195
Dimethyl Ether
2006). The performance of the fuel cell was stated to be a half to a quarter
of that of a hydrogen fuel cell. Performance is similar to that of a fuel cell
operated on methanol. Studies of the direct DME fuel cell have been on a
laboratory scale so far.
Another possibility for the use of DME in fuel cells is to use it as a carrier
and source of hydrogen for a hydrogen fuel cell. The DME is reformed to
produce hydrogen in a similar manner to the formation of syngas with a catalytic reaction at elevated temperature (JDF 2007). Compared to the reforming of methanol, DME reforming requires a higher temperature, but is better
than natural gas. The products of reforming are H 2 and CO 2 . The reforming
process consists of endothermic reactions and thus requires energy to perform. Much of the research to date has been concerned with the development
of catalysts to improve the reforming process. Little data are available concerning complete systems using DME to power fuel cells.
6.5 Economic Issues Regarding DME Applications
Since DME is not yet widespread in its use as a fuel, experience with economic implications of the use of DME on the expected applications is lacking. However, enough is known about the properties and potentials of DME
to name many of the factors that will have an economic impact, both positive
and negative, on the applications where DME can be used. In the following,
some of these factors will be mentioned.
6.5.1 internal Combustion engines
Diesel engines operating on DME will probably eventually use common rail
systems. In this system, one high pressure pump delivers fuel at a selected
pressure to all the cylinders, whose injectors are electronically controlled to
give a highly flexible fuel injection and combustion process. The elements that
are expected to be impacted here are the injection system piping, injectors,
high pressure pump, seals, and fuel cooling. The fuel pressure needed for
DME is lower than diesel, so the fittings and tubing needed are required to
handle lower pressures. The pump will produce lower pressure, but will probably need special treatment or materials for durability. The injectors can be of
the same general design as for diesel, though larger nozzle holes are needed.
A fuel feed pump between the tank and the engine will be needed as is the
case with diesel. A question mark is the seals, as the current options for sealing DME are expensive, and there is a real need for better, cheaper seals for
DME in all applications. If fuel cooling is required, this will increase costs.
Since DME does not generate particulate matter in a diesel engine, a particulate filter in the exhaust should not be needed, and this would give substantial
Dimethyl Ether
2006). The performance of the fuel cell was stated to be a half to a quarter
of that of a hydrogen fuel cell. Performance is similar to that of a fuel cell
operated on methanol. Studies of the direct DME fuel cell have been on a
laboratory scale so far.
Another possibility for the use of DME in fuel cells is to use it as a carrier
and source of hydrogen for a hydrogen fuel cell. The DME is reformed to
produce hydrogen in a similar manner to the formation of syngas with a catalytic reaction at elevated temperature (JDF 2007). Compared to the reforming of methanol, DME reforming requires a higher temperature, but is better
than natural gas. The products of reforming are H 2 and CO 2 . The reforming
process consists of endothermic reactions and thus requires energy to perform. Much of the research to date has been concerned with the development
of catalysts to improve the reforming process. Little data are available concerning complete systems using DME to power fuel cells.
6.5 Economic Issues Regarding DME Applications
Since DME is not yet widespread in its use as a fuel, experience with economic implications of the use of DME on the expected applications is lacking. However, enough is known about the properties and potentials of DME
to name many of the factors that will have an economic impact, both positive
and negative, on the applications where DME can be used. In the following,
some of these factors will be mentioned.
6.5.1 internal Combustion engines
Diesel engines operating on DME will probably eventually use common rail
systems. In this system, one high pressure pump delivers fuel at a selected
pressure to all the cylinders, whose injectors are electronically controlled to
give a highly flexible fuel injection and combustion process. The elements that
are expected to be impacted here are the injection system piping, injectors,
high pressure pump, seals, and fuel cooling. The fuel pressure needed for
DME is lower than diesel, so the fittings and tubing needed are required to
handle lower pressures. The pump will produce lower pressure, but will probably need special treatment or materials for durability. The injectors can be of
the same general design as for diesel, though larger nozzle holes are needed.
A fuel feed pump between the tank and the engine will be needed as is the
case with diesel. A question mark is the seals, as the current options for sealing DME are expensive, and there is a real need for better, cheaper seals for
DME in all applications. If fuel cooling is required, this will increase costs.
Since DME does not generate particulate matter in a diesel engine, a particulate filter in the exhaust should not be needed, and this would give substantial