Dissemination Strategy on Electricity Balancing
for Large Scale Integration of Renewable Energy
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The company Stadtwerke Schwäbisch Hall GmbH
Public utilities Stadtwerke Schwäbisch Hall GmbH developed 1970 by mergerof the company W. Heller & Co. (power station) and the already existing public utilities Stadtwerke Schwäbisch Hall (gas and water). Today the Stadtwerke Schwäbisch Hall,in contrast to many other public utilities enterprises in Germany, still belong , to 100% to the city of Schwäbisch Hall.

Since the liberalisation of the electricity market in 1997 (Stadtwerke) the conditions for the public utilities have changed enormously. New legal conditions and the competition for prices and market shares mean an enormous challenge especially to small supply enterprises. Therefore a lot of Stadtwerke sale part of the shares to upper suppliers and large power supply firms in order to reduce the risks, but they also lose their independence.

The Stadtwerke Schwäbisch Hall assert the claims to operate in the interests of local habitants and want to keep their independence. So they are still 100% owned by the city. Their intention is not alone the maximization of profit but also the compliance of environmental and social interests. Innovative concepts concerning power supply and the development of energy services rendered the Stadtwerke Schwäbisch Hall not only economically successful. The Stadtwerke Schwäbisch Hall is heading the promotion of the CHP in Germany. The consumption in Schwäbisch Hall is covered 47% by CHP, 47% by the German Energy mix and 6% by own RES and landfill gas.


Figure 1: Physical generation and consumption in the distribution area of Stadtwerke Schwäbisch Hall


Stadtwerke Schwäbisch Hall do not only deliver electricity, natural gas, water, heat or operate the public water park as well as the parking systems, but they meanwhile also offer numerous services for industrial customers, municipalities and other power suppliers, like Contracting, bundle radio, counter remote selection, power and monitoring control. Additionally, for Greenpeace energy e.G., NaturStromHandel GmbH and Elektrizitätswerke Schönau GmbH the Stadtwerke offer the service of energy billing procedure as for the supply and completion of approximately 90,000 current customers in Germany.


Apart from the CHP plant Stadtwerke Schwäbisch Hall are running 6 hydro power plants with a power of 1.8 MW, 2 wind power plants with a total of 1 MW as well as several photovoltaic plants with a total power of 2MW. The CHP plants are described in the next chapter.
Figure 2: power and production of the electrical energy systems
1.1.1 CHP plants
The generation plants are distributed in different locations.They are containing 28 block unit heating power plant modules.
Figure 3: Map of Schwäbisch Hall with locations of the district heating and CHP plants


The most important CHP plants are the following:

CHP Teurershof I

The youngest member of the CHP family was put into operation in December 2002.

No. of modules:
Fuel:
Manufacturer:
Electricity:
Heat:
Thermal store:
Additions:
Boiler
Yearly production:

-
Gas
Jenbacher
2.0 MW, efficiency: 42%
2.1 MW, efficiency: 44%
200m³

15MW
11,000 MWhel


Figure 4: picture of CHP Teurershof

The heat of the storage can only be used in the area of Teurershof. Therefore the thermal store is not considered in the reference simulation.

The most important CHP plants are the following:

CHP Alfred-Leikam-Straße

This CHP unit was put in operation in November 1997.

No. of modules:
Fuel:
Manufacturer:
Electricity:
Heat:
Thermal store:

2
Gas
Caterpillar
2 x 2.9 MW, efficiency: 35%
2 x 3.9 MW, efficiency: 44%
440m³


Figure 5: picture of CHP Alfred Leikam Straße



Figure 6: 2.9MW Caterpillar engine
Based on the purpose-built pre-chamber ignition and a lean combustion, an excellent electrical efficiency becomes possible combined with a very low emission of hazardous substances.




CHP Schmollerstraße

This CHP was put in operation in 1987.

No. of modules:
Fuel:
Manufacturer:
Electricity:
Heat:
Thermal store:
Additions:
Boiler

8
Gas
MAN
8 x 0.27 MW, efficiency: 35%
8 x 0.39 MW, efficiency: 57%
440m³

3 x 5.33MW


Figure 7: picture of the 275kWel engines Schmollerstraße


When building CHP Alfred-Leikam-Straße, 9.5 MW boiler, the output of the boiler Schmollerstraße were uncoupled for peak load covering.





Gas and steam turbine power station Salinenstraße

In the course of an extensive contracting project, Stadtwerke Schwäbisch Hall have taken over a steam turbine power station from a hospital in 1993. This steam turbine power station was extensively modernized and extended by two gas turbines.

No. of modules:
Fuel:
Manufacturer:
Electricity:

Heat:
Additions:
Boiler

2
Gas/Oil
Solar
2 x 0.9 MW, 2 x 3,8 MW, efficiency: 33%
35.0 MW, efficiency: 57%

1 x 10.0 MW, efficiency: 98%


Figure 8: picture of Gas ans Steam CHP Salinenstraße


In 2004 the power station produced 500 GWh electrical energy since start-up, which approx¬imately represents the consumption of the total supply area of Schwäbisch Hall within three years.




The gas turbines were some of the first so┬┐called Low-Nox-machines installed in Germany. These turbines get along without additional emission control and reach only 50% of the limit values of TA-Luft.



Figure 9: Gasturbine Schmollerstraße
For peak-load optimization of the gas demand on days with high consumption, the gas turbines can be switched directly from natural gas operation to fuel oil operation. The same applies to the two peak-load boilers.


Additionally, some smaller CHP are located in the area of Stadtwerke Schwäbisch Hall

  • Former barracks, now Solpark 1987 8x275 kWel/ 435 kWth

  • School Centrum east 1989 2x110 kWel 220 kWth

  • School Centrum west 1992 4x50 kWel/100 kWth

  • municipalty building city works 2000 5,5 kWel/12 kWth

  • Public water park Schenkenseebad 2001 1x225 kWel/390 kWth

  • Commercial School 2001 225 kWel/350 kWth

The latest additional project was a 5MWel/ palm oil CHP unit close to Salinenstraße CHP. The new CHP is based on a refurbished engine. The electricity will be paid for with a tariff fixed by the law for renewable energies. Thus the new engine has to operate permanently.
Figure 10: New palm oil 5 MW CHP Salinenstraße