Sustainable Energy Science and Engineering Center. Concentrating Collectors - Power Generation

Transcription

1 Concentrating Collectors - Power Generation

2 Solar Dish-Engine SAIC System SAIC Dish-Sterling System in Phoenix, Arizona Source: Dish Sterling Systems - overview, Thomas Mancini, ASME Journal of Solar Energy Engineering, 125, May 2003, (on the website)

3 Solar Dish-Engine SBP System Two 10 kw SBP Eurodish in Spain System cost: $10,000/kW The receiver tubes absorb the concentrated solar radiation, heating the helium working gas to approximately 650 C. The full load on the receiver is reached at insolation levels of approximately 800 W/m 2.

4 Solar Dish-Engine SBP System

5 Solar Dish-Engine SES System System Cost: $10,000/kW Kockums (Sweden) Sterling engine

6 Solar Dish-Engine SES System

7 Solar Dish-Engine System Dish diameter: 10m

8 Solar Dish-Engine System Use of Heat pipes Use of Sterling Engine

9 Solar Dish-Engine System

10 Solar Dish-Engine System Use of Metal Hydrides Source:

11 Solar Dish-Engine System

12 Fresnel Lens Optics

13 Central Receiver Collectors A fraction of the ground area ψ is covered by mirrors ~ sinφ r cos(φ r δ C max =ψ 2 sin( δ A Fresnel-type concentrator, a parabolic reflector broken up into small segments. If all the reflected beam radiation is to be intercepted by a spherical receiver, the maximum concentration ratio is given by ψ sin 2 φ r C max = 4 sin δ 1 2 For Flat receiver and d is the dispersion angle

14 Molten-salt power tower system Source: Sandia National Laboratories Solar Power Tower Electric power from sunlight by focusing concentrated solar radiation on a towermounted heat exchanger. Best suited for large scale applications: MW Liquid salt at 290 o C is pumped from a storage tank through the receiver where it is at 565 o C and then to a hot storage tank. The hot salt is pumped to a steam generating system that produces superheated steam for a conventional Rankine cycle turbine generator system.

15 Solar Power Tower Electricity dispatchability

16 Thermal Loss Solar Power Tower

17 Variable Load Solar Power Tower

18 Heliostats Relatively few heliostats have been manufactured to date at a cost of about $250/m 2. Low cost manufacturing methods are needed to make solar power tower viable technology for electricity production. Particularly, a low cost drive systems must be developed. Surface area: 150 m 2

19 Solar Power Tower Receiver: Smaller and simpler receivers are needed to improve efficiency and reduce maintenance. Molten salt: Molten nitrate salt, though an excellent thermal storage medium, it is not an ideal material due to its relatively high freezing point of 220 o C.

20 Solar Power Tower

21 High Temperature Fluids Source: Luc Moens. NREL; GCEP Workshop, October, 2004

22 Source: Luc Moens. NREL; GCEP Workshop, October, 2004

23 Source: Luc Moens. NREL; GCEP Workshop, October, 2004

24 Advanced Tower

25 QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. Solar Chimney/Tower A solar chimney power plant has a high chimney (tower), with a height of up to 1000 m, and this is surrounded by a large collector roof, up to 130 m in diameter, that consists of glass or resistive plastic supported on a framework (see artist s impression). Towards its centre, the roof curves upwards to join the chimney, creating a funnel. The sun heats up the ground and the air underneath the collector roof, and the heated air follows the upward incline of the roof until it reaches the chimney. There, it flows at high speed through the chimney and drives wind generators at its bottom. The ground under the collector roof behaves as a storage medium, and can even heat up the air for a significant time after sunset. The efficiency of the solar chimney power plant is below 2%, and depends mainly on the height of the tower, and so these power plants can only be constructed on land which is very cheap or free. Such areas are usually situated in desert regions. However, the whole power plant is not without other uses, as the outer area under the collector roof can also be utilized as a greenhouse for agricultural purposes. As with trough and tower plants, the minimum economical size of solar chimney power plants is also in the multi-megawatt range. Source:

26 Power output: Solar Chimney/Tower Power output: solar input: P Q Ý solar P = Ý Q solar η coll η tower η turbine = Ý Q solar η plant Ý Q solar = G h A coll The tower converts the heat flow column produced by the collector into kinetic energy and potential energy. The density difference of the air caused by the temperature rise in the collector works as driving force. The lighter of air in the tower is connected with the surrounding atmosphere at the base and at the top of the tower. Hence a pressure difference is produced between tower base and the ambient: Global horizontal radiation Δp tot = g H tower o ( ) ρ a ρ tower P tot =Δp tot V tower,max A coll η tower = P tot Q Ý = 1 2 m Ý V 2 tower,max Q Ý ΔT V tower,max = 2gH tower T o η tower = gh c p T o dh =Δp static +Δp dynamic

27 Solar Chimney/Tower

28 Solar Chimney/Tower Ward County, Texas (annual insolation 2400 kwh/m 2 ) is contemplating to have a solar Tower designed by EnviroMission, Australia

29 Levelized Energy Cost

30 Commercial Solar Plant Costs Solar Electric Generating Systems (SEGS) Levelized energy cost

31 The Solar Resource Daggett, California QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. Peak radiation: 1030 W/m 2 Full Day: 10.6 kwh/m 2

32 Solar Thermal Plant Power Output

33 Southwest Strategy Source: Luc Moens. NREL; GCEP Workshop, October, 2004

34 Solar Thermal Power Plant Potential Comparably low power generation costs can be achieved wherever insolation reaches 1,900 kwh per square meter and year or more. Adequate areas would be e.g. Northern and Southern Africa, the Arabic peninsula, large areas of India, Central and Western Australia, the high plateaus of the Andes states, the Northeast of Brazil, northern Mexico and the Southwest of the United States. Potential sites in Europe are located in Spain, Italy, Greece and on some Mediterranean islands.