Synthetic Fuel

Today, the supplier of the world's energy needs, especially gasoline, is still dominated by petroleum based. Petroleum reserves that could be considered not renewable day to day will become thinner and eventually will run out because the rate of formation is not proportional to the exploitation. On the other hand, world energy demand will increase from year to year. Own domestic energy crisis had begun. The high world oil prices brought a very large impact on fuel prices regional economic and the Indonesian economy in general. Limitations of the energy sources are supposed to trigger the discovery of other type of energy sources. One of them is synthetic fuels.

Synthetic fuel can be obtained from the processing of natural materials which contains solid hydrocarbons (chemically compounds composed of hydrogen and carbon). Unlike gasoline, the fuel is processed from crude oil, synthetic fuel obtained by extraction of coal, pieces of solid oil (oil shale), tar sands, natural gas, or biomass. Although both types of fuel have a similar composition, they have different source. Coal can be processed to get liquid synthetic fuel through the process of disbursement (Liquefaction). Oil shale can be processed into liquid synthetic fuels through retorting process. Meanwhile, natural gas processed through the process gas to liquid technology.

As other fuels derived from petroleum, synthetic fuel can also be used for various purposes such as fuel for industrial machinery, motor vehicle fuel and fuel for household needs.

Producing Synthetic Fuel

Manufacture of synthetic fuel requires some fairly complicated process. In general, the process needs to be done is the extraction of hydrocarbons (HC)from coal, natural gas, oil shale, tar sand, or biomass. After that done, rearrangements of chemical structure H-C obtained through a chemical reaction.

a. Coal

Coal is a fossil fuel formed from the remains of plants (organic) ancient gradually buried in the earth. In the span of millions of years, these layers will continue to grow because formed new layers on top and cause increased pressure and temperature layers beneath it. As a result of organic materials are turned into coal. From time immemorial, man had begun to utilize the coal as fuel in the housing and also for production machinery fuel. In its development, currently coal has become one of the largest raw materials for power generation. Coal can be synthesized into fuel gas and/or liquid through a gasification process, by heating it up together with water vapor and oxygen. The result is synthetic gas, which is a gas mixture of CO (carbon monoxide), hydrogen, and CH4 (methane). This synthetic gas can be used directly as fuel or further processed to get more "clean" gas. The process to get this gas can also be done without having to mine the coal first. Burning coal deposits that are still in the ground through a drill, and then pump out the water vapor and oxygen into it. The resulting synthetic gas is then expelled through a separate channel. Coal liquefaction will produce liquid fuel where the composition is very similar to crude oil.

Some common methods used in this process include:

• Indirect Disbursement (indirect Liquefaction)

The first step is gasification, which produces CO, H, and CH4. Carbon monoxide (CO) and hydrogen (H) is extracted and reacted with catalysts include (a substance that accelerates the reaction but he himself did not come to react). This reaction produces liquid fuels.

• Catalytic Disbursement (Catalytic Liquefaction)

Hydrogen gas is added into the solid coal in a pressurized container. The result is heated, also to include a catalyst. Once cooled liquid fuel formed.

• Solvent Extraction

Liquid solvent added to the solid coal. The solvent will lead HC decomposition, and then form a solution that finally will mix with hydrogen to produce liquid fuels.

• Pyrolisis

Solid coal is heated together with hydrogen gas in high temperature. As a result the molecules of coal will be in the condition of the weakest bond and allows hydrogen joined to form a new molecule. Those new molecules are the liquid fuel.

b. Solid oil shale (oil shale)

Oil shale is a fine granule of the composition of sedimentary rock similar to limestone. The difference lies in the content of solid organic materials that can reach 25%. Hydrocarbons in the oil shale can be synthesized by the heating process called retorting. Fine powder of oil shale is heated up to 500oC in the retorting furnace. By heating the hydrocarbon-containing oil out of rock powder.

Similar to coal process, the process of oil shale retorting may also be done on the ground. The process of drilling conducted in oil shale deposits, and then does the burning to remove the oil-containing HC. HC is then drained / dried, collected and pumped to the surface. This retorting process can produce up to 100 gallons of crude oil from each ton of oil shale sedimentary rock.

c. Tar sands
Tar sands is a sandstone sediments that contain organic material called bitumen (solid or oil contains 20% weight of sandstone). Bitumen can not be pumped directly from the tar sands because of the type of asphalt oil content in it. What can be done is to collect first from tar sand deposits, either by retorting or by using solvent. Hydrocarbon can be processed further to obtain bitumen and also to eliminate the usual content of sulfur contained in the bitumen.

Bitumen can also be obtained by steam injection process into the layers of rock, the result of hydrocarbons which can then be pumped out.

d. Natural Gas Natural gas is one byproduct of petroleum and coal. However, nowadays natural gas usage is very diverse. Natural gas composed of methane (CH4) as its main component. Natural gas can be converted into liquid fuels, including gasoline, by utilizing the process of liquefaction (the gas to-liquids technology), the principle is the wiring of hydrocarbons molecules become larger molecules. Methane that has been woven into the carbon chains can be processed to produce gasoline, diesel oil and jet fuel. By adding water vapor and oxygen to the methane would result in the formation of a series of carbon atoms of methane and eventually formed a synthesis gas. This synthesis gas together with hydrogen and the catalyst is heated to high temperatures. The result of synthetic liquid fuels are "clean" and high quality.

e. Biomass
Liquid fuels such as alcohol, ether, and oil can be made of biomass (substances derived from plants and their derivatives). This type of fuel is usually referred to as bio-fuels, which is actually comes from chemical energy during plants photo synthesis. Bio fuels can be synthesized from various types of plants and seeds. Soybean and rapeseed for example, can be processed to produce a kind of diesel oil. Corn and sugar cane can be fermented into alcohol. Wood, paper, and grass can also be synthesized into alcohol with the help of fungi that can accelerate the fermentation.

Economic Aspects

For now, the costs required to obtain a synthetic fuel is still more expensive than the cost of processing fuel from petroleum. This is caused by a series of fairly complex process and the relative amount of raw materials needed to obtain synthetic fuels. To make the synthetic fuel to be competitive we must be able to reduce the cost of production.

Synthetic Fuel Development

Until now, synthetic fuel research and development is still continues, especially by countries that advanced in technology. Prospect to make these fuels more competitive is still wide open. This is based on the more modest equipment or facilities required to produce it. Moreover, with more development in technology, significant breakthroughs will be many more could be done. For example, today's "gas liquefaction technology" (gas to liquids technology) has given great hope as a means to produce liquid fuels from natural gas, which can be used by motor vehicles. Given our natural gas reserves are very abundant, so for future fuel-based synthetic natural gas will be a complement of oil, maybe even replace it.