Researchers in Canada proved last October that a civil aircraft could fly on a 100% drop-in aviation fuel derived from a new oilseed crop called brassica carinata. The company that turned that crop into jet fuel is working towards certification for its product and sees a big future for unblended drop-in aviation fuels.

On 29 October 2012, the National Research Council (NRC) of Canada carried out a test flight using one of its experimental Dassault Falcon 20 aircraft. The jet's General Electric CF700 engines were running purely on ReadiJet, an aviation fuel manufactured by Panama City, Florida-based Applied Research Associates (ARA) using Agrisoma Biosciences' "Resonance" industrial feedstock, which comes from carinata.

The 100min flight took off from and landed at Ottawa's Macdonald-Cartier International Airport and reached a cruising altitude of 30,000ft (9,144m). It was billed as a world first because the renewable fuel used in the experiment was not blended with kerosene. Analysis of data collected by a Lockheed T-33 which tailed the flight showed the fuel to be "cleaner than and as efficient as conventional aviation fuel", according to the NRC.

"This fuel was, if not better than, equal to conventional fuel in most cases," says Wajid Chishty, technology leader alternative fuels at NRC. This included a 50% reduction in aerosol emissions, a 49% reduction in black carbon emissions and a 25% reduction in particulate matter. In addition, fuel consumption was improved by 1.5% compared with traditional jet fuel. "We did static ground testing and flight testing, and in both cases we saw reduced fuel consumption," says Chishty.

No special modifications had to be made to the Falcon 20 or its engines to prepare it for the biofuel flight because the properties of the fuel used mirror those of kerosene.

Falcon 2 


 One step closer: the Falcon test may act as a catalyst for bioful acceptance

ARA produced the fuel using a process known as Biofuels Isoconversion, which it developed with partner Chevron Lummus Global. The process, which is based on ARA's patented catalytic hydrothermolysis technique, uses water pressure to convert virtually any plant oil into 100% drop-in jet fuel, says the company.

"We use a range of feedstocks - we've done it with 16, ranging from soybean to canola to carinata to waste vegetable oil and everything in between," says ARA biofuels programme manager Chuck Red. But he points to carinata in particular as having "huge potential as the next step" on the road to finding alternative fuel sources for aviation. This is partly because carinata has a high erucic acid content, which results in better jet fuel yields, and partly because it can be cultivated on fallow land as a rotational crop, which means it does not compete for land with food crops.

"Carinata has the ability to scale and it handles drought well," says Red. "There are 6 million acres [2.4 million ha] in Canada that sit fallow every year and are looking for a crop like this - farmers are clamouring for it."

Chishty agrees, noting: "It's a 100% industrial crop - you can't eat it. In fact, it's banned [from being eaten] in North America because of its erucic acid content. It was developed for rotational crop purposes to give a breather to the soil after two or three seasons of growing, for example, wheat."

Red believes the fact that ARA's ReadiJet fuel does not need to be blended with petroleum gives it an advantage over hydroprocessed esters and fatty acids (HEFA) fuels, which were approved in July 2011 by certifying body ASTM International for use in commercial aviation as a 50:50 blend.

"There are concerns with HEFA fuels over the long-term effect on engines of blending with petroleum," says Red, adding that blending can potentially lead to the shrinkage of rubber fuel seals. "There's a great desire to have a fuel that doesn't have to be blended." He also points to the "nice aromatic content" of ReadiJet, which makes it "a very inexpensive" alternative, and the fact that "very little" pre-treatment is required. "When you look at HEFA fuels they require lots of pre-treating, deodorising and bleaching."

However, HEFA fuels have the advantage of being certified for use by commercial airlines, a vital milestone that ReadiJet has yet to pass. As part of its effort to gain ASTM approval for its fuel, ARA has teamed up with Blue Sun Energy to build a facility in Missouri, USA, that will use the Biofuels Isoconversion process to produce 100 barrels, or 4,200gal, a day of ReadiJet.

"We've started construction and by early fall we will start producing," says Red, adding that the demonstration will mainly use carinata, alongside other feedstocks such as waste vegetable oil. This project will be "a key enabler for ASTM certification of our fuels", which Red is hopeful will happen in June 2014.

Airbus product manager new energies Etienne Cabaré believes that there may be a market in the future for drop-in aviation fuels that do not require blending, but he does not see this becoming a widespread reality any time soon. "For tomorrow we're not going to see very rapidly the emergence of 100% biofuel on aircraft, even if it can be certified," he says.

A task force for HEFA synthetic kerosene with aromatics - the category under which ReadiJet falls - was established last June and "we've just identified the last couple of tests" to be carried out, says Red. "We're shooting for 2015 to have commercial facilities up and running."

The Falcon 20 experiment in Canada remains the only test flight using ReadiJet, but Red says that "we're talking to several folks about flights next year". Ground tests are being carried out presently: "Rolls-Royce has been testing our fuel since 2011. They recently did a rig test on a larger engine and we're waiting for results," says Red, adding that Pratt & Whitney Canada "is going to test our fuel in June in a commercial engine".

ARA is hoping to sign some uptake agreements for its fuel by early 2014. "We're talking to lots of airlines in the USA, Canada and Europe and they're very excited," says Red.

Following the success of its biofuel test flight last October, NRC is "always open to new ventures" in a similar vein, says Chishty. For instance, the organisation is currently working on a multi-year project to develop a lead-free aviation gasoline for piston-engine aircraft.

"We've gathered some interested people and there's a big push in the USA and Canada to get it done as soon as possible. We're asking for funds and we're hoping to launch in a month or so," says Chishty.

Falcon 1 


 More flights may follow the initial experiment

The NRC will continue to support ARA in its efforts to get ReadiJet certified, says Chishty, who is hopeful that the Falcon 20 flight will act as a catalyst to get things moving on the aviation biofuels front. "The objective of the project was not to do a one-time test flight, it was to get all the stakeholders from the aviation value chain on one project together," he says.

"The purpose of the demonstration was to show that biofuel is a reality and a viable alternative for the aviation industry. Right now the reason the cost is so high is that producers are not encouraged by support from governments. The idea was to show this is a viable thing and to get more attention."

Source: Flight International