The global imperative to decarbonize industrial processes, particularly the heat that accounts for nearly one-fifth of global energy consumption, remains a primary challenge of the energy transition. This report examines a landmark project at the Envases packaging factory in Odense, Denmark, that offers a powerful and replicable solution with district heating.
By Ronak Monga, Head of Sales Development CBS, District Energy
Published in Hot Cool, edition no. 5/2025 | ISSN 0904 9681 |
Photo above: Daniel Bagger, Facility Supervisor at Envases
Through a strategic partnership with the local utility, Fjernvarme Fyn, and the implementation of advanced, commercially available technology from Grundfos, Envases has created a model for a circular energy economy. The project replaced the factory’s fossil-fuel boilers with a direct connection to the city’s district heating network, complemented by a sophisticated on-site heat recovery system. This dual strategy not only secures a greener energy supply but also transforms the factory from a consumer into a “prosumer” of energy, exporting its surplus process heat back into the grid.
The results are definitive: an annual energy cycle of 37 GWh, comprising 23 GWh of recycled heat and 14 GWh of direct savings, and an abatement of 3,000 tonnes of CO₂ per year. This article concludes that the tripartite model demonstrated in Odense, a proactive industrial partner, a capable utility, and accessible smart technology, is a highly scalable blueprint for industrial decarbonization, offering a clear pathway to unlock the vast, untapped potential of surplus heat across Europe and beyond.
The foundation for innovation: Odense’s District Energy Ecosystem
Utility with a vision: Fjernvarme Fyn
The success of any heat integration project depends on a capable and visionary utility partner. In Odense, Fjernvarme Fyn, one of Denmark’s largest district heating companies, is a model of a forward-thinking energy provider. Its vast infrastructure, including over 2,200 km of distribution lines, creates a robust marketplace for heat.
Crucially, Fjernvarme Fyn is driven by an ambitious commitment to decarbonization, with firm targets to phase out coal by 2024/2025 and support Odense’s goal of carbon neutrality by 2030. This transforms the utility from a passive operator into an active agent of the green transition.
Beyond traditional utility: An energy system integrator
Fjernvarme Fyn’s strategy is not a simple replacement of its central coal plant but a sophisticated approach centered on a diverse portfolio of decentralized, flexible assets. This embraces sector coupling, integrating heat from municipal waste, biomass, large-scale electric boilers, and advanced heat pumps that utilize surplus heat sources.
A prime example is the utility’s landmark project with Meta’s hyperscale data center in Odense. Fjernvarme Fyn captures enormous quantities of low-grade surplus heat (around 27°C) from the data center. This water is “boosted” to a grid-suitable 70-75°C by large, electrically driven ammonia heat pumps. When fully operational, this system will provide carbon-free heat for over 12,000 homes.
The successful execution of the massive and technically complex Meta project demonstrated Fjernvarme Fyn’s capabilities, serving as a crucial form of risk mitigation for other potential industrial partners like Envases. An industrial facility needs confidence that its utility partner can reliably receive and utilize exported heat. By proving the concept at an unprecedented scale, Fjernvarme Fyn established a track record that lowered the perceived risk for subsequent partners, creating a positive feedback loop that encourages further collaboration.
Deep Dive case study: The Envases factory transformation
Previously, the Envases factory, a manufacturer of metal cans, operated in an energy silo. Its heating needs were met by an on-site gas boiler system, exposing the company to volatile gas prices and creating a significant carbon footprint. The primary source of waste heat was the coatings workshop, where industrial ovens used for curing and drying lacquers generated a continuous stream of high-value surplus heat that was vented to the atmosphere.
The solution architecture: A symbiotic dual-strategy
The solution was a holistic, dual-pronged strategy that re-engineered the factory’s relationship with energy.
- Connection to District Heating: The inefficient gas boilers were decommissioned, and the factory was connected to Fjernvarme Fyn’s DH grid. This replaced a volatile, carbon-intensive energy source with a stable, secure, and progressively greener supply of heat.
- Internal heat recovery and export: An internal heat recovery loop was installed to capture high-temperature surplus heat from the production ovens. This captured energy is first used to satisfy the factory’s own demand for space heating. The vast majority remaining is then transferred via a heat exchanger to the district heating network, turning a waste stream into a revenue-generating asset and transforming Envases into an energy “prosumer.”
The technological core: The MIXIT solution
The operational success of this dual-mode system hinges on precise energy management, achieved by replacing traditional mixing loops with the advanced system. A traditional mixing loop is a cumbersome assembly of 8 to 12 separate components from multiple vendors, making design, installation, and commissioning a specialized and costly endeavor.
The MIXIT unit is an all-in-one, “plug-and-play” solution that integrates these functions into a single, pre-assembled component, cutting installation and commissioning time by up to 50%. This simplifies energy optimization, allowing facility managers to implement a standardized, reliable product without requiring a team of specialist engineers. As noted by Envases Facility Supervisor Daniel Bagger, it makes sophisticated energy management accessible. Each MIXIT unit communicates wirelessly with a high-efficiency MAGNA3 / TPE3 circulator pump and can integrate with the factory’s Building Management System (BMS) for centralized monitoring and control.
A trifecta of savings: Energy, emissions, and cost
The project yielded remarkable, quantifiable results :
- Energy recycled: The system captures and recycles 23 GWh of thermal energy annually, equivalent to the heat consumption of approximately 1,300 Danish households. This energy is now a valuable commodity sold to the DH grid.
- Energy saved: The system provides a further 14 GWh in direct energy savings for the factory’s own operations, as captured heat displaces the need to purchase heat from the grid.
