Jet-A Alternatives

 
This December, if the planets align properly and the members of the ASTM International concur, it will become legal to operate a business jet on a blend of conventional Jet-A and low-emissions biofuels refined from weeds, soybeans, tallow or algae.After years of research and testing by engine and airframe OEMs, the airlines and armed forces, government laboratories and universities, and the refining and chemical industries, ASTM is expected to approve a biofuel specification as an amendment to the existing D7566 standard, titled “Aviation Turbine Fuel Containing Synthesized Hydrocarbons,” which already covers synthetic fuels, or “syngas,” refined using the Fischer-Tropsch gasification process from coal and natural gas feedstocks. It is noteworthy from safety and performance standpoints that the prime requirement for both ASTM and FAA approval of a jet fuel intended to substitute for petroleum-derived Jet-A and its military equivalents is that it qualify as a so-called “drop-in” alternative. This means that it will perform exactly as the fuel it stands in for, or to use the anthropomorphic analogy, that “neither the aircraft nor the engines will know the difference.”

Two factors are driving the move toward alternative fuels in all modes of internal-combustion-powered transportation and electric power generation: fuels security and the need to address climate change by mitigating the proliferation of greenhouse gases (GHGs), principally carbon dioxide (CO2). The former — ensuring an uninterrupted supply of fuels for defense purposes — is of particular interest to the U.S. military establishment, especially considering the volatility of Middle Eastern politics, given that the majority of petroleum used by the West is imported from the region. Then, too, crude oil is a nonrenewable resource being consumed by all the world’s nations — and especially the developed ones — at an unprecedented rate, and ultimately, suitable substitute sources of energy must be found and exploited. Thus, sustainability is essential if quality of life, the West’s technologically driven lifestyle (including the mobility facilitated by air transportation) and the undeveloped world’s climb to prosperity are to be maintained.

Getting Easier to Be Green — But at a PriceThis report updates “Alternative Fuels for Jet Engines,” an in-depth examination of substitute, or “green,” fuels published by BCA in September 2007, page 82. BCA was curious to know what progress had been made in the ensuing three years in developing processes for refining sustainable and low-carbon-emissions fuels, establishing production and distribution infrastructure, certification status for use as drop-in alternatives and ultimate availability. And we learned that, indeed, alternative fuels development has made significant strides forward. In fact, the effort has reached a juncture where the technology is ready to be exploited.

Alan Epstein, Ph.D., vice president, technology and environment, at Pratt & Whitney Engines in Hartford, Conn., observed that “It may be easier now to ‘go green’ — but it isn’t getting any cheaper. It’s no longer technology that is the issue, it’s money. In a year, the aviation industry will have completed what is needed to enable your readers to use biofuels in their airplanes. The question is, who is going to be making them? We are certifying the fuels to encourage people to invest in their manufacture. We realize that the sustainable future of aviation depends on the availability of biofuels.”

The class of biofuels being considered by ASTM and the FAA for approval for use in jet engines this year is called bio-SPKs, for “synthetic paraffinic kerosenes.” “In other words,” another Epstein — this one, Mike Epstein, leader of alternative fuels at General Electric Aviation in Cincinnati (and no relation to P&W’s Epstein) — said, “they are paraffins [i.e., wax]. We are focused on 50/50 blends with Jet-A, which, not surprisingly, already contains a great deal of paraffinic kerosene, so the chemistry is similar.” Derived from plant oils, or triglycerides, the bio-SPKs thus hold the potential to be sustainable under the right cultivation circumstances. Therefore, selection of appropriate feedstocks from which to extract sustainable plant oils is critical, or as Epstein put it, “[N]o cutting down rainforests to make your bio oil or imposing on food production.”

Bio-SPK developers have changed the proportion of paraffins in jet fuel, while meeting the current ASTM specification, “which is important,” Epstein continued. “These blends meet that standard, which is mandatory for a drop-in fuel. We at G.E. and our competitors and the airframe OEMs will require no changes to either hardware or software [to burn these fuels], no new injectors, combustors or ground support equipment, because these fuels meet the current spec. They create mean shifts, so you are at the edge of the specification in a few areas, notable density. They are slightly less dense than petroleum but within the spec.”

