Waste heat sources, district heating networks and the heat transition: utilising waste heat and reducing energy consumption
Energy efficiency is becoming increasingly important in times of rising energy costs and growing climate protection requirements. Whilst many companies are already implementing measures to reduce their energy consumption, there is often enormous untapped potential: waste heat. In industry, the commercial sector and buildings, large quantities of heat are generated every day, which are often released into the environment without being utilised.
Yet waste heat can be a valuable source of energy that both cuts costs and reduces CO₂ emissions. Combined with modern technologies and concepts such as sector coupling, this opens up entirely new possibilities for using energy more efficiently. In this article, you will learn just how great this potential is, what technologies are available, and how businesses can benefit in practical terms.
What is waste heat? A simple explanation of the definition and untapped energy potential
Waste heat refers to the energy generated as a by-product of technical processes, in industry or in buildings, which is not actively utilised. Typical sources include production facilities, engines, compressors, data centres, and heating and cooling processes.
In many cases, this heat is simply released into the environment – whether via exhaust air, cooling water or exhaust gases. The problem with this is that this energy was previously generated at considerable cost and paid for, yet ultimately goes unused.
The untapped potential is enormous. Almost every business generates waste heat streams that can be recovered and reused, at least in part. Depending on the temperature, waste heat can be used, for example, for space heating, hot water production or even electricity generation.
The use of waste heat is therefore a key means of improving energy efficiency and sustainability – and can often be implemented with relatively little effort.
Also important: Under the Energy Efficiency Act, companies are obliged to reduce the waste heat they generate. Further information is available in the guidelines published by the Waste Heat Platform of the Federal Office for Energy Efficiency (a department of the Federal Office for Economic Affairs and Export Control, BAFA).
Waste heat as an energy source? An overview of the potential in Germany
The potential of waste heat is not limited to individual companies; it is also of enormous significance to the economy as a whole. Studies show that a large volume of industrial waste heat is generated in Germany every year, a significant proportion of which remains unused to date.
Estimates suggest that up to 60 terawatt-hours (TWh) of energy is available in the form of waste heat. A significant proportion of this could be utilised in a technically and economically viable manner. The potential is particularly high in energy-intensive sectors such as the steel, chemical, and food industries. The Waste Heat Platform can also be consulted for further information.
For businesses, this presents a major opportunity: by utilising waste heat, energy costs can be significantly reduced whilst at the same time improving energy efficiency. Local authorities also stand to benefit, for example by feeding waste heat into various networks such as local or district heating systems.
Furthermore, the use of waste heat makes an important contribution to climate protection. Every kilowatt-hour recovered reduces the demand for primary energy and, consequently, CO₂ emissions.
Understanding sector coupling: How industrial waste heat links different energy sectors
One particularly exciting approach in relation to waste heat is what is known as ‘sector coupling’. This involves linking the electricity, heating, and transport sectors in order to use energy more efficiently and integrate renewable energy sources more effectively.
Waste heat plays a key role here. It can, for example, be recovered from industrial processes (also known as process heat) and fed into district heating networks to heat residential buildings. When combined with heat pumps, even low-temperature waste heat can be raised to a usable level.
The potential for sector coupling in Germany is considerable. The intelligent interconnection of energy flows could lead to substantial energy savings. Studies suggest that consistent sector coupling could make a significant contribution to reducing energy consumption and CO₂ emissions.
This opens up new business models for companies. Waste heat is transformed from a ‘waste product’ into a valuable resource that can be actively marketed or utilised in partnership with energy suppliers.
Waste heat recovery technologies: from heat exchangers to heat pumps
Thanks to modern technologies, utilising heat sources is now easier and more efficient than ever. The solution chosen depends primarily on the temperature level and the amount of heat available.
Heat exchangers are one of the most fundamental technologies for supplying heat. They enable heat to be transferred from one medium to another without the substances mixing. For example, hot exhaust air can be used to preheat fresh air.
Heat pumps are often used for low-temperature waste heat. They raise the temperature and make the heat usable for heating purposes. They are a particularly efficient solution when used in combination with renewable energy sources.
Other technologies include:
- Waste heat boiler for steam generation
- Organic Rankine Cycle (ORC) for electricity generation (this system can operate at comparatively low temperatures to drive a turbine)
- Heat storage for decoupling generation and consumption over time
Choosing the right technology is crucial to a project’s cost-effectiveness and should be planned on a case-by-case basis.
The topic of waste heat in industry: practical examples of efficient use
In practice, there are already numerous successful examples of the use of waste heat. In industry, it is often reused directly within the process, for example to preheat materials or to support production stages.
A classic example is the use of waste heat from compressed air systems. The heat generated in this way can be used to heat industrial buildings or to produce hot water.
Data centres also offer great potential. They continuously generate heat, which must be dissipated using suitable systems. Instead of allowing this heat to go to waste, it can, for example, be fed into nearby buildings or district heating networks.
In the building sector, waste heat is increasingly being utilised in ventilation systems. Heat recovery systems ensure that the heat from the exhaust air is not lost, but is instead used to heat the supply air.
These examples show that waste heat recovery is possible in many areas – often with manageable costs and short payback periods.
Cost-effectiveness and funding opportunities for waste heat projects
Cost-effectiveness and funding opportunities for projects relating to waste heat recovery
The use of waste heat is not only environmentally sound, but also economically attractive in many cases. By reducing energy consumption, operating costs can be cut in the long term. At the same time, companies can reduce their dependence on rising energy prices.
Cost-effectiveness depends on various factors, including the amount of heat available, the temperature level, the capital costs and the potential uses. In many cases, waste heat projects pay for themselves within just a few years.
In addition, there are numerous support schemes at national and European level that encourage investment in energy efficiency and waste heat recovery. These can further improve cost-effectiveness and lower the barrier to entry.
Overall, it is clear that waste heat is a previously underestimated source of energy with great potential in industrial plants. Companies that harness this potential not only benefit financially, but also make an important contribution to the energy transition.
Call to action:
Would you like to identify and make economic use of the waste heat potential in your business? Contact us now – we can help you analyse, plan and implement your bespoke waste heat solution.
Cet article de blog a été rédigé à l’aide d’une IA générative, puis soigneusement révisé et relu par nos soins. De plus, des outils similaires ont été utilisés pour optimiser l’article en vue de son référencement sur les moteurs de recherche (afin de garantir que ceux-ci puissent le trouver et lui attribuer un bon classement).