Lars Christersson

Future production and utilisation of biomass in Sweden: potentials and CO2 mitigation

Swedish biomass production potential could be increased significantly if new production methods, such as optimised fertilisation, were to be used. Optimised fertilisation on 25% of Swedish forest land and the use of stem wood could almost double the biomass potential from forestry compared with no fertilisation, as both logging residues and large quantities of excess stem wood not needed for industrial purposes could be used for energy purposes. Together with energy crops and straw from agriculture, the total Swedish biomass potential would be about 230 TWh/yr or half the current Swedish energy supply if the demand for stem wood for building and industrial purposes were the same as today. The new production methods are assumed not to cause any significant negative impact on the local environment. The cost of utilising stem wood produced with optimised fertilisation for energy purposes has not been analysed and needs further investigation. Besides replacing fossil fuels and, thus, reducing current Swedish CO2 emissions by about 65%, this amount of biomass is enough to produce electricity equivalent to 20% of current power production. Biomass-based electricity is produced preferably through co-generation using district heating systems in densely populated regions, and pulp industries in forest regions. Alcohols for transportation and stand-alone power production are preferably produced in less densely populated regions with excess biomass. A high intensity in biomass production would reduce biomass transportation demands. There are uncertainties regarding the future demand for stem wood for building and industrial purposes, the amount of arable land available for energy crop production and future yields. These factors will influence Swedish biomass potential and earlier estimates of the potential vary from 15 to 125 TWh/yr.

Biomass production by irrigated and fertilized Salix clones

Abstract In an attempt to assess maximum biomass production of willows, field experiments with irrigation and fertilization (through the same system) were carried out in the south of Sweden (57°N). The site was near the coast on a sandy soil (pH 5) on which the populations of herbivores (moose and voles) were small. Different irrigation systems were tested on a 1-ha experimental area: drip-, sprinkler, and a subsurface system. Fertilization was carried out from the last week of May until early September. A liquid fertilizer, complete except for calcium and magnesium, was given in an amount corresponding to an addition of 10 kg. ha −1 . week −1 , with the other nutrients in optimum proportions. Irrigation started during the first week of May 1985, and continued twice a week throughout the month with 30 mm on each occasion. The rest of the growing season was very wet, and consequently irrigation was limited to 10 mm a week in June, July, and August. The total amount of irrigation given to the crop during the growing season was 330 mm and precipitation was 271 mm. The crop was fertilized with 150 kg. ha −1 of nitrogen with other nutrients in optimal proportions. Leaves were analysed for macronutrients and the ground-water for nitrate and ammonium. The above-ground production of woody biomass for a Salix dasyclados Vimm. clone during its third year on 4-year-old roots was 3·6 kg. m −2 dry matter for a drip irrigated plot. The comparable result for the subsurface system was 2·8 kg. Two-year-old shoots on 4-year-old roots of the same clone for a drip system plot produced 3·0 kg m −2 . Production of 1 kg. m −2 corresponds to 10 tonne or 25 m 3 . ha −1 . Annual production in clones of Salix viminalis L. was only 1·2–1·8 kg.m −2 during the second and third years. Tests using N 15 -labelled fertilizer have so far shown no leakage in the groundwater. The capacity of some of the Salix clones to convert solar energy into biomass is higher than for any other crop in Sweden, whether in forestry or agriculture.

Future research on hybrid aspen and hybrid poplar cultivation in Sweden

Hybrid aspen and hybrid poplars have been cultivated in Sweden since the end of the 1930s. The hybrid aspen was expected to do best on moraine soils and hybrid poplar on alluvial soils. Some of these plantations still exist but most are in poor condition. The reason for this is largely the origin of the species involved. Most of them are from Oregon and Washington State in the U.S.A., which is about 1000 km to the south of the location where they are now cultivated. This means that introduced poplar clones start to grow too early in the spring and set buds too late in the autum. Frost then damages them severely, particularly late spring frosts in the beginning of the growing season and early autumn frost at the end. Intensive breeding and rapid genetic change requires good knowledge about both genetic control and physiology of important traits. Poplars are probably the species most studied in this respect. In recent years, molecular biology has provided tools suitable for rapid and detailed genetic analysis of higher organisms. It is supposed that the frost problem of poplar plantations in Sweden can be solved by advanced breeding and hybridisation between the species Populus trichocarpa and Populus deltoides from appropriate latitudes in the U.S.A.

The swedish programme for intensive shortrotation forests

The Section of Intensive Short-Rotation Forestry at the Swedish University of Agricultural Sciences incorporates several programmes on biomass production for energy and fibre and its integration with environmental aspects such as biofilters, waste recycling, etc. The major programmes are: Woody biomass production, optimization of woody biomass production of deciduous trees by irrigation and fertilization, deciduous forests on clay soil, utilization of sludge as a fertilizer in short-rotation forestry, and purification of ground water by short-rotation forestry. To achieve the goals, different production systems are being investigated on a wide range of different sites. The emphasis is on intensive short rotation coppice cultivation of Salix spp on agricultural land for production of biomass for energy. Other production systems presently under investigation are extensively cultivated, longer rotation willow plantations, single-tree poplar plantations and mixed deciduous forests.

The future of European agriculture: food, energy, paper and the environment

Abstract European agriculture must progress towards a more multi-faceted utilization of different types of land in order to conserve arable land and thereby food production. The simultaneous production of food, energy and fibres appears economically viable . This also provides a solution to environmental problems of the community. The utilization of waste products as fertilizer when cultivating biomass should be done in such a way that we remain able to return rapidly to full-scale food production if unexpected developments occur. Thus crops chose must be able to be replaced rapidly by grain or pasture on land which has not experienced a loss of fertility or pollution by heavy metals.

Bamboo as bioresource in Ethiopia: management strategy to improve seedling performance (Oxytenanthera abyssinica)

Seedling emergence and subsequent survival and growth are vital for natural forest restoration or plantation establishment by means of seeds. Such information is lacking for the African bamboo species. Two experiments were carried out in a greenhouse to evaluate the influence of seed orientation and sowing depth of the lowland bamboo Oxytenanthera abyssinica on seedling emergence, survival and growth. A randomised complete block design was used. Seedling emergence in the seed orientation experiment followed the order embryo-end-up>lay-flat>embryo-end-down. Survival rate after 62 days decreased in the order lay-flat>embryo-end-down>embryo-end-up. Mean seedling height and number of leaves per seedling followed a similar pattern. Seeds sown on top of the soil surface and at 2.5 mm depth achieved faster and higher seedling emergence than those sown at 5 and 10 mm depths. However, mean seedling height and number of leaves per seedling were higher in 5 and 2.5 mm depths than surface and 10 mm depths. There were significant quadratic relationships between sowing depth and seedling height (p=0.034) as well as number of leaves per seedling (p=0.032), both peaking around 5 mm soil depth. Lay-flat orientation, which is the most frequent position in broadcast sowing, is recommended at 5 mm sowing depth for the lowland bamboo based on overall performance in seedling emergence, survival and growth.