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SPONSORED FEATURE: High cost saving for hospitals through CHPs

Klinikum Weimar saves up to 60% of its energy costs by running a combined heat and power plant from MWM, a brand of Caterpillar Energy Solutions

Klinikum Weimar hospital, Germany

The Klinikum Weimar hospital (Germany) promotes the highest level of professionalism, and medical care according to the latest working methods, standards and research findings. That is why it comes as no surprise that the hospital also plays a leading role in the field of power production. Since opening in 1998, the Klinikum has had two high-efficiency gas engines from MWM for combined heat and power production. 

The cogeneration power plants (CHPs) have now been running for over 100,000 hours without any major faults, which shows in the bottom line: by operating the plants, the Klinikum saves 50–60% on electrical power costs alone. As a result of this positive experience, coupled with the reliable and highly professional MWM service centre in Erfurt, the Klinikum is currently considering the installation of new MWM engines.

About the Klinikum Weimar 

The medical centre in Weimar, formally “Sophien- und Hufeland-Klinikum gGmbH”, is Thuringia’s largest hospital. With over 1,000 employees, the Klinikum is one of the largest employers in the city of Weimar. The hospital provides inpatient care to more than 20,000 and outpatient care to 36,000 people every year. Since the medical centre’s opening at the new site in 1998, more than 21,000 babies have been safely delivered.

Initial situation

The Klinikum Weimar has a wide range of medical devices as well as facilities with a high, relatively constant demand for electricity, heat and cooling. More than 5,900MWh of electricity as well as 9,800MWh of heat and cooling is required to ensure the smooth operation of the hospital. 

The high and constant demand for electrical and thermal energy provides ideal conditions for running a CHP plant. That is why from the onset of planning for the new hospital construction project, the topic of combined heat and power was an important cornerstone of the energy concept. The key objective was significant reduction of energy costs. 

The technical solution

MWM delivered two CHP modules with 320kW electrical output each. The waste heat released in the heat-demand-controlled system is used mainly for the operation of an absorption plant that supplies a major part of the facilities and devices with cooling. In times when the cooling requirement is low, the heat can be used solely for heat supply. 

Benefits and successes

Since commissioning in 1998, the systems have now been running for over 100,000 hours. This translates into some 5,000–6,500 operating hours annually, so that the CHP plant is capable of providing almost 50% of the electrical and 47% of the thermal energy demand. By running the engines, the Klinikum Weimar is capable of reducing its annual electricity procurement costs by 50–60%.

Based on the positive experiences, the strong economic benefits and the good cooperation with MWM over the past 17 years, the Klinikum is evaluating and planning to replace the existing CHP plants with new gas engines. Based on this positive track record, MWM is the logical first point of contact.

Please calculate your own economic benefit here:


Mr Jenszöwski, with the commissioning of two CHP plants, the Klinikum Weimar pioneered combined heat and power in the hospital sector 17 years ago. Where did the foresight for this topic come from back then? 

The foresight came from the engineering firm that developed the overall project for the new hospital construction project in 1998. They showed us the economic benefit we would achieve by operating a CHP plant. After in-depth planning and evaluation, the decision was made relatively quickly to go ahead with the plant. 

The full benefit of combined heat and power is realised when the energy is used from both the electricity and the generated heat. Could you describe how heat recovery works in your operations?

In addition to heat recovery, a cogeneration plant can also be used for cooling, which is a large part of what we are doing. The released heat is then utilised for a so-called absorber plant that supplies cooling to a number of our facilities. This includes rooms with major equipment such as MRT systems or operating theatres that require special temperature conditions. In times when the cooling requirement is low, the heat can be used solely for heat supply.

What has your experience been with your CHP plant over the past 17 years?

We have had very positive experiences, as the CHP plants run very smoothly. In cases where we did actually experience downtimes with one of the two engines, MWM provided us with very quick and competent assistance. The internal effort for operating the system is very low, thus we monitor operations and perform the oil change on our own, for instance. We would reinvest in a CHP plant at any time. 

What concrete advantages have you been able to achieve by running the plant?

The main advantage is the significant cost saving. Several years ago, we performed a cost comparison in which we calculated the costs of external electricity supply compared to the electricity production costs of the CHP plant. The results were conclusive: the power production costs of the CHP plant were merely 50% of external electricity supply costs. Today’s price situation is similarly favourable, so that running a CHP plant enables us to save some 50–60% on electricity costs alone.

As your case demonstrates, CHP can provide great economic benefits. However, CHP has not become totally established in the hospital sector yet. What do you think is the reason for that? 

That is difficult to say, but one reason could be the lack of transparency concerning the clear cost–benefit ratio. Many decision-makers in hospitals are perhaps aware of the technology, yet they haven’t fully realised the economic benefit they can actually achieve. The required building modifications could also be a reason. In my view, that is negligible however, as I think a CHP plant is economical for any hospital, even for small facilities. 

What are the hospital-specific requirements for operating a CHP plant?

The supply reliability and dependability of the system are the most significant aspects for operation in a hospital. For installation in buildings, for example, you have to consider the requirements for exhaust gas handling and noise emissions. What’s more, limited space availability can present challenges for installation. The logical choice here is a container solution which is set up outside. This option is also very effective in fulfilling the described noise emission specifications. 

Are you planning any new energy projects at your hospital?

As the second general overhaul is coming up, we are planning and evaluating the replacement of the existing CHP plants with new units. Here again, we will be pursuing a two-engine strategy. Based on the positive track record with the MWM service centre in Erfurt, MWM is our first point of contact for this.

What advice would you offer interested decision-makers in other hospitals? 

Naturally it depends on the specific situation. My advice is to make sure to gain a clear understanding of the cost–benefit ratio early on in the planning process. Independent energy planners can be hired to handle this, for example. It is also advisable to quickly develop a strong grasp of whether the system needs to be power demand controlled or heat demand controlled. This has considerable influence on the size of the plant and thus ultimately on the total costs and overall benefit.

Interview conducted by Jörg Richter.