Geological and procedural facilities of geothermal usage at the Medical University Hannover (MHH)

Project Participants:

Dipl.-Geophys. G. Bussmann M.Techn. (HS Bochum)
Dipl.-Ing. (FH) Bastian Görke M.Sc. (GeothermieZentrum Bochum)

Client:

GeoDienste GmbH (formerly Rogge & Co. GmbH)

For the Medical University Hannover (MHH) the Geothermalcenter Bochum compiled from August 2007 till March 2008 a pre-study on integration of geothermal energy into the energy concept of the clinical center. Ongoing to the pre-sutdy followed a profitability analysis, which considered the petro thermal and hydro-thermal supply.

Pre-Study

The Medical University Hannover is at the time supplied with gas, electricity and long-distance heating from public utility company for its trinomial energy supply, consisting of steam, space heating and ambient cooling. Because of hydro-geological situation at the location of the MHH is the integration of geothermal energy into the closed heating circuit (direct integration via heat exchanger) as well as into the ambient cooling system (modular operated absorption cooling maschines) proposed. Aim of the integration is to replace conventional, pricewise fluctuating and primary-energetic unfavourable energy carrier, like electricity, long-distance heating or gas, employing geothermal energy, completely or within the scope of the geothermal potentials partly. Thereby efficiency, CO2-record and security of energy supplies rank first. The basic load capacity of the geothermal energy is in the proposed plant configuration completely used. In the area of the peak load coverage geothermal energy is irrelevant. The geothermal supported steam production is in this scenario not considered. This is justified by the internal heat recovery in the steam producer through the economizer for pre-warming of fresh and sanitary water. Because geothermal energy can only add a small energetic contingent to steam production and finance investments would arise, the use of geothermal energy in this area is not considered. Exceeds the provision of geothermal energy in heating and cooling the energy use, caches can be installed which store excess energy efficiently. During peak loads energy can be recovered. This increases the amount geothermal energy in the overall energy provision.

Profitability Analysis

Here 9 different scenarios were examined. They differed in their kind (petro thermal/hydro thermal), the drilling depth (4500m/3000m), their embankment (15-50 l/s), temperature (115°C/160°C) or provision (heat/heat + electricity).
Higher financial investments for petro thermal systems are retained with a higher efficiency (embankment and temperature) and are therefore more economic than hydro thermal systems, which only pay off because of rising energy prices after a couple of years.

Zusätzliche Information

Annual hydrograph of heating and cooling with geothermal energy - (A) Geothermal coverage with a volume flow rate of Q1 = 15 l/s
Concept sketch heating cycle
Concept sketch cooling cycle