Hydrogen Production by Solar Reforming of Natural Gas: A Cost Study

Today’s production of renewable hydrogen using energy sources such as solar and wind is too expensive compared with conventional production, normally by an order of magnitude. The high costs are a major bottleneck for the launch of the hydrogen economy. This paper will present a bypass of this bottleneck, which is a compromise between the use of fossil and solar energy: the solar steam reforming of natural gas (NG). It comprises the production of hydrogen from NG and the use of solar energy as the renewable source at low cost. Using the solar reformer technology for generation of hydrogen, we expect fuel savings of up to 40% compared to a conventional plant. Therefore, the CO2 emissions can be reduced accordingly. Based on the experiences in DLR solar reformers, which were successfully demonstrated at a level of few hundred kW in previous EC co-funded projects (e.g. SOLASYS), industrial plant layouts were developed. For a 50 MWth solar reforming plant a cost study was prepared. Two process layouts were investigated and the hydrogen costs were calculated. Sensitivity analyses of different parameters such as the natural gas prize were conducted. The conceptual layout of a solar driven hydrogen production plant comprises the innovative solar reformer followed by a water gas shift reactor and gas separation units. For the separation of hydrogen and carbon dioxide a PSA unit and gas washing unit using methyldiethanolamine (MDEA) are considered. The remaining methane rich gas is recycled to the process. The results of this cost study show that hydrogen produced by solar reforming costs between 4.5 and 4.7ct€ / kWh (LHV of H2). Therefore it is only about 20% more expensive than conventionally produced hydrogen. Increasing the cost of methane (NG) will result in favorable conditions for the solar hydrogen.