If for some reason you want to raise the temperature from a pleasant 20°C to boiling point, a heat pump from the German company MAN Energy Solutions (MAN ES) can do it. And it takes less time than Kenneth Branagh’s film version of Hamlet.
“We can do it in less than four hours,” explains Raymond Dekorvet, Business Development Specialist at MAN ES. “Or we could freeze the entire process for about 11 hours.”
These are some of the largest heat pumps in the world. Heat pumps increase the temperature of these fluids by compressing warm and heated refrigerant. The heat can then be transferred to domestic or industrial equipment.
Heat pumps need electricity to operate, but for every kilowatt-hour of electricity consumed, they generate about three to four kilowatt-hours of heat.
Heat pumps are becoming more and more popular with some homeowners, but home appliances are relatively small and power output is often around a few kilowatts. The largest commercial MAN ES heat pump is thousands of times more powerful, with a total heat output of 48 megawatts (MW).
It can generate temperatures up to 150 degrees Celsius and heat thousands of homes, not just one. The company recently installed two such machines in the Danish port city of Esbjerg.
In this installation, the heat pump’s CO2 refrigerant will absorb a small amount of heat from the sea water. The compressors raise the temperature of the carbon dioxide, which can then be vented to supply water up to 90 degrees Celsius to a district heating system that serves 27,000 homes.
“Demand for district heating is growing rapidly,” said Mr. Decorvet. The urgent need to move away from fossil fuels has led to hype – especially in Europe – for larger, more powerful heat pump systems that could power entire cities. But who has the largest megawatt class?
This seems like a relatively simple question, but it’s actually hard to give a definitive answer. Moreover, heat pumps do not always operate at full capacity. For example, in Esbjerg, MAN ES heat pumps will operate at about half their potential capacity.
Trying to compare the largest heat pump systems in the world is difficult because they usually consist of several small heat pumps connected together. Take the district heating system in Stockholm, Sweden, often referred to as the largest heat pump installation in the world.
A spokesman for energy supplier Exergi in Stockholm explained that this may be true at a maximum capacity of 215 MW, but the total capacity is the sum of seven heat pumps, two 40 MW units and five 27 MW units.
Elsewhere in Sweden, in Gothenburg, there is a 160 MW heat pump system consisting of four units. Two of them are actually larger than in Stockholm, 50 MW each.
They have been in operation since 1986 and can be considered the most powerful stand-alone heat pumps in use today, although they are clearly comparable to newer units such as those made by MAN ES.
Last year, German chemical companies BASF and MAN ES announced their intention to build a 120 MW heat pump that will reportedly be the world’s largest.
It will provide heat for industrial facilities in Ludwigshafen. However, it is not. “BASF has made the decision not to proceed with the project,” a spokesman for the BBC said. The company is exploring other potential sources of heat that it hopes will be more economically attractive.
Dave Pearson, director of sustainability at Star Refrigeration, points out that size isn’t everything. Efficiency is important, and he believes ammonia, his company’s preferred refrigerant, helps make heat pumps particularly efficient.
Veronika Wilk from the Austrian Institute of Technology and her colleagues are investigating the use of heat pumps for industrial applications such as providing heat to pharmaceutical, food or paper mills.
Dr. Wilk believes that as long as they don’t need very high temperatures above 200°C, companies will increasingly turn to heat pumps as it allows them to move away from natural gas, which has become extremely expensive since Russia’s invasion of Ukraine.
However, industrial heat pumps are often only a few megawatts or so. Dr. Wilke says you’re more likely to find really giant heat pumps in district heating systems like the ones mentioned above.
Many other examples of district heating systems powered by heat pumps have emerged. A 55 MW system using three heat pumps will be commissioned in Vienna this autumn.
Linda Kirchberger, manager of asset decarburization and new technologies at Wien Energie, explained that the machines will capture approximately 6 degrees of heat from treated wastewater.
Previously, purified water was dumped directly into rivers. “Now it is bypassed and we run it through the heat pump system,” she said.
The system will raise temperatures from 6 degrees Celsius to 90 degrees Celsius, and heat will continue to power 56,000 homes. In 2027, Wien Energie plans to double the capacity of the system by adding three more heat pumps, bringing the total capacity to 110 MW.
While they are still impressive and weigh over 200 tons each, individual units have a capacity of less than 20 megawatts. Manufacturer Johnson Controls has confirmed to the BBC that its largest heat pump has a maximum output of 28 MW.
Hamburg is reportedly planning to build a similar system that also uses wastewater heat. A spokesperson for the Hamburg Wasser water company involved in the project said it would have a capacity of 60 megawatts, although it would also rely on multiple heat pumps connected together.
But watch the future. In Helsinki, the capital of Finland, plans are underway to build a huge heat pump system with a total capacity of 500 megawatts.
This could consist of multiple units such as Stockholm, Gothenburg and Esbjerg, but Helen, the energy company behind the scheme, has yet to reveal how they will be combined.
MAN ES was one of the companies bidding for the contract. The spokesperson declined to explain what specific heat pump configuration would allow the company to provide 500 megawatts of heat. Mr. Decorvet simply said, “I hope we win.”
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