"THE PROBLEM IS THE LACK OF IMPLEMENTATION OF TECHNOLOGIES"
Greentech will play an even greater role in Germany in the future. VIVID spoke to Prof. Dr Mario Adam, Head of the ZIES Centre for Innovative Energy Systems at Düsseldorf University of Applied Sciences, about the situation in the building sector in particular and how the heating and energy transition can succeed.
Greentech is on everyone's lips. How are we doing in this country, especially in the building sector?
In the building sector, as in the transport sector, we are unfortunately not yet on track at all. Let`s take a closer look: last year, the proportion of electricity consumed that was produced using renewable energies was around 60 per cent - in the heating sector, this proportion was less than 20 per cent and in the transport sector it was even less than 10 per cent. However, in terms of final energy consumption in this country, heat supply dominates with a share of around 50 per cent, followed by transport with around 30 per cent and only then electricity with 20 per cent. This means that we already cover 60 per cent of the 20 per cent of electricity with renewable energies - and for heat, which is much more relevant, it is less than 20 per cent! If we do take climate protection and the energy transition seriously, then at long last heat supply must be taken into account, too, as well as the transport sector.
What are the most promising technologies in the building sector when we firstly just consider individual buildings?
In an individual building, it is the heat pump, which can utilise various heat sources. The dominant heat source on the market at the moment is outside air, but there are also systems that work with heat from the ground. And so-called PVT collectors, a combination of photovoltaic module and thermal function, which then supplies the heat pump with environmental heat, are currently becoming increasingly popular. This technology has the advantage that, in comparison with external air systems, it makes no noise and is not visually disruptive. I see wood pellet boilers as another technology for individual buildings - but only to a limited extent. This is because wood is just too valuable to heat a building to 20 degrees Celsius. Wood pellet boilers or wood in general are actually ideally suited to create high temperatures in commercial or industrial processes. In comparison heat pumps, for example, have low efficiencies here. Ideally, wood pellet boilers should be combined with solar thermal energy so that during the summer the solar system can supply all the heat and the wood boiler can remain switched off.
Although heating accounts for around half of the country's final energy consumption, currently only around 20 per cent of this is produced using renewable energies. As with the transport sector, there is room for improvement here.
And what about technologies in local and district heating networks?
Large heat pumps can also be considered as heat generators, even with other heat sources. For example, rivers and lakes can be tapped. The Rhine is perfect for this, too. We will certainly see plants being built there in the near future. Waste water from sewage treatment plants can also be used as a heat source. The same goes for raw water, which is extracted groundwater that is abstracted for drinking water. Or waste heat from industrial processes or data processing centres. A second promising technology is large solar thermal systems, some with seasonal heat storage, which transfer the heat from summer to winter. There are already many such systems in Denmark and the first ones are now being built in Germany, some with huge collector arrays spanning a collector area of several 10,000 square metres. And the third technology that I consider to be groundbreaking is deep geothermal energy. This involves drilling 1000 metres or more deep to access hot water. The first explorations are now being carried out in NRW and I am curious to see when the first plant will be built.
Artificial intelligence, for example in the form of machine learning, is also playing a growing role in the supply of energy. What does this look like in practice?
Machine learning plays a role in a number of different areas, for one in the optimal configuration of systems. In the past, a boiler was built to cover the peak load, or a combined heat/power plant with a peak load boiler was used - so usually a maximum of two technologies. In the future, this will be more diverse and we will see a mix of several technologies much more frequently. One question then automatically arises: How do you put this together sensibly? Instead of calculating a few variants as in the past, we can use machine learning methods to compare tens of thousands of variants very quickly. This offers great advantages when it comes to finding optimal system configurations. A second promising technology is large solar thermal systems, And then, when the system is up and running, it needs to be controlled. Here too, machine learning processes and artificial neural networks or other methods from the field of AI can provide valuable services. This allows important projections to be made: Depending on the weather forecast, how much electricity from renewable energies will I have tomorrow? How are energy prices developing at the stock exchange? How will the consumption of electricity and heat develop in the respective supply area? This allows not only one-dimensional optimisation, for example according to costs, but also optimisation for several economic and ecological criteria at the same time.
