Driving decarbonization in the industry

Heat pumps in industry for waste heat recovery

Wärmepumpen in der Industrie zur Abwärmenutzung

Heat pumps in industry are a key technology on the path to decarbonization, as they enable the electrification of heat generation and can therefore replace oil and gas as energy sources. Interest and concrete demand from companies is increasing noticeably. We summarize the possible applications, potential and our recommendations for you.

Heat pumps What’s that about?

Heat pumps are offered as compression heat pumps, exhaust and adsorption heat pumps, but also as open processes, for example in the form of vapor compression. A distinction is made between conventional heat pumps up to approx. 70 °C useful temperature level, high-temperature heat pumps up to approx. 90 °C and ultra-high temperature heat pumps up to currently approx. 165 °C useful temperature level, which can be used depending on the requirement profile.

The classic heat sources are ambient air, groundwater or the ground, although waste water, exhaust air and other process waste heat can also be used specifically as heat sources. Each heat source has various advantages and disadvantages or specifications that need to be taken into account.

For example, it is very easy to use the ambient air as a heat source for space heating without major excavation work. This significantly reduces the time and expense involved and can usually be easily implemented in existing buildings. However, fluctuating outside temperatures and possible icing of the evaporator have a detrimental effect on the performance of the air source heat pump.

“Ground source heat pumps take advantage of the constant temperature of the ground, but are much more demanding and cost-intensive in terms of installation and space utilization. I therefore recommend weighing up which heat source and therefore which heat pump offers the best possible cost-benefit value depending on the application.”

Sylvia Jacobi, expert for cooling and heating supply systems at ÖKOTEC

Depending on the heat pump, the installation options, noise protection, water and mining law issues and neighborhood law must also be examined.

In order to utilize the free heat sources via the heat pump, electricity is required to operate the heat pump. Companies should only use green electricity for this, from their own generation or by purchasing green electricity, in order to contribute to decarbonization.

Keeping the focus on efficiency

In order to keep the electricity requirement and therefore the operating costs of the heat pump as low as possible, it is crucial how efficiently the heat pump can work. When assessing efficiency, the temperature difference between the temperature of the heat source, for example the ambient air, and the target temperature required for space heating or industrial processes must be taken into account. The higher the temperature difference, the lower the efficiency. The higher the temperature of the heat source and the lower the target temperature, the higher the efficiency. Our expert Sylvia Jacobi therefore recommends ensuring that the temperature difference is as small as possible and that the useful temperature level is minimized.

Heat pumps for heating buildingsWhat should I bear in mind?

Heating buildings is an interesting application for a heat pump in industry, as the required temperatures are generally not particularly high and the heat pump can therefore work efficiently. However, here too, the cost-effectiveness of implementation is influenced by a number of factors.

The condition of the building, the design of the heating systems and the installation conditions are crucial, which is why the use in existing buildings can sometimes be challenging. Before planning a new heating system, we therefore recommend checking the energy status, adapting heating systems and, if necessary, renovating the building envelope. This can sometimes drastically reduce the heat requirement so that the heat pump subsequently required can be designed smaller and work more efficiently.

Reduce temperature levels, increase efficiency

To further increase the efficiency of the heat pump, we recommend taking a close look at the various heat requirements. In our experience, the efficiency of the heat pump can often be increased if the hot water supply can be disconnected in order to reduce the required temperature level. The domestic hot water is usually required at a significantly higher temperature level and the hot water storage tank can also cause considerable heat losses. In the event of decoupling, alternatives for heating the drinking water should be examined, such as solar thermal energy in combination with an instantaneous water heater or an electric boiler.

As described above, the source and actual system temperature have a major influence on the efficiency of the heat pump, meaning that both control options and usage behavior must be examined. There are also factors such as the quality of the installation, the quality of maintenance and the system settings.

Heat pumps for process heat – what potential is there?

In the vast majority of industrial companies, heat is traditionally provided using fossil fuels. Electrification of the heat supply is therefore an absolutely key starting point for decarbonization. Due to the high efficiency of heat pumps, they are predestined to take over the heat supply – at least to a large extent.

“There are many possible applications for heat pumps in industry. However, these are currently limited to a maximum useful temperature level of around 165 °C and the economic criteria of the companies. In order to exploit the full potential of waste heat utilization, a detailed analysis of the heat sources and reductions and further planning are required in advance. In this way, heat pumps can tap into a high potential for CO2 savings.”

Sylvia Jacobi, expert for cooling and heating supply systems at ÖKOTEC
Heat pumps in industry for waste heat recovery
Space and process heat from heat pumps (Copyright ÖKOTEC Energiemanagement GmbH)

A classic application for heat pumps is, for example, to harness waste heat potential. If the temperature level of the heat source, i.e. the (process) exhaust air or the (process) waste heat, is too low for direct further use and therefore no direct heat exchange via heat exchangers is possible, this can be raised with the help of a heat pump.

High temperatures in the process heat sector can now also be achieved using heat pumps and the technologies are being continuously developed. Our expert Sylvia Jacobi advises checking internal cascaded heat pump connections and the series connection of heat pumps to maximize efficiency.

In industrial companies in particular, where heating and cooling are required at the same time, it may be possible to use conventional cooling systems as heat pumps or to supplement or replace them with heat pumps with simultaneous heating and cooling generation. The combined generation of heat and cold increases overall efficiency and avoids waste heat at low temperatures.

Our conclusion on heat pumps in the industry

Heat pumps can be used in many different ways – from heating buildings to substituting fossil fuels for the provision of process heat. However, in order to achieve high efficiency and thus a good cost-benefit ratio, we recommend a precise analysis of the heat sources and sinks and the exploitation of efficiency measures. This is the only way to tailor your heat pump system precisely to your needs.

We work with you to develop a needs-based concept and clarify the following questions with you, among others:

Only when these questions have been answered and a coherent overall concept for your company’s heating and, if necessary, cooling supply has been drawn up do we recommend that you start implementation.

Image: GEA

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Steffen Held Team Sales & Project Management

Steffen Held

Senior Account & Project Manager