USA — Air Force Scientists Test, Develop Bio Jet Fuels

WASHINGTON — While the world search­es for more effi­cient ways to fuel auto­mo­biles and cre­ate usable ener­gy, Air Force sci­en­tists are look­ing for clean­er, more effi­cient ways to fuel the military’s air­craft. On March 25, an A‑10 Thun­der­bolt II flew sole­ly on a blend of bio­mass-derived fuel and con­ven­tion­al JP‑8 jet fuel – the first flight of its kind.

Air Force Materiel Com­mand fuels experts Jeff Braun, direc­tor of the Air Force’s alter­na­tive fuels cer­ti­fi­ca­tion office; Tim Edwards, a senior chem­i­cal engi­neer with the Air Force Research Laboratory’s propul­sion direc­torate; and Bet­ty Rodriguez, chief engi­neer for the alter­na­tive fuels cer­ti­fi­ca­tion office, direct the research and cer­ti­fi­ca­tion of syn­thet­ic and bio­mass-derived alter­na­tive avi­a­tion fuels from Wright-Pat­ter­son Air Force Base, Ohio, and they par­tic­i­pat­ed in a “DoD Live” blog­gers round­table and offered their per­spec­tives on the his­to­ry-mak­ing demon­stra­tion flight.

The A‑10 was pow­ered by a blend of con­ven­tion­al JP‑8 and a bio­mass fuel derived from cameli­na, a non­food rota­tion crop sim­i­lar to soy­bean and mus­tard. The alter­na­tive fuels cer­ti­fi­ca­tion office is prepar­ing to test fuels made pri­mar­i­ly from plant oils and ani­mal fats. They are part of a fam­i­ly of fuels Braun said are called “hydro-treat­able renew­able jet,” or HRJ, fuels. He and his col­leagues hope to cre­ate bio­mass fuels that the Air Force will cer­ti­fy for use across its spec­trum of air­craft and sup­port vehi­cles.

The A‑10 flight is the lat­est phase of a long research and devel­op­ment process eval­u­at­ing can­di­date bio­fu­els from var­i­ous indus­try sources. Part of that process, Edwards said, is test­ing dif­fer­ent kinds of bio­mass mate­ri­als and bio­mass pro­cess­ing meth­ods.

“This is the first step of many we’re going to fol­low through,” Rodriguez said. “We’re going to con­tin­ue expand­ing the enve­lope, basi­cal­ly test­ing engines and test­ing air­craft.”

To a cer­tain extent, researchers can tai­lor the new bio­fu­els by spec­i­fy­ing desir­able chem­i­cal prop­er­ties which enable clean burn­ing, for exam­ple. Braun under­scored the Air Force is “feed­stock agnos­tic,” not­ing that what the fuel was made from isn’t impor­tant so long as it has the desired per­for­mance and safe­ty spec­i­fi­ca­tions.

“The way we look at it is to fig­ure out what fuels make the most sense from an avi­a­tion indus­try per­spec­tive — which ones have the poten­tial to make the most fuel the most afford­ably with the least envi­ron­men­tal impact,” Edwards said.

He added that the Air Force Research Lab­o­ra­to­ry has invest­ed a lot of mon­ey in envi­ron­men­tal research cov­er­ing life­cy­cle green­house gas foot­prints and oth­er fac­tors in devel­op­ing mate­ri­als for bio-fuels.

“We’re just try­ing to fig­ure out which kinds of process­es for mak­ing jet fuel for avi­a­tion seem to be the win­ners, and look into those for fur­ther devel­op­ment,” Edwards said.

A major ben­e­fit HRJ fuels offer the Air Force is that they can be pro­duced with­in exist­ing refiner­ies – new facil­i­ties don’t nec­es­sar­i­ly need to be built. But some new plants are being built sole­ly to pro­duce bio­mass fuels such as HRJ or “green” diesel, Edwards said.

One such refin­ery is being built by Tyson Foods and will use ani­mal fats from its food pro­duc­tion fac­to­ries to cre­ate bio­mass fuels. Anoth­er com­pa­ny, called AltAir Fuels, is build­ing an HRJ plant near an exist­ing refin­ery in Wash­ing­ton state, Edwards said.

“It turns out the pri­ma­ry cost comes from feed stock; the pro­cess­ing isn’t all that expen­sive,” Edwards said. “In places where you can get afford­able feed stock, at least the indus­try seems to think it’s cost-effec­tive, because they’re get­ting cap­i­tal to start build­ing plants.”

The Air Force is the Defense Department’s largest con­sumer of jet fuel, but burns only the equiv­a­lent of a mid-sized air­line. It’s close­ly coop­er­at­ing with indus­try as part of a con­sor­tium of com­mer­cial air­lines and engine man­u­fac­tur­ers called the Com­mer­cial Avi­a­tion Alter­na­tive Fuels Ini­tia­tive. The expec­ta­tion is that once bio­fu­els are cer­ti­fied for use, pro­duc­tion economies of scale will make them afford­able, on par with petro­le­um-based jet fuel.

Bio­mass fuels also can be made from algae and oth­er plant oils. Both options are being vig­or­ous­ly pur­sued by the avi­a­tion indus­try and the Air Force as well, Edwards said.

“Where we can get our hands on algae oils, we’ve proven that those fuels are pret­ty much the same as the cameli­na oil we flew on last week,” Edwards said. “Look­ing ahead to when algae hits it big – peo­ple are putting hun­dreds of mil­lions of dol­lars into it – we’re help­ing to enable that algae feed­stock for avi­a­tion appli­ca­tions.”

Reduc­ing demand and increas­ing sup­ply are two of the legs of the Air Force’s ener­gy strat­e­gy, Edwards said, with a focus on cre­at­ing and build­ing more effec­tive, clean­er engines. Rodriguez added that the advance­ment of bio­fu­els and cre­at­ing effec­tive, effi­cient blend­ed fuels that can be dropped in with­out any mod­i­fi­ca­tions to air­craft or sys­tems are a big part of that.

Edwards said even as the Air Force pre­pares to begin cer­ti­fi­ca­tion test­ing of HRJ fuels, sci­en­tists at the Air Force Research Lab­o­ra­to­ry are explor­ing the next gen­er­a­tion of new fuels, made from cel­lu­losic bio­mass sources or derived from advanced fer­men­ta­tion process­es that pro­duce hydro­car­bons. These aren’t near­ly ready for cer­ti­fi­ca­tion, as they require fur­ther devel­op­ment, Rodriguez said, but they do show promise.

“We’re at the cut­ting edge of alter­na­tive fuels,” Rodriguez said. “Everybody’s pulling togeth­er to make this pos­si­bil­i­ty a real­i­ty, to cre­ate a fam­i­ly of fuels we can burn safe­ly and won’t impact the per­for­mance of our air­craft and ground sup­port equip­ment.”

U.S. Depart­ment of Defense
Office of the Assis­tant Sec­re­tary of Defense (Pub­lic Affairs)