부산대학교 도서관

The demand for renewable energy is increasing in Stockholm as well as the rest of the world. Imperative factors, such as the need to reduce anthropogenic green house gas emissions and security of supply, force this development. The European Commission distinguishes the organic compound in municipal solid waste as food waste. Food waste may be digested, form biogas and after upgrading, the biogas may be used as fuel in automotive applications. This study is based on the food waste potential estimations performed by the Stockholm County Administration Board in the County of Stockholm, both in 2009 and in 2030. The County Administration Board aim for this food waste to be converted to the vehicle fuel biogas since this would improve the share of renewable transport fuels and, simultaneously, decrease the green house gas emissions coupled with the degradation of organic material. In 2009, Stockholm generated 122 000 tonnes of food waste which could have been converted to 130 GWh biogas. This amount of biogas corresponds to approximately 15 million litres of petrol. In 2030, the County Administration Board estimates the food waste has increased to 152 000 tonnes, which converted would correspond to 170 GWh biogas. This study will expand the analysis and will consider the option where the biogas from the food waste is use to generate electricity to fuel electric vehicles in Stockholm.  In 2009, no large-scale introduction of electric vehicles in Stockholm had begun but it is vital for decision-makers to assess this option for 2030 in order to obtain a resource and energy efficient Stockholm.When considering electricity as vehicle fuel, converting the energy carrier will include additional steps such as electricity generation, distribution, charging of the vehicle as well as the electric powertrain. The overall energy efficiency, from biogas to electric propulsion, is in the order of 40 %. Even though when adding process steps, which imply losses, the more energy efficient energy carrier is electricity. Converting the biogas from the food waste to electricity adds approximately another 10 % of driving distance. Assuming an annual driving distance of 15 000 kilometres, in 2030 this would imply either 27 450 biogas or 30 200 electric passenger cars in the county of Stockholm. The most resource and energy efficient usage of the biogas from food waste would be to convert it to electricity for electric vehicles.