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Mr. Sebastian Webel
Mr. Sebastian Webel

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Pictures of the Future
The Magazine for Research and Innovation
 

Sustainable Power Generation

Record-breaking Hat Trick

The Fortuna combined cycle power plant unit at Düsseldorf’s Lausward Power Station: the new unit houses a world record-holding turbine from Siemens.

The world’s most efficient combined-cycle power plant is located in Düsseldorf. With its Siemens gas turbine, the plant sets no less than three benchmarks — with regard to efficiency, electrical output, and decoupled heat.

Where can you find the best views of Düsseldorf? Undoubtedly from the top of the 240-meter Rheinturm telecommunications tower. But an alternative is the observation platform of a recently completed, 65-meter building operated by the municipal power company – the Stadtwerke Düsseldorf AG. Through the center of the glassed-in building, a huge pipe of shining silver steel rises into the blue sky – it’s the stack of the Block F (“Fortuna”) unit of the Lausward power station, the most modern and powerful combined-cycle power plant in the world. You see nothing, hear nothing, and smell nothing here, and the heat on the platform comes from the sun shining through the glass facade, not from the stack.

Thanks to the fully glass-enclosed platform at a height of 65 meters, the “City Window” of the new power plant unit provides a spectacular view across the city of Düsseldorf.

The power station’s Fortuna unit began commercial operations on January 25, 2016. It will be officially commissioned at the 150th anniversary celebration of Stadtwerke Düsseldorf on May 22, 2016. The Latin word “fortuna” means “luck” or “destiny,” and Stadtwerke Düsseldorf hopes the plant will exemplify the first of these two meanings. The prospects for this are good, because no other power plant using fossil fuels is as quiet, environmentally friendly, and low in emissions as this one. And none are as aesthetically pleasing either. Below the glass tower, the power plant hall’s stylish facade contains thousands of LEDs that turn the building into an illuminated work of art at night.

No other power plant using fossil fuels is as quiet, environmentally friendly, and low in emissions as the new Fortuna unit.

It’s What’s Inside That Counts

Although the municipal power company wants a facility that’s beautiful on the outside, it’s the plant’s inner workings that interest it most. Here, the power plant boasts no less than three world records. At 61.5 percent, it has the highest electrical efficiency, which results in CO2 emissions of 230 grams per kilowatt-hour when the plant is operated with simultaneous district heat extraction. By way of comparison, Germany’s entire electricity mix (including renewable sources of energy) produced average emissions of 609 grams per kilowatt-hour in 2014. The Lausward facility also delivers the highest generating capacity (603.8 megawatts) and the most thermal energy (300 megawatts) in the form of hot water of any combined heat and power (CHP) power plant.

Although world records are nice, they can’t guarantee that a plant will be profitable. This is demonstrated by the Irsching power plant in Bavaria, for example, where, since 2011, the Block 4 unit has been powered by a Siemens gas turbine that’s nearly identical to Lausward’s. But the Irsching facility – formerly the most efficient power plant in the world with a 60.75 percent efficiency rating – is currently operating at a mere 400 hours (16.66 days) per year. Despite Germany’s energy transition, electricity from coal and nuclear power is still so cheap that it forces even ultramodern gas-fired power plants out of the market, with negative consequences for the world’s climate. That the Irsching unit still supplies electricity now and then is due to its importance for the south German grid. Whenever too little electricity is produced by means of wind and solar power, the unit is switched on. The operator, E.ON. subsidiary Uniper, receives compensation for keeping the power plant’s capacity in reserve.

The power plant unit’s control room: the operations center for supplying the region with electrical power and heat.

District Heating Makes the Difference

Unlike the Irsching facility, the Fortuna unit has the advantage of also being used for district heating – the decisive factor in making it economically competitive. For instance, hot water from the plant is channeled to the Vodafone Campus, a large office complex for 5,000 employees on the other side of the Rhine. The temperature at the front blades of the Fortuna plant’s gas turbine is 1,500 degrees Celsius, and its waste heat is extracted by a downstream heat exchanger to power a steam turbine and generate additional electricity. The steam turbine is located along the same axis as the gas turbine and the generator. The steam from the steam turbine is channeled through three thick pipes to heat exchangers in the adjacent building. From there, hot water at more than 95 degrees Celsius flows through an insulated pipe underneath the Rhine River to downtown Düsseldorf.

Siemens’ technology at the Fortuna facility enables the operator to better utilize operating time even in Germany’s challenging electricity market.

On days when sufficient electricity is available from solar and wind power systems, the Fortuna facility is operated in a heat-controlled mode to maximize waste heat. A 40-meter-high tank is also being built to hold 35,000 cubic meters of water. Beginning next winter, the tank will be able to store hot water for several days, enabling the power company to freely decide which mix of electricity and heat the Fortuna unit should supply.

Focusing on Cost-Effectiveness and Environmental Protection

Thanks to its faster and fuel-saving ramp-up and ramp-down of gas and steam turbines and the use of a new feature for reducing emissions at low loads, Siemens’ technology  at the Fortuna facility enables the operator to better utilize operating time even in Germany’s challenging electricity market.

The facility’s flexibility is greatly boosted by the fact that its 445-ton gas turbine only takes 25 minutes to reach its maximum output when starting up. “This is a world first,” says Willibald Fischer, Siemens’ program director for the power plant’s SGT5-8000H gas turbine. Siemens is also using a co-start feature to significantly increase the entire power plant’s flexibility. Instead of starting with a delay, as was the case in the past, the steam turbine now starts up along with the gas turbine. It also increases its output at the highest rate possible until it reaches its full load. If electricity needs are low, the facility can reduce its output to 35 percent of capacity. In most power plants, such a reduction would cause emissions of carbon monoxide and other pollutants to rise sharply. However, this is not the case with the Lausward facility, because Siemens engineers developed a new, Lausward-specific system called Clean-Range, which keeps emissions below statutory limits even when the power plant is running at low loads. Moreover, they also developed “Flex-Ramp” technology, which enables output to be changed quickly by up to 55 megawatts per minute.

State-of-the-art combined cycle power plants are ideal and necessary for the quick provision of electricity to compensate for output fluctuations associated with photovoltaic and wind power systems. New technical features, including those that Siemens is now using for the first time in the Fortuna unit, improve power plants’ participation on the German electricity market and thus increase operators’ profitability. Combined cycle power plants are currently in demand in many countries worldwide. For example, in South Korea, where Siemens is already operating eight H-Class gas turbines and assembling seven more. However, the biggest order at the moment comes from Egypt, where three large power plants are currently being built. Each of these facilities has eight gas turbines the size of that in the Lausward plant. Between late 2016 and mid-2018, the new plants will gradually increase their combined output to as much as 14.4 gigawatts, which will provide a major boost to the Egyptian grid.

Bernd Müller