Pathway toward cost-effective green hydrogen production by solid oxide electrolyzer

Solid oxide electrolysis cell (SOEC) is one way to regulate wind power by producing green hydrogen. However, degradation increases the resistance of SOEC, especially at high current density. This work simulates the heat balance and the degradation process at the system level and compares the Levelized Cost of Hydrogen (LCOH) at different locations through three scenarios: heat integration, super grid connection, and SOEC development. Both heat source and wind power costs are involved in the analysis and optimization of a 5000 kg H-2 per day SOEC recirculating system. The voltage and operating conditions of minimum LCOH are located with a two-stage stochastic optimization approach. As a result, SOEC generates extra ohmic heat and reduces the external heat demand from 29.9 MW to 1.8 MW after degradation. LCOH reduced to $3.60 per kg with heat integration. The super grid will cut the LCOH further to $2.59 per kg. SOEC development will break through the trade-off between current density and degradation, resulting in an LCOH of $2.18 per kg. By 2035, green hydrogen is expected to reach an LCOH of $1.40 per kg and outperform gray hydrogen.

Automated summary

This study investigates the heat balance and degradation process of solid oxide electrolysis cell (SOEC) at the system level, comparing the Levelized Cost of Hydrogen (LCOH) at different locations under three scenarios: heat integration, super grid connection, and SOEC development. It is found that SOEC generates additional ohmic heat and reduces the external heat demand significantly after degradation. Through heat integration, the LCOH is reduced to $3.60 per kg, further lowered to $2.59 per kg with the super grid connection. SOEC development breaks the trade-off between current density and degradation, resulting in an LCOH of $2.18 per kg. By 2035, green hydrogen is expected to achieve an LCOH of $1.40 per kg, surpassing gray hydrogen.