Exergetic and exergoeconomic analyses of novel methanol synthesis processes driven by offshore renewable energies

Highlights: • Exergy and exergoeconomic performance of novel CH₃OH processes are investigated. • Offshore solar-wind energy is integrated into CO₂ hydrogenation and CH₄ oxidation. • Wind-diesel power plants show the worst exergy performance in both schemes. • CH₃OH synthesis gives the highest share to total costs in CH₄ oxidation option. • Use of oil&gas sources in the process improves exergy efficiency and cost savings. -- Abstract: In the current context of global energy transition, the coupling of methanol production with offshore oil & gas operations appears to be a promising option to share infrastructures and convert renewable energy into valuable fuel. However, renewable methanol synthesis has not yet reached the commercial stage. Moreover, there is no evidence on studies integrating offshore multiple resources into methanol process. The novelty of this paper is a performance analysis of emerging routes for methanol production driven by offshore wind-solar energies through exergy and exergoeconomic techniques. Two production schemes (catalytic hydrogenation of carbon dioxide and direct radical oxidation of methane) are properly designed to produce a fixed methanol rate driven by offshore wind farm and solar-thermal plants at a given oil & gas rig. The results demonstrate that carbon dioxide-based route shows the lowest exergy destruction rate (66 MW) and total cost rate (1000 $/h) compared to other option. In conjunction with this, the methane-based route gives a satisfactory exergy efficiency of 87% against a mere 2% of other pathway, as well as higher potential to increase cost savings due to lower exergoeconomic factor. Furthermore, influences of varying some key variables on the proposed parameters of the two options are investigated.