There are many different alternatives of renewable fuels and Volvo is looking into all viable alternatives. They are evaluated based on seven different aspects: effects on climate, energy efficiency, land use effectiveness, fuel potential, vehicle adjustability, fuel cost and fuel infrastructure.
Bio diesel is made by transesterification of vegetable oils. The most common basis is rape seed or sunflower. It can be blended with conventional diesel, but the energy efficiency well-to-wheel is low, it also produces more NOx emissions with the present vehicle fleet and there is a limited potential for production of large quantities. Volvo's products are today compatible with bio diesel when blended into diesel.
Synthetic diesel is a mix of synthetically produced hydrocarbons made by gasification of biomass. It can be blended into conventional diesel and is compatible with existing Volvo engines. There are several sources and it has a variety of uses. It has however lower energy efficiency than other synthesis gas products and the current production is limited.
DME - dimethyl ether
Dimethyl ether is a gas handled in liquid form under low pressure. It is produced by gasification of biomass and it is a simpler chemical product than synthetic diesel and thus cheaper to produce. DME is also relatively easy to handle and distribute. Furthermore only modest modifications are required to convert a diesel engine to run on DME. If the fuel is produced from biomass, such as black liquor from the pulp industry, DME is CO2 neutral.