Technical and Economic Assessment of a High-Quality Syngas Production Process Integrating Oxygen Gasification and Water Electrolysis: The Chinese Case

[Image: see text] Natural gas shortage, waste treatment, and renewable energy utilization and storage are the common issues in China. This research aims to evaluate a simple and reliable biomass and power-to-syngas process for high-quality syngas production integrating oxygen gasification and water electrolysis. The technical and economic evaluations are successively performed based on the simulation data. The single-stage and two-stage gasifiers are integrated and compared. The results show that the process with a two-stage gasifier has advantages in both technical and cost performances over that with a single-stage gasifier. Then, the optimal values of the operating variables are determined by investigating their effects on syngas composition and yield and the overall energy and exergy efficiencies. Then, by setting appropriate amounts of water for electrolysis and methanation pressures, the process can generate two typical products: thermochemical synthetic biogas (TSB) or synthetic natural gas (SNG). The overall energy and exergy efficiencies of TSB can reach 74.1 and 69.5%, respectively, while those of SNG can achieve 64.8 and 64.1%, respectively. The unit product cost of TSB is about one third of that of SNG, indicating that TSB makes a profit while SNG results in loss. A sensitivity analysis of the cost indicates that the constraints for TSB are much looser than those for SNG to gain profit. Additionally, this study proposes two indicators to characterize the electricity-storage capacities of biomass and syngas. The indicators show that SNG has big advantages over TSB in the specific capacity of electricity storage, and the capacities of SNG and TSB are approximately 52.0 and 4.7 times of the specific energy density of the lithium-ion battery pack in 2019, respectively. The work could be used as a reference for the countries lacking natural gas and valuable to guide the development of a two-stage gasifier, reduction in equipment cost, and evaluation of electricity-storage performance using biofuels.