E.ON turns sewage into a valuable resource with GEA heat pump technology

Power from waste

Heat pumps are fast becoming the technology of choice for renewable district and domestic heating to meet increasingly stringent environmental regulations and reduce CO₂ emissions and operating costs. The heat pumps operating in Malmö use waste heat from sewage and waste incineration plants. E.ON decided to use recycled sewage water for the system due to the higher temperatures emitted by the sewage plant (14˚C) – making the water warmer than the seawater near the city which was too cold for efficient use.

Withdrawing 30MW of heat from the sewage water, the energy harvested is upgraded to useful heat for the district heating network, with the integrated heat pumps working in conjunction with the nearby waste incinerator plant. The heat pump is designed for delivering up to 80˚C but will rarely be required to deliver temperatures above 71˚C.

Warming to the task

Kenneth Hoffmann summed up the science behind the cost-effective heat pump technology that is transforming district and residential heating and is delivering the recycled energy that will keep the citizens of Malmö warm well into the future.

He said: “The four heat pumps work in parallel to deliver the promised temperatures. Each has a coefficient of performance (COP) above 3.5, so for each 1kWh of electricity used by the heat pump, 3.5 kWh of heat is produced for the city.”

A heat pump system requires comprehensive analysis of the requested temperatures and assessment of the right process parameters. Every degree counts with a heat pump and the more accurate the initial design, the more energy can be saved. Instead of focusing on small pipes with large temperature difference to keep the initial cost down, a heat pump investment is based on continuous savings every day.

Driving increased sustainability

Heat pump technology delivers energy-saving advantages regardless of the industry in which it is used or the extent to which it is utilized. It can do basic jobs, like heating and cooling a small suburban home, right up to taking a central role in a super smart, zero-emissions strategy for district heating.

In countries where emission requirements are less stringent or where cap and trade policies allow, some manufacturers are choosing to maintain the status quo given that fossil fuels still tend to be cheaper than cleaner energy solutions. However, to meet sustainability goals the International Energy Agency (IEA) says that the share of clean energy technologies, such as heat pumps and solar thermal heating, needs to triple to more than one quarter of new heating equipment sales by 2030. So, let’s take action now and engineer for a better world together!