Interview with Paul Kuentzmann (Onera)
“30% biofuels in aircraft by around 2020”
By Isabelle Smets | Monday 15 June 2009
Paul Kuentzmann is Senior Scientific Adviser at Onera, the French aeronautics and space research centre. From 1996 to 2005, he was scientific director for fluids and energetics. As a specialist in aviation fuels, he comments here on research into alternative fuels.
Do synthetic fuels represent an attractive option?
There have been flight demonstrations with satisfactory results. The aircraft flies normally and there is no apparent difference between an aircraft fuelled with traditional jet fuel and one fuelled with synthetic fuel. There are even slight advantages because the synthetic fuels form less soot than traditional fuels, which is interesting for air quality in and around airports. They contain fewer aromatic chemical species than traditional jet fuel and aromatics are precursors of soot. Installations are being built today for the production of GTL [Ed.: gas to liquid, synthetic liquid fuel derived from natural gas]. The process – known as ‘Fischer Tropsch’ – has been mastered. It dates from the 1920s and was used during the Second World War in Germany to produce aviation fuels.
If these technologies have existed for years, why are they not being used more today?
There are two problems. First, there are not enough plants to provide the volumes required. At present, only Sasol [Ed.: Suid Afrikaanse Steenkool en Olie – South African Coal and Oil, a petrochemical company] has major industrial installations. However, Shell and Qatar Petroleum are in the process of building a large plant to produce GTL and others are considering working from coal. The second problem is that, if the whole chain is taken into account, CO2 emissions are high. More CO2 is emitted than with traditional oil refineries. So on the one hand, we stand to win in terms of energy independence, but on the other we lose in terms of climate change.
So does that make it a credible solution?
It is a solution that primarily interests the military. Many American military aircraft have already flown using these blends, and some civilian aircraft as well. Synthetic fuels can also be considered transitional fuels until more interesting options can be developed. The question is whether there will be investments in big plants to produce the quantities needed. Some oil companies, like Shell, are moving forward, but others are waiting.
The other possibility is biofuels…
For the moment, though, we’re still at the stage of scientific research rather than industrial production. The processes are much less advanced.
What are the prospects for the medium term?
In the medium term, for military use we will be moving towards the use of blends of traditional jet fuel and GTL or CTL [coal to liquid], especially in the United States. That can happen very quickly because the US Air Force is going to certify its entire fleet for these blends in 2011 – that represents a total of 1,600 aircraft – and will supply them in 2016. At European level, there are no objectives for the military at present.
And for civilian aircraft?
There is disagreement among manufacturers, especially on the use of biofuels. Some say they will be available very soon, around 2013. Others, like Airbus, think this will happen much later, between 2020 and 2030. My personal opinion is that we will start to use 30% biofuels in aircraft by around 2020. We will always start with blends containing traditional jet fuel, with minimal adaptations to aircraft and engines. The CO2 result will be much more interesting than with oil, and it will also be interesting for other polluting emissions, notably soot particles.
When will there be fuels that can entirely replace today’s jet fuel?
That will not occur in the medium term. The basic problem is that major industrial installations will have to be built to produce large quantities. And extremely heavy investments will be needed, of around $50,000 per barrel/day: to produce a barrel a day will require an initial investment of $50,000. Who is going to make these investments? The oil companies or who? We don’t know yet.
What do you see as the most promising technique?
Taking the time factor into account, the easiest to manufacture at present is GTL. But natural gas reserves are not very large, enough for a few decades. I think that a transitional fuel can be produced from fossil resources but that the big research investments need to be made in fuels based on renewable resources. In 2020, there will already be quite a few aircraft flying on blends and we will start using biofuels.