Techno-economic assessment of solar driven high temperature electrolysis

Abstract

Hydrogen could become one of the most important energy carriers for great parts of renewable mobility and industry. Producing hydrogen with competitive costs compared to the common methane reforming will be the most crucial step. Today many research projects are ongoing to develop techniques and Systems to produce hydrogen through wind energy, biogas or solar radiation. As Partner of the European funded SOPHIA project (Solar Integrated Pressurized High Temperature Electrolysis) the German Aerospace Center (DLR) develops and investigates a solar driven high temperature electrolysis process. Using solar thermal generated electricity and steam a solid oxide electrolyser cell (SOEC) is driven at high temperatures about 750 °C to produce hydrogen. Compared to other electrolyser systems the efficiency of SOECs is higher and it is a promising Technology for future hydrogen production. Using a large quantity of mirrors, the solar radiation is concentrated to a receiver based on a central tower within the solar field. Molten salt is used to collect the solar heat from the receiver to evaporate water for a Rankine cycle which generates electricity for the electrolysis process. Within this thesis future component costs for required components were collected and calculated to estimate the installation and operating costs of a solar driven hydrogen plant in Huelva, Spain. A production of 400 kg and 4,000 kg hydrogen per day were estimated for the year 2025. Using local weather data and different solar multiples of the solar field the yearly output of the plants were calculated. The estimated costs of hydrogen are 25.66 €/kg at 400 kg/day and 11.47 €/kg at 4,000 kg/day. With additional on grid production on cloudy days the price will decrease to 22.16 €/kg respectively 10.28 €/kg. These costs are significantly higher than current hydrogen production costs via steam reforming with less than 2 €/kg. However in comparison to photovoltaic driven hydrogen production they are nearly on the same level. Rough calculations predict possible costs on industrial level when the solar generated electricity costs reach a value of 0.03 €/kWh.