Technology Status - NET Nowak Energie & Technologie AG

Dish/engine systems will be used in smaller, high-value applications. In
theory, power towers and parabolic dishes can achieve higher solar-toelectric
efficiencies and lower costs than parabolic trough plants. Parabolic
dish systems are the most efficient of all solar technologies, with currently
about 25% solar-to-electricity efficiency. The 4-95 Stirling Power Conversion
Unit (PCU) now holds the world’s efficiency record for converting solar
energy into grid-quality electricity, with almost 30% efficiency at 1,000 watts
per square metre.
● Hybridisation
Because of their thermal nature, each of the CSP system technologies can be
“hybridised”, or operated in combination with conventional fossil fuels.
Hybridisation has the potential to dramatically augment the usefulness of
CSP technology by increasing its dispatchability, improving its performance
by making more effective use of power generation equipment, and reducing
technological risk by using conventional fuel when needed.
Hybridisation efforts are currently focussed mainly on the parabolic trough,
but the learning from these studies may be transferred to the other types of
systems. The Integrated Solar Combined-Cycle System (ISCCS) design offers
a number of potential advantages to both the solar plant and the combinedcycle
plant. For power tower systems, hybridisations are possible with
natural gas combined-cycle and coal-fired or oil-fired Rankine plants. Initial
commercial-scale power towers will likely be hybridised with conventional
fossil-fired plants. Because dish/engine systems use heat engines, they have
an inherent ability to operate on fossil fuels. However, hybridisation for
dish/engine systems is still a technological challenge.
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Table 18
Peak Efficiency and Annual Capacity Factors
for the Three CSP Technologies, 2000
CONCENTRATING SOLAR POWER
Parabolic Power Dish/engine
trough tower system
Peak efficiency
Annual capacity factor
21% 23% 29%
(without and with thermalstorage)
24% 25%-60% 25%
Net annual efficiency 13% 13% 15%
Sources: DOE; SolarPACES.
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