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Combined cycle power plants from Siemens are among the world’s safest fossil-fired plants for the environment and climate. They combine a gas-powered turbine with a steam turbine to make twice the use of the fuel they consume: The exhaust heat from the gas turbine is exploited to power the steam turbine, greatly improving overall power-plant efficiency. Today’s combined cycle plants already achieve an efficiency of around 58 percent, but raising the combustion temperature could boost this even further.
Another advantage of these power plants is that the natural gas they run on is less carbon dioxide-intense than other fossil fuels. This means that the generators in combined-cycle plants are one of the key power generating technologies in the battle against climate change.
In December 2007, Siemens first ignited a new 375-megawatt gas turbine – the most powerful yet most eco-friendly unit of its kind in the world – at the Irsching 4 power plant in Bavaria.
The Irsching turbine’s improved efficiency means it not only consumes less fuel per generated kilowatt hour, it also emits less nitrogen oxide (fewer than 15 parts per million) and carbon dioxide. When the turbine goes into combined cycle operation, it is expected to set a new world efficiency record of more than 60 percent and, compared to current combined-cycle plants with the same capacity, it will emit 45,000 tons less carbon dioxide a year.
Due to the significant advantages offered by the combined-cycle process, the technology will be adapted to fuels other than gas, including coal, biomass and refinery residue. Integrated gasification combined-cycle power plants (IGCC) in particular look to be a promising way forward.
|Much higher efficiency, due to combined gas and steam turbines|
|High flexibility and availability, low life-cycle costs|
|Lower fuel consumption|
|Lower operating costs|
|Much lower carbon dioxide emissions per kilowatt hour – 345g/kWh for modern combined-cycle plants, compared to 578g/kWh on average for power generating facilities worldwide|
|Further emissions reductions are anticipated – 45,000 tons less carbon dioxide due to efficiency gain of 2 percentage points over earlier plant technologies|
2011-Feb-28 | Author