Miscanthus "Giganteus" as industrial raw material and for thermic use

The supply of industrial raw material and energy in form of heat and electricity from annual, biannual and permanent crops is an important substitute for the current use of fossil resources in Austria as well as in all industrial countries in the middle and long term. Miscanthus "Giganteus", a permanent crop, needs a period of one to two years to establish itself depending on the location. Biomass yield starts to be economical from the second year. Based on results and experiences so far a 20 year exploitation period is possible. Field trials from 1989 to 2001 on five locations differing in climate and soil properties resulted in a dry matter yield between 17500 and 24000 kg/ha. Differences in annual yields are between 2000 and 4000 kg/ha depending on the location. There are remarkable differences in yield in-between the locations. High yields were gained at ILZ (Steiermark) and ST. FLORIAN (Oberösterreich) with an average annual precipitation of 700 to 900 mm. Due to lower amounts of precipitation the yield level in MICHELNDORF, MARKGRAFNEUSIEDL, GROSS ENZERSDORF and STEINBRUNN is lower. Irrigation of 100 to 150 mm (from July until September) increases biomass yield by about 2000 to 5000 kg/ha. Maximum yield is reached at the end of November - beginning of December. Till the usual harvest time at the end of February till mid of March the yield decreases due to leaf - losses and the breaking of thin stems and sprouts. Water content in yield is above 50 % when harvested at the end of November - beginning of December. It decreases until the end of February depending on stem diameter and winter weather to 30 to 42 %. Nitrogen fertilisation above 60 kg/ha has almost no effect on yields. Liquid manure as fertiliser has only a slight effect, due to an often thick layer of leaf mulch. Essential quality criteria for thermic use or industrial raw material are constant. The ash content of the material is between 3.2 and 5.0 %. Also the N-content of the harvested material from the third year of growth stays almost constant between 0.3 and 0.43 %. The biggest part of the ashes of Miscanthus is siliciumoxyd (about 40 to 50.5 %) and potash (K2O) (12 to 20 %). Yield of Miscanthus can be used as raw material for celluslose production if the technology is appropriate. The content from the third year onward is approximately 47.5 %. This is only slightly lower as in wood.