Managing intermittency of renewable power in sustainable production of methanol, coupled with direct air capture

• Published in: Energy & environmental science 2024-07, Vol.17 (13), p.4594-4621
• Main Authors: Fulham, George J, Mendoza-Moreno, Paula V, Marek, Ewa J
• Format: Article
• Language: English
• Subjects: Alternative energy sources; Carbon dioxide; Carbon sequestration; Catalysts; Climate change; Electric power generation; Electricity pricing; Electrolysis; Fossil fuels; Global warming; Installation costs; Intermittency; Life cycle analysis; Life cycle assessment; Methanol; Natural gas; Offshore; Offshore energy sources; Power consumption; Power plants; Renewable energy; Sustainable production; Wind farms; Wind power; Wind power generation
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d4ee00933a

Coupling direct air capture (DAC) with methanol production is a technically attainable opportunity for CO 2 capture and utilisation (CCU). The process, known as power-to-methanol (PtM), consumes large amounts of renewable electricity for water electrolysis and DAC. However, the time-variability of renewable power remains a major challenge. Here, we consider erecting a wind farm as part of a PtM facility and propose using four parallel reactors to adjust the methanol production according to daily wind power generation, which we model for 90 onshore and offshore locations with real-world data. Batteries and reserve storage of compressed H 2 and CO 2 allow methanol production during near-zero availability of wind power. We investigate different operation strategies, aiming to either minimise the reserve storage or maximise production, ultimately finding minimised storage as more cost-effective. The resulting selling price of methanol from a plant powered by an onshore wind farm is $1400 per tonne, rising to $2200 for offshore wind power because of higher farm installation costs. However, with a well-located wind farm, coupled with improvements to DAC, electrolysis, and catalysts, the selling price falls as low as $300 per tonne of methanol, reaching parity with fossil fuel-derived methanol. Purchasing stable grid power for PtM avoids issues of intermittency, and results in a lower methanol selling price of $960 per tonne, falling to $340 with process improvements. However, life cycle assessment (LCA) shows the global warming potential (GWP) of the grid-based cases is no better than producing methanol from natural gas; whereas, wind-powered DAC-PtM delivers net-negative GWP between −760 and −1240 kg CO 2 eq. per t MeOH , demonstrating successful CCU. This study leverages worldwide wind data, process modelling, and life cycle assessment to reveal the potential of dynamic methanol production for atmospheric CO 2 drawdown, while handling power intermittency and minimising reliance on reserve storage.