Germany is, through its recently launched Effizienzoffensive policy, putting a great deal of effort into energy efficiency, with cogeneration technologies set to play a big part.

At POWER-GEN Europe on Wednesday, Andreas Pickard, Siemens Head of R&D Management Energy Solutions explained the tremendous advantages of combined heat and power technology in the modern energy landscape.

Speaking at a conference session at the Milan event entitled Development trends in cogeneration and combined heat and power plants, Pickard told an audience of power professionals that current subsidy legislation in the area, driven by economics and defined energy-efficiency and climate protection goals, is aimed at expanding combined heat and power generation to the extent that 25 per cent of Germany’s electric power will be produced by cogeneration plants by the year 2020.
Andreas Pickard
“Yet even as lawmakers recognize the contribution made by cogeneration to increasing energy efficiency, there are ongoing discussions about whether these subsidies make good sense. The doubters, in most cases, use contrasting figures and data that make no sense in comparative analyses, pitting, for example, the energy utilization factors of cogeneration plants against the electrical efficiency of plants generating purely electric power.”

“Ultimately, it is the efficiency of the systems in our energy supply network that are the decisive variable. When electricity has to be generated from fossil fuels because currently available renewable energy sources are unable to completely meet the demand, waste heat is generated that is discharged to the environment without being utilized.”

Mr Pickard said cogeneration in that context was a sensible option given that it facilitates fuel savings of anywhere from 10 to 20 per cent compared with the separate generation of heat and power. In industrial plants, savings potentials of up to 40 percent are possible.

The Siemens R&D chief used the example of the company’s Lausward combined heat and power plant in Dusseldorf, which was constructed in conjunction with the city’s municipality. The state of the art facility set a world record of 61.5 per cent efficiency, using a heat recovery system generator to help it achieve the feat.

The Lausward facility, which supplies district heat to the city, demonstrates the upper range of what can be achieved with a positive view of combined heat and power’scapabilities.

“Steam is extracted from the low-pressure steam turbine section at volumes of 300 MW of thermal energy in combined cycle operation. The plant’s high electrical efficiency combined with its efficient use of heat generated in combined heat and power generation increases the overall fuel efficiency of the natural gas to 85 percent.”

The technology also optimises startup and shutdown procedures enabling significant savings. Co-Start technology means, startup time for hot starts has been shortened from 50 minutes to less than 25 minutes.

This translates to significant fuel savings by increasing efficiency during startup, which also reduces the associated CO2 emissions.

“Assuming that 200 hot starts will be run per year, this amounts to savings of €1.1 million in fuel costs alone,” Pickard said.