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Currently the efficiency for hydrogen production by water electrolysis of electricity amounts to 75 to 85% [19] with potential up to 93% until 2030. [25] Efficiency for methanol synthesis of hydrogen and carbon dioxide currently is 79 to 80%. [19] Thus the efficiency for production of methanol from electricity and carbon dioxide is about 59 to 78%.
providing water along with methanol would make the fuel supply more cumbersome, so water has to be recycled in a loop; CO 2 has to be removed from the solution flow exiting the fuel cell; water in the anodic loop is slowly consumed by reaction and drag; it is necessary to recover water from the cathodic side to maintain steady operation.
The fuel cartridge stores the methanol fuel. Depending on the system design either 100% methanol (IMPCA industrial standard) or a mixture of methanol with up to 40 vol% water is usually used as fuel for the RMFC system. 100% methanol results in lower fuel consumption than water-methanol mixture (Premix) but goes along with higher fuel cell system complexity for condensing of cathode moisture.
Renewable fuels are fuels produced from renewable resources. Examples include: biofuels (e.g. Vegetable oil used as fuel, ethanol, methanol from clean energy and carbon dioxide [1] or biomass, and biodiesel), Hydrogen fuel (when produced with renewable processes), and fully synthetic fuel (also known as electrofuel) produced from ambient carbon dioxide and water.
Autothermal reforming (ATR) uses oxygen and carbon dioxide or steam in a reaction with methane to form syngas. The reaction takes place in a single chamber where the methane is partially oxidized. The reaction is exothermic. When the ATR uses carbon dioxide, the H 2:CO ratio produced is 1:1; when the ATR uses steam, the H 2:CO ratio produced is ...
The stored energy can be recovered by burning the methanol in a combustion engine, releasing carbon dioxide, water, and heat. Methane can be produced in a similar reaction. Special precautions against methane leaks are important since methane is nearly 100 times as potent as CO 2 , regarding the 20-year global warming potential .
After removing hydrogen sulfide and carbon dioxide , which form as side products during the gasification step, methanol can be made using conventional methods. [15] This route can offer renewable methanol production from biomass at efficiencies up to 75%. [17] Production methods using carbon dioxide as a feedstock have also been proposed.
A mixture of water and methanol with a molar concentration ratio (water:methanol) of 1.0 - 1.5 is pressurized to approximately 20 bar, vaporized and heated to a temperature of 250 - 360 °C. The hydrogen that is created is separated through the use of Pressure swing adsorption or a hydrogen-permeable membrane made of polymer or a palladium alloy.