Energy storage comparison of chemical production decarbonization: Application of photovoltaic and solid oxide electrolysis cells

The fossil fuel driven chemical production leads to significant greenhouse emission, and the low-carbon emission technologies are necessary for carbon neutrality. The integration of solid oxide electrolysis cells (SOEC) and H-2-O-2 combustion can replace the fossil fuel and supply high-temperature heat for reactions. However, the energy demand keeps consistent but the renewable energy fluctuates with time. Therefore, energy storage is important for such a change. Clean fuel replacement and electrification are applied in a case study of ethylene plant, which requires 147 MW of clean fuel and 91.36 MW of grid power. Photovoltaic (PV) solar energy drives SOEC and liquefied H-2, compressed H-2, compressed air energy storage (CAES) are compared. A mixed integer nonlinear programming model is proposed to evaluate decarbonization effect and cost, which are balanced by multi-objective optimization. The results show that the liquefied H-2 is superior to other choices because of the high efficiency. The hydrogen of 126.27 MW is the optimal point, which requires 415 MW SOEC and PV panels. Also, this study proposes that the power grid should communicate with energy consumers such as chemical plants to ensure the energy storage method, or supply renewable energy directly, which avoids energy loss and unreasonable energy transition.