Utilising excess heat from power-to-methanol plants

Power-to-Methanol plants have a potentially important role to play in terms of providing sustainable fuels to hard-to-electrify sectors. In an integration with district heating, excess heat from methanol production can be used for heating buildings. Many district heating systems already have CO₂ point sources that theoretically could provide carbon inputs, e.g., combined heat and power plants and waste-to-energy plants. However, the analysis of such system integration of methanol production is quite complicated. It must take into consideration both the system effects of the district heating supply units and the transition into a future sustainable energy supply, where the operation of these potential CO₂ point sources may change. One example is the decreased use of thermal power plants for electricity production. This paper presents a detailed model of the district heating system of Greater Copenhagen and four different sites and combinations of CO₂ point sources. The hourly operations of district heating and Power-to-Methanol are simulated using the advanced energy system analysis tool energyPRO alongside the mixed integer linear solver Gurobi. The study finds important synergies. However, the utilisation of excess heat reduces the operation of the other district heating production units in the system and thereby also reduces the potential for methanol production in this type of set-up. In the case of Greater Copenhagen, in a 2030 scenario, only 34–57 % of the potential excess heat can be utilised. However, in a sustainable energy system of a 2045 scenario, the utilisation potential is 69–92 %.