Preparing for the next phase at Stadtwerke Kiel’s super- flexible multi-purpose plant

10 November 2016



Once completed, in 2018, Stadtwerke Kiel’s new gas fuelled plant, which will combine highly efficient gas-engine-based CHP with thermal storage and a power-to-heat electrode boiler, will set a new benchmark for operational flexibility.


The project, at Stadtwerke Kiel’s Kieler Förde site on the Baltic Sea coast of northern Germany, is being executed in two phases. Phase 1, already started, consists of a 60m high heat store (construction underway), electrode boiler (completed) and pump house (nearing completion) that connects the facility to the Kiel district heating network. Work on phase 2, construction of the new 190 MWe/192 MWt piston-engine-based natural-gas-fired combined heat and power plant, is expected to start before the end of 2016.

As of mid-October a final decision to proceed on phase 2 had not been announced, but appeared imminent. Larger scale CHP plants, such as Kiel, are incentivised under the new German CHP law, which came into force on 1 January 2016, but approval of that law is still required from the European Commission to confirm it meets state aid rulings. 

The new natural gas fired facility, with an electrical efficiency of 45% and fuel efficiency of over 90% in cogeneration mode, will replace an existing municipally- owned coal-fired CHP plant that has been in operation since 1970.

The hope is to have the new CHP plant, with its twenty GE Jenbacher J920 Flextra 9.5 MW gas engines, in operation by October 2018.

Extreme flexibility

The modular concept, with a large number of gas engines each controllable individually, is designed to achieve considerable operational flexibility and be highly responsive to the needs of the German energy market, for example able ramp up from zero to full power in 5 minutes and to provide grid support services to accommodate fluctuating renewables in a region with a high proportion of wind generation, thereby creating extra revenue streams and improving the economics of the overall project.

Considerably enhancing the flexibility, the CHP plant will be operated in conjunction with the 200 MWt/1600 MWh thermal store currently being constructed on the site, able to provide eight hours of district heating to around 70 500 Stadtwerke Kiel customers without the combined heat and power plant needing to be in operation.

In addition the 35 MWe power-to-heat electrode boiler enables excess electricity in the grid during periods of low power prices to be used to produce heat, for storage in the thermal store or supplied to the district heating network.

The electrode boiler enables the facility to participate in the secondary balancing market, another valuable source of income.

For the execution of the new pump building and the machine houses for the 20 reciprocating engines, Stadtwerke Kiel placed a two-step order with Kraftanlagen München, which is general contractor for the project. Step 1, construction of the pump building connecting the new facilities (heat storage and electrode boiler power- to-heat plant) with the existing heating network and power plants was started in the summer of 2015. The pump building will be commissioned for the heating period 2016/17.

The site photographs on page 33, taken in September 2016, show progress to date.

Financing

The European Investment Bank is helping finance construction of the 290 million euro project with a 105 million euro loan signed in September 2016, under the Investment Plan for Europe’s European Fund for Strategic Investments. 

Kiel Photograph taken from a drone flying over the construction site in early September 2016. The 30000 m3 (useful volume) heat store is 60 m high. To the left is the electrode boiler (completed in 2015) and in the centre of the picture is the pump house (almost complete). Photo: Stadtwerke Kiel AG/ Luftbildservice Bernot
Kiel Another drone shot, early September, showing existing coal fired plant in the background. Photo: Stadtwerke Kiel AG/ Luftbildservice Bernot
Kiel Visualisation of completed facility, with CHP plant and thermal store
Kiel Electrode boiler (power-to-heat) during construction
Kiel J920 engine
Kiel As part of the preparatory work for the new CHP plant, Ramboll carried out hydraulic analysis of the Kiel district heating network for Stadtwerke Kiel. The new CHP plant has a maximum supply temperature to the district heating network that is lower than the design temperature of the network so it was necessary to investigate the hydraulic implications. A hydraulic model of the Kiel district heating network was constructed by Ramboll based on Stadtwerke Kiel’s GIS registration of pipes and consumers. The hydraulic model has over 6000 branches and nodes


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