- CO₂ abated: The combined energy savings of 37 GWh annually result in a direct reduction of 3,000 tonnes of CO₂ emissions every year. This is roughly equivalent to the annual emissions from 670 gasoline-powered passenger vehicles.
The view from the factory floor
Beyond the data, the project delivered profound qualitative benefits. The MIXIT system provided a level of operational intelligence that was previously unattainable. “We can now control our heating system down to the smallest detail,” stated Daniel Bagger, Facility Supervisor at Envases. This granular control empowers the management team to move from reactive maintenance to proactive, continuous optimization, fine-tuning the system in real-time to maximize both economic returns and environmental benefits.
| Metric | Before retrofit (boiler system) | After retrofit (DH + heat recovery) |
|---|---|---|
| Primary energy source | Natural gas | District Heating (from diverse sources) & recycled process heat |
| Energy security | Exposed to volatile gas market prices | Stable, long-term pricing from DH utility |
| Operating cost | High, volatile fuel costs | Lower, predictable heat tariff |
| CO₂ emissions | High (fossil combustion) | Substantially reduced |
| Waste heat | Vented to atmosphere (wasted asset) | Recycled internally & sold to DH grid (valuable asset) |
| System control | Basic, static control | Granular, dynamic, zone-based control via BMS |
| Sustainability profile | Standard industrial operation | Leader in circular economy and industrial symbiosis |
The industrial energy challenge and the surplus heat opportunity
The global imperative for industrial decarbonization
Industrial heat constitutes two-thirds of all industrial energy demand and nearly 20% of total global energy consumption. The overwhelming majority is generated by burning fossil fuels on-site, making it a primary source of direct CO₂ emissions. Unlike the electricity sector, where transitioning large power plants to renewables has wide-reaching effects, industrial heat is decentralized.
It is generated and consumed within individual facilities, each with unique requirements. This distributed nature makes top-down solutions difficult. Meaningful carbon reduction in this sector demands innovative, site-specific, and collaborative solutions that integrate industrial facilities as nodes in a larger, circular energy system.
Unlocking Europe’s wasted resource: The scale of surplus heat
Within this challenge lies an immense opportunity: surplus heat. Across the European Union, industrial processes release vast quantities of thermal energy as an unwanted byproduct. A comprehensive analysis by the sEEnergies project quantified this potential, revealing that a staggering 425 Petajoules (PJ) of excess heat is available annually from heavy industry at 95°C or higher – a temperature directly compatible with most existing district heating (DH) systems.
The analysis further identified that 151 PJ of this high-temperature surplus heat is generated by industrial sites located within a 10-kilometer radius of existing DH networks. This subset represents the “low-hanging fruit” of industrial decarbonization, as it relies on connecting existing assets rather than building new infrastructure.
This readily available energy is sufficient to supply approximately 8% of the EU’s total district heat demand, displacing an equivalent amount of fossil fuel generation. The Envases case study validates how this theoretical potential can be transformed into a practical, economically viable reality.
The Danish context: A national hotbed of potential
Denmark, a pioneer in district heating, provides fertile ground for industrial heat recovery. The nation’s manufacturing industry alone has an estimated excess heat potential of 22.58 PJ per year, equivalent to 21% of its final energy consumption. The food and beverages industry, a critical part of the supply chain for a packaging manufacturer like Envases, is particularly energy-intensive and has historically relied on fossil fuels, making its decarbonization a strategic priority.
Recognizing this, the Danish government has fostered a supportive policy environment. In January 2022, the parliament abolished a tax on the utilization of surplus heat for certified businesses. This legislative action directly improved the financial business case for projects that capture and sell waste heat, encouraging the kind of industrial-utility collaboration seen in Odense.
Scaling the model: From Odense to Europe.
The Envases project is a proven pilot for a much larger European strategy, demonstrating a practical method for tapping into the 151 PJ of high-grade surplus heat near existing DH networks. The total annual energy contribution from this single factory is 37 GWh (approx. 0.133 PJ).
A simple calculation reveals the power of replication: a portfolio of roughly 1,100 similarly sized projects could theoretically capture the entire 151 PJ of “low-hanging fruit.” This reframes the solution not as a single mega-project, but as the mass replication of smaller, proven, local successes.
Future-Proofing with 4th Generation DH
This model is also aligned with the future of district heating, which is moving towards lower operating temperatures (4th Generation District Heating, or 4GDH). These advanced networks minimize heat loss and better integrate low-temperature renewable sources.
This trend is highly beneficial for industrial heat recovery. As the required temperature of DH networks decreases, the pool of viable industrial surplus heat sources expands. The sEEnergies report shows that available heat potential from industry more than doubles, from 425 PJ to 940 PJ, if the target utilization temperature drops from 95°C to a 4GDH-compatible 25°C.
This creates a virtuous cycle: modernizing DH networks makes more industrial heat recovery projects viable, and the availability of this cheap, low-carbon industrial heat strengthens the business case for utilities to invest in modernizing their networks.
The Envases project proves that the path forward is collaborative, built on the three pillars of a proactive industrial partner, a capable utility, and accessible technology. It shows that industrial waste heat is not a liability but a valuable asset that can be integrated into a community’s energy supply.
By closing the loop between industrial waste and community warmth, this model saves money, enhances energy security, and delivers dramatic CO₂ reductions. It is a model that must be championed and replicated to accelerate the green transition on a meaningful scale.
For further information, please contact: Ronak Monga at rmonga@grundfos.com
“Closing the Loop: How Industrial-Utility Symbiosis in Odense Forges a Blueprint for Decarbonization ” was published in Hot Cool, edition no. 5/2025. You can download the article here:
