The economics of renewable CaC2 and C2H2 production from biomass and CaO

Abstract

This article presents the economics of a bio-based CaC2/C2H2 production concept plant. The aim of the research was to study if renewable CaC2/C2H2 production could be competitive in comparison with current technologies. The starting point was to integrate a wood char production unit into a combined heat and power (CHP) plant with a bubbling fluidized bed (BFB) boiler. The wood char was reacted with CaO in an electric arc furnace (EAF). The production costs of the CaC2 were determined based on the wood char production costs as well as the EAF electric power consumption. The results showed that the C2H2 yield (18%) is similar to the current fossil-based production. However, the production costs proved to be even higher than the current selling prices of CaC2 and C2H2. With the chosen basic feedstock (20 €/MWh) and electricity prices (45 €/MWh) the production costs of CaC2 were calculated to be 725 €/t and for C2H2 1805 €/t. The cost effectiveness of the concept plant was determined using the payback time method including the time value of money. The break even selling prices were 747–920 €/t for the CaC2 and 1940–3015 €/t for C2H2 depending on the desired payback time (4–30 years). The key factors in the production costs of CaC2 and C2H2 are the price of electricity and the electrical efficiency of the EAF. The results also showed that recycling the Ca at the site could save up to 48% in fresh Ca material costs.