Biofuels Could Be Cleared For Aircraft Use

by Graham Warwick (AviationWeek) In just five years, the aviation industry’s decades-long reliance on petroleum-based fuels has been turned on its head. The future lies in fuels from sources that range from animal fat to microalgae. But with the technology in hand, the question now is whether biofuel producers can raise the investment needed to launch commercial-scale production.

Approval of biofuels for use in aircraft, expected by mid-2011, is a critical step. A standard for jet fuels using synthesized hydrocarbons has already been crafted and the first annex, covering synthetic paraffinic kerosene (SPK) produced via the Fischer-Tropsch (F-T) process, was approved last year. But a second annex covering bio-SPKs—also called hydrotreated renewable jet fuel (HRJ)—is eagerly awaited, as these promise to reduce aviation’s greenhouse-gas emissions....

Data from the additional fuel and engine testing will be presented to ASTM members, and a re-ballot in December is expected to succeed. This should lead to approval early next year of an annex to the D7566 synthetic-fuel standard allowing bio-SPKs to be used in aircraft in blends of up to 50% with conventional jet fuel. This will be a pivotal event, as certification is expected to remove a significant barrier to investment in large-scale facilities to produce HRJ fuels in economic quantities.

...The creation of AltAir illustrates the challenges of starting biofuel production. Sustainable Oils works by signing contracts with farmers to grow camelina that it will buy back at an agreed price. Farmers grow a specific strain of camelina developed by biotechnology company Targeted Growth. Sustainable Oils extracts the oil from camelina seeds, “but we hoped someone else would build the refinery,” says Todaro.

Eventually, to kick-start the market, Sustainable Oils decided to form AltAir as an independent company. The business plan is to build add-on units at traditional refineries. With 100-million-gal. capacity, these bolt-on facilities will each cost “a couple of hundred million dollars” and provide about 10% of the fuel required annually at an average-sized airport, he says.

...JetE has licensed small-scale hydroprocessing technology from Danish company Haldor Topsoe and is offering a 7.5-million-gal.-per-year plant for $40 million and a 30-million-gal. plant for $85-90 million.

...One of the most promising new pathways, Edwards says, is being called “alcohol oligomerization.” This starts with an alcohol-like ethanol or butanol, removes the oxygen and grows hydrocarbons from the molecules. Gevo, Virent and Swedish Biofuels are among the companies working on this “catalytic renewable jet” pathway. Brazilian biotechnology company Amyris, meanwhile, is pursuing an advanced fermentation process that goes direct from cellulosic biomass to liquid fuel using specially tailored microorganisms.

...Synthetic paraffinic kerosenes are limited to 50% blends by the need for aromatic hydrocarbons found in conventional jet fuel, but synthesized aromatics—or changes to engine seal materials—could allow 100% synthetic fuels. “We are doing a lot of work on fully synthetic fuels,” says Edwards. Honeywell and the FAA are working to determine by 2013-14 the minimum aromatics required in engines, says Rekoske, adding that “100% synthetic is still the goal.” READ MORE