Decarbonisation Technology - May 2023 Issue

Advantages

Disadvantages

Utilisation of a waste product : CO 2 is a waste product generated from various industrial processes, and direct conversion to methanol provides a sustainable and carbon-neutral way of utilising this waste product. Reduction of greenhouse gas emissions : Direct conversion of CO 2 to methanol can help reduce greenhouse gas emissions by avoiding the release of CO 2 into the atmosphere. Methanol is a versatile fuel : Methanol is a versatile fuel that can be used as a feedstock for various chemicals, as well as a transportation fuel.

For a large 1,000 t/d e-methanol plant, an electrolyser of at least about 420 MW would be necessary. To replace a conventional mega- methanol plant with a production capacity of 2,500 t/d, an electrolyser in the gigawatt range would be needed. Such large electrolysers are still in the development phase. Since production is currently low, limited data are available on actual costs, meaning that potential costs must be estimated. The bio- methanol production cost will depend on the bio-feedstock cost, investment cost, and the efficiency of the conversion processes. In the short term, biomass could be co-fed into a coal-based gasifier, or biogas fed into a natural gas-based methanol plant, so allowing for the gradual introduction of biomass as a feedstock and making methanol production more sustainable at a potentially lower cost. The cost of e-methanol depends to a large extent on the cost of hydrogen and CO 2 . The cost of CO 2 depends on the source from which it is captured, such as from biomass, industrial processes or DAC. The current production cost of e-methanol is estimated to be in the range of $800-1,600/t, assuming CO 2 is sourced from BECCS at a cost of $10-50/t. If CO 2 is obtained by DAC, where costs are currently $300-600/t, then e-methanol production costs would be High energy requirements : Direct conversion of CO 2 to methanol is an energy-intensive process that requires a significant amount of energy, usually from fossil fuel sources. High cost : The production of methanol from CO 2 is currently more expensive than the traditional production of methanol from natural gas. Limited scalability : The technology for direct conversion of CO 2 to methanol is entering the commercial readiness phase with several projects announced e.g. (Veolia, 2022) (Raimon, 2022). Catalyst deactivation : The catalysts used in the conversion process can be easily deactivated by impurities and other substances in the feedstock, reducing their effectiveness and requiring frequent replacement.

High energy density : Methanol has a high energy density compared to other renewable fuels like hydrogen, making it a more practical fuel for transportation.

Table 1

by-products, biogas from landfill, sewage, MSW, and black liquor from the pulp and paper industry. Green e-methanol is produced from CO 2 captured from BECCs and DAC together with low-carbon-intensity hydrogen. E-methanol cost In general, each molecule of CO 2 entering the process will exit as a methanol molecule. However, each CO 2 molecule requires three molecules of hydrogen and will produce one molecule of water for each molecule of Green e-methanol is produced from CO 2 captured from BECCs and DAC together with low-carbon-intensity hydrogen methanol. Accordingly, about 1.38 t of CO 2 and 0.19 t of hydrogen (~1.7 t of water) are needed to produce one tonne of methanol. About 10- 11 MWh of electricity is required to produce one tonne of e-methanol, most of it for the electrolysis of water (assuming CO 2 is available). With a 100 MW electrolyser, about 225 t/d of e-methanol could be produced. Such electrolysers, although large, are already available from Thyssenkrupp.