Graham Ellis, business manager for chemicals at UOP, a Honeywell subsidiary once known as United Oil Products and based in Chicago, elaborated on bio-SPKs by way of providing a chronology of their development. (Founded in 1914, UOP develops catalysts and refining processes, the latter which it leases to refiners.) “Three years ago, after we had completed an eco-fining process for making green diesel, DARPA [the Pentagon’s Defense Applied Research Projects Agency] approached us to make a [military] JP8 biofuel. From that we developed a trademarked refining process that wound up as Honeywell Green Jet Fuel. Over the last three years it has also come to be referred to as SPK and HRJ [hydro processed renewable jet], although it’s all exactly the same product. SPK is a generic term and HRJ is a military acronym, as used for HRJ5 or HRJ8.”

(For the sake of clarity, JP8 and JP5 are current specifications for fuel used, respectively, by the U.S. Air Force and U.S. Navy. JP5 is formulated for, among other conditions, long-term storage aboard ships.)

“The bio-SPK is the one that is going through the ASTM certification process,” Ellis continued, “the vehicle for which is ASTM D7566. The way we are looking at certifying for commercial use is as an annex to D7566. The concept is that the chemical composition is so similar to the Fischer-Tropsch fuel covered by D7566 that HRJ can be a subset of that specification. If the ASTM vote passes, then this fuel will be an up-to-50 percent blending component [with conventional petroleum-derived Jet-A] requiring no modifications to jet engines.”

The DARPA synthetic JP8 program lasted 18 months, ending in 2008 when funding was terminated, “since we had developed the necessary chemistry,” Ellis said. “We then took over and completed the industrial process development. As of December 2009, we declared we were ready and willing to license the process. Early this year, we were pleased that Altair Fuels of Washington [State] elected to be the first to move with this, and we are in the middle of doing engineering for them.” Altair claims it has lined up 15 airlines as potential customers for Honeywell Green Jet once it’s available in commercial quantities. “Today we are working with a number of potential investors — about 15 — willing to develop this process if there is significant interest in the marketplace,” Ellis revealed. “A typical [eco-fining] unit will produce 50 million gallons a year of jet fuel. Also, each of those units is feedstock-flexible, meaning it can take any natural oil — from camelina, jatropha, to algae — as the chemistry works for all three.” Camalina and jatropha are weeds with high natural oil content that can be grown in semi-arid regions, thus not competing with food crops that must be raised on arable lands.

Breaking the Egg”If you want to do certification, you need to have fuel available, but you can’t build the commercial eco-fining unit if the fuel isn’t certified — a chicken-and-egg situation,” Ellis observed. “That was our problem and dilemma 15 years ago. To break that egg we went into production with a small demo unit in Houston that currently can produce up to 10,000 gallons of biofuel a day.” (UOP historically has not been a fuel producer.) Due to the feedstock flexibility, UOP chemists were able make jet fuel from jatropha, camelina, tallow, algae, even used cooking oil, all meeting the proposed spec, Ellis claimed.

“About a year ago, we were bidding to the Defense Energy Support Center [DESC, the Pentagon’s procurement wing] to fill a solicitation to provide jet fuels to the Navy and Air Force, working in partnership with [eco-finers] Sustainable Oils, Cargill and Solazyme. We were successful and won the entire solicitation, or 500,000-plus gallons of supply.” The bio-HRJ was subsequently tapped for demonstration flights of an Air Force A-10 and Navy F/A-18, appropriately dubbed the Green Hornet, in a 50/50 blend with conventional JP8 and JP5. “We are working through those deliveries and continue to process the fuels out of the plant in Houston,” Ellis said. “We have also been able to supply various airlines from the unit, as well, for their demo flights.”

The U.S. military is a prime mover behind the development of bio-jet fuels. “Approving, qualifying and certifying biofuels and other alternatives has been a collaborative effort between the commercial and military side,” Mike Epstein said. “The military has been very supportive with technical expertise and funding. The experience of running it in military engines can easily be transferred to the civil marketplace. The Air Force and Navy have been most active and supportive. There have also been some forward-looking airlines sponsoring initial flight tests.”

