By 2020 Germany must replace 40 GW of ageing or nuclear plant, a fact that has prompted a new-build regime on an unprecedented scale. Among the new plants will be two new ultrasupercriticals of 823 and 750 MW in an identical CHP configuration and with identical emissions control technologies. They will be built by a consortium of Siemens, Austrian Energy & Environment (AE&E), and IHI of Japan at the industrial centres of Luenen to the northeast of the great Essen-Dortmund-Dusseldorf agglomeration and at Mainz-Wiesbaden to the southwest of Frankfurt.

The 823 MW plant will be built at the existing KMW power plant site in Mainz. ‘Thanks to the advanced technology the power plant will attain a very high efficiency of 46 % and will be one of Europe’s most modern plants’ stated Michael Suess, CEO of the Siemens Energy Division. Beside electricity the cogeneration plant will also produce 200 MW of district heating for as many as 40 000 households and approximately 30 MW process steam for industrial plants in Mainz. ‘We will thus achieve an optimum fuel efficiency of 60 per cent’ added Suess. The location is eminently suitable for CHP, and will help industrial plants in the vicinity to avoid some of their own emissions

The value of the order for the consortium totals approximately r1 billion, with the Siemens share amounting to around half, and about r360 million going to AE&E. The power plant licensing phase is already underway and construction is scheduled to commence late 2008 / early 2009.

In July 2007 KMW signed a contract with Siemens covering planning, supply, erection and commissioning of the main components for this power plant, a move that was designed to sidestep supply difficulties in the power plant construction sector, making it possible to set the completion date for 2013, and ensure planning security. ‘Despite the very tight situation relating to planning and erection resources, and delivery bottlenecks worldwide for key components such as turbines, pumps, piping, tanks and vessels, we have succeeded together with the customer in achieving an optimised division of the scope of supply and scope of services’ said Suess. ‘There is thus a balanced distribution of risk among all parties involved and, at the same time, it will be possible to attain the desired cost-effectiveness and meet delivery deadlines.’

Key components

Siemens’ scope of supply encompasses key components such as the steam turbine and generator, and the electrical and I&C systems, including the associated planning, installation and commissioning. The working group comprising AE&E and IHI will supply the tower boiler, the flue-gas desulphurisation plant, and other supply and disposal systems.

The power island will be the same as that at Luenen, which employs a Siemens STT5-6000 steam turbine to power a generator providing 812 MWe at terminals, 756.5 MWe net. Steam will be provided at 600°C, 280 bar for inlet to the turbine at 600/610°C, 270 bar.

Within the working group AE&E is also responsible for overall erection. Further key supplies such as the plant’s coal handling and ash removal systems, and principal civil structures will be provided by the customer and integrated into the plant.

‘AE&E will be equipping the new power station with state- of-the-art flue gas purification technology, providing the region with a secure supply of energy – and most importantly – clean energy. Using our products and solutions guarantees compliance with the strictest emissions limits within the statutory norms, and satisfies stringent climate protection requirements as well’ said AE&E chief executive Georg Gasteiger.