Hästgödsel - framtidens energiresurs

Sammanfattning: Horses have a great social, cultural and economic importance in society and contribute to the open landscape. There are currently more than 360,000 horses in Sweden, which together produce over 2.7 million tons of manure per year. This represents 10% of the total amount of manure from all livestock in the country. Most horses are found in urban or near-urban rural areas, which means that there is often no arable land available nearby to spread the manure on. This create a waste problem and therefore an environmental problem. This study shows how horse manure could be used as a resource for energy and the energy potential of three extraction methods; biogas, combustion and heat recovery from the dunghill. It’s not a well-studied area today, and few attempts have been done. Those that are available show that the possible energy potential of horse manure is good at the right conditions. Heat recovery from the dunghill, in a stable with 40 horses, could save up to 1400 kWh during one year. Energy extraction through biogas, which is the most studied method, has been shown to provide an energy of about 50-250 kWh/ton of manure depending on which bedding material that were used. This would be corresponding to 0.1-0.4% of electricity consumption per year in Sweden. Energy extraction through combustion has been shown to provide an energy of 1900-5400 kWh/ton manure depending on bedding materials, which would correspond to 3.7-10.4% of electricity consumption in Sweden. However, the environmental impact is greater from this method because of the emissions of greenhouse gases during the combustion. The use of waste and by-products from agriculture are an important part of Sweden's goal against a society free from fossil fuels in 2050 and is a step towards a sustainable society in which yesterday's waste is today's fuel.