Modifications must be implemented at the production plants, but George Braly, chief engineer at GAMI, said the fuel can be made with components "that are found inside the fence of any refinery." Braly predicted a price of $5 to $6 a gallon for G100UL, the company's replacement fuel. Braly added, "G100UL can be made at any of the seven or eight refineries around the country that produce 100LL avgas."
Swift Technologies of West Lafayette, Indiana, has a different plan. The Swift formulation is a binary (two-part) fuel consisting mostly of mesitylene mixed with a small amount of isopentane (2-methylbutane). The difference is that the Swift supply of mesitylene will be extracted from biomass through a catalytic process developed by John Rusek, who has a doctoral degree in chemical engineering and atomic physics, and Jon Ziulkowski, vice president of renewable fuels at Swift. The production process has been proved on a small scale.
Mary Rusek, spouse and partner, said that one of the advantages of Swift fuel is that it can be made from local biomass such as "wood chips in the Northwest, sorghum in the South or sugar beets from Maine." Rusek also said that Swift already has signed letters of intent from five out of the six oil companies to distribute 100SF.
"We have plans on paper where we would take an ex-ethanol plant, make a few changes and produce our fuel," Rusek said. "We believe we can scale up for full-scale production in one year," said Swift CEO Dave Perme, who also said, "Research shows that we can get to a competitive price compared to 100LL."
A recent survey lists 216 ethanol production facilities in the United States. Projected ethanol demands have not approached the production mandates passed by Congress. As a consequence, plant construction has slowed, some plants are mothballed, and a few are being sold at auction.
It appears that GAMI and Swift are the only two players in the new avgas game. But underneath all the formulations, standards, testing and approvals required to get to the new avgas is a plan to introduce another leaded avgas: an ultralow-lead 100 octane fuel.
94UL and Auto Gas
In 2009 TCM flight-tested 94UL — which approximates today's 100LL without the lead — in a Hawker Beechcraft G36 with a 300 horsepower, fuel-injected IO-55B engine and in a Cirrus SR22T 315 horsepower, turbocharged, fuel-injected TSIO-550 engine. Flying's Robert Goyer flew the SR22 with 94UL and was impressed by the power and performance of the low-compression engine on the unleaded version of our current avgas.
Johnny Doo, TCM's vice president of engineering, agrees that the higher-horsepower turbocharged engine — with 7.5:1 compression — ran fine on 94UL fuel. Unfortunately, the 300 horsepower normally aspirated engine, with 8.5:1 compression cylinders, "was not happy," Doo said.
The telling difference between the two engines is the compression ratio.
Doo said TCM tested the fuel to determine how well the company's high-powered engines performed on 94UL.
"94UL has an existing ASTM spec, so we wanted to see where we stood if it was the final fuel," Doo said. He said that installing lower-compression pistons or "smart" ignition systems, or limiting takeoff power, would be required to provide the required detonation protection for TCM's 8.5:1 compression ratio engines if 94UL is adopted as the new avgas.
According to TCM, the piston change to lower the compression ratio from 8.5:1 to 7.5:1 would reduce the engine's maximum power by 3 or 4 percent. This swap would reduce a 300 horsepower engine's maximum power output to between 288 and 291 horsepower.
