MAN Turbo AG is supplying a steam turbo-generating set with an output of 50 MWe for the Spanish solar power plant Andasol 3. The double-casing machinery train with intermediate superheating was rated for use specifically in this solar thermal application. The complete water-steam cycle was optimised in collaboration with the customer and the steam turbine suitably adapted.

Using this concept, significant improvements in efficiency are achieved, considerably increasing the efficiency of the solar power plant as a whole. This is also reflected in a higher electricity yield, with a portion of the solar energy generated during the day being conducted into thermal storage. This permits power production to be planned, and facilitates electricity generation even at night.

The client is Solar Millennium AG, Erlangen. The project is being handled by MAN Solar Millennium AG, a joint venture company between MAN Ferrostaal AG and Solar Millennium GmbH. Andasol 3 is a parabolic-trough power plant under construction in Andalusia, Spain. It is sited next door to its two sister projects Andasol 1 and 2, the first parabolic-trough power plants in Europe. Once completed, Andasol 3 will provide solar sourced electricity to up to 200 000 people.

Parabolic reflectors with an area of around 500 000 square metres concentrate the sun’s energy, heating thermal oil circulating in pipelines to to just under 400 °C. This heats water to produce steam in a second circuit via a heat exchanger. The steam is expanded in a MAN Turbo steam turbine to drive the electrical generator.

MAN Turbo was able to bring its expertise in the construction of complete turbomachinery trains to the design of Andasol 3, and its successful outcome has extended the application range of its steam turbines. Against the background of the growing global requirement for energy, even the corner occupied by solar technology is characterised by rapid growth.