Design and Multi-Objective Optimization of CO 2 Value Chains for the Waste to Energy Sector: A Swiss Case Study

Abstract

This study investigates the optimal design of CO2 value chains aimed at decarbonizing the waste to energy (WtE) sector on a national scale and presents the case study of Switzerland. Switzerland has 30 WtE plants that generate a total of 4.2 million tons of CO2 emissions per year. Half of these emissions are from biogenic sources and half are fossil-based, corresponding to 4.5% of the overall Swiss emissions. On the one hand, this indicates the relevance of decarbonizing the WtE sector. On the other hand, it implies that a net-negative-emissions WtE sector can be achieved by adopting carbon capture and storage (CCS) technologies. The CO2 value chains considered here consist in capturing CO2 at the WtE production sites, transporting it to the storage site, and permanently storing it underground. An optimization problem is formulated to determine the optimal design of the CO2 value chains in terms of size and location of carbon capture technologies, and structure of the network transporting the CO2 from the capture to the storage sites. The optimization algorithm is a mixed integer linear program that minimizes the total annual cost and CO2 emissions of the overall system. Several transport options are assessed, namely truck, train, pipeline and ship, as well as different transport paths.