Synthetic gas from green electricity

How can electricity from solar, wind and hydropower be stored on a large scale? How can it then be used to heat homes, in transportation and in industry? Power-to-gas is the answer: Synthetic gas can be obtained from environmentally-friendly electricity and water.

Source: Getty Images

Urgently sought: Replacement for fossil fuels

The United Nations have recognized the need for action. They intend to keep the rise in global temperature to below two degrees Celsius this century as compared to pre-industrial levels. Furthermore, the worldwide emission of greenhouse gases such as CO2 should not continue to increase. Germany and other industrialized nations bear a particular responsibility compared to less developed nations and have set ambitious targets for national CO2 reduction.

At the UN Framework Convention on Climate Change in Paris in December 2015, 196 countries reached an agreement – the global climate treaty. China, India and the USA were, for the first time, all in agreement – this represents a major breakthrough. The countries are gradually approving the agreement and setting out national measures and climate protection targets. The global climate treaty came into force in November 2016.

UN Framework Convention on Climate Change in Paris 196 countries reached an agreement to take joint action against global warming. Source: UNFCCC / Hajue Staudt

An important building block in reaching these targets is the extensive avoidance of fossil fuels in electricity production, transportation as well as heating and cooling. This gives rise to numerous challenges:

  • How can electricity from renewable sources be stored?
  • What energy can be used to power long-distance traffic on the road, on water and in the air?
  • How can investments in infrastructure be kept low?

Climate-neutral electricity can be used to produce artificial gas and in further process steps even liquid fuels. These are the challenges that we must overcome. In Germany, the first plants with such potential are already in operation and bring us closer to our targets in CO2 reduction.

Power-to-x: flexible energy sources from renewable electricity

The power-to-gas technology can be used to produce an artificial, climate-neutral substitute for oil, natural gas or coal. For this purpose, renewable electricity is fed into an electrolyzer. Here, water (H2O) is split into flammable hydrogen (H) and oxygen (O) using electricity. The hydrogen can be easily stored in tanks and is thus an alternative to batteries. Industrial companies or, for example, vehicles with fuel cells can even use hydrogen today.

The electrolysis: Starting point for many new energy products

Most electricity today is still generated conventionally, but electricity from renewable energy sources is gaining importance. As a rule, electricity is consumed directly by industry and households. There is no link with liquid and gaseous fuels.

Renewable electricity is gaining importance. Electrolysis is used to generate hydrogen from electricity. Serving as an energy store, this hydrogen can, for example, be used by fuel cells and be fed into the gas grid to a limited degree. This creates a link between renewable electricity and conventional fuels.

As environmentally-friendly electricity grows, so does the importance of additional electricity consumers such as transport and heat generation. But storage capacity also needs to increase in order to compensate for fluctuations in power generation. With the new methanation step in the process, synthetic natural gas is produced from the hydrogen and can be fed into the gas grid with no limitations. Erdgas aus dem Wasserstoff erzeugt und kann unbeschränkt in das Gasnetz eingespeist werden.

In a further step, liquid fuels are produced from the methane. The ships or mobile working machinery of the future will be able to refuel with “solar energy”. The synthetic fuels allow the emissions performance to be optimized and drive climate-neutral, low-pollutant combustion engines.

However, the handling of hydrogen places high demands on safety and there are still limited possibilities for use. But if hydrogen is combined with carbon in further chemical processes, methane is produced, which boasts almost the same properties as conventional natural gas. Thereby, carbon can be taken from industrial exhaust gases or even from ambient air. This is therefore referred to as carbon recycling.

In further process steps, liquid fuels (power-to-liquid), plastics or chemicals can be produced from methane. The term power-to-x encapsulates all these processes.

Energy providers are producing climate-neutral gas from renewable electricity

The method of electrolysis to produce hydrogen was first used in the chemical industry. The energy industry is continuing to develop power-to-gas with the aim of producing larger quantities of synthetic climate-neutral gases. Stadtwerke Mainz (the municipal services in Mainz), for example, generated around 18,000 kilograms of hydrogen in the first nine months of using its electrolyzer at the Energiepark in Mainz. With this amount, a Mainz transport company fuel cell bus could be operated for about six years or 25 single family houses could be heated for over a year in a climate-neutral manner.

Since July 2015, the Energiepark in Mainz has been producing gas from wind energy for customers of the municipal services. Source: Stadtwerke Mainz, Siemens, Linde, Hochschule Rhein Main

„To limit global warming, 80 percent of coal, 50 percent of gas and 30 percent of oil reserves worldwide need to remain in the ground.“

McGlade & Ekins (2015)University College London

Renewable electricity without additional CO2

It is renewable electricity which primarily makes power-to-gas climate-friendly. If the energy comes from solar, wind, renewable plant materials or from the hydrological cycle, then the CO2 deposits that are bound in petroleum and natural gas must not be compromised.

