|Sustainable Energy News - No. 13 June 1996 (INFORSE, 1996)|
By Gunnar Boye Olesen, INforSE Europe Coordinator.
The article is an abbreviated guideline for quick estimates of renewable energy potential, based on the European project "Partnership for Assessment and Support of Renewable Energy Solutions" The project was a cooperation of a number of INforSE Europe organisations. It was supported by the EU Phare Partnership Programme, FED in Denmark and others.
Biomass from Forests
Many commercial forests have unused potential for energy in the form of woodchips or firewood. From forest statistics it is possible to estimate the theoretical potential This should be reduced to the practical, environmenrtally acceptable level of extraction, considering the nature of the forest and un-official extraction by the local population.
Industrial wood waste
In sawmills, pulp mills and all wood processing industries, residues are made that can be used for energy purposes: bark sawdust, edgings, chips, etc. An analysis of 7 European countries shows that 30-70% of wood-industry residues are used for non energy purposes like paper and fibreboard
Larger residual pieces can be chipped for use in wood-chip boilers, while sawdust can be burned in special furnaces or compressed into wood pellets or briquettes that can be used in smaller furnaces and ovens.
Many wood industries use wood residues to meet their own energy demands, but surpluses are often available at low or no cost.
Agricultural crop residues
Straw and prunings of fruit trees, as well aswine- and olive oil residues, are among the agricultural residues that can be used for energy purposes. In Northern and Central Europe, straw is by far the most important and is used in large quantities in some countries. The straw surplus varies greatly from year to year, depending on weather.
Straw surplus can be ploughed into the field to enrich the soil. When this is needed for a sustainable agriculture, less surplus straw will be available for energy. Pesticides and salty winds can leave unwanted chlorine compounds in the straw in certain situations.
Agricultural overproduction and setting the land aside are now common in the European Union and can be expected in Central and Eastern Europe as well. This set-aside land can be used for different purposes, one of them being energy-crop production. Promising crops which can be planted for energy purposes in Europe include short-rotation trees (coppices of various willows and poplars), Miscanthus and Sweet Sorghum.
Other promising energy crops include plants that can be processed for liquid fuels, e.g. rape seeds for bio-oil.
The largest potential for biogas is in manure from agriculture. Other potential raw materials are include organic, bio-degradable waste from industries, in particular wastes from slaughterhouses and food-processing industries, sludge from waste-water treatment, and organic household waste. Care should be taken not to include waste with heavy metals or harmful chemical substances when the resulting sludge is to be used as fertilizer, which is usually the case.
In sufficiently windy areas where little conflict exist with human settlements (noise) or natural life (bird-protection areas), the wind is one of the most environmentally benign energy sources. The energy in the wind is highly dependent on the average wind speed of the site, which depends on altitude, the regbnal wind regional and local obstacles Sites with average wind speed below 4 m/s at a height of 10 m are not considered viable for larger wind turbines, at least in the near future while in areas with wind speed above 7 m/s at a height of 10 m, wind turbines are cost-effective compared with most alternatives. Many areas still lack good estimates of wind potential and such estimates can be quite expensive to make. Simple estionmates can be based on averages of meteorological measurements, but they give quite rough results
The most environmentally benign form of energy is probably direct use of solar heat. The largest factor limiting its use is not the amount of the resource, but the demand that can be covered with present technologies. Solar hot water heaters are successful because the steady hot water demand during summer can be met with just one day's accumulation of heat.
Most renewable energy solutions generate more jobs than do so}utions that use fossil fuels. The following table cntains overviews of the direct employment in jobs resulting from some of the proposals. In direct employment. we include jobs in manufacturing, installation, operation, and maintenance, as well as jobs in suppliers of goods and services. The wider societal employment effects of the activities such as the effects of increased income, are not taken into account here Such effects are generally positive where societal costs and/orimports are reduced.
Figures are new, full-time permanent jobs in the construction, operation, and maintenance of renewable energy technology to generate 1 TWh annually of energy with current Western European technology; except for small hydro, where the figure reflects job-years to install hydro-power to replace 1 TWh annually.
Using the above-mentioned methods and local data we estimated the renewable energy potential in Slovakia The figure shows potential for renewable energy to deliver a total of 30.1 TWh/year with currently used technology in Europe. This is equal to 13% of the country's energy demand of 230 TWh/year. The potential for solar energy, estimated TWh/year, is not included in the figure.
This article is based on the report "Guideline for Estimation of Renewable Energy Potenhals, Barriers, and Effects which is available from INforSE- Europe.