Biomass for ethylene production or for electricity generation?: A comparative assessment for CO2 emissions

This paper compares the fossil CO2 emissions which are released from the use of biomass for ethylene production and for electricity generation. Ethylene can be produced from biomass by dehydration of bioethanol, by flash pyrolysis or by the Methanol-to-Olefins process (MTO). in a first step, these technologies are compared with the conventional production of ethylene by steam cracking of naphtha. According to our calculations fossil CO2 emissions from conventional steam cracking, which amounted to at least 6.3 Mt in Germany in 1995, could be eliminated almost totally in the case of flash pyrolysis and the MTO process. This would be equivalent to a 20% reduction of the current fuel-related CO2 emissions of the German chemical industry (30 Mt CO2 in 1995). However the comparison with co, mitigation by using wood for electricity generation reveals that the savings enabled by flash pyrolysis and the MTO process are relatively small, i.e. fossil CO2 emissions could be reduced to a larger extent ii biomass (wood) were used for electricity generation as compared to olefin production. It is concluded that further case studies should be conducted and additional environmental parameters should be taken into account; this could provide a better understanding for which groups and types of products the manufacture from biomass feedstocks is particularly beneficial from an ecological point of view and when, on the other hand, the bioenergy option is more advantageous.