S.E.P.P. - Solar Energy Power Plant (1975 - 1986)
Various methods for capturing and converting solar energy in a useful way to man's requirements are known today, ranging from low temperature small domestic applications in flat plate collectors to concentrating devices such as parabolic troughs, bowls, heliostat-tower and dish systems as well as photovoltaic systems for electricity and process heat generation.
Solar thermal power systems utilize concentrated solar energy from direct radiation (as part of the entire solar insolation, i.e. diffuse and direct radiation) onto a surface normal in order to drive - via a suitable heat exchanging system - a heat conversion engine (prime mover) which produces either electric power or industrial process heat using steam, sodium, or gas (air, helium) as a working medium.
Advantages of Large Parabolic Dish Systems
Our discussions are confined to the smaller and medium scale solar thermal power plant for producing high temperature industrial process heat and/or electricity up to single dish systems for 2000 kW el, using large parabolic dish collectors with an open cycle industrial gas turbine in the case where electricity production is implemented.
Comparisons with other types of solar thermal power plants show, that the Large Parabolic Dish System has considerable advantages over the heliostat-tower and farm concept:
- higher output in annual kWh(electric or thermal)due to constant two axis solar tracking without a cosine loss factor,
- higher conversion efficiency due to higher process temperatures,
- higher efficiency in electric power conversion due to constant heat flux distribution in receiver,
- high availability through the use of proven components,
- process heat availability in a wide spectrum of temperatures,
- waste heat utilization at temperature levels of 200 o Celsius in case of electricity production can bring plant efficiency up to 85%,
- service and maintenance requirements low,
- simple and reliable cycle using air as working medium,low thermal inertia for fast system start-up time,
- potential for even higher usable process temperatures through the use of ceramics in receiver and turbine for future generations of LPDS,
- compact, stand-alone system with 24 h system use due to hybrid mode (electricity generation).
The markets and user profile of this type of solar power plant today can be described as the isolated load market where the user is generally isolated from a national grid. The local utility plant, if there is one at all, consists of a few diesel generators with possibly a small transmission and distribution network. This application is typical of small communities on islands, remote military installations, isolated industrial sites, and villages in developing countries. It is certainly these markets that will allow the economic penetration of solar energy in the very near future, together with co-generation in suitable industrial countries with sufficient insolation per year to warrant the installation of costly solar energy conversion hardware.
