Sylvia Larsson at Swedish University of Agricultural Sciences SLU shows in her thesis that today's pelletising methods are unnecessarily energy demanding.
The perennial reed canary grass is an alternative to the energy crop Salix in the north of Sweden, where Salix finds it difficult to cope with the winter. Reed canary grass is today grown on about 1000 hectares, but in Finland its cultivation is much more extensive. Last year's grass can be cut early in the spring when the annual shoots are small, and the crop is a dry raw material that can be pressed into pellets.
Sylvia Larsson shows that in Västerbotten County alone there are about 30,000 hectares of arable land that are available and suitable for growing reed canary grass. This is land that is not necessary for farming today, and is therefore either abandoned or has very little labour input. Cultivation on former arable land preserves an open landscape and does not compete with other activities.
Cultivation of reed canary grass on these 30,000 hectares in Västerbotten County could produce an annual energy increment of more than 1 TWh, which would cover the electricity and heating needs of 30,000 houses. For such cultivation to be profitable, the farmer needs a fuel price corresponding to at least SEK 130/MWh when collected from the farm.
Conversion of reed canary grass into fuel pellets gives a market adapted fuel which is well suited for handling, storage and transport. By investigating the frictional properties of pellet raw material, Sylvia Larsson refers to a previously unknown relationship between friction and pellet strength, and points out that the pelleting process of today provides good pellet strength through an unnecessarily energy demanding frictional process. By developing other methods for producing strong pellets, for example by using a temperature controlled process, it should be possible to reduce energy use during pellet production.