DME - The NextGen Fuel
DME (Dimethyl Ether, CH3–O–CH3) is an LPG-like synthetic fuel that is produced through gasification
of various renewable substances or fossil fuels. The synthetic gas is then catalyzed to produce DME.
It is produced from natural gas but it can also be produced from other sources like biomass and coal.
The production of DME is very similar to that of methanol: Natural gas at remote locations is the most
economic feedstock for both alternative fuels.
DME is a clean burning (completely sootless) synthetic fuel that can substitute for conventional diesel,
liquified petroleum gas (LPG) or be reformed into hydrogen for fuel cells. As a diesel fuel replacement
it reduces NOx emissions 90%, meeting the 2007 diesel emission standards, and features high
cetane.
It can be transported as a pressurised liquid similar to LPG. Also, as mentioned earlier, DME
can be economically produced from a number of feedstock: coal, natural gas, biomass. Countries
which are seeing an exponential increase in their energy demand are extremely interested in setting
up DME plants and China has taken the lead in the same. China, in particular, because of its
enormous coal reserves, is interested in the Coal to DME process.
Oil and gas companies are focusing on DME as a way to efficiently use their natural gas resources.
They want to utilise the natural gas produced by wells that are far from distribution infrastructure and
are looking to convert the gas to product (liquid, fuel, chemical) close to the well site and transport
that instead. This is where DME is being thought about in a big way.
Uses of DME
DME already has an environmentally clean background and good safety record as propellent in spray
cans for the cosmetic industry. It has been used in a low pressure gaseous state as ignition improver
of methanol.
DME is a new fuel planned for introduction as a safe, environmentally benign energy source for fuel
cells or diesel engines. DME can serve as a synthetic fuel that is to diesel what LPG is to gasoline. It
is gaseous at ambient conditions but can be liquefied at moderate pressure. With a high cetane
number, DME has very attractive characteristics as an alternative fuel for diesel engines.
DME can be blended upto 20% with LPG and used for household cooking and heating, without any
modifications to equipment or used as a replacement. DME can also be used as a clean burning
substitute for diesel in transportation and as a clean fuel for power generation.
DME would be particularly attractive for countries which have large coal reserves or forest produce.
Just to give an example, it is possible to use black liquor, a residual product from production of paper
pulp (from forest produce), as a feedstock for manufacturing DME.