System approaches to understand and roll out defossilisation interventions for the chemical sector

The energy consumption of the world’s chemical sector accounts for 30% of the industrial energy use [1]. Oil and natural gas are the main inputs – representing 11% and 10%, respectively, of the global fossil demands – and their consumption patterns are increasing [2]. The main driver for this trend is the rising consumption of chemical products, which stands today at about 1 Gt – comprising of 420 Mt of plastics, 290 Mt of fertilisers, and the rest are solvents, additives, and explosives [1]. Consequently, the chemical sector is responsible for two billion tonnes of (direct and indirect) CO2 emissions in 2020 [3], and the direct CO2 emissions alone are projected to increase by 30% in 2050 [4]. It is imperative to decarbonise the chemical sector, but it is hard to imagine it without carbon-based inputs [3]. Thus, the chemical sector must aim to defossilise by decoupling itself from fossil resources to achieve netzero emissions. Several interventions are now available that include near- to net-zero carbon solutions (biomass feedstocks, green hydrogen, electrification, and carbon capture, storage & utilisation), recycling technologies, and demand reduction strategies. However, rolling out these interventions will be a challenge given the interchangeability of inputs in chemical value chains, the increasing complexity of product streams, and the interconnectivity of petrochemical clusters [2]. Moreover, the feasibility of these interventions within a specific region needs further clarity considering its locally available yet constrained resources [3]. Hence, there is a need for system approaches that can help understand the interplay of the various interventions and pave a path that can maximise their synergies and minimise unwanted consequences. To fill this gap, we present below two system approaches developed.