Schematic Diagram Of A Micro-Turbine

Figure (2-3): Schematic Diagram of a Micro-Turbine
 Advantages:
•Micro turbine unit costs around $1500 to $2500 per installed kW. That could lead to niche applications in areas with high-energy costs for power quality, peak shaving or replacement energy. They can run on a variety of fuels, including natural gas, propane, and fuel oil.
• The other advantages over other types of DG technologies are a small number of moving parts, compact size, lightweight, good efficiencies in co-generation, low emissions and can utilize waste fuels. Maintenance costs for micro-turbine units are still based on forecasts with minimal real-life situations.
 Disadvantages:
•The major issues involved in micro turbines are the low fuel to electricity efficiencies
The high-quality power of fuel cells alone could provide the most important marketing factor in some applications. Coupled with longevity and reliability this could greatly advance fuel cell technology.
• Disadvantages of FCs. From the electrical point of view, as a result of aging the FC internal impedance slowly increases, therefore, we need a power electronic interface to regulate the output voltage. Figure (2-5): Fuel Cell
2.4 DG Applications
There are many different applications of DG technologies:
Some customers use DG to reduce demand charges imposed by their electric utility while others use it to provide primary a power or reduce environmental emissions. Electric utilities use the DG to enhance their distribution systems. Figure (2-6) shows a list of those of potential interest to electric utilities and their customers [], []. A brief discussion on each application is given in the next subsections.

Continuous power Base load Peaking
The steam may be used for heating the buildings. The CHP fuel is gas or oil and the whole efficiency of the systemis increased through the utilization of the heat. In the next decade, therewill be CHP micro units with FC technology. The power output and the whole efficiency are the same, but the advantages of this technology are the higher electrical efficiency and the higher efficiency in part load. Furthermore, the FCs can use hydrogen directly in a future hydrogen system [].
 Peaking Power
In a peaking power application, DG is operated between 200-3000 hours per year to reduce the overall electricity costs. It is operated to limit the power peak in the network and in this case the DG application can be called peak shaving. Therefore, DG units will be operated to reduce the utility’s demand charges, to defer buying electricity during high-price periods, or to be allowed for lower rates from power providers by smoothing site demand [], [].
 Base Load
In this application, the DG unit will be usually owned by the utility. The DG will provide a part of the required power. Moreover, it will be used to support the distribution network by improving the voltage profiles and decreasing the power loss and enhancing the power quality