Why Germany’s energy transformation depends on sector coupling and green hydrogen

The long-term goal of the German energy transition is a carbon-free energy supply across all sectors, including heat, electricity, mobility and industry. Can it be done? Yes, with the help of green hydrogen, two Siemens Energy experts are convinced. An interview with Armin Schnettler, CEO of the New Energy Business, and Thomas Thiemann, Senior Vice President Energy Transition Technologies, at Siemens Energy.


By Nina Terp

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In many countries the gap between consumption and fluctuating feed-in of renewable energy, i.e. the residual load, is still bridged with conventional power plants in order to keep the energy supply stable. Germany, for instance, will phase out nuclear power and coal by 2022 and 2038 respectively – what concepts do you envision to successfully generate this load without CO2 emissions?

Thiemann: We will succeed by vigorously advocating climate-neutral energy generation solutions in the future – as a society and as a company. Of course, the supply must remain stable: As a direct replacement for nuclear energy and coal, I therefore see highly efficient gas and steam power plants with efficiencies of well over 60 percent. This “coal-to-gas shift” benefits from the existing infrastructure at the existing locations, such as good grid connections.


It is also important to note that a major part of the energy demand in Germany is heat. With such modern power plants, we can achieve energy efficiency rates of up to 90 percent by means of heat extraction. However, it is crucial that these investments should always be future-proof, i.e. they must also be able to function with alternative fuels.

What would those alternative fuels be?

Thiemann: Hydrogen, or more specifically, green hydrogen produced from renewable energy. Once all infrastructure has been made hydrogen-compatible, this is a carbon-free energy source we can use in the long term.


Schnettler: Hydrogen is incredibly versatile. It requires a certain effort to compress and store it under high pressure, in high density, and over a very long period of time as a gas or in liquidized form. However, hydrogen plays the most important role when used directly, e.g., in the steel industry or in fuel-cell drives, or when used as an input product for the production of hydrocarbons. Of course, hydrogen can also be fed into the gas grid or used for re-electrification as fuel gas in gas turbines.


Thiemann: The main attraction is: In most countries we can – to a large extent – even use existing infrastructures such as existing pipelines or caverns to store or transport H2.

What do grid operators and power producers say about green hydrogen?

Your solution initially relies on gas-fired power plants – aren’t you continuing the energy supply’s dependency on fossil fuels?

Thiemann: Not at all! It is entirely conceivable to convert an entire gas-fired power plant to carbon-free fuel technology, and at a fraction of the cost of a new power plant. From our point of view, it is vital that the hydrogen upgrade capability is already taken into account as far as possible in the construction of new plants. For us as a manufacturer, it is a top priority for our customers to be able to invest in future-proof products. And we have to prepare our technological solutions and power plants as well as possible for a future retrofit. In this way, we can ensure that the investments are really future-proof – and that power generation can turn green in the future.

Schnettler: And there’s one thing we shouldn’t forget: We believe green hydrogen is the key to a successful energy revolution in Germany and in other countries as well. But currently, it is not yet available in sufficient quantities at acceptable cost. At around 95 percent, the overwhelming share of the hydrogen produced today is still based on fossil fuels and is used industrial applications. We are therefore in a transitional phase – green hydrogen will initially be used in new, less price-sensitive markets. And these transition periods naturally require temporary solutions.

It is crucial that we also guarantee security of supply in future supply systems characterized by a high share of renewable energy. Battery storage systems for short-term balancing and, in particular, gas-fired power plants will play an important role for the coming decades.


Thiemann: Exactly. These periods can be bridged directly with fully or admixed green hydrogen, and can be stored in large quantities in a hydrogen infrastructure.

How much can hydrogen technology achieve already today?

Schnettler: In principle, for the time being, all necessary technologies are already available. However, many details still require intensive research and development work. And of course, the technology still lacks industrial scaling.

And how far is Siemens Energy in terms of Hydrogen?

Schnettler: Siemens Energy offers all the core technologies for a long-term carbon-free – i.e., fully decarbonized – energy supply from generation to consumption. We are fully committed to the goal of clean energy generation. Starting with the generation of electricity and heat using renewable energy or gas-fired power plants with hybrid concepts if necessary, continuing via power transmission and distribution to efficient PEM electrolysis of hydrogen using a so-called polymer electrolyte membrane or proton exchange membrane, or PEM for short.


