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Glossary · Energy industry & energy transition

Fuel switching

Fuel switching power plant H2-ready hydrogen natural gas Biomass Decarbonization Industry

Fuel switching refers to converting a plant, a power station or an industrial process from one fuel to another. Examples include the switch from coal to natural gas, from natural gas to hydrogen, from fossil fuels to biomass, or from conventional to synthetic fuels. The term does not stand for a single technology. It describes that the energy basis of a process changes while the basic principle stays the same: something is still being burned.

A fuel switch can be permanent or take the form of mixed operation. Often only part of the previous fuel is replaced at first. In a coal-fired power plant this is, for example, the co-firing of biomass; in a gas-fired power plant, the blending of hydrogen into natural gas. The switch is only complete when the plant actually performs its regular operation with the new fuel and the technical, legal and economic prerequisites for this are met.

Technical differences between fuels

Fuels differ not only in carbon content. Calorific value, density, flame speed, ignition behaviour, moisture, purity, ash content, corrosive effect, transportability and safety requirements are also important. Hydrogen is a good example. It reacts much faster and has a far higher flame speed than natural gas. Burners built for natural gas therefore cannot simply be operated with pure hydrogen, because the flame can flash back into the burner. In addition, hydrogen molecules are very small and easily penetrate materials. Flanges, seals and materials therefore have to be adapted.

Nitrogen oxide formation is another factor. As the hydrogen share rises, the flame becomes hotter. Without countermeasures such as exhaust gas recirculation, dilution or special burner concepts, this produces more thermal nitrogen oxides. Burning hydrogen therefore releases no CO₂, but it is not automatically free of pollutants.

The difference between volume share and energy share is easily overlooked. One cubic metre of hydrogen contains only about one third of the energy of one cubic metre of natural gas. Blending 20 to 30 percent hydrogen by volume therefore covers only about 3 to 10 percent of the heat input, based on the lower heating value. The CO₂ savings from such blends are correspondingly small. Manufacturers state that, depending on the model, modern gas turbines can handle blends of up to around 75 percent by volume. So far they have demonstrated operation with 100 percent hydrogen mainly in test and demonstration projects.

Biomass behaves differently from coal. It is less uniform, usually contains more moisture and leaves different residues that affect slagging and corrosion in the boiler. Synthetic fuels can ease the technical burden on existing plants because they are chemically similar to fossil fuels. However, their production requires a lot of energy.

Distinction from electrification and decarbonisation

Fuel switching is something different from electrification. In electrification, a process is converted to electricity instead of being run on another fuel. If a gas boiler is replaced by a heat pump, this is not a fuel switch in the narrower sense but a change of technology and energy form. An industrial furnace that is converted from natural gas to hydrogen, by contrast, remains a combustion process, just with a different fuel.

Fuel switching also does not automatically mean decarbonisation. Switching from coal to natural gas reduces direct CO₂ emissions per kilowatt hour or per tonne of product in many applications, but fossil emissions remain. A switch to hydrogen can avoid emissions at the stack. How good the overall balance is, however, depends on production: if hydrogen is produced from natural gas and the resulting CO₂ is not largely captured, part of the climate impact shifts to the upstream chain. A gas-fired power plant prepared for hydrogen also remains a thermal power plant with combustion, turbine and generator. Batteries, electrolysers or heat pumps work according to different principles.

Significance in the power system

In the power system, the term matters above all for dispatchable power plants. These are meant to supply electricity when wind and solar plants generate little. H2-ready plants are often cited as a transition from natural gas to hydrogen. This means a gas-fired power plant that is planned or built so that a later conversion is possible or easier. It does not mean that the plant already runs on hydrogen today, let alone on green hydrogen.

For security of supply, convertibility on the data sheet does not count. What matters is whether the plant can actually provide output when needed. This requires sufficient fuel quantities, storage, pipelines, supply contracts, permitted operating modes, trained personnel and an economic framework that pays for availability even when the plant runs only rarely. A fuel switch in the power plant fleet is therefore closely linked to grid planning, a hydrogen network, market design and capacity mechanisms.

