Lausward power plant

Credit: Siemens

Fortuna may be an apt name for a new combined-cycle CHP unit in Germany, as the fortunes of Europe’s large-scale gas turbine plants may depend on projects like it, writes Kelvin Ross

Large-scale gas turbine power plants in Europe are commercially dead in the water, right? They have no place in the European power system of today?

Wrong. The gas-fired sector may be on the ropes, but it has a couple of sucker punches up its sleeve – and one of them is in Germany, at the very heart of the European power transition.

At a time when several gas-fired power plants in Europe are being mothballed, the launch of a new large-scale gas turbine project is newsworthy. Throw in the fact that the plant in question has also set three world records for efficiency, and it demands attention.

This is the case with the Fortuna unit at Lausward power plant in Dusseldorf, Germany’s seventh most populous city. Opened as a coal plant in 1957, Lausward’s units have since all been converted to gas and the latest unit has seen the plant step firmly from the 20th century into the 21st.

The combined cycle power plant – equipped with a Siemens H-class gas turbine – is located in Dusseldorf harbour on the banks of the Rhine and was handed over to its operator, utility company Stadtwerke Düsseldorf, in January.

The turnkey plant has set three new records by worldwide comparison. During a test run, the Fortuna unit achieved a maximum electrical net output of 603.8 MW, “a new record for a combined cycle plant of this type in a single-shaft configuration”, says Siemens.

A new world record of around 61.5 per cent for net power-generating efficiency was also achieved, enabling Siemens to beat its own efficiency record of 60.75 per cent set in May 2011 at the Ulrich Hartmann plant in Irsching in the south of Germany.

In addition, Fortuna can also deliver up to around 300 MW for Düsseldorf’s district heating system – a statistic which Siemens says is a further international peak for a power plant equipped with only one gas and steam turbine.

“This boosts the plant’s fuel utilization up to 85 per cent, while reducing CO2 emissions to a mere 230 grams per kWh,” says Willi Meixner, chief executive of Siemens’ Power and Gas Division.

“The increase in the capacity and efficiency levels is the result of consistent ongoing developments, for example in the design of components, in the materials used, in the overall construction of the plant, and in the perfect interworking of all plant components.

“We optimized the power plant to enable it to be ideally positioned in one of the world’s most demanding power markets.”

The gas turbine can run at full load in less than 25 minutes after a hot start, enabling it to also be used as a backup for renewables-based power production.

It is this flexibility that Siemens says makes Lausward – and subsequent plants like it – the optimal power stations for now and the future.

Delivering the gas turbine

Credit: Siemens

The plant can start up in under 25 minutes

Credit: Siemens

The power system merit order in Germany – which measures plants by production (mainly fuel) costs – has seen gas come fourth behind nuclear, lignite and hard coal. But add in the 80 GW of onshore and offshore wind and solar that Germany had in installed capacity in 2015, and gas is pushed to the brink.

“So the gas plants are the first who are out of operation,” says Lothar Balling, Siemens Energy Solutions’ executive vice-president of Global Project Management.

Talking to Power Engineering International at Fortuna, Balling says: “This merit order model still exists in Germany and that is why so few gas plants are running.”

But he adds: “We have a chance in the market – the plants that are the most flexible can step in and support solar and wind. And that requires highly flexible power plants.”

He explains that he believes the use of gas will reduce between now and 2020, but then “it is expected to expand again because of the reduction of coal-fired units and the phase-out of nuclear in 2022”.

Balling says that the district heating aspect of Lausward also “makes it attractive commercially and from an emissions point of view”.

“We have three extraction points extracting low pressure steam which has already been used for the steam turbine, and the heat exchanger is transforming the steam into hot water, which goes out into the city of Düsseldorf.

He explains that Stadwerke Düsseldorf has decided to build a storage system “because sometimes the power prices are so low that it is not sustainable with the gas price, so they can shut down the power plant but maintain for two days the full support of the heating system.

“So, on good days, they are pumping out to the storage system with hot water, and on bad days for electricity production they can shut the plant down but run the whole city heating from the huge water reservoir.”

FORTUNA FACTS

The steam turbine is designed with a generating capacity of about 215 MW

It was delivered to Lausward by barge on the Ruhr and Rhine rivers

The gas turbine was manufactured at Siemens’ Berlin manufacturing plant and was also transported by barge to Lausward

15,500 m³ of concrete, 5500 tonnes of steel, 850 tonnes of piping and 315 km of cable went into building Fortuna

The heat recovery steam generator measures 35 x 26 metres at its base, is 40 metres tall, weighs some 6000 tonnes and contains 400 km of tubing

The total project working time was 2,148,561 man-hours – all without a single accident to any employees

The project was handed over 19 days ahead of schedule

The start-up time is <25 minutes

This, he says, is “another feature to cope with the market conditions”.

The H-class turbine is being increasingly utilized in CHP applications

Credit: Siemens

Gas turbine transport by barge

Credit: Siemens

He adds that this use of H-class turbines in combined heat and power mode is a large market in Asia – Siemens has four or five such units in South Korea and another under construction in Malaysia.

They are not, however, direct replicas of Fortuna. “These combined heat and power plants are very specific to the demand. What temperature you extract is very customized – but the basic principle is still the same,” says Balling.

But why opt for a large-scale gas turbine when so much talk in Europe is about distributed generation with smaller units?

Willibald Fischer, Director of Siemens Gas Turbine Product Management, says: “With large scale you have the benefit of the highest efficiency. With the largest units you can build, you will always end up with the highest efficiency. The smaller units you can’t scale production tolerances.”

As an example, he explains: “We had a customer who has asked for three smaller units and one steam turbine – a three-on-one – ending up at 600 MW, versus one large one. I said, ‘yes, we can give you three smaller units, but you will have to pay more because that will be more expensive at the end of the day and it will be slightly lower efficiency’.”

Instead he suggested “a one-on-one unit with the best capex at the same operating flexibility. Because the reason why they asked for three units was operating flexibility, because you have a staggered shutdown or startup.

“The key to making large units acceptable in the market is you need to combine it with operational flexibility. And one of the key things here is that, in our engine technology, we right from the start use fully air-cooled engine technology in the hot section – we have no steam. No external boosters which can slow the engine and the whole process down.”

And he says bigger is better when it comes to grid support.

“The larger the unit, the more rotating mass you have, which helps you to buffer any short-term grid fluctuations – you have a more certain element in the grid, which makes it more robust against fluctuations.”