Biomass gasification can convert biomass into syngas under the oxygen-deficient environment. Using gas engine or boiler, the syngas can be utilized to generate electricity of high efficiency and low pollution emission. The bio-energy in the biomass that is hardly combustible can thus be effectively extracted. To evaluate the feasibility of transforming the refuse incinerators to bio-energy center, this study reviewed the information of biomass gasification technology in the developed countries, and set up criteria for selecting the feasible technology based on the following factors: less environment pollution, lower carbon dioxide emission reduction, higher power generation efficiency and more diversified application of power generation from the gasification products. The “biomass direct chemical looping process” was selected as the first priority. Additionally, considering the property specification of the feed of biomass gasification system, this study evaluated the properties of seven biomass species, including elephant grass, vetiver, china fir, straw, corn cob, municipal sludge cake, and screening fiber-rich trash, and discussed the most updated development of applicable pre-treatment technology (torrefaction, autoclaving and pelleting), in order to separate the non-biomass materials from the biomass and increase the calorific value. Finally we have planned a comprehensive process including the pre-treatment units and chemical looping system.
The study also evaluated the development of several product utilizations of biomass gasification and their individual feasibility in Taiwan, including co-firing power generation, chemicals transformation, gas-engine power generation and fuel-cell power generation. It also suggested the prevention measures for the possible air pollutions from biomass gasification, including tar, corrosive gas, heavy metals, alkali and silica. While taking the efficiency of the carbon emission reduction into the consideration, the biomass direct chemical looping process decreased 90% CO2 emission when comparing with the commercial coal-fired system.
To further understand the development of gasification technology, EPA Taiwan also visited the gasification technology and the relevant facilities of pre-treatment technology in Austria, Netherlands, UK and USA. Furthermore, there were two workshops of the gasification technology held in March and September, 2009, respectively, to provide a platform for communication of the related technology of biomass gasification and pretreatment.