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Schlaich Bergermann
and Partners (SBP)spent many years developing the principal of the
Solar Tower that they later proved and tested when they built a 50
kW prototype. Detailed theoretical preliminary research and a wide
range of wind tunnel experiments led to the establishment of an
experimental plant in 1981/82 with a peak output of 50 kW on a site
provided by the Spanish utility Union Electrica Fenosa in Manzanares
(about 150 km south of Madrid). The German Ministry of Research and
Technology (BMFT) funded the project.
View Video:
"Beyond 2000" - a 5 minute article on
the Pilot Plant in Spain (12.5MB - Windows Media Player format)
The construction and
subsequent operation of the pilot plant was not only an exciting
experiment but also proved the technology beyond all reasonable
doubt. The simulation program developed prior to the construction,
and proven during the operation of the plant, forms the basis in
conjunction with the tests completed during the operation of the
pilot, for the construction of commercially sized plants. The Solar
Tower is now more than a technology; it is a commercially viable
alternative.
The aim of this research project
was to verify, through field measurements, the performance projected
from calculations based on theory, and to examine the influence of
individual components on the plant's output and efficiency under
realistic engineering and meteorological conditions.
A tower 600 feet high and 33 feet
in diameter was built with a single pressure staged turbine at the
base, surrounded by a collector 800 feet in diameter. The
plant was equipped with extensive measurement data acquisition
equipment. The performance of the plant was
registered second by second by 180 sensors.
 Completion of
the construction phase in 1982 was followed by an experimental
phase, the purpose of which was to demonstrate the operating
principle of a solar tower. The goals of this phase of the project
are (1) to obtain data on the efficiency of the technology
developed, (2) to demonstrate fully automatic, power-plant-like
operation with a high degree of reliability, and (3) to record and
analyze operational behavior and physical relationships on the basis
of long-term measurements.
The experimental plant in operated for about 15,000 hours from
1982-1989 without the use of any water for the production of energy.
Through until 1986 components were being tested that made occasional
operational interruptions necessary.
From mid 1986 to early 1989 it was possible to run the plant on a
regular daily basis, except for a period of four months that was set
aside for special measurements and specific modifications.
During this 32-month period, the plant ran, fully automatically, an
average of 8.9 hours per day for a total of 8611 operating hours.
One person at the most was needed for supervision.
Measurements
taken from the experimental plant in Manzanares and solar chimney
thermodynamic behavior simulation programs have been incorporated to
design large plants with outputs of 200 MW and more. Detailed
investigations, supported by extensive wind tunnel experiments,
showed that thermodynamic calculations for collector, tower and
turbine became more reliable for large plants as well. Despite
area and volume differences between the Manzanares pilot plant and a
projected 100 MW facility, the key thermodynamic factors are of
similar size in both cases.
The data gathered allowed for the definitive conclusion that there
is no doubt that solar chimneys can be built, run in the long term
and reliably maintained even in countries that are technologically
less developed. Unlike most other renewable power sources it
was found that the Solar Tower could operate on a dispatchable basis
which makes it that much more of an attractive and economic
proposition when scaling the plant up to a commercial sized plant.
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