Overcoming the energy–water nexus in dry regions – water-positive production of green hydrogen carriers and base chemicals: the DryHy project – technical aspects†

Abstract

The application of Direct Air Capture (DAC) for extracting CO₂ from the atmosphere has a great potential to reduce net CO₂ emissions and help achieve climate goals. Besides storing the separated CO₂, it can be used as a carbon feedstock for producing CO₂-neutral e-fuels, marking a critical research focus area. Despite advancements in various DAC technologies and processes, their large-scale implementation remains limited, among other reasons, because of the large amounts of energy required to power such processes. This article explores the utilization of DAC for water-conscious production of methanol in sunny regions, using cost-efficient photovoltaic power. The selected approach is presented, which involves a process on demonstrator scale with amine-based DAC for CO₂ and water separation from air, high-temperature electrolysis using solid oxide electrolysis cells (SOEC) for syngas production, and subsequent methanol synthesis. We also discuss alternative methods, potential locations, and implementation strategies, highlighting the advantages but also the challenges of producing green methanol in sunny regions outside Germany.