Legal framework in Germany (as of November 2026)

Since 2026, Germany has been supporting new dispatchable capacity through the Electricity Security of Supply and Capacity Act (Strom-Versorgungssicherheits- und Kapazitätengesetz, StromVKG). The Federal Network Agency (Bundesnetzagentur) conducts tenders for this purpose. According to the legislative materials, all gas-fired power plants that receive an award must be built to be hydrogen-capable for a commitment period of 15 years. The law does not provide for a binding date by which all plants must have been converted to hydrogen. The early conversion of some of the plants is to be regulated by a separate law, with first tenders from 2027. Hydrogen capability is thus a condition for how the plant is built here, not an obligation to operate with hydrogen from a specific point in time.

Fuel switching in industry

In industry, the focus is often on high temperatures, continuous production and consistent product quality. The steel, chemical, glass, cement, paper and food industries use fuels not only for heating but in part also as reaction partners, for example hydrogen as a reducing agent in steelmaking. A fuel switch can therefore change the entire plant operation. In some applications direct electrification is more efficient, in others hydrogen or biomass is technically closer at hand. The decisive factors are temperature requirements, process chemistry, operating hours, on-site infrastructure and costs.

Typical misconceptions

  • Just a new burner: The new fuel has to be produced, transported, stored, measured, billed and handled safely. Hydrogen needs suitable pipelines or other logistics, pressure and storage technology, and regulations. Biomass needs sustainable supply chains and quality control. Synthetic fuels need large amounts of electricity, carbon sources and conversion plants.

  • Stack equals balance: Direct emissions are only one part. Methane losses in the natural gas upstream chain, emissions from hydrogen production, land-use consequences of biomass or the electricity mix for synthetic fuels can change the climate balance considerably.

  • H2-ready equals hydrogen operation: Technical preparation implies neither a conversion date nor a price nor a secured quantity of hydrogen.

  • Volume percent equals climate impact: Blending 20 percent hydrogen by volume replaces, in energy terms, only a small single-digit percentage of the natural gas.

Economic and institutional conditions

Whether a fuel switch pays off depends on prices and rules. The CO₂ price in emissions trading makes fossil fuels more expensive compared with low-emission alternatives. In EU emissions trading, biomass is in principle assigned an emission factor of zero. However, this applies only to the extent that the sustainability criteria and the greenhouse gas saving criteria of the Renewable Energy Directive are applicable and are met. Biomass that fails these criteria is treated like a fossil fuel. A switch to biomass therefore reduces the cost of emission allowances only if sustainability is demonstrated.

In addition, grid fees, levies, funding programmes and guarantees of origin play a role. Often it is not the fuel price alone that decides, but the sum of investment, retrofitting, maintenance, possible efficiency losses, logistics and plant utilisation. For power plants, full-load hours play a major role. A plant that runs only in rare scarcity situations to cover peak load can bear high fuel costs more easily than a plant in continuous operation. In industrial plants with very many operating hours, by contrast, fuel costs have a strong impact on product costs.

Responsibility is spread across several actors. Operators decide on investments, grid operators on connection and transport capacity. Authorities review safety and emissions, legislators set the framework, and suppliers must provide the quantities. Conflicts arise when a plant is convertible but the infrastructure is missing, or when political goals expect a switch but market rules do not reflect the additional costs.

What the term achieves and what it does not

The term is useful because it directs attention to real plants. It asks which boilers, furnaces, turbines or engines can continue to be used and under what conditions. But it can also obscure. Switching from coal to gas reduces emissions in the short term but creates dependencies on gas prices and import infrastructure. Biomass can make sensible use of residues on site, but on a large scale it leads to competition for land. Hydrogen avoids fossil emissions only if it is produced with low emissions and used where alternatives are lacking.

Fuel switching describes the conversion of the fuel, not its success. A statement becomes reliable only when fuel quality, plant capability, supply chain, emissions balance, costs and responsibilities are considered together.

Sources

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Edited by eCMS on 11.11.2026 16:22

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