Life cycle environmental performance of methanol production through photocatalytic dry methane reforming

Photocatalytic dry methane reforming uses light energy and a nanostructured photocatalyst to convert both carbon dioxide and methane gas to syngas for production of fuels and value-added chemicals. The conversion of these two greenhouse gases (GHG) makes photocatalytic dry methane reforming a potentially environmentally attractive process; however, little research has been done to assess its life cycle environmental impacts in comparison to conventional commodity chemical production methods. Further, practical research has been limited to lab scale studies, which do not fully reflect the technical and environmental performance of commercial scale systems. In this work, a simulation describing the production of methanol from a photocatalytic dry reforming process is used to inform a life cycle assessment to estimate its potential environmental impacts at scale. Results indicate that for methanol produced via photocatalytic dry methane reforming to have the same life cycle GHG intensity as methanol produced through conventional steam methane reforming, a combination of improved technological performance and process intensification is required. This includes increased chemical conversion, electricity grid decarbonization, and the use of low greenhouse gas intensive feedstocks. Promisingly, results indicate that methanol produced using a photocatalytic dry methane reforming process that employs landfill gas as a feedstock and 100% renewable electricity, could potentially produce methanol with a negative global warming potential. Opportunities to improve the environmental impact of a photocatalytic dry reforming process so as to widen its scenario applicability are also discussed.