Systematic waste heat utilisation with potential analysis

Every refrigeration machine is a heat pump. This can be described using the example of a refrigerator. If warm beer is placed in the refrigerator at +4°C, heat is transferred from the beer to the cool interior of the refrigerator. The refrigerant circuit extracts the heat energy from the beer. This ‘beer energy’ is then brought to a higher temperature level, e.g. +30°C, by the compressor, which is driven by electrical energy. The ‘beer energy’ together with the electrical energy from the compression is then released to the kitchen as waste heat. As a rule, the ‘beer energy’ is many times greater than the electricity input. The total amount of energy is available at a higher temperature level and therefore makes the ‘beer energy’ usable. The ratio of ‘usable heat’ and ‘electricity’ is the coefficient of performance (COP). With a COP of 5, 1 kWh of electrical energy can raise 5 kWh of heat to a usable level. With electric heating, a maximum ratio of 1 is possible. This means that heat pumps can very efficiently raise heat to a usable level.

In a refrigeration system, the energy to be dissipated is raised to a temperature level at which it can be released into the environment. This energy is therefore available at a higher level than from the ambient air. Utilising this waste heat from refrigeration processes is more efficient than recovering ambient heat and should be used directly. It is important to note that heat pumps for industrial processes, i.e. for temperatures above 70 °C, are usually only economically viable if the heat from the company's own processes is utilised as waste heat. Some of these sources can be tapped with little effort. Most chillers can already reach temperatures of over 40 °C, which means that the first heat sinks can only be utilised using heat exchangers and distribution networks. Other systems such as heat pumps can be used to serve processes that require higher temperatures, which is technically feasible up to a temperature of 200 °C.

The picture shows cooling towers that release heat into the environment at low outside temperatures. Instead of releasing the energy into the environment, the heat can be used to heat buildings, as hot water, process heat and for electrical steam generation. This saves fossil primary energy and reduces both CO2 emissions and operating costs.

The amortisation period is determined by the ratio of operating cost savings to the coefficient of performance. The higher the coefficient of performance (COP) compared to the ratio of the electricity costs for the heat pump to the costs of saved fossil fuels, the faster the heat pump will amortise. With a low ratio of electricity to gas prices, heat pumps can amortise in less than a year. Rising prices for CO2 emissions shift this ratio in favour of the heat pump in the long term.

In our approach, we attach particular importance to working with your company's own data. We analyse the required temperature levels and carry out a detailed potential analysis to determine the optimum solution in terms of energy efficiency and sustainability. This process includes the development of various concepts with comprehensive profitability calculations. Cost developments such as CO2 taxes are also taken into account, as are funding opportunities for heat pumps and concepts for CO2 savings.