Feasibility study and reflection on agro-industrial CO2 point sources as feedstock for chemicals and materials

Abstract

This paper investigates the opportunity to produce chemicals from carbon dioxide rich side streams from the agro-industry by the application of carbon capture and utilisation (CCU) technologies. It takes into consideration economic feasibility and puts the potential from sugar beet factories into perspective by comparison with current plastic use and forest area that would be needed to reach a comparable carbon dioxide uptake. A sugar beet factory with anaerobic digestion of sugar beet pulp and fermentation of molasses to ethanol was reviewed as a potential point source of carbon dioxide. Ethanol and methanol were taken as example chemicals produced via CCU. Ethanol is assumed to be produced via gas fermentation and methanol via reversed water gas shift and subsequent methanol synthesis. Mass balances and economic key figures on relevant technologies were taken from literature. In the default scenario, the production costs are 1738 € per ton for ethanol and 1058 € per ton for methanol. In both cases, the major cost factor is the use of electricity that is largely used for the reduction of carbon dioxide. If a significant penalty for fossil carbon dioxide emission (189 € per ton CO_2eq) is in place, the costs of production of methanol from carbon dioxide are comparable with current methanol prices under the energy surplus scenario (energy costs reduced from 100 € per MWh to 50 € per MWh and doubled capital costs). Ethanol can be converted to ethylene to produce biobased polymers. The use of carbon dioxide from sugar beet processing could fulfil half of the future ethylene biobased plastic demand under the assumption that recycling will reduce the demand for virgin plastics by 50%.