Heat pumps fast-track district heating decarbonization

According to the International Energy Agency (IEA), nearly two-thirds of heating energy use still relies on fossil fuels. Is that still necessary today?

Kenneth Hoffmann (KH): Not at all. Reliance on gas is totally unnecessary. If your home is kept at a steady temperature between, say, 18-21 °C (64-70 °F), there’s really no need to burn gas at 600 °C (1,112 °F) to make it comfortable. It just doesn’t make sense.

Is there a better solution?

KH: Yes, there is: heat pump technology. With a heat pump, we can boost the temperature of air brought in from outside to make homes very comfortable without using gas.

The IEA confirms that a shift is happening, but things are moving way too slowly.

KH: That’s right. Efficient, low-carbon heating technologies are on the rise. But although heat pumps and other clean heating options are readily available and have proven effective, significantly faster deployment rates are needed to get on track with the net-zero emissions by 2050 scenario.* According to the IEA, district heating networks are a key stepping stone to achieving zero-carbon heating and cooling. In its Roadmap for the Global Energy Sector, the IEA targets 350 million connections in cities globally by 2030.

*Per the Paris Agreement

It will soon be 2030. Would you say we need a revolution rather than evolution to decarbonize heat in towns and cities?

KH: Yes, and, in fact, that’s exactly what we can achieve with district heating based on heat pump technology. You see, if you apply the concept to a number of houses, it’s a significant step forward. But if you do it on an industrial scale – for entire districts and communities – you have the much-needed game changer.

How exactly does it work?

KH: A modern, efficient district heating system uses ammonia-based heat pumps. With a small input of ideally renewable electricity, this solution can generate heat from various sources, such as industrial waste heat (like data centers), sewage water, ground source, subway networks or air. The heat can then be boosted to temperatures of up to 95 °C (203 °F) to supply heating or hot water (or both) directly to the neighborhood.

Can it be applied everywhere?

KH: The system works best in areas with high population density. It makes the most economic sense to install it when an area is first developed or during major infrastructure projects, though this is not a prerequisite. In Malmö in southern Sweden, for example, four 10 MW (34,121 MBH) GEA heat pumps are installed next to a sewage treatment plant and waste incinerator near the harbor. They now provide 8% of the total energy usage of approximately 100,000 homes, saving close to 50,000 tons of CO2 every year. And in Tallinn in Estonia, four GEA heat pumps – including three GEA Grasso LT screw compressors (XB model) and the innovative 70-bar GEA Grasso L XHP screw compressor (the first to be put into service) – efficiently reuse waste heat from biomass CHP plants. They reduce the need for fossil fuels during peak demand periods, lower carbon emissions and provide stable, cost-effective heat to approximately 8,000 homes and businesses. These are just a few examples of the tireless work that GEA engineers do every day all over the world to bring the benefits of GEA’s ammonia-powered heat pumps to district heating systems.

Heat pumps rely on electricity. Will this significantly increase electricity demand?

KH: Not at all. Heat pumps generate up to five times more heat energy per kWh usage of primary energy (electricity) compared with burning gas or direct electric boilers. That way, total electrical usage can be kept within acceptable limits. And as electricity is increasingly generated from renewable sources, a heat pump installed today will have a smaller carbon footprint each year until the electricity comes from 100% renewable sources. By combining energy efficiency with burning less gas, the decarbonization of society is within reach.

How about emissions?

KH: Heating accounts for more than half of global energy consumption, so it undoubtedly plays a huge role in carbon emissions. We cannot overstate the importance of a systems-led approach to dramatically scaling up renewable energy and utilizing heat that would otherwise be wasted. Equally imperative is phasing out coal and other fossil fuels while innovating for the future. Using heat pumps in district heating not only helps the global environment but also has local effects. Unlike gas boilers, heat pumps do not emit nitrogen oxides (NOx). They therefore result in cleaner air in cities and other urban areas — and also offer financial advantages. Additionally, using ammonia is a key advancement in the development of district heating technology. Many older systems still use fluorinated (F-) gases for refrigeration, which are being phased out across Europe. Unlike F-gases, ammonia is climate-friendly, widely available, inexpensive, and has no impact on global warming.

What is GEA’s role in battling carbon emissions?

KH: I believe we have an important role to play. In recent years, GEA has been at the forefront of developing this technology. Having first investigated and perfected the methodology, our engineers then applied the technology in ways that make a real difference in terms of serving local communities better and drastically reducing the amount of CO2 generated by utilities. GEA is constantly innovating to expand its heat pump portfolio and stay ahead of the district heating curve. You see, heat pumps are nothing new, but with the rapid rise in renewable energy use, they have become more important in the battle against carbon emissions. Combine this highly efficient method of heat conversion with initiatives to develop district heating systems for residential and municipal buildings, and you have a potential revolution in the making. Add to this the increasing use of natural refrigerants, such as ammonia, and all the technology is in place for a genuinely “green” communal heating solution.