A small percentage–about 20 percent–of the piston-powered fleet requires 100-octane fuel. Yet these aircraft burn about 70 percent of the total avgas volume, according to Allen Bretz, director of general aviation market at ConocoPhillips.
Most of the avgas producers said that annual avgas production is fairly stable, although ConocoPhillips has seen slight growth in avgas deliveries and now produces about 170 million gallons of avgas annually, 40 to 50 million of which is sold outside the U.S. ConocoPhillips makes avgas at refineries in Sweeney and Borger, Texas, and Billings, Mont.
At Chevron, avgas production has been stable, said Keith Sawyer, general manager of Chevron Products. The company produces about 30 to 33 percent of annual avgas consumed, he said, at four refineries in Richmond, Calif.; Salt Lake City; Pascagoula, Miss.; and Hawaii. “Over time the demand for avgas will be quite finite,” he said. “It’s not going to grow.”
Chevron continues to invest in upgrading the lead plants at its refineries. Tetraethyl lead (TEL), which is essential for high-compression piston engines used in high-performance airplanes, needs to be injected into the gasoline during the blending phase. In the U.S. and many other countries, TEL has been completely phased out of automotive gasoline, although some developing countries have yet to outlaw its use.
While four companies are still committed to producing avgas in the U.S., only one still manufactures TEL needed for avgas production (even 80 octane contains TEL). The 80 percent of piston-powered airplanes that don’t need 100-octane fuel could operate safely with a lower-octane alternative fuel such as autogas, but so far no alternative exists for engines that run on 100 octane, and TEL is essential.
Fortunately, Innospec, the chemical company that makes TEL at a plant in Ellesmere Port in England, is just as committed to continuing the production of TEL for the automotive and aviation industries. Innospec won’t say how much of the TEL it makes is solely for aviation, but the automotive TEL business continues to shrink while aviation remains stable, according to David Turner, director of Innospec’s aviation octane division. “[Innospec] will stay in the TEL business as long as there is a business,” he said.
Innospec’s aviation TEL, or Avtel, accounts for 3 percent of the cost of a gallon of avgas. “Avtel is a unique product,” Turner said, “with a lot of bang for the buck in terms of octane enhancement of the base fuel.”
Innospec, formerly Associated Octel, operates three main businesses: octane additives, fuel specialties (fuel additives) and specialty chemicals. Money earned from the TEL business is used to keep the company healthy and research other additives, and Innospec is constantly seeking a replacement for TEL, which is not exactly environmentally friendly. “We have other octane enhancers available for motor gasoline,” Turner said, “but as yet nothing for aviation gasoline.” While it is searching for an octane-boosting replacement for aviation, he said, “rest assured we’ll continue to supply Avtel as long as it’s required.”