And what about Fischer-Tropsch (F-T) fuels? Given the immense coal and natural gas deposits in North America and Europe — though these hydrocarbon sources are nonrenewable resources — one would assume that F-T products would offer at least near-term fuel security until usable quantities of biofuels come on line. After all, three years ago, the Air Force was flying demos with a B-52 fueled with blends of F-T syngas and JP-8, and South Africa’s mining, chemical and energy conglomerate Sasol has been selling a drop-in F-T jet fuel to airlines for years.

As far as F-T fuels are concerned, “it’s a done deal,” P&W’s Alan Epstein proclaimed. “We have certified all our engines for F-T fuels. ASTM has amended this spec — they did a clever thing so that you can use pure F-T fuels in your engine independent of the source of the carbon [feedstock], so it can use coal, natural gas or bio.” The “cleverness” is how ASTM did it, Epstein believes: by amending the existing D7566 specification to include the other carbon feedstocks as they were introduced. “If you read the fine print,” he said, “it says you can use these fuels to meet the engine manufacturer’s specification to include F-T syngas from multiple feed stocks.”

But today, P&W’s Epstein thinks it’s unlikely that we’ll see much F-T either produced or used in the United States. “Shell makes F-T fuel from natural gas in Indonesia, and some of the Emirates are making it that way, as well, since they have more natural gas under their land than oil,” he said. “I don’t think we’ll be making it here, though, as Congress has passed an amendment to a bill that the military can’t buy any fuel in which the lifecycle CO2 emissions are higher than those of the petroleum LCA [lifecycle analysis] unless the excess CO2 can be sequestered.” LCA measures total CO2 emissions released into the atmosphere from production of a fuel through the actual burning of it. (LCA for biofuels also includes CO2 released in the cultivation of the feedstocks.)

“Now,” Epstein continued, “sequestration is a very expensive process, and there are some ‘nimby’ [“not in my back yard”] issues with it, as well. In the news this week [late May] there was an item about a town in Ohio that is protesting a proposed plan to sequester CO2 by pumping it into the ground under its location.

“And it looks like the excess gas-to-carbon rate — the amount of CO2 released to the atmosphere [during the refining process] — amounts to 8 percent more added to the burning of it. So coal-to-jet fuel [LCA] is about 8 percent more than petroleum. For environmental and climate change [mitigation], no one is thinking of coal-to-jet fuel as a good way to go.”

That is, F-T’s time has passed, at least here. For comparison, consider the LCA comparison between biofuels and petroleum-derived jet fuel, provided by UOP’s Ellis: “In terms of CO2 reduction, [biofuels] are better than 50 percent and the very best of them is 80 to 90 percent lower than petroleum-based fuels. In all cases, that is a very significant savings.”

Then there is the economic issue that dogs F-T in that the conversion plants are huge refineries costing on the order of $100,000 per barrel per day of capacity to operate. “So if I had a 10,000-barrel-per-day capacity,” P&W’s Epstein said, “it would cost $1 billion dollars [for a day’s production]! So you need billions of dollars, and then mandatory sequestration doubles that. Three years ago the plug got pulled in the world capital markets, and so the last thing investors are looking for now is an expensive process like that.”

Place Your Bets on BiofuelSo the smart money today, at least on the western side of the Atlantic (and probably in Europe, too, given the E.U.’s aggressive stance on mitigating CO2), appears to be on the establishment and expansion of biofuel production, now that the eco-fining processes have been perfected.

“We are doing the same thing with the biofuels as we did with the F-T fuels — changing or amending the spec [for inclusion],” Epstein said. “I am predicting that some time in 2011, you will be able to fill your airplane with a blend of jet fuel and bio-SPK fuel — if you can find it.” That is, he believes the ASTM vote this December will succeed (see sidebar on how the ASTM vetting process works).

