Biomass integrated-gasification/gas turbine power generation in Zimbabwe.

摘要

Power generation using Biomass Integrated-Gasification/Gas Turbine (BIG/GT) systems is an emerging technology with potential for significant environmental and development benefits: when the biomass fuel is produced renewably, there is a low net carbon dioxide emission; particulate and sulphur emissions are inherently very low; dedicated energy plantations growing hardy crops could be used to restore degraded land and provide a new income source for rural populations. This dissertation is a technical and economic assessment of BIG/GT technology and its implications for rural development in the context of Zimbabwe.; The dissertation presents a methodology for representation of the gasification process in a system model by simple mass and energy balances, demonstrating that useful information about gasifier performance and overall cycle efficiency can be generated without detailed modeling of the gasification mechanism and without an exact prediction of the product gas composition. The methodology is incorporated in the modeling of biomass integrated-gasification combined cycle systems and is used to investigate the impact of biomass moisture on gasifier and overall cycle performance.; Results from the cycle modeling show that fundamental thermodynamic constraints lead to a substantial efficiency difference between a combined cycle coupled with either a pressurized or an atmospheric pressure fluidized bed biomass gasifier, so the difference is unlikely to be reduced significantly due to technology improvements. Investigation of the impact of biomass moisture on overall cycle efficiency shows that a combination of air-drying and flue gas drying can significantly reduce the efficiency penalty associated with biomass moisture.; Results of the system modeling are inputs to a case study focusing on the economic and rural development prospects of BIG/GT technology in Zimbabwe's poorest regions where the potential rural development benefits are most needed. The main conclusion is that economic success of 100 MW scale BIG/GT power generation in Zimbabwe could be achieved along with rural development and local environmental restoration in the poorest regions, provided appropriate government policies are implemented to gain the development benefits and avoid unwanted consequences.