In so called RES-directive the European Union has established 10 % target for energy from re¬newable sources in transport to be achieved in each Member State by 2020. One source of renewable energy in transport is biofuels. A methodology for assessing the greenhouse gas impact of biofuels is presented in the RES-directive, and is tested in this Master’s Thesis. As an example the calculation of greenhouse gas emissions is tested for bioethanol concept based on waste-derived bioethanol production integrated with CHP plant producing heat and electricity. During this calculation it becomes evident that the methodology of the RES-directive is open to various interpretations. The system boundary of calculation can be set in several ways and the results of calculation vary remarkably depending on the interpretation of the methodology. The emission saving results of waste-ethanol are also very dependent on the emission factor given for the waste material used in the process. Based on this calculation it can be concluded that the emission saving results given by the calculation methodology of the RES-directive are very uncertain and depend on the assumptions made for calculation as well as on the interpretation of the directive. The calculation methodology of the RES-directive can also be considered as very narrow approach for assessing the greenhouse gas impacts of biofuels. The calculation is carried out with a narrow system boundary and some effects, like indirect emissions caused by biofuel chains, are excluded. The calculation methodology of the RES-directive is based on traditional static life cycle assessment called attributional life cycle assessment and is not suitable for assessing the change. As the targets and the schedule of the climate change mitigation are very challenging, the climate effects of biofuels should also be assessed more comprehensively by using consequential life cycle assessment. It would be important to compare the emission reductions gained by the biofuels with the emission reductions gained by other means, so that the most efficient means for rapid emission reductions could be supported to be introduced.