Stadtwerke Bayreuth implements innovative CHP concept for Bayreuth University

Source: Energy & Management Powernews, January 31, 2022

The Stadtwerke Bayreuth have implemented an innovative CHP plant on the grounds of the university. It now supplies part of the site and saves 5,000 tons of CO2 a year.

Lecture halls, seminar rooms or libraries: in the future, they will also be supplied by means of an innovative CHP plant on the campus grounds of the University of Bayreuth. The iKWK plant for the heating and cooling supply of the University of Bayreuth has been realized in the Energy Center North on the campus. In addition, the south energy center was modernized, from which the botanical garden also receives the heat it needs. The iKWK system went into trial operation in the fall of 2021, and has been in continuous operation since January 2022. 

What makes the iKWK system special is precisely the interaction of all the system components, emphasizes Stadtwerke head Jürgen Bayer. "The energy transition is technically very complex. Of course, it's great that almost half of our electricity is now generated sustainably. Unfortunately, however, this energy is not available to us evenly. On the contrary: sometimes there is too much, sometimes too little. Pioneering concepts like ours help to reduce the problem." And the iKWKS of the University of Bayreuth helps with an often neglected topic: 

"We would do well as a society to focus on the heat transition." For an iKWK system, the tender rules provide for the coupling of CHP plants with regenerative heat generators. These must generate at least 30% of the reference heat. In addition, an electric heat generator must be included that can provide at least 30 % of the installed thermal CHP capacity. Stadtwerke Bayreuth had been awarded the contract for the university's facility in 2018 in the Federal Network Agency's tender and supplies the university via a contracting agreement. 

The campus is supplied via three networks 

The University of Bayreuth requires around 27 million kWh of heat per year as well as 6 million kWh of cooling. Before the modernization, the energy supply included two gas boilers, a 6 MW electrode boiler, three chillers and three buffer storage tanks of 800 cubic meters each. "The existing three buffer tanks will continue to be used. A buffer is available for each heating and cooling network on the site," explains Matthias Koppmann, project manager for industry & commerce at the Institute for Energy Technology (IfE). In the future, the gas burners will only cover the peak load. 

Also, of the three chillers in the central office in the north of the campus, two will continue to be used. The third has been replaced with a new one. For the iKWK plant, the existing cooling towers at the north energy center were also demolished, a new building was erected and a transformer station was installed. In addition, two heat pumps (Carrier 30XWP) with about 1.3 MW, a combined heat and power plant from the manufacturer Innio Jenbacher with 3.3 MW of electrical and 3.4 MW of thermal output and two cooling towers were added. 

The Bayreuth-based utility is supported by the Institute for Energy Technology of the East Bavarian Technical University Amberg-Weiden. "The IfE then also provided us with intensive support in the following steps - from the feasibility study to the interpretation of the funding guidelines. It will certainly continue to accompany us closely in this and future projects," explains Bayer. The institute also created the heating and cooling supply concept. 

There are three networks on the grounds of the University of Bayreuth: a 90-degree Celsius network, one with 50 and one with 6 degrees Celsius. The two energy centers are connected via the existing heating and cooling networks on the university campus. There is the option at each energy center to feed into either grid to supply the 40-hectare campus. 

In Bayreuth, the iKWK system had scientific support

All the building blocks are linked via a new measurement, control and regulation technology. According to the utility, the system will save around 5,000 tons of CO2 annually - compared to the state of the energy supply before with boilers and chillers. The combined heat and power plant will run primarily in winter and for about 3,500 hours over the year. "The heat pumps will be in operation primarily in the summer," Koppmann explains. Due to the higher outside temperatures, they are then more efficient to operate. 

Before the iKWK system, the energy center south on the campus was already renewed: Here, in addition to the two new natural gas block-type thermal power stations with an electrical output of 450 kW each, a natural gas boiler and a power-to-heat plant were also installed. These plants also ensure the emergency supply for the botanical garden, which is located in the immediate vicinity of the southern energy center. Two chillers are also installed there. 

Further research on the plant is planned

Research and practice are closely intertwined in this case. "With their work, the scientists are providing important findings that we can use for the sustainable and economical operation of the heating and cooling supply for the entire University of Bayreuth," Bayer emphasizes. For this to succeed, Stadtwerke Bayreuth, IfE and the Center for Energy Technology (ZET) at the University of Bayreuth are working together as part of a research project funded by the Bavarian Ministry of Economic Affairs. 

The goal is to analyze and optimize the energy system during operation. The operating data will be evaluated and compared with predicted values. In addition, IfE will help explore how system services can be provided by the installed components. "In this context, it motivates us scientists when the ideas developed in the laboratory and simulations are also applied in large, real systems and we can contribute to the transfer of knowledge between university and industry," points out Florian Heberle, managing director of ZET. 

The optimization will be software-based. For this purpose, digital images of all systems are generated, which are processed with further data and specifications in a simulation model. The desired system-serving mode of operation means that the electrical energy generated by the innovative cogeneration system can be produced in a market-oriented manner. With the optimization, start/stop operations of all plants could also be reduced, while the cooling and heating supply is always ensured at all times. 

The plant at a glance

• Operator: Stadtwerke Bayreuth 
• plant in the Energy Centre North: CHP from Innio Jenbacher (3.3 MW electrical, 3.4 MW thermal), two heat pumps Carrier each with 180 kW electrical and 690 kW thermal output, electrode boiler with 6 MW and two natural gas boilers for peak load each with 9.3 MW thermal
• Savings: 5.000 t CO2 annually 
• Scientific support: Institute for Energy Technology IfE GmbH at the East Bavarian Technical University Amberg-Weiden 
• Contact: Matthias Koppmann, Project Manager Industry & Trade, Institute for Energy Technology IfE GmbH at the East Bavarian Technical University Amberg-Weiden, Contact by Mail

Author: Heidi Roider