Tognum, MTU Onsite Energy: Giessen-Marburg University Clinic, Germany

Large quantities of electricity, cooling power and heat are needed to run a clinic. The university clinic of Giessen-Marburg, Germany, for example, has around 1150 beds and consumes on average 35 000 kWh daily. The clinic one of 50 run by healthcare provider Rhön-Klinikum AG is to generate over half of its energy requirement in-house instead of using the public grid. That is the reason for the clinic’s decision to opt for a combined solution from MTU Onsite Energy using three complementary technologies: gas-powered combined heat and power modules (CHPs), a fuel cell for trigeneration (heat, power and cooling) and diesel engines for standby power gen-sets.

It is the first time that all three technologies are to be combined at one location, the company said. The power supply will be controlled by Energiezentrale Giessen GmbH, a company specially set up by Rhön-Klinikum AG and Giessen’s public utility. Combined cooling, heat and power generation will be achieved by three natural gas-powered GR 385 N5 CHP modules based on Series 400 12-cylinder gas engines in combination with a HotModule HM346 fuel cell also driven by natural gas. Heat and power will be generated costeffectively and sustainably with an outstanding overall efficiency of up to 90%.

The fuel cell is to take up the base load while the combined heat and power modules will be automatically switched online and offline according to requirements. Two diesel gen-sets powered by MTU Onsite Energy engines will provide the clinic’s standby power. The electricity generated through combined cooling, heating and power will be fed to the power supply. Each of the three CHP modules will be laid out for 385 kW electrical output, while the fuel cell generates 345 kW. Any surplus power will be fed into Giessen’s public grid.

Thermal energy or heat will be harnessed from the waste heat produced by the fuel cell and engines and from the high-temperature emissions of the CHP modules. The HotModule will be capable of 230 kW thermal output, while the engine on each of the CHP modules will generate 231 kW, plus about 260 kW in the form of emissions. The clinic will utilize the thermal energy in two ways for heating the building and providing hot water and for air conditioning using absorption refrigerators.

For clinics especially, combined cooling, heating and power is an ideal solution. Ultra-modern facilities, in particular, need higher cooling capacities, for example for their IT installations, large-scale medical equipment, operating theatres and for air conditioning the building as a whole. According to Rhön- Klinikum AG, cooling its IT installations alone uses up 12% of its total energy requirement. In 2008, the clinic inaugurated its new pediatric facility and in spring 2011 another new building with an additional 650 beds is to be opened. Thus, the combined heat and power modules will not just be activated for spikes in demand, but, like the fuel cell, work around the clock.

Next to the fuel cell and CHP modules, MTU Onsite Energy is to supply two diesel engines for the standby gensets, which will provide parts of the clinic with emergency power should the public grid break down. In this event, the larger of the two gen-sets, driven by a 20V 4000 G23 diesel engine, will ensure that building facilities continue to function, while the smaller unit with a 12V 4000 G23 diesel engine will feed power to medical equipment. A standby gen-set based on an MTU engine has been in operation in the pediatric facility since 2008.

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