Environmental Risk Assessment of MEA and its Degradation Products from Post-combustion CO₂ Capture Pilot Plant: Drafting Technical Guidelines

To significantly reduce the amount of emission of carbon dioxide (CO₂) to the atmosphere, which is a principal cause of climate change (global warming), and to realize a low-carbon society, the introduction of Carbon dioxide Capture and Storage (CCS) into coal-fired power plants is expected to be effective. Emissions from post-combustion CO₂ capture plants using amine solution may affect the human health and environment. It is, therefore, important to evaluate the environmental impacts by conducting environmental risk assessment, and to, if necessary, employ emission reduction technologies, for effectively introducing CCS. Case studies on amine emissions from the CO₂ capture process and the results of environmental risk assessment are reported. However, there are no guidelines on environmental risk assessment method for the CO₂ capture process which enable plant owners to reduce the environmental impact of the process, to increase understanding of local residents (near CO₂ capture plants) and public, and to promote the introduction of CCS. In this study, as part of the project by Ministry of the Environment (Japan), Mizuho Information & Research Institute, Inc. (MHIR) and Toshiba Corporation drafted the guidelines presenting the basic principles (methods, basic points) of environmental risk assessment with regard to exhaust gas and other parameters involved in the CO₂ capture process. Based on Toshiba's emission data from 10 ton-CO₂/day scale pilot plant using MEA solution at Mikawa coal fired thermal power plant, MHIR conducted a trial of environmental risk assessment for the CO₂ capture process, examined the risk assessment procedure, and drafted technical guidelines. The guidelines are expected to enable plant owners to make reasonable judgement on "how far emission should be reduced", and thus to decide "to what extent they should employ emission reduction technologies". And, the guidelines include "whole-mixture approach", which not only helps to conquer the issues typical of the CO₂ capture process but also is easy to understand and thus familiar to local residents and public.