Mike Epstein at G.E. Aviation added that the industry may see at least two startup eco-fineries in production as early as 2012. “Domestically, you’re looking at a 20-billion-gallon-per-year market for Jet-A,” he pointed out, “and these units may be producing something in the range of 50 to 100 million gallons per year of biofuels. In my opinion, near term, camelina has the most potential [as a feedstock] for jet and diesel fuel. It is a great crop and a good fit for certain regions of the country. Another is algae, which Boeing is researching over the long term.”

In addition to sustainability, cost-parity with conventional petroleum-based fuels is going to be a critical issue for aviation. “When you listen to the airlines,” Mike Epstein continued, “they say these biofuels have to reach cost parity with conventional petroleum — that’s a must, as no one will pay more for them [given the choice]. There is a strong economic component to all of this. Hopefully, that combination of sustainability and cost parity will even out the [economic] volatility of conventional crude-oil-derived fuels. Otherwise, when the price of Jet-A fluctuates constantly, it’s very hard [for managers] to plan ahead . . . both on the OEM side and among our customers.”

While “growing” our fuels may be the ultimate answer to both sustainability and the CO2 conundrum, the notion tips on the realities of biofuel economics and land requirements for necessary crop yields — an unprecedented set of considerations for both the aviation and energy-production industries. Alan Epstein at P&W has devoted considerable research to the crop-yield issue. “At the moment,” he said, “for a U.S. soybean fuel, you get about a 100 gallons per acre [per crop] for your jet fuel. Jatropha is about 200, camelina is about 100. People want this to be sustainable and not compete with food products. In North America, I would guess that the near-term source will be camelina, which shares no common pests, so farmers can plant it alongside wheat. This provides a market for it.

Epstein thinks that camelina cultivation could provide 3 to 5 percent of jet fuel, “a sustainable amount,” by 2020. “The economics are that 70 percent of the cost of making biofuel is feedstock. Since we know that crop prices fluctuate, if you’re a fuel producer, you want to buy whatever is cheapest. That’s the good part of the process [since as UOP has shown, you can make bio-jet or -diesel with a variety of feedstocks].”

In 2009, P&W tested a biofuel in a Boeing 747 that was a mix of fuels eco-fined from camelina, jatropha, and algae. “That proves we’re ‘agnostic’ in terms of the feedstock,” Alan Epstein said. “We mixed it because it takes a lot of jet fuel to fill up a 747, and we couldn’t find enough of any one kind for the run, which shows there are limited amounts available. The Air Force is aggressively pushing biofuels, so we will be testing our military engines on any biofuel that the Air Force can get to us. The Air Force has also been aggressive in fostering the demand by putting out purchase orders for several hundred thousand gallons of biofuel [e.g., the UOP contract mentioned earlier].”

The Not-So-Good NewsCarry the issue of crop yields forward to meet the world’s overall annual requirement for just jet fuel, and the real challenge to the biofuels industry becomes obvious at the present state of agri-technology. According to calculations by biotech experts, the amount of arable land on the globe necessary to support 100-percent operation on biofuel is equal to 700 percent of the arable land in the United States alone. “Plant all the land east of the Mississippi,” P&W’s Epstein quipped,” and you can do it. At 100 gallons per acre per year, it is not a feasible amount.

“We use 30 percent of the world’s jet fuel,” he continued, “so we only need 200 percent of all the arable land in the United States. You have to use technology to increase the yield of the plants to get away from this. You can hybridize plants to increase yield two to four times. Then there is bio-engineering, whose proponents claim they can get up to 10,000 gallons per acre per year. Actually, there is a little bit of support for this in the scientific literature, but much of it comes from biotech startups — that is, the capitalization people. At 10,000 gallons per acre, you could grow all the world’s jet fuel in just North Dakota! So the point is that’s enough to fill the U.S. need for jet fuel.”

Yet, none of this takes into consideration the increasing problem of soil exhaustion from over-planting and lack of crop rotation, as well as climate issues. For example, a widespread drought or a bad growing year from, say, an infestation of pests, could drastically reduce the amount of feedstocks necessary to meet these quotas.

