<p><b>Modelling the German greenhouse gas reduction quota using a merit order approach based on greenhouse gas abatement costs</b></p><p>In the transport sector in Germany, climate-damaging emissions are reduced by the greenhouse gas reduction obligation for fuels, the so-called greenhouse gas avoidance quota. Defined compliance options are available for the emission reductions to be achieved. In addition to reducing emissions in the supply chain of fossil fuels, these are primarily energy carriers based on renewable sources. The design of the quota obligation is subject to numerous specifications and regulations. The fulfilment of the quota obligation is also made possible through the trading of emission reductions. This trading has a major impact on the use of compliance options. Since trading is not public and the compliance system is highly complex, a simulation model was developed to provide information on the development of quota prices and the use of certain compliance options. The model developed is based on the assumption that the compliance options, ranked according to their specific greenhouse gas abatement costs, lead to a so-called merit order in the market. This approach can be used to determine the order in which the individual options are used. In addition to the specific energy quantities and emission factors, numerous technical and legal conditions have to be taken into account. The functionality of the calculation is demonstrated using example scenarios. The results are subject to considerable uncertainty due to the major influence of the assumptions. They therefore only represent a limited selection of possible developments.</p>