Electrification & renewable energy integration: a case study of methanol production

The electrification of the chemical industry is of paramount importance in meeting reduction targets in greenhouse gas emissions. However, it is tenable only if the electricity is generated from renewable sources. This project aims to investigate electrification schemes using methanol production processes as a case study, and to explore strategies for how to power such an electrified process with renewable energy. Taking a methanol production basis of 400,000 tonnes per annum, the energy and material flows are obtained from process simulations while renewable energy systems dedicated to the production are optimised through a modelling approach. In this work, direct (via heat pumps) and indirect electrification strategies (via sourcing alternative feedstocks) are compared, with results showing that the indirect electrification scheme has a more significant impact on the process energy structure. Based on the fully electrified methanol process, renewable power systems with an optional dispatchable power backup are modelled to fulfil the energy requirement aiming at the economic optimality. A two-regime behaviour of renewable penetration against dispatchable energy price has been found, which increases dramatically at the onset and slowly approaches 100% when the dispatchable energy price is above a critical point. The optimal operation of the renewable energy systems results in voluntary curtailment of renewable power, of which the cost analysis shows modest economic potential for its further utilisation. The benefits of a flexible process are shown to be significant, which can reduce the levelised methanol cost by up to 35%. Two geographical locations with distinct meteorological data are selected to investigate the impact of renewable source characteristics on the performance of methanol production and its renewable energy system. In particular, the diurnal and seasonal fluctuations of renewable sources and their impact on energy storage need are compared. The lessons of this project not only provide numerical results in terms of energy needs and production costs but also implications to policymaking, both of which will facilitate the energy transition from the current fossil fuels-based chemical industry to greener production.