Large-scale power systems

D. L. Bertsekas, G. S. Lower, N. R. Sandell, and T. A. Posbergh. Optimal short term scheduling of large-scale power systems. IEEE Trans. Automatic Control, AC-28 1, 1983. 

From the energetic point of view all the above-mentioned fields of application can be called small-scale power systems. For each of the devices mentioned self-contained power sources are needed, not depending on large-scale power systems - stationary power plants and power supply lines. In small-scale power systems each individual consumer needs much lower electrical power values and a shorter operation time than one in large-scale power systems (see Figure 2). 

Fig. 2. Small-scale and large-scale power systems. 

For developed countries with large-scale power systems, it may still be economically effective to use large modular power plants. The maximum possible capacity of a modular type power plant depends only on the number of modules. 

Electrostatic filters have been used in many coal-fired power stations, and they have been used in some biomass combustion facilities. Their use in medium- or large-scale gasification systems is limited. Electrostatic filters are best suited for large-scale operation due to their physical size and cost, and the primary impediment to their use in current gasification systems is an economic one. 

The remaining classes of nuclear reactors range from zero-power, subcritical neutron sources for university training to large-scale reactor systems for plutonium-239 production. Portable reactors have provided heat, power, and water to U.S. bases in Alaska, Antarctica, and Panama. Private industry has operated various test reactors for reactor studies and radioisotope production. 

Another approach to increasing power plant efficiencies is to use a nonther-mal conversion method for power production, such as fuel cells. Fuel cells rely on electrochemical conversion of the chemical energy in the fuel to electric power. In the cogeneration mode, these systems have been reported to be operable at overall efficiencies as high as 85% (Schora, 1991). Large-scale power plants based on fuel cells have not been developed yet and are not expected to be available for generating central station power until well into the twenty-first century. 

A variety of hydrogen energy applications of a demonstration character have been started or are projected worldwide encompassing autonomous or partial power systems on different scales as well as vehicle research projects. Some examples of large-scale Hi systems are presented in the following. 

In industrialized countries like Germany electricity is mainly produced in large-scale power plants, but the share of production in distributed units is increasing. Electricity is distributed by a transmission network which results in a homogenized load and an increased security of supply. However, unlike a gas distribution system, the power grid does not inherently offer storage capacity. Therefore, production and consumption of electricity generally have to be simultaneous. 

Higher conversion and selectivity to desired products More compact reactors with less heat and mass transfer limitation High versatility in terms of applications and scale, i.e. from integration in micro-systems to large scale power plants with CO2 capture. 

Overall, the thermal regeneration approach in its current state of development may be suitable for small-scale systems but is probably not applicable for large-scale power generation and H2 generation processes. 

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