tailieunhanh - Chapter 2: Energy Sources

The motivations of moving towards small-scale and distribution energy systems are many, such as. | Chapter 2 Energy Sources Distributed Generation The motivations of moving towards small-scale and distribution energy systems are many such as Engine generators providing economic advantages of on-site cogeneration of heat and power or trigeneration of heat electric power and cooling Small groups of generators being localized and independent of distribution network or grid failures Reducing the utilisation of distribution networks and the power transmission lines losses by locating energy systems closer to end-user Increasing the reliability of the power systems and distribution networks and Minimizing the impact of individual generator s failure in the distributed generation systems. For the future Australian electricity supply industry emphasis in the National Energy Market NEM will be shifted away from the present use of a small number of large centralised generators such as coal-fired power plants towards many smaller generators like natural-gas powered microturbines photovoltaic arrays and wind generators on industrial and commercial sites. 32 2. Energy Sources 33 Figure Microturbine power plant. From Cler and Shepard 1996 1 . Microturbine A microturbine is a small gas turbine which can generate from 500W to some hundred kW power. Fig. displays a simplified microturbine configuration. It contains a compressor a turbine and a permanent-magnet generator all mounting and sharing the same shaft a recuperator and a combustion chamber. Below is the operation principle 1. Incoming air is first compressed to 3-4 atmosphere pressure and sent through to a heat exchanger called recuperator where the compressed air is heated up by the hot exhaust gases from the turbine. Recall the higher the heat source the higher the thermal efficiency. It is found that with the recuperator the efficiency can be improved by up to 15 . 2. The hot and compressed air is burned with the fuel in the combustion chamber. The following fuels can be used such as natural gas .