Institut für Technische Thermodynamik Energy Research Institute @ NTU Department of  Materials Science and Engineering Principal Investigators: Prof. Chan Siew Hwa (NTU) Prof. Qiang Sun (PKU) Prof. K. Andreas Friedrich (DLR) Contact Persons: Mr. Jan Pawel Stempien Prof. Chan Siew Hwa Conceptual analysis of Solid Oxide Electrolyzer integration in energy system Introduction Securing energy supply for future generation must meet stringent environmental, technical and economical criteria. Typically long lifetime of energy infrastructure means that investments made in the next 20 to 50 years will continue to serve in 70 to 100 years. The scientific community must, therefore, test the novel technologies against their capability to work in highly non-fossil energy system. One of the challenges of such system is a capability of the grid to manage intermittency of the renewable energy sources. It can be met by demand side management, increased flexibility in production and by energy storage. Solid Oxide Cells are highly efficient and environmentally benign devices, that are able to transform chemical energy directly to electrical (Solid Oxide Fuel Cells, SOFC) and store electricity in form of chemical fuel (Solid Oxide Electrolyzer Cell, SOEC). They are one of many candidates to form a backbone of the future energy system. Grid balancing strategy for Singapore SOEC SOFC Syngas Methanol Thermodynamic classification of Solid Oxide Electrolyzer Efficiency of Electrical Energy Transformation (EEET) of Solid Oxide Electrolyzer EEET is equivalent of the coefficient of performance (CoP) of a heat pump. It is greater than 1 for voltages below thermoneutral, below one for higher voltages and equal 1 for V=Vtn Technical assessment Parameter Hydrogen Syngas Methanol Thermal efficiency LHV based [%] 79.4 89.0 61.2 EEET LHV based [%] 108.3 133.2 68.4 Feedstock gases conversion [%] 83.1 57.6 40.8 Cell voltage [V] 1.2 1 Cell current density [A/m2] 0.55 0.25 Cell area [cm2] 81 100 Cell total current [A] 44.55 25 Fuel production LHV based [kJ] 202.8 33.2 20.4 Thermodynamic simulation of hydrogen, syngas and methanol cases Hydrogen production from wind energy Syngas production from grid balancing Methanol production from grid balancing Environmental assessment The hydrogen scenario is beneficial due to replacing of carbon-intensive steam methane reforming (dominant source of hydrogen). Parameter Hydrogen Syngas Methanol Emission reduction for 1% substitution N/A Up to 0.45% Up to 0.37% Emission reduction for 100% substitution 45% 37% Emission reduction due to increased overall generation efficiency by 1 to 3 % (due to SOFC generation) 2 - 6% 1.7 – 5 % Emission reduction due to complete energy transformation and closed loop systems 100% Acknowledgement: The authors would like to thank National Research Foundation, Singapore for the funding support to this project http://erian.ntu.edu.sg