Synthesis of natural gas from thermochemical and power-to-gas pathways for industrial sector decarbonization in California

Abstract

In this work, we focus on industrial sector decarbonization in California through the synthesis and injection of Synthetic Natural Gas (SNG) into the existing natural gas pipeline using two technology approaches: (1) a net carbon-negative biomass SNG process from wood residue gasification, and (2) a carbon-neutral Power-to-Gas (PtG) SNG process for the chemical storage of surplus electricity from high adoption of intermittent renewable sources in the electricity grid (e.g., more than 20% of electricity supply from wind and solar). SNG is a key potential low-carbon fuel to meet an array of industrial process requirements without replacing application-specific end-use equipment. We outline and model pathways that can make these technologies more competitive and present a case study for the industrial sector in California, accounting for industrial fuel demand, feedstock supply, and recent federal incentives for carbon capture and storage (45Q federal regulation). A performance assessment and economic analysis with single and coupled parameter sensitivity have been carried out. BioSNG with carbon capture is found to be less expensive today ($96.67/MWh SNG) than PtG SNG ($421.21/MWh). PtG SNG has more opportunity for cost reduction with electrolyzer capital costs and electricity prices the most critical cost parameters. The estimated cost for bioSNG in 2050 ($73/MWh SNG) is lower than the projected reference citygate price of conventional natural gas in 2050 ($87.57/MWh), but the projected cost of PtG SNG is still two to three times higher unless a high capacity factor can be achieved with low electricity prices and lower electrolyzer cost. SNG can reduce up to 17% of industrial natural gas demand and almost 19 Mt CO2 from California's industrial GHG emissions in 2050. These pathways represent significant opportunities to decarbonize the industrial sector but represent dramatic production changes and underscore the need for sustained policy commitments to support these technologies.