Green electricity: Turbo for the heat transition?

Many of us believe that the share of renewable energies in the energy mix is already decent at around 50% and that we in Germany are well on the way to decarbonisation. Unfortunately, this is not true. This value refers to the electricity sector, where at least 80% is also necessary by 2030 in order to keep the climate impacts within limits. Overall, the status quo is even more sobering. Not even 20% of Germany’s final energy consumption is covered by renewable energies. Especially in the energy-guzzling heating sector, the need to catch up is huge – and possible at the same time. Now it is important to trim the building stock for efficiency, to rely on sustainable local heating networks and to use object-related renewable energies such as solar thermal energy and heat pumps. By 2030, five to six million heat pumps will have to be installed in Germany for the success of the heat transition, but they need electricity. Green energy.

by Martin Betzold | Reading time: 6 minutes

It is pointless to close one’s eyes to reality, the bad news from the German heating cellars first. In Germany, in four out of five cases, an oil heating system is replaced by a gas-powered heating system. We are currently weighing up the consequences of these investment decisions in the current energy price crisis. No wonder that the share of renewable energies in the heating sector has stagnated for years at around 14%. This is dramatic, because heat supply (including cooling) accounts for 51% of final energy consumption in Germany. Seen from the sunny side, one could rave about the enormous climate protection potential that lies dormant in the heating sector. Renewable technologies for heat supply are mature and available, ranging from pellet and wood chip heating to solar thermal systems.

If you look at the heat pump, it becomes clear how closely the transformation in the heating market is linked to the electricity sector. Heat pumps work inverted refrigerators and extract heat energy from the environment outside buildings and make it usable for indoor heating. Although only 3.4% of German residential buildings are heated with heat pumps, their market share in new buildings exceeded 50% for the first time in 2020. After all, the trend is going in the right direction. “Decarbonisation with the help of heat pumps can help to compensate for deficits in building insulation and electromobility by 2030,” states the study “Heat Transition 2030” by the Agora think tank. By then, however, the climate-friendly building heat mix must consist of around 40% gas, 25% heat pumps and 20% heating networks, according to the researchers. In other words, heat pumps are an indispensable key technology for a CO2-neutralheat supply.

 

In order to increase the market share from 3.4 to 25%, about 5-6 million heat pumps would have to be installed in the next 10 years, oil heating systems must be replaced as far as possible by environmental heat. We are talking about a tripling of the expansion speed in order to close the heat pump gap. Let’s assume that the traffic light coalition recognizes the potential and creates attractive framework conditions for a heat pump boom in existing buildings. In order to achieve our climate targets, the additional electricity consumption for the heat pumps must of course be covered CO2-free. This is a challenge in addition to the net amount of electricity generated by additional wind and solar plants of several terawatt hours, considering that a large number of heat pumps (and in the future also electric cars) are likely to increase peak load demand. The intelligent coupling of demand to the supply of fluctuating energy sources is a decisive factor in achieving our climate protection goals. However, our energy system can be set up with intelligent control concepts in such a way that decentralized generators, storage systems and loads can increasingly assume system responsibility. At this point, the focus is on technical solutions such as the conversion of surplus green electricity into hydrogen or heat (Power-to-X).

Without green electricity, the energy transition in the heating cellar falls flat

What we cannot afford is to play the technologies off against each other. Power-to-X offers
in addition, the advantage of (long-term) storability and thus becomes an important regulator in an energy system based on renewable energies. According to the Agora study, in view of the long-term limited land potential of renewable energies in Germany, it will be a matter of ensuring the highest possible energy efficiency when using one kilowatt hour of green electricity. Due to conversion losses, only 0.24 to 0.84 kWh of heat remain for one kilowatt hour of green electricity in power-to-gas applications. The heat pump, on the other hand, generates 3 to 4.5 kWh of heat with one kilowatt hour of green electricity, so the use of electricity in heat pumps is clearly superior to the use via power-to-gas from the point of view of energy efficiency. Generating a lot of heat with little electricity is the basic principle.

The race against time is won or lost in our heating trowels. Green electricity also has the potential to decarbonise our heat supply if we create the technical prerequisites for it. What is indispensable, regardless of this, is the acceleration of the expansion of renewable energies. After all, green electricity is also a decisive element for the heat transition.

In the column “This is what it looks like!”, our energy and climate protection expert Martin Betzold deals with socio-political topics in the context of the energy and transport transition and the associated changes. It appears on a regular basis, because now is the time to act.

 

Sources:

Agora Energiewende, Agency for Renewable Energies, Federal Environment Agency, Bund der Energie- und Wasserwirtschaft e.V.