Distillates are petroleum products that includes diesel, jet fuel, and fuel oil. Renewable distillates may be categorized as substitutes or drop-in replacements. The most common distillate substitute is biodiesel, and drop-in replacements can be produced via hydrotreating or gasification plus Fischer-Tropsch (FT) technology.
Biodiesel is produced by reacting fats like vegetable oil (sources include soybeans, oil palm, or even oil from algae) or animal fats with an alcohol like methanol. The products of the reaction are biodiesel and glycerin. The chemical structure of biodiesel differs from that of petroleum diesel in that biodiesel contains oxygen. This is what makes biodiesel a distillate substitute instead of a drop-in replacement, in manner analogous to that of ethanol and gasoline.
Biodiesel is the 2nd largest volume biofuel produced in the world. In 2010 global production was 5 billion gallons. Major producers include Germany, France, Brazil, Argentina, and the U.S. The technical barrier for biodiesel production is quite low, and as a result there are numerous companies involved in biodiesel production, as well as hobbyists who produce biodiesel in their garage.
“Green diesel” produced from hydrotreating technology utilizes the same feedstocks as does biodiesel production. Instead of reacting the feedstocks with methanol, they are reacted with hydrogen. The products of this reaction are diesel-range hydrocarbons — green diesel — and propane (as compared to glycerin as the biodiesel byproduct).
The technology hurdle for hydrotreated green diesel is higher than for biodiesel, and as a result there are fewer players. The global leader is probably Neste Oil in Finland. They began developing their NExBTL technology in 2002, and in May 2007 started up a plant with a capacity of 50 million gallons per year of renewable diesel fuel from a feedstock of vegetable oil and animal fat. In November 2010, Neste Oil commissioned the world’s largest renewable diesel refinery (and to my knowledge the largest renewable fuel plant of any kind in the world) in Singapore. The feedstock for this plant is palm oil and the capacity is 245 million gallons per year. Neste Oil also operates a renewable diesel refinery in Rotterdam, with a capacity close to that of its Singapore facility.
Some of the other companies involved in developing hydrotreated green diesel include Italian oil company Eni, Brazilian oil company Petrobras, and Honeywell’s UOP-which is a major provider of refinery upgrading technology.
The second major method of making a drop-in diesel replacement involves gasification of a feedstock such as coal (coal-to-liquids, or CTL), natural gas (GTL), or biomass (BTL) and then conversion of the syngas into fuel. Gasification was described in last week’s issue, but once syngas has been produced it can be reacted via the Fischer-Tropsch reaction to produce diesel and jet fuel.
Gasification has been used to commercially produce liquid fuels for decades. CTL was used during World War II by the Germans, when they had limited access to petroleum but needed fuel for their military. South Africa during apartheid had a similar experience. With sanctions restricting petroleum imports, South Africa turned to CTL, using its large coal reserves to produce liquid fuel. Sasol (South African Coal, Oil and Gas Corporation) operates a number of gasification facilities, including the 160,000 barrels per day (bpd) Secunda CTL facility in South Africa.
Shell is a major developer of GTL technology. Shell has operated a GTL plant in Bintulu, Malaysia, since 1993, with a current capacity of nearly 15,000 bpd. Shell commissioned the 140,000 bpd Pearl GTL plant in Ras Laffan, Qatar in 2011 – by far the largest GTL plant in the world.
BTL is well behind CTL and GTL in development because biomass is trickier to handle. The BTL leader is probably Rentech (RTK). They have been developing BTL technology for a number of years, and currently operate a 10 barrel per day demonstration facility in Colorado. They are to my knowledge the only company in the world producing diesel at a scale of barrels per day from biomass. (Full disclosure: Rentech’s Chief Technology Officer was formerly my manager when I worked for ConocoPhillips).
This article was republished with permission from Consumer Energy Report under a content partnership with Biofuels Digest, and appeared originally in Energy Trends Insider, a free newsletter from Consumer Energy Report, which focuses on financial and investment issues in the energy industry.
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