Technology And Policy Research On Solar Aided Coal-fired Power Generation System In China

In response to climate change, to improve energy efficiency and reduce fossil energy consumption has become the energy policy objectives of countries across the world. Because of the energy resources endowment in China, coal fired power generation dominates the electricity supply industry, which makes chinese electric power industry facing great challenges in the respects of energy conservation and emissions reduction. Solar aided coal-fired power generation provides a direction of energy conservation and emissions reduction for coal-fired power plants. Solar aided coal-fired power generation system is based on the design of conventional coal-fired power units, according to the thermodynamic characteristics of the solar thermal system, rationally integrating the solar energy into the conventional coal-fired power units. Based on the practice and development of solar thermal power generation, parabolic trough collector is suitable for the integration with coal-fired power units for the heat transfer fluid, more easily controlled temperature and mass, and the system stability and economy of the parabolic trough collector. Solar aided coal-fired power generation system is conducive to the utilization of solar energy at the time when solar radiation is available while reducing coal consumption during the power generation, on the other hand the solar and coal hybrid system can overcome the problems about the intermittent and fluctuating of the solar energy by making full use of the adjustable ability of the coal-fired unit, and reducing the storage device, at the same time the turbine of the system is shared because the steam generated by the solar energy can be fed into the regenerative and reheating Rankine steam system in the pulverized coal power plant, which avoid additional expenses of the overall system for the utilization of solar energy. Solar aided coal-fired power generation is a feasible, environmentally friendly and efficient power generation technology, and it has good prospects for development.The thesis focus on the system and optimization analysis of the solar aided coal-fired power generation technology based on the varying operation theories of the coal-fired unit and the thermodynamic characteristics of the parabolic trough collector, and the development policies for the solar aided coal-fired power generation are also analyzed through the developed model. The main work and results are as follow:Firstly, the layout schemes were proposed for the coal fired unit integrated with solar energy from parabolic trough collectors based on the principle of "energy grade equivalence" and the thermodynamic characteristics of the parabolic trough collector. Based on the varying operation theories of the coal-fired unit, the models are built respectively from the boiler side, the turbine and auxiliary side, and the integration schemes are analyzed through these models, and some rules and results are summarized respectively from the boiler side, the turbine and auxiliary side. For instance, the results show that the measures to adjust the steam temperature such as desuperheating water etc. are the main factors to keep the superheat/reheat steam temperature constant for the boiler integrated with solar energy. By improving the control ability of superheat/reheat steam temperature, more solar energy can be integrated into a pulverized coal boiler, and the results also show that the levelized electricity costs (LEC) of the schemes is influenced by the cost of the parabolic trough collector, the economic life of the integration systems, coal price, the direct solar irradiance. And if CO2 avoidance is included, the LEC would be much lower.Secondly, According to the thermodynamic characteristics of parabolic trough collector and the impact on the coal fired unit by the solar energy integration, the analysis models are built based on the equivalent enthalpy drop method, which can simplify the analysis of the solar and coal hybrid system. Based on the analysis of the abatement cost, the comprehensive models which can reveal the main factors of the solar and coal hybrid system are built for the detail and optimal analysis of the solar aided coal fired generation system.Thirdly, the analysis models for the power generation sharing and for the greenhouse gas (CO2) reduction are built respectively by setting system boundary and the baseline based on the analysis of the solar aided coal fired power generation system, and the quantitative calculation methods are put forward for the electricity by the solar energy and greenhouse gas (CO2) emissions, which provides scientific basis of the quantitative analysis of the solar aided coal-fired power generation.Finally, the computable general equilibrium (CGE) model for the solar aided coal-fired power generation is built based on the principle of CGE model and the technical and economic characteristics of the solar and coal hybrid power generation system. Though the developed CGE model, the impacts on the solar aided coal-fired power generation are analyzed from the respects of the solar power generation planning, a carbon tax, and indirect tax, which provides scientific basis for policy decision.