Everything is connected

On a site fifteen kilometres east of Hanover, the past and future of Germany’s energy supply nestle cheek by jowl. Right next to the Mehrum power plant, which burns 240 tonnes of coal a day at full capacity and generates 750 megawatts of power, about a dozen wind turbines are to be found which, on this day, are spinning particularly fast. The wind they are harnessing here is supplying the electricity of the future; whereas the power plant, which is to be shut down in 2021, represents the energy supply of the past – this, at least, is what a superficial acquaintance with the topic would appear to tell you, wherever you look. But if you talk to Lennart Klüppel and Ingo Sonnenberg of TÜV NORD, things quickly get put into perspective. The former is an expert in load and safety technology in wind energy; in contrast, the latter’s field of expertise is in steam and pressure generation in coal, waste, lignite, gas and oil boilers. Both experts say that not everything is as simple as it seems. They share their insights into the future of energy.

Mr. Klüppel, in 2019, wind energy generated more power than any other source in Germany for the first time. Do you think this is going to continue?

Lennart Klüppel (LK) Yes, the share of wind will grow, but it won’t do so infinitely. Wind energy has great advantages: it is regenerative, and the only carbon emissions come from the construction of the turbines. On the other hand, however, it fluctuates – it obviously only gets produced when the wind blows. Which is why we always need to look at it in context.

What do you mean by that?

LK Wind turbines alone are not capable of providing a baseload; in other words, they can’t guarantee to cover 100% of energy supply needs at all times. When it’s very windy at night, for instance, a lot of power can be fed into the grid which isn’t needed at that time by private or industrial customers. Conversely, when the wind drops, there may be too little electricity for industrial or private customers, for example. This shortfall can’t currently be compensated for by energy from photovoltaic or biomass plants.

What happens in such phases?

Ingo Sonnenberg (IS) The wind turbines currently get switched off, but this isn’t very efficient. Because of this, we’re left with two options: we need to either store the electricity or transport it to where it’s needed.

How do things currently look?

LK In the case of the grids, there should be a pan-European solution, but there’s no current prospect of one. High- and low-pressure areas are always very large, which also means that it’s always either stormy or dead calm somewhere in Europe. So, you’d have to move energy across the entire continent. To do this, we would need large interconnected grids to compensate for fluctuations and provide capacity for everyone. But the disadvantage of these is that transferring electricity always results in losses. On the other hand, you have storage, for which various approaches are being worked on – for example, using electric cars, large batteries or compressed air storage. Another promising concept is power-to-gas.

“For me, it’s a very realistic prospect that Germany will have completely switched to renewable energies by 2050.”

What does this mean?

LK The energy from wind power, for example, can be used to produce hydrogen through electrolysis. This can then be methanised into gas by adding CO₂ which is produced in industrial processes or extracted from the air. A particularly attractive scenario would be if the CO₂ required were to come from gas-fired power plants in which methane is burned. This would create a very sustainable cycle.

IS Here, you can see the synergy effects. We use CO₂ emissions to become more ecological and also more efficient. The gas produced can be fed back into the natural gas grids and used in conventional power plants for electricity and heat generation. If the energy for this comes from renewable sources, that’s also good for the climate.

That sounds logical. Is the technology mature?

IS It’s being tested in pilot and research plants, but the energy can’t yet be converted cheaply enough. Investments in a plant haven’t yet paid off because, unlike wind or solar energy, there aren’t any subsidies. The science tells us that this kind of storage should be invested in, but the policymakers haven’t yet caught on. Sooner or later, however, this will have to happen if we’re going to solve the storage problem associated with the new technologies.

Mr. Sonnenberg, you and your colleagues know conventional power stations very well. Do you think integrating them into this kind of new system will work?

IS Yes, the plants we’re testing can do this just fine. Incidentally, they’re also becoming more efficient and emitting much less pollution than used to be the case. There’s also enough capacity in the gas caverns to store the fuel for months. And it makes no difference in technological terms whether you burn natural gas or gas produced by water electrolysis and using green electricity.

“It makes no difference in technological terms whether you burn natural gas or gas produced by water electrolysis and using green electricity.”

At the moment, however, this solution isn’t yet in sight.

IS No, that’s why we need conventional coal or gas-fired power stations. But it’s very exciting to keep thinking outside the box. We’re very well positioned for the future and have our own teams for all kinds of technologies, including storage solutions and hybrid grids.

LK The Renewables division of TÜV NORD is currently in the process of moving from TIC to TICCET, i.e. Testing, Inspection, Certification, Consulting, Engineering and Training. However, we keep these areas completely separate. At the same time, we’re all looking at new technologies by reading specialist literature, attending conferences or swapping ideas with colleagues from the other departments. Even if this doesn’t always have a direct effect on our daily work, we both have a good few years of work ahead of us, so there’s no doubt that we’re going to witness some major upheavals.

Are there already plants that didn’t exist when you started your career?

LK A lot has been done in recent years. For example, I saw a hybrid solution at first hand the other day. The energy generated by a wind turbine was being used to operate a connected pumped storage plant. This arrangement made it possible to use surplus wind energy to pump the water uphill to allow it to be used to drive a hydroelectric turbine to generate electricity during windless periods.

Do you see things the same way, Mr. Sonnenberg?

IS Our primary focus is on the plants we currently have, but we need to be very flexible. After all, policymakers are setting us targets that can sometimes change at the drop of a hat. For example, we were inspecting a power plant whose decommissioning had been postponed to 2030; millions were then invested in upgrading the systems, but a year later the whole thing was shut down. There’s an awful lot of uncertainty.