Initial System Application Hybrid Plants

To reduce the financial risk associated with the deployment of a new power plant technology and to lower the cost o f delivering solar power, initial commercial-scale (>30 MW e) power towers will likely be hybridized with conventiona l fossil-fired plants. Many hybridization options are possible with natural gas combined-cycle and coal-fired or oil-fired Rankine plants. One opportunity for hybrid integration with a combined cycle is depicted in Figure 4.

In a hybrid plant, the solar energy can be used to reduce fossil fuel usage and/or boost the power output to the steam turbine. Typical daily power output from the hypothetical "power boost" hybrid power plant is depicted in Figure 5. From the figure it can be seen that in a power boost hybrid plant we have, in effect, "piggybacked" a solar-only plan t on top of a base-loaded fossil-fueled plant.

In the power boost hybrid plant, additional electricity is produced by over sizing the steam turbine, contained withi n a coal-fired Rankine plant or the bottoming portion of a combined-cycle plant (Figure 4), so that it can operate on both full fossil and solar energy when solar is available. Studies of this concept have typically oversized the steam turbin e from 25% to 50% beyond what the turbine can produce in the fossil-only mode. Oversizing beyond this range is no t recommended because the thermal-to-electric conversion efficiency will degrade at the part loads associated wit h operating in the fuel-only mode.

Figure 4. Power tower hybridized with combined cycle plant [4]. Power is produced in the gas turbine (fossil only) and from the steam turbine (fossil and solar). Steam from the solar steam generator is blended with fossil steam from the heat recovery steam generator (HRSG) before entering a steam turbine.

Power Plant

Figure 4. Power tower hybridized with combined cycle plant [4]. Power is produced in the gas turbine (fossil only) and from the steam turbine (fossil and solar). Steam from the solar steam generator is blended with fossil steam from the heat recovery steam generator (HRSG) before entering a steam turbine.

Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

Get My Free Ebook


Post a comment