Introducing the World’s Largest Heat Pumps

A monumental heat pump project is set to take shape along the banks of the River Rhine in Germany, featuring a remarkable pipe system so expansive that individuals can walk through it comfortably.

Felix Hack, the project manager at MVV Environment, an energy firm, revealed, “We aim to extract 10,000 liters every second,” as he explained the 2-meter diameter pipes designed to draw river water in Mannheim and return it after extracting thermal energy.

In October, MVV Energie, the parent company, unveiled plans to construct what may be the most powerful heat pump modules ever developed, with two units each boasting a capacity of 82.5 megawatts.

This impressive output is sufficient to heat approximately 40,000 homes collectively through a district heating infrastructure. The energy company is planning to establish this system on the grounds of a coal power facility transitioning to more environmentally friendly technologies.

The size of these heat pumps is influenced by restrictions pertaining to the transportation of machinery through Mannheim’s streets, or possibly by river transport along the Rhine. Mr. Hack remarked, “We remain uncertain about the transportation method; it could potentially be via the river.”

Alexandre de Rougemont from Everllence, a competitor specializing in large heat pump technology, affirmed his awareness of the ongoing project, stating, “It is indeed a competition, and we are transparent about it.”

Heat pumps function by absorbing warmth from the air, ground, or, in this instance, bodies of water. The refrigerants within the heat pumps vaporize at even slight increases in temperature.

By compressing this refrigerant, the heat is amplified further. While this mechanism is identical to that in smaller, residential heat pumps, it operates at a much larger scale in these colossal systems that provide energy to entire urban areas.

As municipalities worldwide endeavor to reduce carbon emissions, many are opting for substantial heat pumps capable of integrating with district heating networks.

Such networks enable the distribution of heated water or steam to numerous buildings, interconnected through extensive piping. The demand for increasingly larger heat pump models is on the rise.

Mr. Hack elaborated on the urgency to modernize heat generation to utilize new and renewable sources, particularly as coal-fired units are phased out at the Mannheim facility. Given its proximity to the Rhine, established electricity grid connections, and integration with district heating networks, the installation of heat pumps at this site is a logical choice.

He noted that advancements in technology are partly due to the availability of large compressors typically used in the oil and gas sector for the compression of fossil fuels.

The Mannheim initiative is slated to commence construction next year, with the heat pumps, which will deliver a combined output of 162 megawatts, expected to be fully operational by the winter of 2028-29. Mr. Hack assured that a multi-tier filtration system would prevent the pumps from capturing fish from the river, and projections indicate that the system will only slightly alter the river’s average temperature by less than 0.1 degrees Celsius.

However, such large-scale installations come at a significant cost. The budget for the Mannheim heat pump project stands at €200 million (approximately $235 million; £176 million). Mr. de Rougemont mentioned that at Everllence, the expense for heat pump systems averages around €500,000 for each megawatt of capacity, excluding additional costs for construction and infrastructure.

Everllence is engaged in a project in Aalborg, Denmark, which promises to surpass the Mannheim system with a total capacity of 176 megawatts. This project will deploy smaller modules, consisting of four units, each rated at 44 megawatts, and is anticipated to commence operations in 2027, fulfilling nearly one-third of the town’s heating requirements.

In Esbjerg, south of Aalborg, these 44-megawatt units are already operational, albeit at a reduced capacity of 35 megawatts each. Additionally, massive hot water storage tanks, each capable of holding 200,000 cubic meters, will enhance system adaptability. Mr. de Rougemont remarked, “When electricity prices soar, you can halt the heat pump and solely draw from the storage supply.”

Veronika Wilk from the Austrian Institute of Technology emphasized, “Heat pumps are ideally suited for district heating systems.” These setups can capture thermal energy from water bodies or even from wastewater generated by sewage treatment facilities.

Dr. Wilk pointed out that deploying multiple large heat pumps within a district heating network increases both flexibility and efficiency. For instance, during autumn when heating needs are lower, two out of four heat pumps could be operational.

While the systems discussed thus far primarily harness energy from water sources, some exceptionally large heat pumps can also utilize air as a thermal source, even in chilly cities like Helsinki.

Timo Aaltonen, senior vice president of heating and cooling at Helen Oy, an energy company, explained, “The sea near Helsinki is too shallow,” adding that calculations indicated a need for a tunnel exceeding 20 kilometers to access sufficiently warm ocean water.

Helsinki is currently undergoing a comprehensive transformation of its district heating framework, incorporating heat pumps, biomass burners, and electric boilers into an extensive 1,400-kilometer network serving nearly 90% of the capital’s buildings.

Heat pumps can convert one kilowatt-hour of electricity into multiple kilowatt-hours of heat, a feat that electric boilers cannot achieve, rendering them less efficient. When questioned about the installation of numerous megawatts of these boilers, Mr. Aaltonen explained that they are more cost-effective to install than heat pumps and allow for a diversified energy source, reducing dependence on air, which has limitations regarding large-scale heat supply.

Furthermore, electric boilers can absorb excess renewable energy and aid in balancing the electricity grid.

While the UK currently lacks heat pumps comparable to those being developed in Denmark, Germany, and Finland, new district heating projects are emerging, such as the Exeter Energy Network, which will service the University of Exeter and other clients.

The network aims for a minimum capacity of 12 megawatts and will include three air-to-water heat pumps, each rated at 4 megawatts, with the first unit projected to be operational by 2028.

Keith Baker from Glasgow Caledonian University, a researcher in district heating systems, remarked that the UK has significant potential to harness this technology. For instance, water from abandoned mines, which maintains a stable temperature, is beginning to supply larger heat pump systems in the region.

Post-industrial and rural areas with sufficient space for the installation of heat pumps and thermal storage tanks represent optimal opportunities for development, he concluded.