This thesis focused on the development of marginal CO2-abatement costs (MAC) of Wind Onshore, Offshore and Photovoltaics (PV) in the power sector of Germany until 2050. The paper was divided into two parts, a literature research on past studies on that topic, and the development of a model, that shows a possible trajectory of these costs until 2050 and compares to two different CO2-price scenarios. The MATLAB model solved an optimization problem, with fossil generators coal, CCGT and OCGT being the optimization variables at a given injection of renewables. The MAC were determined by increasing this injection by a margin of 10%, while leaving demand and mix at the same level. The difference in CO2-emissions and market value of one MWh, as well as the respective levelized costs of electricity generation (LCOE) for each year, were the base for the calculation of the MAC for the years 2020, 2030 and 2050. For Wind Onshore, these costs decrease from 150-300 /tCO2 in 2020 to about -50 100 /tCO2 in 2050. Wind Offshore develops from 200-300 /tCO2 in 2020 to about 50-80 /tCO2 in 2050. Photovoltaics (PV) see a projected cost curve from 150-500 /tCO2 towards negative abatement costs -100 - -50 /tCO2 in 2050. At the starting point of this examination in 2020 all abatement costs are well above the EU ETSs carbon price. Therefore the current support measures are well justified and necessary to stimulate the further extension of the technologies. Without those support policies, a shift to a low-carbon power generation and a fulfilling of any emission target would be very hard to realize, as none of the RES are expected to operate completely viable any time soon. Even when solely relying on financing through the ETS, this cannot be expected before 2030, with current technological state-of-the-art and CO2-price development kept in mind. With an optimistic projection of the carbon price, the first technology to work economically without additional support is PV, between 2030 and 2035. This could be due to the fact that PV capital costs are expected to fall by over 70% from 2010 levels according to the DIW. (Schröder, Kunz, Meiss, Mendelevitch, & von Hirschhausen, 2013) The great range of MAC at 2020 stems from the LCOE range by the ISE, it narrows down until 2050, as an averaged value for different PV technologies (open space, building integrated and others) is used for the LCOE calculations. The costs for Wind Onshore are expected to be phased out from subsidies after 2035, when the CO2-price reaches levels of 45-64 /tCO2, depending on the carbon price scenario. This technology is expected to have less falling capital costs, which are the main cost driver for the LCOE and the MAC. Due to significantly higher FLHs than PV, this factor doesnt influence results as much as those from solar power. From 2020 to 2050 the abatement costs are falling by about 130%. The thesis shows the importance of incentives and support measures as an instrument of climate policy. Without proper financial support an economically viable operation of low-carbon technology is simply not possible. To shorten the time until these subsidies can be phased out, a more stringent CO2-target or the reduction of the surplus of allowances, as planned by the European Commission, could be a possibility, as it could lead to higher CO2-prices, thus more revenue of the emission trading system (ETS). This revenue in turn could be used to finance faster extension and therefore a quicker cost decline of wind or solar technologies.