IN Brief:
- Ardagh is replacing Obernkirchen's previous gas-based heat supply with an electricity-powered system.
- Two ammonia heat pumps will combine with waste heat recovered from four annealing lehrs.
- Full operation is targeted for November as electrification extends beyond the site's glass-melting furnace.
Ardagh Glass Packaging-Europe is installing two ammonia heat pumps and a new hot-water and waste-heat recovery system at its Obernkirchen glass plant in Germany, replacing the site’s previous gas-based heating arrangement with an electricity-powered system.
The project, developed with RheinEnergie AG – next energy solutions, will deliver around 3.5MW of combined thermal output. Construction and installation are under way, with full operation expected in November 2026. Waste heat will also be recovered from warm process air leaving four annealing lehrs and redirected towards the packing area.
The change follows the installation of Ardagh’s hybrid NextGen Furnace, which altered the plant’s previous heat balance. Obernkirchen had used steam generated from hot furnace flue gases for site heating; as the melting process becomes more electrified, the plant is redesigning lower-temperature heat supply around electricity and recoverable process energy.
Furnace electrification changes the wider heat system
Container-glass decarbonisation is usually discussed at the furnace because melting is the dominant thermal process, but a continuous glass plant carries heat demand well beyond the melting chamber. Building services, hot water, annealing, packing areas, cooling, and other utilities still have to operate as the furnace energy mix changes.
Ardagh’s NextGen Furnace entered commercial production at Obernkirchen in October 2023. In June 2024, the company reported an average electrical-heating rate of 60%, against a design direction of up to 80% electricity and 20% gas, while modelled carbon emissions per bottle had fallen by 64% compared with the conventional reference case. The furnace can produce up to 350 tonnes of amber glass a day and use up to 70% recycled cullet.
That shift reduces reliance on combustion but also changes the quantity and temperature of waste heat available elsewhere in the site. The new heat-pump system addresses that second-order engineering problem by upgrading recoverable heat to a useful temperature rather than rebuilding a conventional gas-fired heating system around an increasingly electric furnace.
Annealing lehrs are a logical source. Bottles leaving forming machines are cooled through a controlled temperature profile to relieve internal stresses, producing warm exhaust air that would otherwise carry useful energy out of the process. Capturing heat from four lehrs and feeding it towards the packing area gives the site a stable industrial source close to the demand it is intended to serve.
The use of ammonia adds a familiar industrial-refrigeration technology to that system. Its thermodynamic performance makes it suitable for large heat-pump duties, but the installation still has to be engineered around containment, detection, ventilation, maintenance access, and trained operation. Those requirements are established practice in food and industrial refrigeration, although applying them to a glassworks heat network creates a different operating environment and integration challenge.
Packaging carbon extends into plant utilities
For food and beverage customers, glass-packaging emissions are shaped by more than container weight and recycled content. Melting, forming, annealing, compressed air, cooling, and site utilities all contribute to the manufacturing footprint, so lowering furnace emissions while leaving surrounding heat systems unchanged would limit the gain.
Heat pumps add electrical demand, making the source and availability of power increasingly important as Obernkirchen electrifies several functions at once. Ardagh has already linked the NextGen Furnace to renewable electricity arrangements, and the company intends to use hybrid and other lower-carbon melting technologies in future furnace rebuilds where the necessary electrical infrastructure is available.
The technology also has to prove itself operationally. Glass furnaces run continuously over long campaigns, customers depend on stable container supply, and site heating cannot become a weak point during winter production. The November commissioning target will therefore test controls, heat recovery, electrical capacity, maintenance arrangements, and the ability of the system to follow changing plant demand without disrupting production.
Control strategy will be as important as installed capacity. Waste-heat availability varies with production conditions, while space-heating demand changes with weather, so the heat pumps, recovery circuit, and hot-water system must balance supply and demand without creating unstable operating conditions. The 3.5MW figure describes combined thermal output, not a constant requirement from every part of the site.
Two ammonia heat pumps and 3.5MW of thermal output are small beside the energy involved in melting hundreds of tonnes of glass each day, but the project closes an important gap created by furnace electrification. Obernkirchen is no longer treating the furnace as a standalone decarbonisation asset; the supporting heat network is now being redesigned around the same energy transition.
