Techno-economic assessment of power-to-methane and power-to-syngas business models for sustainable carbon dioxide utilization in coal-to-liquid facilities

Abstract

The work reported in this paper aimed to evaluate and assess the technical and economic prospects of implementing a renewable-energy-based technology namely power-to-gas (PtG) for sustainable utilization of CO2 emissions from syngas islands within coal-to-liquid facilities. Two possible PtG technology vectors (business models) namely power-to-methane (PtM) and power-to-syngas (PtS) were investigated. Three cases for each business model were developed namely PtM-Scenarios 1–3 and PtS-Scenarios 1–3 corresponding to CO2 feed-in scales 10%, 20%, and 50% of the total CO2 emission throughput, respectively. The mass flows generated for each case were used to develop a cost model, which evaluated and compared the economic merits of the various scenarios of the PtM and PtS value propositions based on an economic indicator vis-à-vis levelized cost of syngas production (LCOS). This study indicated that at present market conditions, only PtS-Scenarios 1–2 demonstrated cost competitiveness against the reference syngas plant. In addition, we concluded that PtM is not a viable proposition for sustainable CO2 utilization in coal-to-liquid facilities at least for the near-to-medium term. However, a sensitivity analysis indicated that viability for PtM Scenarios 1–2 and all PtS business model scenarios is possible under future market conditions particularly when the CAPEX and OPEX relating to methanation and electrolyzers decrease, low electricity price, as well as when a CO2 emission credit/tax scheme (>30$/ton) is instigated for the reference syngas plant. Even so, it will not be possible to completely decarbonise a syngas plant within a coal-to-liquid facility using power-to-gas at competitive costs.