Currently we are running, e.g., the world’s most powerful PEM electrolyzer with our partners in Linz, Austria. In addition, the largest PEM electrolyzers have already been operating successfully in Germany for years – but each with an installed capacity in the megawatt range. We are aiming for the gigawatt class in order to successfully implement the energy transition and achieve sector coupling.


In this respect, we were very pleased when German Federal Minister Altmaier announced the hydrogen real laboratories. It’s an important step into the future. All processes, even following electrolysis, are tested there. The hydrogen is initially stored ...


Thiemann: ... and can, for example, be converted back into electricity by using it to fuel retrofitted gas turbines or converted into methanol. For this purpose, Siemens Energy offers the turbines, transformers, grid connection, and medium-voltage switchgear for power distribution – so basically the core technology components are available.


Schnettler: Without forgetting the heat pumps, which enable waste heat to be used as district heating. And of course intelligent network control systems.


Thiemann: Incidentally, the turbine manufacturers who are members of the EUTurbines association made a “Renewable Gas Commitment” in January 2019. They announced that they would supply gas turbines by 2020 that can run on 20 percent H2 – and by 2030 on 100 percent H2. The manufacturers have placed a strong focus on this topic.


Today, Siemens Energy is already able to offer 30 percent – and in some cases even up to 60 percent – of H2 with low-emission premix technology (dry low emission, DLE) for most new gas turbines in its portfolio. We are working full steam to continue develop this DLE technology in order to enable even higher H2 admixtures in low-NOx operation in the future. For existing plants, we have modernization packages in our program which, depending on the type and age of the machine, can enable similar H2 admixture values.

But why is it that we are still a far cry from a comprehensive hydrogen infrastructure?

Thiemann: Because first and foremost we need a further, significant expansion of renewable energy infrastructure so that we can produce and store sufficient quantities of green hydrogen. That is one of the biggest challenges we face.


Schnettler: Indeed. The system studies, e.g., anticipate more than 240 gigawatts of installed capacity from renewable energies in Germany by the time coal is phased out in 2038. But in the future we will also have to import more carbon-neutral energy sources from abroad. And we hope that there will be a sufficiently high and stable demand for green hydrogen as soon as possible, which depends to a large extent on the respective production costs.


A holistic approach is therefore crucial. In order to optimize the overall system and limit the associated costs, we need a strategy that gradually integrates all sub-segments of the energy system. This includes green energy sources such as green hydrogen as well as the expansion of small and large storage facilities, grids and clever energy management systems. We need not only technical but also system innovations so that we can intelligently combine infrastructural and socio-economic aspects such as new business fields and forms of participation.


Thiemann: In addition, the legal framework for a hydrogen economy is simply lacking. This is why we need a stronger regulatory integration of a future hydrogen economy into the energy system, initially combined with financial incentives for green hydrogen and its further use in the heating, electricity, mobility and industry sectors. This is what we need for the breakthrough of hydrogen as an energy source – and frankly, for the breakthrough of the energy transition.


Schnettler: Now is the time to push ahead with innovations in the overall system as quickly as possible and at the same time create the necessary framework. The real laboratories provide a good context for technological development and scaling.

Does carbon-free energy supply already work in the real laboratory projects?

Thiemann: We’re only just getting started. But from my point of view these projects are mostly very promising. This is where we – i.e., the energy suppliers, research institutions and technology manufacturers – can show jointly that a carbon-free, environmentally-friendly energy supply under real conditions and using existing plants is possible and sensible. We are collaborating to master the challenges that lie ahead before the use of hydrogen is ready for series production and large-scale application, and to send a clear message to the world: Hydrogen is our future. This is what we are committed to as a company.


Mr. Schnettler, Mr. Thiemann, thank you very much for the interview.

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Nov 29, 2019

Nina Terp is an independent journalist.

This article was first published in the German BWK Magazin.


Combined picture credits: Siemens Energy, RWE AG, Thyssengas GmbH, Amprion GmbH / Rüdiger Nehmzow