Everything about Synthetic Fuel totally explained
Synthetic fuel or
synfuel is any
liquid fuel obtained from
coal,
natural gas, or
biomass. It can sometimes refer to fuels derived from other solids such as
oil shale,
tar sand, waste
plastics, or from the
fermentation of
biomatter. It can also (less often) refer to gaseous fuels produced in a similar way.
Processes
The technology for transforming natural gas or coal into synthetic fuel was invented by Franz Fischer and Hans Trophsch in the 1920s. The Fischer-Tropsch process transforms gas derived from coal (or other substances) into liquid gas. The
Fischer-Tropsch synthesis process is the best-known synthesis process and was used on a large scale in Germany during
World War II. Other processes include the
Bergius process, the
Mobil process and the
Karrick process. An intermediate step in the production of synthetic fuel is often
syngas, a
stoichiometric mixture of
carbon monoxide and
hydrogen, which is sometimes directly used as an industrial fuel.
The process of producing synfuels is often referred to as
Coal-To-Liquids (CTL),
Gas-To-Liquids (GTL) or
Biomass-To-Liquids (BTL), depending on the initial feedstock. Synthetic crude may also be created by
upgrading bitumen (a tar like substance found in
tar sands), or synthesizing liquid
hydrocarbons from
oil shale and
synthesis gas: a mixture of
carbon monoxide and
hydrogen.
Commercialization
Sasol
The leading company in the commercialization of synthetic fuel is
Sasol, a company based in
South Africa. Sasol currently operates the world's only commercial coal-to-liquids facility at Secunda, with a capacity of
(External Link
). Other companies that have developed coal- or gas-to-liquids processes (at the pilot plant or commercial stage) include
Shell,
Exxon,
StatoilHydro,
Rentech, and
Syntroleum (External Link
). Worldwide commercial gas-to-liquids plant capacity is
(External Link
), including plants in South Africa (
Mossgas), Malaysia (Shell Bintulu) and New Zealand (Motor-fuel production at the New Zealand Synfuel site has been shut down since the mid nineties, although production of methanol for export continues
(External Link
). This site ran on the Mobil process converting gas to methanol and methanol to gasoline).
Commercialization in the United States
Numerous US companies (
TECO,
Progress Energy,
DTE,
Marriott) have also taken advantage of coal-based
synfuel tax credits established in the 1970s, however many of the products qualifying for the subsidy (for example slurries or briquettes) are not true synthetic fuels since they're not the portable, convenient, end-user liquids that the credit was established for. The coal industry currently uses the credit to increase profits on coal-burning powerplants by introducing a "pre-treatment" process that satisfies the technical requirements, then burns the result the same as it would burn coal. Sometimes the amount gained in the tax credit is a major factor in the economic operation of the plant. The synfuel tax credit has been used primarily in this manner since the
cheap gas prices of the 1980's killed any major efforts to create a transportation fuel with the credit, and its continuation is seen as a major "pork project" win for coal industry lobbyists, to the tune of $9 billion per annum.The total production of such synfuels in the US was an estimated 73 million tons in 2002.
The
United States Department of Energy projects that domestic consumption of synthetic fuel made from coal and natural gas will rise to 3.7 million
barrels per day in 2030 based on a price of $57 per barrel of high sulfur crude (
Annual Energy Outlook 2006, Table 14, pg52
).
Economics
Synthetic fuels require a relatively high price of crude oil in order to be competitive with petroleum-based fuels without subsidies. However, they offer the potential to supplement or replace petroleum-based fuels if oil prices continue to rise. Several factors make synthetic fuels attractive relative to competing technologies such as
biofuels, ethanol/methanol or
hydrogen:
- The raw material (coal) is available in quantities sufficient to meet current demand for centuries
- It can produce gasoline, diesel or kerosene directly without the need for additional steps such as reforming or cracking
- There is no need to convert vehicle engines to use a different fuel
- There is no need to build a new distribution network
Environmental concerns
One issue that has yet to be addressed in the emerging discussion about large-scale development of synthetic fuels is the increase in
primary energy use and
carbon emissions inherent in conversion of gaseous and solid carbon sources to a usable liquid form, assuming the energy used to drive the process comes from burning coal or hydrocarbon fuels. Recent work by the
United States'
National Renewable Energy Laboratory indicates that full fuel cycle greenhouse gas emissions for coal-based synfuels are nearly twice as high as their petroleum-based equivalent. Emissions of other pollutants are vastly increased as well, although many of these emissions can be captured during production. Emerging
Carbon sequestration technologies have been suggested as a future mitigation strategy for greenhouse gas emissions.
Liquified coal emits twice as much carbon dioxide as burning oil, so
carbon sequestration is proposed to prevent an adverse impact on
greenhouse gas emissions.
However,
biomass gasification technology may offer a less carbon-intensive alternative. Biomass-powered synthetic fuel plants may become technologically and economically-convincing energy possibilities for a
carbon-neutral economy in the future, although there are currently problems in scaling up the process to commercial volumes
Hybrid hydrogen-carbon processes have also been proposed recently as another closed-carbon cycle alternative, combining
'clean' electricity, recycled CO, H
2 and captured CO
2 with biomass as inputs as a way of reducing the biomass needed.
Further Information
Get more info on 'Synthetic Fuel'.
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