Around a third of electricity produced in Germany comes from renewable energy plants. It is becoming apparent that the Federal Government’s target of up to 45 percent of electricity from renewable sources in 2025 will be achievable.

Renewable energies are growing and driving the manufacturing industries

Ambitious and binding political targets for the expansion of renewable energies are not only driving the energy transition forward, they are also creating jobs and encourage the manufacturers of generation systems to be more cost-efficient and innovative.

German energy policy triad

An environmentally-friendly, cost-effective and reliable energy supply; this is the triad along which the policymakers are developing the German energy transition. With a 10-point plan on energy policy measures and proposed legislation, the Federal Government is working on its targets.

The framework conditions for power-to-gas depend on all 6 of these 10 points – namely those that belong to the complex of the sector coupling. The risk assessment for investors who want to finance a power-to-gas plant is correspondingly uncertain and complicated.

With this agenda, the Federal Government bundles and synchronizes the main energy transition measures. It contains the regulations for:
1.) Renewable energies*
2.) European Climate and Energy Framework
3.) Reform of the European emissions trading system
4.) Design of the electricity market
5.) Efficiency strategy*
6.) Buildings strategy*
7.) Transmission grids*
8.) Distribution grids*
9.) Monitoring
10.) Consultations with civil society in the energy transition platform
*relevant for power-to-gas

Energy occurs in various forms; as electricity, heating/cooling or as kinetic energy (movement, pressure etc.). Correspondingly, the energy industry can be divided into three sectors: electricity market, heating market and transportation. Sector coupling is the joint optimization of all sectors by linking them together. Electricity produced from renewable energies is to be used with sector coupling in heating supply, transportation and in industrial production processes.

The restructuring of the energy system: ambitious targets, high quality

The energy transition needs ambitious targets in regard to the conversion of the energy system. This is necessary so that Germany’s industry can continue to rely on the excellent quality and reliability of the electricity supply.



On average electricity failure in Germany. In an international comparison, it is the highest supply reliability. (CEER)



The reduction target for greenhouse gas emissions by 2050 (BMWi)



The renewable energy expansion target by 2035 (BMWi)

Converting electricity: Efficiency is politically relevant

In electrolysis, the energy content of electricity is currently converted with an efficiency of about 80 percent. According to Dr. Dorothee Mühl from the German Federal Ministry for Economic Affairs and Energy, it is now important that the valuable resource of electricity is used in a particularly energy-efficient manner, in other words with the least amount of conversion loss as possible.

In electrolysis, the energy content of electricity is currently converted with an efficiency of about 80 percent. The hydrogen gas generated from electricity thus has a 0.8-fold energy content. Let us assume that the hydrogen would then be burned in a combined heat and power generation plant with a heat efficiency of 90 percent. 80 percent by 90 percent results in 72percent – the initial energy of the electricity would thus have been converted to 72 percent in thermal energy. The remaining 28 percent of the energy would have been consumed by the process of conversion itself.

“As a matter of priority, those technologies which substitute as much fuel as possible using as little renewable electricity as possible should be used for sector coupling. For instance, efficient applicable heat pumps and electric vehicles,” she says.


Overview of sector coupling technologies

Power-to-gas technologies are the only ones that connects all three fields of application. Source: Fraunhofer ISI

Short interview: Technology funding under the primacy of energy efficiency

VDMA: Dr. Mühl how does the power-to-gas technology fit into the energy policy of the Federal Government?

Dr. Mühl: Our main objective is to promote the efficient use of renewable electricity in other sectors. Sector coupling must be considered in the context of energy efficiency and the direct use of renewable energies. Power-to-gas is an additional option to decarbonize other sectors, such as the heating market.

VDMA: An advantage of power-to-gas is that such renewable electricity can be stored as gas. Does this make the technology relevant to the energy transition?

Dr. Mühl: The focus is on optimizing the entire system. It is also important that the sector coupling develops an additional element of flexibility for the electricity market in order to compensate for the fluctuating production from wind and solar. This can reduce the overall cost of the energy transition. However, as the first matter of priority, those technologies which substitute as much fuel as possible using as little renewable electricity as possible should be used for sector coupling, for example efficient applicable heat pumps and electric vehicles.

VDMA: When do you see the time coming for power-to-gas plants?

Dr. Mühl: When we reach roughly 75 to 80 percent renewables. Prior to this, other building blocks to increase flexibility are urgently needed, such as grid expansion or the organization of supply-oriented consumption through so-called load management.

Caption: Storage becomes important for the increasing share of renewable energy

Source: BMWi

VDMA: How else are you preparing in the meantime for power-to-gas and other storage?

Mühl: We are making sure that the prices for sources of energy reflect the costs they generate. In order for the most cost-efficient decarbonization technologies to be implemented, fair conditions for competition must be established. That means for us that we need to thoroughly check taxes, fees and charges.

