The energy potential of forest biomass in Ireland.

Abstract

Wood has several important advantages over other biomass sources for energy production. Vigorous juvenile growth, low moisture content and the capacity to coppice are the ideal characteristics of species grown for this purpose. The Forest and Wildlife Service is participating in an EEC Energy Project with the aim of investigating the energy potential of forest biomass. The first phase of this project, consisting of growth trials of a range of woody species at four representative forest sites (western blanket bog, midland raised bog, old red sandstone podzol and drumlin-gley) was established in 1977. Plant spacing was narrower than that used in conventional forest management practice in order to increase productivity per unit area. Early results of plant survival and dry matter production from the growth trials indicate that, of the species being investigated, lodgepole pine, Sitka spruce and Eucalyptus are performing best. Above average forest land is required for satisfactory growth of species capable of coppicing and, of the four sites, only the drumlin-gley appears to fulfil this requirement. The possibility of direct seeding reducing the establishment costs of the successful, though non-coppicing conifers, is being tested. Preliminary results from these trials, of seedling emergence, are encouraging. Yields of forest biomass ranging from 25-40 tonnes dry matter/ha/year have been obtained on productive forest lands in the United States; this is a productivity almost competitive with coal at 1974 prices. Similar yields are possible in Ireland on comparable sites. Estimates of the possible energy contribution of forest biomass, as waste materials and as pure energy plantations, are made. It is postulated that the energy import demands of this country could be reduced by 27% based on 1977 imports and assuming the equivalent of half the total forest area were managed on a 20 year rotation.