Thermochemical recycling of plastics – Modeling the implications for the electricity system

Abstract

To achieve a circular economy, we need to reinvent the ways in which plastic products are produced, used and recycled. This study investigates the cost-optimal design and operation of an electrified process for the production of plastics that employs thermochemical recycling of plastics and waste. In addition, the impact of this process on the north European electricity system is investigated. A techno-economic optimization model, with the objective of meeting the demand for electricity and plastic to the lowest cost, is developed. The model minimizes the investment and operating costs of electricity and plastic production units while meeting the demands for electricity and plastics without adding carbon-dioxide to the atmosphere. The model considers different flexibility options that can be applied in the plastics production process.A fully flexible plastics production process that has flexibility in relation to time, location and CO2 utilization shows the lowest cost for plastics production and the highest carbon circularity. At the same time, a fully flexible process has the lowest capacity utilization rate, i.e., there is an investment in overcapacity. The results show that a process with flexibility in time renders 100% carbon recovery beneficial, whereas inflexible operation of the plastics production process requires the development and scaling-up of carbon capture and storage facilities. Furthermore, the results show that for the thermochemical production of plastics, the availability of large volumes of waste and favorable conditions for generating electricity at low cost determine the location of the plastics production units. The additional electricity demand to produce plastics is mainly covered by increased generation from wind and nuclear power plants, while wind and solar power dominate in the modeled electricity system mix.