Dr. Dorothee Mühl

Undersecretary at the Federal Ministry for Economic Affairs and Energy

The Head of the Electricity subdivision of the Energy Policy department – Electricity and grids is dealing with the legal framework of sector coupling. She studied law and administration in Germany and the USA. After working in the legal department of a bank, she is now assuming various functions at BMWi.

Short interview: Technology funding under the primacy of energy efficiency

Dr. Dorothee Mühl
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Energy management: A sustainable benefit for the industry

In obligatory energy audits, the Federal Government demands companies to account for their handling of energy. So-called energy managers monitor the energy footprint of the German industry and ensure a safe and efficient use of electricity, heat and mechanical energy.

In order to implement the EU Energy Efficiency Directive and the German energy saving targets, large companies have been obliged since December 5, 2015 to comprehensively inform the authorities about their energy saving capabilities. In order to systematically identify opportunities for improvement in company energy supply systems and develop them economically, the energy audits are to be carried out according to certain rules and thus every four years.

What does an energy manager do?

Matthias Hippeli from ABB in Mannheim on energy efficiency networks, digitized energy flows and why his job “should not work like the Wild West”.

Storable gas provides the buffer between production and consumption

Power-to-gas provides a technological answer to the problem that the production of wind and solar electricity does not always correspond with the electricity consumption in the right places. If the electricity is not used by the consumer, it cannot remain in the electricity grid for physical reasons. In the least favorable case, the energy systems must even be regulated in order to prevent grid overloads.

For gas, however, the lines of the well-developed gas grid can function as storage. In addition, the synthetic gas can be stored in tanks and natural storage caverns under the ground for future use.


The fill-in

For physical reasons, electricity cannot be stored in the electricity grid. This is why the Forschungszentrum Jülich (Jülich research center) is faced with the task of finding a store as a fill-in between electricity production and energy consumption.

Fuel for engines from green electricity

Power-to-gas and power-to-liquid can substitute fossil fuels such as gasoline and diesel. This is an important aspect for achieving the climate goals and to continue to carry out important tasks in transport, agriculture and construction, because charging infrastructure and sufficient storage capacities for electricity are not always available.

Combustion engines are also providing power in remote areas

Mobile machinery, ships or trains often run with higher-capacity which is not always fueled by electricity. Synthetic fuels are flexible, clean and climate-friendly sources of energy for these applications.

Climate goals can only be achieved with power-to-x

In an interview, Lars Mönch from the Umweltbundesamt (Germany’s environmental protection agency), reiterates the need to completely shift transport to renewable energy sources.

“There are areas within transportation which cannot be electrified using technologies available at the moment. For these modes of transport, such as long-haul trucks, marine transportation or also airplanes, we need gaseous or liquid fuels.”

Lars Mönch

His specialist field encompasses pollution reduction and energy saving in transportation at the Umweltbundesamt.

He is responsible for the Pollution Abatement and Energy Saving in Transport department at the Umweltbundesamt. The focus is on technical reduction possibilities in all transportation sectors. This includes road transport, river and maritime shipping, air transport, but also non-road applications such as mobile work machines.

Designer fuels for optimal climate protection

It is not enough that power-to-x forms the basis for the climate-friendly replacement of fossil fuels and thus promotes the energy transition in the heating and mobility sector. In addition, synthetic fuel can also be designed in such a way that fewer harmful exhaust emissions are generated. For Wolfgang Maus, a recognized expert in exhaust gas aftertreatment technologies, synthetic fuels are the key to climate and environmental protection, while at the same time utilizing existing infrastructure and drive technologies.

Synthetic fuels are an opportunity to protect the climate, the environment and enhance mobility

Wolfgang Maus, WM Engineering & Consulting GmbH

I believe that future mobile energy sources must meet five key sustainability criteria:

  • CO2 neutrality
  • Sustainable, unlimited availability of energy
  • Minimum environmental impact, low emissions
  • High profitability
  • High functionality

These criteria are met in the power-to-x concept presented here. Electricity from renewable sources has an almost unlimited availability and is produced without CO2 emissions. Hydrogen can be produced using this electricity, which is then combined with carbon to form methane in further process steps. This carbon can come from CO2 in the exhaust gas of industrial sources such as cement plants, electricity generation or the steel industry. The CO2 from industrial exhaust gases is, so to speak, recycled and thus becomes the raw material for the production of synthetic fuels. It is even conceivable that in the future the CO2 will be extracted from the ambient air for the production of methane

In further process steps, methane becomes a liquid fuel. Under the abbreviation OME, such a synthetic substitute for fossil fuels is already well-known and available. These OME fuels burn with low emissions in conventional diesel engines. State-of-the-art exhaust gas aftertreatment technology should enable us to clean urban ambient air with combustion engines in “sub-zero vehicles” in the foreseeable future – an advantage that other technologies do not offer.

