US Air Force moves closer to greening its fleet

For the US Air Force, proving that the Lockheed Martin F-22 can break the sound barrier powered by something else but petroleum is a scientific achievement. But the 18 March test flight of an F-22 using a 50-50 blend of conventional JP-8 and a camelina-derived hydrotreated renewable jet (HRJ) fuel is more of a financial breakthrough for entrepreneurs like Tom Todaro.

As founder and chief executive of Seattle-based AltAir Fuels, Todaro is still raising money to build the first refinery for the mass production of HRJ. His business case depends on getting the product certificated as a standard aviation fuel, and demonstrations like the F-22 supersonic flight help answer any lingering doubts about its compatibility.

"It changes the dynamic," says Todaro. "From a practical point of view, it's a bit of a challenge to ask a bank to write you a couple-of-hundred-million-dollar cheque when your fuel isn't certified."

Certification may now be less than two months away. Nearly 10 months have passed since the ASTM International Committee D02 withdrew a ballot to revise the D7566-09 standard for aviation turbine fuels to include alternatives to petroleum, including HRJ.

The key to certification is proving that biomass or synthetic fuels can match the performance and characteristics of petroleum in existing turbine engines. At the time, the committee's members lacked enough data to support a decision to revise the standard. Just three months earlier, the USAF had flown an aircraft using a fuel blend partly comprising biomass feedstock for the first time.

That first flight, by a Fairchild A-10 Thunderbolt II on 25 March 2010, has been followed by a wide-ranging series of flight tests over the past year. The A-10 flight was completed using a blend of 50% JP-8 and 50% camelina converted into an HRJ fuel.

On 27 August last year, a Boeing C-17 was flown with a fuel comprising 50% conventional JP-8, 25% HRJ fuel and 25% coal or natural gas converted into liquid using the Fischer-Tropsch process. The HRJ fuel was derived from a waste animal fat called beef tallow.

©Altair Camelina is favoured by some, but Rand analysts say there is little evidence to back it

More recently, the F-22 supersonic flight also demonstrated that an alternative fuel blend is compatible with the complexity of the Pratt & Whitney F119 engine.

ASTM's D02 committee is expected to vote in June or July to include petroleum alternatives in the fuel standard for aviation turbine engines, clearing the final barrier for mainstream integration of such fuels in both commercial and military operations. However, the path from certification to mass production of HRJ fuels is uncertain. AltAir's route to market offers a vivid example of the kind of challenges facing the alternative fuel industry as it seeks to transition from a research and development project to commodity-scale production.

The company was established three years ago to take advantage of growing interest from the military and commercial airlines in finding alternatives to petroleum. For the military, the interest was both economic and security-related. The US Air Force's annual energy bill is about $6.7 billion, with more than 80% of that total spent on jet fuel. The Department of Defense accounts for about 1.5% of all fuel consumed in the USA each year.

The same year AltAir was founded, both the air force and navy committed to dramatically increasing their purchase of alternative fuels by the end of the decade. The air force committed to source half its domestic fuel supply with alternative blends by 2016.

The navy, meanwhile, pledged to create the "Green strike group", with all vessels supporting its nuclear-powered aircraft carriers using alternative versions of F-76 fuels, within the same timeframe as the air force's project. But those commitments are not open-ended. To compete for contracts of that scale in five years' time, the cost of biofuels must fall rapidly.

Recent contracts for biofuels signed by the Defense Logistics Agency give some idea of the price reduction challenge. For example, Sustainable Oils, which is affiliated with Alt­Air, has delivered 380,000 litres (100,000USgal) of HRJ-8 fuel for the air force's research and development activities. The fuel cost $6.68 million, or $17.6/litre ($66.8/USgal). Honeywell-owned UOP has also supplied the same amount of HRJ-8 fuel for $6.4 million, or $16.9/litre.

Alternative fuel suppliers wanting to be considered for sharing half the USAF's jet fuel budget in 2016 must meet three requirements. First, the fuel must be a "drop-in" replacement for the service's existing aircraft engines, which has so far been successfully demonstrated on the A-10, C-17 and F-22. Second, the fuel must be accessible without reducing the world's fuel supply or increasing greenhouse gas emissions. Third, biofuel candidates must be cost-competitive with market rates for petroleum or synthetic blends derived from coal or natural gas.

©UA Air Force A USAF C-17 has flown with a fuel comprising 50% conventional JP-8, 25% HRJ and 25% coal or natural gas converted into liquid

Primarily for the third of these reasons, a Rand think-tank in January released a report recommending the USAF cancel all investments in HRJ-based fuels, including Alt­Air's method. Citing the successful flight demonstrations, Rand's report, Alternative Fuels for Military Applications, concludes: "Technical viability is not an issue." But Rand analysts James Bartis and Lawrence Van Bibber take exception to the biofuel industry's claims about cost and environmental concerns. "The problem lies in uncertainties regarding production potential and commercial viability, especially affordability and lifecycle greenhouse gas emissions," write Bartis and Van Bibber. "Jatropha and camelina are often mentioned as ideal plants to meet these requirements, but there exists little evidence to back these claims."

More promising in the near term, says Rand, are synthetic paraffinic kerosene oils produced through the Fischer-Tropsch process.

Introducing any new technology within a five-year period may seem ambitious, and Alt­Air's progress since it was founded in 2008 reveals some of the challenges. For example, AltAir's original plan was based on being able to rely on an oil refinery in Anacortes, Washington, called Tesoro, which would convert camelina seeds into HRJ fuels for Seattle-based airlines and the US Navy. But the Tesoro refinery suffered a setback in April 2010, when an explosion killed five people. Since that incident, Alt­Air has backed away from its original plans to collaborate with Tesoro, says the refinery.

"We have other refinery locations and greenfield options," says AltAir's Todaro.

Meanwhile, AltAir's original goal to open a scaled-up refinery for camelina in 2012 has been delayed as the company waits for the ASTM committee to approve the revised standard. AltAir needs at least two years after the standard is approved to build the refinery and start producing HRJ fuels, says Todaro. If the standard is approved by July, the refinery could begin deliveries in the first quarter of 2014.

The facility is planned to deliver about 380 million litres a year. "We can expand that, but you sort of want to walk before you can run," Todaro adds.

To keep up to speed on the global defence industry, read Stephen Trimble's blog: flightglobal.com/thedewline

Source: Flight International