Search

With focus on renewable energy from agriculture governments can either support the growing production of energy crops or it can invest in technology or measures to reduce the energy consumption. But what is more efficient with regard to the use of the limited resource arable land: to insulate a building with fibre material grown on arable land to reduce the heating demand or to use such land for growing energy plants for the sustainable energy supply of a building? To answer this question, a long term balance calculation under consideration of numerous framework parameters is necessary. Based on traditional fibre plants like hemp, flax, and woody fibre crops (e.g. poplar), these agricultural plants and their processing to insulation material were examined. Based on available data for the typical building structure of detached and semi-detached houses in Germany, models of buildings were developed and the accessible potentials for heating energy savings by using suitable insulation measures with natural fibre materials were determined. As a comparable system for the supply of renewable energy, bio-methane from silage maize was chosen, since it can be used efficiently in conventional gas boilers for heat generation. The different levels of consideration allow the following interpretations of results: in a balance calculation period of 30 years, the required acreage for heating supply with methane can be reduced by approx. 20%, when at the beginning of the use period fibre plants for the insulation of the houses are grown on the arable acreage. Contrariwise, to compensate only the existing loss in heating energy due to inadequate insulation of older detached and semi-detached houses (build prior to 1979) an annual acreage of approx. 3 million ha silage maize for bio-methane would be required in Germany. Therefore, from the land use perspective the production of biogas plants in agriculture for heating should be accompanied by the production of fibre plants for a reasonable improvement of the heat insulation of houses. [ABSTRACT FROM AUTHOR]

The lack of knowledge regarding cost-efficient design of whole production chains as well as the availability of powerful harvest machinery are some of the main obstacles for competitive production of bioenergy from short rotation coppices (SRC) at practice. In general, two different harvest lines are available: the cut-and-chip and the cut-and-store lines. Whereas the cut-and chip line provides wood chips which have to be stored until next heating season, the product for intermediate storage of the cut-and-store line are whole trees. Both process lines have major differences not only in harvesting, but also in transport, storage and process losses leading to different costs of the end product wood chips. On basis of data from several SRC harvest campaigns, production costs for wood chips have been calculated to identify best practice solutions taking the following factors into account: chip size determined by the harvest system, storage including related costs and losses, field size and shape as well as transport to storage. According to the results, mower-chippers and forage harvesters can provide wood chips at lowest production costs (43#8230;45 ⊂tdm-1) if field shape is favourable for harvest operations. Under less favourable field conditions costs are approx. 7 to 14% higher. Highest production costs have to be accepted if whole trees are harvested with a shoot harvester (64 to 72 ⊂tdm-1). The reduction in storage losses and storage costs are not sufficient to compensate higher machine costs for harvest and additional comminution with mobile chippers from forestry. [ABSTRACT FROM AUTHOR]