DFIC plans energy supply for the University of Cologne based on trigeneration and geothermal energy

Client

Uni Köln

Background

In the coming years, considerable expansion and refurbishment measures will be carried out on the real estate of the Mathematical-Scientific Campus (MatNat) of the University of Cologne (UzK) including an addition of a total gross floor area of more than 100,000 m2.

Against the background of the climate policy objectives of the state government, UzK commissioned DFIC to conduct a study on future-oriented, climate-friendly and economic energy supply options for the MatNat Campus. Furthermore, UzK commissioned DFIC (as part of a consortium) in July 2017 with the design and planning of the project through all phases of the implementation process as defined in the Architects and Engineers Fee Structure (HOAI).

The energy demand to be services for the properties on the MatNat Campus is in the megawatt range for each, the electricity as well as the cooling and heating demand.

Objective

The energy-intensive chemical, physical and further institutes are to be supplied with heat and cold and the entire MatNat Campus should be supplied with electricity (base load) from a highly efficient combined cooling, heat and power (CCHP) energy centre. This should ensure a significant improvement of the economic efficiency and climate friendliness of the future energy supply in the MatNat Campus.

For the planned construction of a new geological building, the aim is to implement an economic and climate-friendly heating and cooling supply based largely on renewable energies. The future supply system will have to meet cooling and heating requirements of more than 500 kWth each and contribute to the DGNB certification.

The planning services are to be provided in accordance with HOAI (service phases 1-9).

Results

Project Phase 1 – MatNat energy centre CCHP with over 90% total efficiency

The future MatNat energy centre will consist of two identical, highly efficient cogeneration units with a total electrical and thermal output of 3 MW. The plant is planned as a CCHP plant, i.e. the waste heat from the two cogeneration units is used for both heating and cooling purposes. Two heat-driven absorption cooling machines, each with a cooling capacity of 1 MW, are going to supply the cooling requirements.

The time lag between the completion of newly constructed buildings and the refurbishment measures of existing buildings, each with different connection times for the energy supply in individual construction phases requires special care during the planning phase.

Finally, the extremely high efficiency of the primary energy utilisation in CCHP with an efficiency of over 90% ensures a considerable cost reduction of the MatNat energy supply.

The necessary use of natural gas in the gas engines of the energy centre is procured carbon neutrally. The achievable CO2 savings amount to up to 14,000 tonnes of CO2 per year compared to a "standard" energy supply based on district heating and the usage of the electricity grid (including needed electricity for refrigeration purposes using vapour-compression refrigerators).

Project Phase 2 – Near surface geothermal energy trough high-performance energy poles

A geothermal energy supply is planned for the construction of the new geology building during Project Phase 2. The near-surface geothermal energy supply is based on two core technologies:

  • High-performance energy poles (HEP) and
  • Brine/ or water/water heat pumps (WP).

These two core technologies are combined to form a highly efficient overall supply system.

The High performance energy poles (HEPs) are 28 m long, cylindrical and water-filled stainless steel tanks with a diameter of 1.60 m. The pillars use the throughout the year almost constant ground temperature level by means of heat exchangers to supply cooling and heating requirements.

Depending on the geothermal capacities at the site on the one hand and the energy requirements of the building on the other, the HEP system is dimensioned to fully supply the future cooling and heating requirements of the new building.

HEP system and simultaneity of cooling and heating requirements increase efficiency

The year-round almost constant ground temperature level of approx. 12°C at a depth of 30 m is brought to the necessary temperature levels of the different heating and cooling requirements in the new geological building by means of special heat pumps.

Temperature spread up to 30 m depth and functional scheme HEP
Temperature level and functional diagram of the high-performance energy poles (HEP)

The preheating (in case of heating requirements) or precooling (in case of cooling requirements) of water within the HEP system considerably reduces the temperature stroke to be performed by the heat pumps and thus ensures a higher efficiency of the heat pumps. In combination with high simultaneity, the efficiency (Coefficient of Performance (COP) or Energy Efficiency Ratio (EER)) of the HEP-WP system is further improved. This is in particular due to year-round process cooling requirements. Carbon-neutral electricity for the operation of heat pumps comes from the MatNat CCHP energy centre (see TP1 above), which is planned in parallel.

The HEP system can also reduce the re-cooling capacity to be installed in the building, as the HEPs act as heat sinks and can also be used as seasonal storage units.

Vapour-compression refrigerators and district heating transfer stations become redundant. The achievable CO2 savings amount to up to 400 tons of CO2 per year compared to "standard" energy supplies based on district heating and vapour-compression refrigerators.

Individual Optimisation

We would be pleased to support you in optimising your energy supply projects and inform you about innovative, economical and climate-friendly options for heating, cooling and electricity supply. You will find our services in this regard here.

Of course, we are also personally at your disposal to tailor our services specifically to your needs.

Please do not hesitate to contact us:

Dr. Jörg-W. Fromme Contact

Olaf Mecke Contact

Christine Evennou Contact

 

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