GLOSSARY OF TECHNOLOGIES:
Heat pump: Takes energy from a heat source at a low temperature and raises it to a desired higher temperature level (usually) using electricity, e.g. sufficiently high for space heating and hot water.
With outside air: outside air is used as a heat source and a fan conveys it via the heat conveyor of the heat pump. With geothermal heat: a pump conveys brine (a mixture of water and antifreeze) in a closed circuit through pipes laid in the ground, collecting heat from the ground and releasing it back to the heat pump.
With PVT collector: a PVT collector is a combination of a photovoltaic module for electricity production and a heat conveyor underneath to collect heat from the outside air, which, from the outside, is almost indistinguishable from a pure PV module. Here too, a pump moves brine in a closed circuit through the pipes of the heat conveyor under the PV module and then to the heat pump and back again.
Wood pellet boiler: Similar to an oil boiler, wood pellets are burned in a boiler, with wood pellets stored instead of oil. Various options are available for automatically feeding the pellets from the store to the boiler. Emptying the ash pan is usually only necessary once or twice a year in a detached house because the ash content of wood pellets is very low.
Solar thermal energy: The sun's rays are used to produce hot water, which is temporarily stored in a heat storage tank for later use. There are flat-plate and tube collectors. Both are well suited for space heating and domestic hot water. The heat storage tanks can bridge a few days without sunshine or store solar energy for the winter.
Deep geothermal energy: Water-bearing rock layers are tapped at depths of several hundred to several thousand metres. The hot water is extracted from the subsurface via a production borehole and, once cooled, returned to the ground at a sufficiently large distance via a second borehole. It then flows back to the production well via fissures in the underground rock and can heat up in the process.
What is still missing for entire city districts to be completely energy self-sufficient or climate-neutral in the future?
The technologies are basically there! The problem is the lack of implementation of technologies. It starts with the activation of private capital, which is perhaps unnecessarily sitting somewhere in low-interest accounts instead of being invested in renewable energies. A different prioritisation of consumption would also help. When we buy an expensive car, a longdistance trip or a fancy kitchen, we don't ask whether it will pay for itself. Such money could also be spent on renewable energy sources. And this would actually result in a return on investment - and a good feeling.
So, to conclude: What is your most important message to ensure that the energy transition will not be left to words alone?
We should be 100 per cent convinced that an energy supply based on renewable energies is a great thing that makes a pleasant life possible. It also makes you feel good when you are no longer dependent on countries like Russia or Saudi Arabia. And it's cheaper in the long term anyway. Specifically, reliable framework conditions should be created, such as a clearly defined path for CO2 pricing. That way fossil energy becomes more expensive instead of subsidising renewable energy - because this always gives the impression that renewable energies are not being profitable. And this, in fact, is no longer the case. It is also very important that the energy transition becomes part of a social agenda. We should involve society as a whole and not just make the energy transition possible for those who have enough private funds to buy a PV system or an electric car. •
ABOUT MARIO ADAM
Since 2017
endowed Professor for "Sustainable Energy Systems and Energy Efficiency" and Head of the ZIES Centre for Innovative Energy Systems at Düsseldorf University of Applied Sciences
1998 - 2016 Professor for the teaching and research area "Renewable Energy Systems" at Düsseldorf University of Applied Sciences, set up and led the research team "E² - Renewable Energies and Energy Efficiency"
1992 - 1998 Vaillant, Remscheid, senior employee and project manager. Responsible for new technologies in heating, ventilation and hot water technology in the central research unit, among other things
1988 - 1992 RWTH Aachen University, research assistant at the Chair of Technical Thermodynamics; working on innovative energy systems, thermodynamics and air pollution control
1981 - 1988 RWTH Aachen, studied mechanical engineering, specialising in thermal engineeringWärmetechnik
Text: Tom Corrinth
Pictures: Hochschule Düsseldorf