The new heat storage facility is being built on the site of the Tiefstack power station in the Billbrook district of Hamburg and will serve as a large-capacity heat buffer for the district heating network. Excess heat from sources such as industrial waste heat, waste-to-energy plants or river water heat pumps is stored and fed into the grid at a later time, making the energy system more flexible, increasing security of supply and sustainably reducing CO₂ emissions in the Hamburg metropolitan region.

Specialist civil engineering and building construction join forces

Specialist civil engineering plays a fundamental role. As up to 43 million litres of water will later be temporarily stored in the thermal storage tank, generating a correspondingly high load, 60 foundations must first be installed at a depth of 22 metres before the floor slab can be constructed. A total of 59 large bored piles with a diameter of 88 centimetres and a length of around 21 metres are being constructed for this purpose.

Due to the high groundwater level, the work is being carried out using water pressure and casing to ensure stability and prevent hydraulic ground failure. Challenging ground conditions, wintry weather and high standards for safety, quality and deadlines characterise the work. PORR Spezialtiefbau Planung GmbH is responsible for the design of the pile foundations and the construction planning.

“With the start of the foundation works, we are sending out an important signal for the Tiefstack transformation. We are laying the foundations for a structure that will play a central role in Hamburg’s climate-neutral heat supply in the future,” says Bernd Westendorff, Project Manager for Special Civil Engineering at PORR.

The construction of the foundation slabs will follow from summer 2026. In parallel, PORR Hochbau is erecting a new technical building, scheduled for completion in February 2027. The thermal storage facility is due to be structurally completed by the end of 2027 and commissioned in the first half of 2029.

A strong signal for phasing out coal

The unpressurised, water-filled thermal storage tank is 51 metres high, has an external diameter of 35 metres and holds around 43 million litres of water, which is heated to up to 98°C. As a key component of the future Tiefstack Energy Park, it can theoretically provide heating for over 27,000 residential units for a single day on a cold winter’s day.

Construction work officially began on 4 March 2026. Katharina Fegebank, Deputy Mayor of the Free and Hanseatic City of Hamburg and Senator for the Ministry of Environment, Climate, Energy and Agriculture, and Michael Prinz, Managing Director of Hamburger Energiewerke GmbH, jointly laid the symbolic foundation stone for the planned energy park – a launch that underlines the great significance of the project for the sustainable energy future of the city of Hamburg.

At the same time, with this project, PORR is demonstrating its expertise in the implementation of complex infrastructure projects for the energy transition. The integrated implementation of specialist civil engineering and building construction exemplifies technically sophisticated, sustainable solutions and sends a strong signal regarding the phase-out of coal in Hamburg.