For the past nine years, South Africa-based Sasol has supplied a fuel mixture comprised of a coal-to-liquid (CTL) component blended with crude-oil-derived kerosene to international airlines operating from OR Tambo International Airport in Johannesburg. Based on the success of the alternative-fuel blend and following several years of “rigorous testing and evaluation,” the company announced earlier this year that international aviation fuel authorities including the U.K. Ministry of Defence (MOD)—which governs the DEFSTAN 91-91 standard—approved its 100% synthetic jet fuel produced by its proprietary CTL process as Jet A-1 fuel for commercial use in all types of turbine aircraft.
According to the company, Sasol CTL is the first fully synthetic fuel to be approved for use in commercial airliners. Engine-out emissions of Sasol’s jet fuel are said to be lower than those from jet fuel derived from crude oil due to its low sulfur content. The fuel is compatible with existing engine requirements and can be used with conventional crude-oil-derived jet fuelling systems.
American Society for Testing and Materials (ASTM) has also been working closely with the MOD and is expected to include Sasol CTL synthetic jet fuel in its ASTM D1655 specification following the publication of DEFSTAN 91-91. Jet A-1 according to the 91-91 specification is very similar to Jet A-1 defined by the ASTM D1655 except for a small number of areas where 91-91 is more stringent. Sasol says that in keeping with the stringent regulation of the Joint Checklist, aviation industry stakeholders, including airframe, engine, and ancillary equipment manufacturers; airlines and aviation authorities, such as the International Air Transport Association; and relevant oil companies have all participated in the approval process.
“This approval recognizes the absolute need to develop aviation fuel from feedstocks other than crude oil to meet the world’s growing needs,” said Pat Davies, Sasol Chief Executive. Research is also under way to find an effective process to produce synthetic fuel from biomass.
The current approval covers jet fuel produced at Sasol’s synfuels facility in Secunda, South Africa, where more than 40-million t of coal a year are converted into liquid fuels, industrial pipeline gas, and a range of chemical feedstock. That facility produces 150,000 barrels of synthetic fuels per day, which is expected to increase to 180,000 barrels a day by 2015. Sasol uses a low-temperature Fischer-Tropsch process to produce its CTL fuel. Coal is first fed into large “gasifiers” to produce raw gas, and then purified into the gas needed for Fischer-Tropsch synthesis. The product created through the synthesis can be upgraded using conventional, product-specific petrochemical processes, including hydrocracking and chemical workup, as well as refining through a conventional refinery.
Sasol views the CTL fuel’s approval for commercial aviation as a milestone in securing a domestic energy supply for South Africa and other countries with significant domestic coal and natural gas reserves. It believes its processing technology could allow other countries to monetize natural resources and increase energy security. The company currently supplies about 35% of South Africa’s liquid fuel needs, according to Benny Mokaba, Sasol Executive Director.
Also to be submitted for approval are jet fuel products from Sasol joint ventures in Qatar and Nigeria. The company is also considering potential CTL joint ventures in the U.S., China, and India.