Life Cycle Analysis aspects of CO2 capture for production of methanol as energy storage

We have investigated the environmental life cycle of the CO2-to-methanol (CO2MeOH) chemical process. The frame of this study is the CO2MeOH project (Call Ra&D HES-SO 2011 Smartcity) which aims to recover CO2 from cities and industrial sources and capture it on ionic liquids (liquid salts at a temperature below 100 °C) and then, by hydrogenation, convert this captured CO2 into methanol. Methanol could finally be burnt as fuel for energy production or transportation applications. A priori, the industrialization of this process should contribute to reduce greenhouse gas emissions and the consumption of non-renewable energy. The CO2MeOH process, combined with solar energy, resembles artificial photosynthesis – a technological dream. Basically the life cycle analysis (LCA) approach seeks to quantify in which way those environmental objectives could be achieved according to the usage conditions. Therefore we have investigated, from the life cycle analysis standpoint, several scenarios that are likely to benefit from the CO2MeOH process. One of the more promising scenarios includes CO2 recovery from industrial smoke stacks. In that case the CO2MeOH process should be considered as a way of extending the carbon cycle one step further, the CO2 acting as a raw material rather than an emission. However, hydrogenation is necessary to produce methanol, thus the origin of hydrogen (i.e. how it was produced) has a strong impact on the environmental impact of the overall process. In the first part of this study, we will discuss in detail this CO2MeOH process to produce methanol as chemical energy storage (i.e. fuel); since today’s hydrogen available on the market is mostly a by-product of the petrochemical industry, this pathway is obviously too carbon intensive and fossil-energy based. Therefore only renewable energy sources for hydrogen production must be considered and we quantify the benefits of the renewable pathway. In the second part, extending the system boundaries, we will investigate in detail the specific scenario in which CO2 is captured from the smoke of a thermoelectric power plant to produce methanol as a fuel for cars. For this study we have used the LCA method IMPACT 2002+ to quantify damages on Global Warming and Resources, along with the Cumulative Energy Demand method to quantify each kind of Primary Energies; SIMAPRO software and ecoinvent database were used to perform LCA.