Methanol for Renewable Energy Storage and Utilization

Today's efforts to substitute fossil energy carriers by renewable energy sources suffer from fluctuations of wind and sunlight for which there is a lack of appropriate energy storage technologies, in particular for electricity. A promising method in this direction is chemical energy storage, as the energy density of the chemical bond is unrivaled. At present, there are chiefly two alternatives under discussion: powertogas (PtG) producing methane (synthetic natural gas, SNG) and power-to-liquid, which stores electric power in the form of methanol. However, the pros and cons of either technology are typically discussed without regarding the process economy and the overall efficiencies, and the material use of the target compounds has also been neglected. Detailed analyses of operational experiences from existing methane and methanol plants by AirLiquide (formerly Lurgi) revealed significant differences between both approaches, among which methanol has emerged to have the best overall efficiency (44.9%). In addition, methanol has the additional advantage of being a universal chemical and fuel feedstock, thus re-presenting the ideal candidate for not only chemical energy storage, hut also for substituting fossil raw materials.