Community Research and Development Information Service - CORDIS

Direct solar steam

The aim of the 'Direct solar steam' project was to construct and test a pilot solar thermal power station using an innovative mirror concept.

The prime technical results achieved in the project were the following:
- The use of a fixed, non-moving solar collector, constructed from the least-cost materials available, in order to achieve temperatures of <800C at the inlet of a solar receiver at the focal point.

- The first-ever integration and on-site operation of a volumetric solar receiver with a gas turbine-alternator to generate electricity using solar energy.

All ‘state-of-art’ concentrating solar technologies currently utilise moving mirror collectors which track the sun through the course of the year and/or day. Whether the systems are based on
- Parabolic trough collectors,

- Heliostats and a central tower or

- Dish-engine configurations - they all share this feature in common.

Such systems require numerous moving parts and have, to date, involved costs at such a level as to prove a major barrier to commercial market entry of the technologies.

The ‘fixed collector’ principle had been used prior to the Solargen experiment under this Contract: notably, the ‘Pericles’ installation by the Radio-Astronomy Department of the University of Marseilles - now moved to the University Campus in Recife, Brazil - was one example; similarly a US team constructed a large fixed spherical dish in Crosbiton, Texas. Indeed, a patent for a similar configuration had already been taken out in France in 1927 by an Algerian inventor. In each case, it is believed that the physical relationship of collector to receiver, as well as the receiver design itself, did not allow for sufficient energy to be harvested and transferred in order to produce electricity - and these ‘historical’ attempts remain in the annals of solar energy, never having achieved commercial take-up.

While the Solargen technology involves the construction of larger reflective areas of mirror than any of the existing ‘state-of-art’ concentrating solar technologies, it was the contention of Solargen and the Partners that, if the collector could be constructed at a significantly low cost, being the least expensive part of the entire system, then it could be shown that lower costs might be achieved for a total system, generating electrical power. The intention of the work carried out under the Contract was to demonstrate a cost prototype, as well as a technical prototype.

Both the cost and technical objectives were achieved.

After considerable and lengthy commissioning problems with 3 Czech-manufactured turbines and the British hydraulic drives (neither of which were caused or affected by the fact that they were included in an innovative solar energy system) the prototype built under the Contract finally operated in April ’99.

The overall technical goal of driving a gas turbine with compressed air, superheated to 800?C in the solar receiver, was achieved. The result was a monitored peak output of 31kWe, the loss anticipated due to ambient temperature. The hybrid use of propane gas was also successful.

The system of thermocouples and remote monitoring was generally successful.

Construction of the first design of low-cost fixed collector, both robust and resistant to weather-damage from high winds and storms, was successful. The collector delivered the desired air temperatures at the receiver inlet - with indications that even higher temperatures could be achieved.

Finally, extrapolations from the costs of the prototype indicate that the target of an installed system price of 1,700 dollars - 1,800 dollars /kWe (~1,700-1,800 euros) is achievable for a 100kWe Solargen system. This would indicate that there could be market opportunities that might not be available with technologies requiring even higher premiums over conventional fossil-fuel options.

Reported by

CIEMAT-Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas
Apdo. de Correos, 22
04200 Tabernas
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