global aviation industry is roughly the same as the emissions of greenhouse gases by the whole of Germany, and they’re still on the rise.

Our best hope for reducing the carbon dioxide pumped out by our giants of the sky may rest with so called biofuels – but it’s well documented that they are themselves surrounded by controversy.

Biofuels produce less carbon dioxide than the fossil fuels they replace. Aviation biofuels are obtained by turning materials such as vegetable oil or even algae into synthetic jet fuel. This synthetic fuel is then blended with conventional jet fuel called kerosene to reduce the amount of greenhouse gas an airliner pumps out.

However, many environmentalists are concerned that the crops used to produce aviation biofuels take up land that could have grown food badly needed in some parts of the world.

They are also worried that the energy required to turn them into fuel is more than what is gained from using them. What is more, the goal to replace half of all the fuel used to fly us on holiday with biofuel by 2050 seems hopelessly lacking in ambition given runaway climate change.

The airline industry has a different point of view. Aviation chiefs have just signed a deal to ensure the growth in commercial aviation is carbon neutral by 2020. It will compensate for the growth in emissions of carbon dioxide – it is expected to almost double – through improved aircraft efficiency and planting trees but perhaps most crucially the use of biofuels.

When the aviation industry first committed to use aviation biofuels, many environmentalists were sceptical that it was little more than a stunt. Now, however, more than 5,000 flights have taken place using a blend of biofuels and jet fuel. Airlines such as KLM, United and Continental have taken the lead in using alternative fuels, while others including Virgin and British Airways are also investing in the companies that make them.

Many materials can be made into these fuels. These feedstocks can range from the conventional – vegetable oil, corn starch, and alcohol – to more unusual substances such as tallow (made from animal fat) or even excrement. Some seem to come straight from science fiction, including algae, yeast and genetically engineered organisms – even if it is more in theory than practice at times.

Whereas jet fuels have been used since the 1940s, the first biofuel was certified in 2009. Since then, five methods of turning these feedstocks into biofuel have been approved, using a variety of feedstocks and even existing oil refineries. However, just because you can produce these fuels does not mean you can make any money from doing so. The number of flights that have used biofuels remains a small proportion of the total.

“The problem is that there is a lot of talk about many different kinds of aviation biofuels,” says Almuth Ernsting, co-director of Biofuelwatch, an advocacy organisation focusing on the impacts of bioenergy. “Many of these are not the fuels you are going to see used in the near future. The technologies are not viable yet. Or they take a huge amount of effort and

Many materials can be made into fuel, ranging from tallow to excrement

investment to produce and then only in tiny quantities. The energy balance is often very bad and the refineries struggle to make any money from them.

“However, there are big plans for vegetable oil – and we are very worried. For example, palm oil has been used for the production of biodiesel and is associated with massive land change – worries that don’t go away even if a different vegetable oil is used. For the moment using palm oil is taboo for airlines, certainly in PR terms.”

“Rather than biofuels we prefer the term sustainable aviation biofuels due to the negative
connotations of the word,” says Chris Goater, assistant director, corporate communications at the International Air Transport Association. “There are some people who continue to claim that biofuels for aviation are a bad thing because they damage the environment – and some policymakers are still influenced by this.

“We are very clear that sustainable aviation biofuels won’t do this and we wouldn’t support these fuels if they did. The challenge is that aviation biofuels need the right kind of framework in place so that producers will take a gamble.”

The controversies around these biofuels makes it tempting to turn to technology. Yet the alternatives such as solar and electric power which are often hyped as the next big thing are actually decades away from being ready to power full-sized planes – if they ever are. Aircraft on the drawing board today will still be flying in 2050.

In September in Germany, the twin-fuselage HY4 took to the air was the first to use a kind of battery called a hydrogen fuel cell and an electric engine to lift more than just one or two people into the air. This time it was four people.

“Biofuels are just a bridging technology,” says Josef Kallo, director of the Institute for Energy Conversion and Storage at the University of Ulm, which helped to develop the HY4. “By going from the one-seater to the four-seater we are showing the potential of the technology to go bigger.

“Our goal over the next 10 to 15 years is to build a 40-seater like the [short-haul airliner] ATR-42, which is often used for commuter flights. This depends on time, money and people. However, the big problem is that the fuel energy density of our fuel cells doesn’t match that of fossil fuels. The other is that we need the price of jet fuel to triple to make it commercially viable. I am convinced that in my lifetime I will see an electric plane.”

In the end, Jacques Rocca, head of media content for Airbus, thinks that there are reasons to be optimistic. “The aircraft we are putting on to the market are more efficient. We are working to offset emissions with carbon trading. We can even make air traffic management more efficient. And then there are biofuels.

“We will be able to go beyond 50 per cent biofuels in the end, but that will take a lot more research into how the fuels behave and interact with the engines. By 2030- 35 production of biofuels will also have reached an acceptable level.

“A truly innovative electric or solar aircraft is not for tomorrow or perhaps even 2050,” he adds. “But we will spend a lot of money on innovation and we will do our best to push for the technology.”

However, not everyone is so optimistic.

“Aviation is the one sector where there is no techno fix,” says Ernsting. “There may be companies out there that are hopeful, but there is no technology out there now. We are going to have to simply have less aviation.”