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要旨:
Ethylene is one of the most important building blocks in the chemical industry, making its decarbonization a natural starting point for achieving emission targets of the industrial sector. We here present an in-depth analysis of carbon and energy flows of two main strategies that could potentially reduce emissions from ethylene production: (i) direct electrification of heat supply in the traditional steam cracking process and (ii) indirect electrification through a novel production route based on Power-to-Gas and Oxidative Coupling of Methane (OCM–PtG). By calculating carbon footprints of all processes as a function of electricity carbon intensity, we show that fueling the steam cracker with renewable electricity can achieve a maximal emission reduction of 30% while OCM–PtG can achieve a net-zero emission production process if electricity supply is completely decarbonized and resulting products are at least partially recycled at the end of their life cycle. An integrated analysis within an economy-wide, global climate policy scenario shows that these conditions are likely to be met only after 2030 even under very stringent climate policy in line with the climate targets of the Paris agreement. If not met, OCM–PtG can actually increase the carbon footprint of ethylene. We also show that OCM–PtG is currently not cost-competitive, but can become so under suitable boundary conditions. It becomes clear that policy instruments that support the market introduction of carbon capture utilization technologies like OCM–PtG are only justified, if conditions are ensured that enable a positive mitigation potential over their life cycle.
