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Glossary · Energy industry & energy transition

Dispatchable Generation

Dispatchable Generation controllable generation power plants flexibility security of supply residual load

Dispatchable generation refers to electricity generation whose output can be planned and deployed in a targeted way. It covers plants that can be started, stopped, ramped up or ramped down within technical limits. They can thus respond to demand, market prices, grid situations or system requirements. In German, the term usually used is steuerbare Erzeugung. The English term is not a fixed legal term. Laws and grid rules work with their own, in some cases narrower, definitions.

The central technical quantity is electrical power. It is stated in kilowatts (kW), megawatts (MW) or gigawatts (GW) and describes how much electricity a plant can provide at a given moment. This must be distinguished from the amount of energy generated over a period of time, for example in kilowatt hours (kWh) or megawatt hours (MWh). An example: a storage unit with 100 MW of power and 200 MWh of capacity can feed in at full power for two hours. A 100 MW gas-fired power plant, by contrast, can run for days, as long as fuel is available. For dispatchable generation, it therefore matters not only how much energy a plant generates per year. What is decisive is when it can provide how much power and for how long.

Dispatchable generation includes, among others, combined-cycle gas turbine power plants (CCGT), gas turbines, reservoir hydropower plants, biomass and biogas plants, combined heat and power units (CHP) and coal-fired power plants. In certain modes of operation, electricity storage also belongs here when it feeds stored energy back into the grid. However, storage does not generate electricity from a primary energy source; it releases previously drawn electricity with a time delay. The German StromVKG does treat electricity storage as generation plants, but expressly assigns it to a separate group of energy-limited technologies. Power plants that are to be operated with hydrogen in the future also fall into this category, provided that fuel, grid connection and operating rules allow demand-based deployment. Technology alone is not a sufficient criterion, however. A power plant can be technically dispatchable and still remain only of limited usability, for example because of fuel availability, heat supply obligations, permit conditions, minimum run times or market rules.

Dispatchability is not the same as availability

The terms dispatchable, available and firm are often treated as equivalent. Dispatchable only means that feed-in can be actively influenced. Availability describes whether the plant is technically ready for operation at a given moment. Firm capacity is the part of the capacity that can be relied on with high probability in a scarcity situation. This distinction is central to assessing security of supply. The StromVKG reflects it concretely: there, the nominal capacity of a plant is multiplied by a technology-dependent reduction factor. The result is called reduced capacity and is meant to reflect the actual contribution to security of supply.

Some examples: a gas-fired power plant is dispatchable but can fail because of maintenance, fuel shortage or grid restrictions. A hydropower plant with a reservoir responds very flexibly but is limited by fill level, inflow and ecological requirements. A battery storage system delivers power very quickly but has only a limited amount of energy. How quickly a plant can provide power therefore says nothing about how long it can sustain that power.

Flexibility is also not identical to dispatchable generation. Flexibility is generally the ability of a power system to respond to fluctuations in feed-in and consumption. It arises from dispatchable generation, but also from storage, controllable loads, grid expansion, cross-border electricity trading, heat storage or the managed charging of electric vehicles. Dispatchable generation is an important source of flexibility, but not the only one.

Distinction from variable generation

Dispatchable generation is often used as the opposite of variable generation. Wind and photovoltaic plants generate electricity depending on the weather. The StromVKG refers here to supply-dependent technologies. Their feed-in can be forecast and curtailed if necessary. However, it cannot be increased beyond the current supply of wind or sun. An increase is only possible if a plant was deliberately operated below its potential beforehand. When wind and sun are absent, this generation cannot step in on request.

Variable generation is not entirely random, however. Weather forecasts allow predictions over hours and days, and their uncertainties are taken into account in grid operation. Conversely, dispatchable generation is not automatically perfectly plannable. Power plants can fail unexpectedly, fuel chains can be disrupted, and many plants have minimum loads or start-up times. The practical question is therefore not whether a form of generation is plannable or not. It is about which uncertainties, response times and costs are associated with it.

