Jätelämpö

Jätelämpö, or waste heat, is the heat emitted as a byproduct of energy production and industrial processes that is not used for the intended process and would otherwise be released into the environment. It spans a range of temperatures, from high-temperature exhaust of furnaces and turbines to low-temperature heat from data centers, refrigeration, and chemical processes. Recognizing waste heat as a potential energy resource is a central principle of energy efficiency and decarbonization efforts.

Common sources include power plants, steel mills, cement kilns, chemical plants, data centers, and commercial refrigeration. The temperature of waste heat varies widely: high-grade heat above roughly 100–200 °C is more easily reutilized, while low-grade heat below 100 °C requires additional technology to be economically useful. The volume of waste heat can be substantial, but its capture and reuse depend on temperature, timing, and geographic distribution.

Utilization technologies include heat exchangers and recuperators to recover heat at the source, combined heat and power (CHP) systems, and district heating networks that distribute recovered heat to buildings. For lower-temperature streams, heat pumps or absorption chillers can upgrade heat for space heating, hot water, or cooling applications. Waste heat can also serve industrial processes that require preheating or process heat.

Benefits include reduced fuel consumption, lower greenhouse gas emissions, and improved overall energy efficiency. Challenges involve upfront capital costs, matching heat supply to demand, variability in heat generation, and the need for suitable infrastructure and policy incentives to connect sources with users. Jätelämpö is a focus in many energy strategies aiming to enhance sustainability and resilience.