With optimized production processes for synthetic fuels and efficiency increases in the generation of electricity from renewable sources, the new fuels are also attractive in terms of the price – especially if taking into account the climate and environmental benefits. The existing infrastructure can easily be used with gaseous and liquid synthetic fuels. Storage, distribution and fueling remain unchanged. Vehicles and mobile working machinery remain independend from a socket.

Electrification is a barrier to many applications. Necessary, climate-neutral alternatives to electric drives are obtained through power-to-gas and power-to-liquid.

Wolfgang Maus

WM Engineering & Consulting GmbH

After his studies in mechanical engineering, Wolfgang Maus gained a wealth of experience in energy and automotive engineering. In 1986, he founded Emitec, a manufacturer of exhaust gas aftertreatment technologies. After his retirement in 2012, Emitec, with more than 1000 employees at the time, was taken over by Continental AG. Today, he consults the Executive Board of Continental AG. In addition to Supervisory Board mandates, he is intensively involved in the future issues of the engine industry.

Synthetic fuels are an opportunity to protect the climate, the environment and enhance mobility

Wolfgang Maus, WM Engineering & Consulting GmbH
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Here you can find out more about the keywords concerning power-to-gas

Energiepark Mainz

The project of the Stadtwerke Mainz, RheinMain University, Siemens and Linde provides information about the specific application of power-to-gas in the energy industry.


Climate change

In its Big Picture report, the UN Intergovernmental Panel on Climate Change concretely summed up what is to be done against climate change.


Grids and storage in the energy transition

An animated presentation by Prof. Armin Schnettler (RWTH Aachen & Siemens) illustrates the energy scenario in 2025.


Integration into the energy system

The Umweltbundesamt highlights the role of P2X in the process towards a greenhouse gas-neutral system. The UBA website contains a wealth of information on the subject.


Fuels from CO2 and water

Emitec’s animation shows in detail the technical process of how water and CO2 combined together can become fuel.


Flexible electricity market

The Federal Ministry for Economic Affairs and Energy describes in the White Paper “An Electricity Market for Germany’s Energy Transition” how to enhance flexibility in the generation and consumption.



There are many sectors of mechanical and plant engineering that play a key role in the creation of the power-to-gas energy transition technology and which dedicated themselves to their further development. From power transmission engineering to wind turbine generators. These authors represent everyone involved in this report and the VDMA organizational units responsible for the respective content.


Responsibility for the content

VDMA Power Systems: Matthias Zelinger

Managing Director and Energy Policy Spokesman

Since 2015, the mechanical engineer (BA) has been the Managing Director of the Power Systems Association, as well as the Energy Policy Spokesman of the VDMA, and since October 2015 also Deputy Managing Director of the Research Association for Combustion Engines (Forschungsvereinigung Verbrennungskraftmaschinen – FVV). He has been Member of Board of Directors of the WindEurope association since June 2016.

Peter Müller-Baum

Managing Director of VDMA Engines and Systems

The graduate and industrial engineer (Diplom) has been Managing Director of the Engines and Systems Association since 2014. Since 2013, he has also been responsible for the “International Council on Combustion Engines” (CIMAC) based in Frankfurt am Main. Since 2005, he has been working for VDMA in various organizational units.

VDMA Energie: Dr. Carola Kantz

Managing Director of the VDMA Energy Forum

She coordinates the Association’s activities in the field of energy and represents the energy policy interests of mechanical and plant engineering. From 2009 to 2013, she worked as a senior energy consultant at IFOK GmbH. She received her doctorate at the London School of Economics and taught environmental policy and international political economy there.

VDMA Photovoltaik Produktionsmittel: Dr. Jutta Trube

Director of VDMA Photovoltaic Equipment working group

Since December 2015, Dr. Trube has been directing the Photovoltaic Equipment working group. She was previously Director for new technologies in mechanical engineering. The markets concerned, amongst others, were photovoltaics, architectural glass, storage technology. She studied physics at the Georg-August-Universität in Göttingen and gained her doctorate in electrical engineering in Berlin.


Catherine Diethelm

Public Relations Consultant for VDMA Power Systems

Diethelm has been doing press and public relations work in the energy systems topic field since 2014 – from wind turbine generators to combined heat and power plants to water pumped storage and steam turbines. She studied journalism and sociology in Zurich and worked, among other things, in the area of corporate communication of the Husum Wind wind energy fair.

Jens Slama

Public Relations and Business Consultant, VDMA Engines and Systems

After studying publishing, the graduate in industrial engineering (FH) began as a project manager at VDMA Publishing House. Since 2007, he has been a consultant for business and public relations at VDMA Engines and Systems. In the Association, he also oversees issues of environmental and climate protection in maritime transport.