Greenhouse impact assessment of some combustible fuels with a dynamic life cycle approach: Dissertation

Climate change mitigation requires steep reductions in greenhouse gas emissions. New sustainable solutions to provide low-carbon energy production will be needed. In this thesis the greenhouse impacts of some combustible fuels were comprehensively assessed using Life Cycle Assessment. A dynamic analysis method called Relative Radiative Forcing Commitment was developed in order to provide clear, unambiguous data to inform effective climate change mitigation strategies. RRFC gives a dynamic approach to greenhouse impacts and demonstrates their significance. The greenhouse impacts of a variety of fuels were assessed: peat, coal, forest residues and reed canary grass, together with different diesels - Fischer-Tropsch (from peat and forest residues), Jatropha and fossil crude oil. Biomass-derived fuels are considered as one way to decrease greenhouse gas emissions. In the past, they were often held to be carbon-neutral fuels. However, all biogenic fuels considered in this thesis have a warming impact on the climate, as their production requires fossil fuel inputs, and in addition, land use emissions from changing carbon pools may have large effect on the total greenhouse impact. If raw materials for fuel are produced by cultivation, the manufacture and use of fertilisers may be of great importance. If global warming is to be halted at the level of 2 to 3 °C degrees Celsius, deep emission reductions will have to occur during the next decades. The RRFC of coal is about 180 over 100 years, thus if 1 MJ of coal is used for energy, the energy absorbed into the global atmosphere-surface system warms the globe by 180 MJ. Warming occurs due to the radiative forcing caused by concentration increases due to greenhouse gas emissions. The use of forest residues and reed canary grass for energy has one of the lowest greenhouse impacts, causing only about a tenth of the impact of coal. Natural gas has a greenhouse impact nearly one third lower than coal. The greenhouse impact of using peat for energy depends strongly on the type of peatland used of peat production, resulting in a lower or higher greenhouse impact than coal.