So if the world is to ultimately transition to 100-percent use of biofuels, it will be up to biotechnologists to considerably increase crop yields. “As a result,” Epstein said, “I can see a future where you start out at a low percentage, say 2 to 5 percent, and then as the technology improves, more and more fuel will be bio-derived. Biotech will increase the yield and drop the price. The farmer has to generate so much per acre to be economically viable, so if you can generate more feedstock per acre, you can drop the price of the feedstock per pound. A lot of the cost of this is transporting the feedstock, so the answer is to have small [eco-fining] units close by the growing centers to refine the oil — an intermediate step — and then railroading the oil to the larger refinery for conversion to jet fuel. As an intellectual exercise, I looked at how much land is put into land banks at the behest of the Department of Agriculture, and if you used that land to make jet fuel, you might get 20 percent of what you need. So that scheme alone could lower the price per gallon somewhat.”

Yet, Epstein maintains, “plant science” has yet to become an important part of this. “We have spent thousands of years domesticating food crops. If you look at the efficiency of taking an acre of soybeans and making jet fuel, the efficiency rate is 0.05 percent, or one-twentieth of 1 percent of the solar energy that falls on the field in a year — a high level. The algae people say they can get 10,000 gallons per acre per year, which would represent 5 percent efficiency. Is that a credible number? To me it is credible, based on what I know about solar cells and photosynthesis.”

Technologically, there are “plausible” ways of improvement. Considering cellulous — e.g., another potential feedstock in the form of wood chips, corn stocks, wheat chaff, etc. — “most of the energy goes into the stems and is unused for food but could, with the right process and plant, be used for making jet fuel,” Epstein pointed out. Or greater use of algae: “You could plant algae in ponds around coal-fired power plants to absorb the CO2 emissions, and then make jet fuel from the algae.”

Then we get to the cost factor. “With existing processes, the breakeven for the supplier is equivalent to $70 a barrel for petroleum,” P&W’s Epstein said. “At the moment [late May] on the spot market, jet fuel is $90 a barrel, which translates to $2.14 a gallon. Then the other factor is the carbon tax. In Europe, you have the ETS [Emissions Trading Scheme], which mandates that you have to buy credits to operate there or even overfly the Continent, and when filing from here to Europe, the meter begins ticking the minute you leave your originating airport. In order to help the proliferation of biofuels, the CO2 savings will have to be recognized by the government to get credit for the CO2 they are not putting into the atmosphere — and how you do that is being debated in Europe now. This could act as a subsidy for biofuels.”

Now It’s Up to the EntrepreneursThe biofuels technology has been demonstrated, “and now it’s up to the entrepreneurs and capitalists to step up to the challenge of starting a biofuels industry,” P&W’s Epstein believes. And there is at least one advantage that the SPK process has going for it: It shouldn’t take a lot of capital, as the eco-fining plants are relatively small and much less complex than typical petroleum or F-T refineries. “Eighty percent of the U.S. jet fuel is used in 35 locations,” Epstein observed, “so you don’t need a big infrastructure to transport the fuel. You can build the plants near those 35 locations. Thus, it doesn’t take as long to get a payback.”

In the meantime, research and testing continue. The engine OEMs have united to explore other bio-feedstocks in scientific efforts underwritten by the U.S. Department of Energy and DARPA.Of particular interest to business jet operators, Pratt & Whitney Canada is leading a consortium with the Canadian National Research Council and agencies in India to study the behavior in small turbine engines of biofuels made from new feedstocks, like cellulous.

Initially, operators should expect they’ll be burning blends of bio-SPK and Jet-A for the foreseeable future. This interim strategy holds the advantage of both stretching petroleum reserves and lowering overall CO2 emissions, thus addressing both fuel security and climate-change goals.

“So today we have a commercial process available for license, we are still in production of fuel for certification purposes, we are supporting the airlines and military, and when we look out to the future, we see 100-percent renewable jet,” UOP’s Ellis said. “And as we look forward, we will continue to develop the technology for 100-percent renewable jet fuel.” BCA

by David Esler/Aviationweek

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