Modern power plant engineering
Niederaussem, 20 kilometres northwest of Cologne: Seven power plant units make this complex a big energy location of RWE. Between them, they produce nearly 3,400 MW – enough energy for 3.4 million households. One of the power plant units in particular catches the eye: the "BoA" unit, 173 metres high and a milestone in fossil-based electricity generation. With an efficiency of more than 43% this "lignite-fired power station with optimized plant engineering" is about one third more efficient than conventional systems. A record value – and at the same time a clear avowal of the future viability of lignite-based power generation.
Like many other new developments that RWE has been translating into practice for decades now, the BoA power plants units, too, has its origins in tried-and-tested technology: electricity may still be generated according to the same principles as in conventional plants, but important further developments in specific plant components and process steps must be added. For example, pressure and temperature of the steam are significantly higher. Additional heat exchangers intercept some of the residual heat contained in the flue gases – and return it to the process of electricity generation.
Reducing energy losses
All process steps are dovetailed in such a way that energy losses in the power plant process are reduced to the technically and economically possible minimum. This makes better use of the deployed lignite, and efficiency rises with a corresponding fall in CO2 emissions per kilowatt hour generated. All in all, the BoA power plant units cut environmental impact by up to eight million tons of CO2 per year. BoA Niederaussem was commissioned in 2003.
In 2012, two further power plant units of this type (BoA 2/3) were taken into operation, this time at the Neurath site in Neuss County. With an efficiency of more than 43%, they are the world's most modern lignite-fired power stations. New, high-grade types of steel permit higher pressures and temperatures to be reached; the large blade wheels of the turbines have for the first time been manufactured from titanium. This increases the efficiency of electricity generation by over 30 percent compared with the legacy plants that were decommissioned for the benefit of BoA 2&3. Each unit of BoA 2&3 can reduce or increase its output by more than 500MW within 15 minutes.
In other areas of fossil-based power generation, too, RWE makes use of state-of-the-art technology for even more efficiency and lower emissions. Modern natural gas-fired combined-cycle gas turbine plants (CCGT) with combined CHP systems reach a utilization rate of about 80%. Here, electricity and heat generation are optimally coordinated, which yields a definite plus in the way of efficiency.
While yesterday's research results are being used in today's practice, the next technology generation is already being in pre-commercial trials by RWE. Example lignite: planned power plants with coal pre-drying reach an efficiency that is up to four percentage points higher compared with BoA.
In the last years, RWE invested amounts running into billions in the new-build and conversion of fossil-fired power plants. On the road toward less raw-material consumption and improved climate protection, Research and Development work is of great importance and will remain so in the future. For a number of projects and trials, RWE has recourse to special labs and test facilities. For instance samples are tested under real operating condtions in our power plants and the chemical and mineralogical properties of coal is being analysed in our own laboratories.