That’s what it’s all about: The "byproduct Using heat efficiently
While the "Hawaii" pizza is baked to a nice crisp on the tray, the oven generates a lot of hot air. And it is released into the environment as soon as we open the oven door. Caribbean temperatures briefly prevail to match the pineapple chunks on the pizza. The refrigerator also constantly dissipates heat to the outside so that the inside stays nice and cool. What anyone can observe at home takes place on a large scale in industrial processes: Whether engines are running, metals are being melted at high heat, compressed air is being generated or halls are being cooled – in very many industrial sectors, heat energy is generated that is "left over" at the end of the process is. This energy is called waste heat.
A very high proportion of industrial waste heat is still lost unused – in the form of hot air or hot water. Companies can use this "by-product and significantly reduce their energy costs. In this way, they not only strengthen their own competitiveness, but also make an important contribution to the energy turnaround almost as a side effect. Because around two-thirds of all industrial energy consumption in this country is accounted for by waste heat. According to estimates, the savings potential in the process temperature range from 60 degrees is around 125 terawatt hours. In euros, that’s five billion a year. Waste heat does not even have to be 60 degrees to be of use.
Heating, cooling or lighting: Waste heat can be used in many ways
How exactly can waste heat be reused?? Let’s start small, i.e. in private households: passive houses show how it can be done. In this type of house, in addition to the body heat of the occupants, the waste heat from electrical appliances such as the stove or refrigerator is also used to heat the rooms (read more about passive houses here). This principle also works in industrial plants. Depending on what temperature the waste heat is, it can be used for very different purposes. A few examples:
- Heat recovery: The waste heat is fed back into the production process in which it was generated.
- Space heating and hot water: Offices or production halls can be heated with waste heat. Water can also be heated with it. Large quantities of waste heat of 90 degrees or more can also be utilized outside the company and fed into heating networks, for example. To find out how an industrial company in Hamburg will be supplying heat for an entire city district in the future, click here.
- Cold: Sounds illogical at first, but thermal energy can actually be used for cooling. So-called sorption refrigeration machines use thermal energy to evaporate a refrigerant (usually water).
- of electricity: Waste heat can also be converted into electricity and used in a variety of ways in this way, for example to cover the company’s own electricity requirements in production.
Avoiding or using waste heat – there are subsidies for this
The German Federal Ministry for Economic Affairs and Energy promotes measures for the avoidance and use of waste heat with various support programs: the Energy Efficiency Program – Waste Heat (via K), the Support Program for Highly Efficient Cross-Sectional Technologies (via BAFA), and the Program for Energy-Efficient and Climate-friendly Production Processes (via the Karlsruhe Institute of Technology). Expert advice is also eligible for funding.