Session: 07-02: CSP Systems Analysis for Heat and Electricity Applications

Paper Number: 122128

122128 - Cost Optimal Design of Solar E-Methanol Production Powered by Csp/pv Hybrid Power Plants. 

Abstract: 

Global trade in green hydrogen derivatives is seen as an important element of the future global energy system. Fossil energy carriers and their CO₂ emissions could thus be replaced by chemically bound renewable energy from regions with favorable conditions. Due to the enormous potential of solar energy and the availability of unused land, the Earth's sun belt is particularly interesting as a future energy supplier. Methanol, produced with green hydrogen and CO₂ from a sustainable source, is one of the most auspicious energy carrier molecules in this context. As a versatile chemical building block, methanol could not only be used directly as a fuel, but also as a feedstock for the chemical industry. The use of electricity from renewable energy sources for electrochemical water splitting is a common approach to producing green hydrogen, which can then be further processed into so-called e-methanol.

However, the production of hydrogen derivatives such as e-methanol with fluctuating renewable energy sources such as solar energy is a challenge. With photovoltaics (PV), it is possible to provide electricity at attractive prices, but only during the day and with fluctuations. Since electricity storage with batteries is too expensive to ensure a continuous power supply, an electrolyzer system powered solely by PV operates with relatively low full load hours. This increases the specific costs of e-methanol, as the synthesis process can be operated more economically with a continuous supply of hydrogen, electricity and often also thermal energy.

This work therefore proposes combining photovoltaics with concentrated solar power (CSP) and thermal energy storage (TES) to operate an e-methanol production plant. In this concept, stored solar high-temperature heat can be used to generate electricity in a steam cycle when needed, which allows a very continuous operation of the e-methanol plant. These hybrid solar energy systems for the production of synfuels offer a wide variety of operating modes and system configurations. Due to this diversity, finding the best configuration that leads to the lowest levelized product cost is a complex optimization problem.

To address this problem, we have developed an energy system model for solar e-methanol production based on power supply with CSP/PV hybrid power plants, which includes also an operational strategy. By incorporating techno-economic data, the model is able to determine cost-optimal plant designs based on a global optimization algorithm. The plant optimization shows that the inclusion of CSP and thermal storage is beneficial and can ensure the continuous operation of the plant at locations with high solar irradiation. Depending on the location and cost assumptions, this can lead to significantly lower e-methanol production costs compared to a system powered solely by photovoltaics.

Presenting Author: Christian Sattler Deutsches Zentrum für Luft- und Raumfahrt

Presenting Author Biography: Prof. Dr. Christian Sattler studied chemistry at the University of Bonn, Germany. He is divisional Board Member for Energy and Transport of the German Aerospace Center (DLR) and director of DLR’s Institute of Future Fuels. He is also professor for solar fuel production at RWTH Aachen University, Germany. He serves as vice president of the association Hydrogen Europe Research representing the European research institutions in the European Clean Hydrogen Joint Undertaking. He is the national representative to tasks of the IEA’s SolarPACES Implementing Agreement. He is an ASME fellow and member of the ASME’s Clean Energy Technical Group.

Authors:

Andreas Rosenstiel Deutsches Zentrum für Luft- und Raumfahrt
Nathalie Monnerie Deutsches Zentrum für Luft- und Raumfahrt
Martin Roeb Deutsches Zentrum für Luft- und Raumfahrt
Christian Sattler Deutsches Zentrum für Luft- und Raumfahrt