In a power system with a lot of wind and solar power, dispatchable generation does not simply lose importance, but its mode of operation changes. In the past, many conventional power plants ran steadily over long periods. Today, dispatchable plants are needed above all when the residual load is high. Residual load is, at its core, electricity consumption minus feed-in from wind and sun. Some definitions additionally deduct other renewable or inflexible feed-in. Residual load can rise sharply on windless winter evenings and fall sharply at midday when there is a lot of solar power. In a multi-day Dunkelflaute (prolonged period of low wind and solar output), a brief, fast response is not enough. What is needed is dispatchable capacity that holds out for many hours or days.

Technical limits of dispatchability

Dispatchability comes in degrees. A gas turbine starts significantly faster than a large steam power plant. A battery storage system responds within seconds, but only for as long as its state of charge lasts. A biomass power plant is in principle controllable, but is often operated less flexibly than technically possible for economic or subsidy-law reasons. Geothermal power plants usually run steadily and are adjusted to demand only to a limited extent. In combined heat and power plants, electricity production additionally depends on heat demand and on available heat storage.

Important technical characteristics are:

  • Start-up time: time from standstill to grid feed-in or to full load.

  • Minimum load: output below which no stable or sensible operation is possible.

  • Ramp rate: how quickly a plant can change its output, for example in megawatts per minute.

  • Part-load efficiency: efficiency when operating below rated output, usually lower than at full load.

  • Minimum run time and minimum downtime: how long a plant must run after starting or stand idle after shutting down.

  • Energy reserve or delivery duration: how long a plant can sustain its output, which is particularly important for storage and reservoir hydropower.

These properties determine what a plant is suited for: for balancing reserve, for covering peak load, for bridging longer periods of Dunkelflaute or for congestion management. The StromVKG shows how important duration is. In the tenders for long-term capacities, only plants are admitted that can feed in 80 percent of their installed capacity for at least 10 hours without interruption. Storage and other energy-limited plants must in addition be able to meet this requirement again at any time at the latest after 3 hours.

The technical limits have a direct effect on costs. A power plant that runs only a few hours a year must recover its fixed costs over those few hours. A storage unit that is charged and discharged frequently loses energy through efficiency losses and ages with every cycle. A hydrogen power plant can be operated in a climate-friendly way if the hydrogen is produced from renewable sources. However, it is expected to cause high fuel costs and requires upstream infrastructure. Dispatchable generation is therefore not just a technical category, but also a question of investment incentives and market design.

Role in the electricity market

In the electricity market, dispatchable generation is deployed when the expected revenue covers the variable costs or when contracts, reserve products or grid requirements provide for deployment. At low prices, for example when there is a lot of wind and solar power, dispatchable plants run less often. At high prices, which signal scarcity or high residual load, they run more often. This creates an incentive to provide capacity precisely when it is scarce.

However, this market incentive does not solve every system task. Security of supply requires enough firm capacity even for rare scarcity situations. If power plants are needed only a very few hours a year, an energy-only market can provide uncertain investment signals. This is why there are debates and instruments such as capacity mechanisms or a strategic reserve. Under EU law, a capacity mechanism is a measure to achieve the necessary level of resource adequacy. Resources are paid for their availability, not for energy generated. Ancillary services and congestion management are excluded. In the original version of Regulation (EU) 2019/943, such a mechanism was still defined as a temporary measure. The consolidated version of 2024 no longer contains this feature in the definition. For new plants in the capacity mechanism, a CO₂ limit of 550 grams from fossil fuels per kilowatt hour applies. The StromVKG adopts this value as a condition for participation.

In Germany, the Strom-Versorgungssicherheits- und Kapazitätengesetz (Electricity Security of Supply and Capacity Act, StromVKG) of 21 July 2026 creates the framework for a capacity market. The aim is to provide sufficient firm capacity in the delivery period starting 1 November 2031. Two bid deadlines for long-term capacities of 4.5 GW each are planned: on 8 September 2026 and on 29 December 2026. These are followed by a tender for generation capacities of 2 GW in May 2027 and technology-neutral tenders in 2027 and 2029, in which controllable loads can also participate. Gas-fired power plants with a 15-year obligation must be prepared for operation with hydrogen. On 3 November 2026, the Bundesnetzagentur (Federal Network Agency) published the results of the first round: 11 awards for around 5,160 megawatts of reduced capacity. 4,500 had been tendered. The awards apply for an obligation period of 15 years.

Role in grid operation

In grid operation, dispatchable generation fulfils further tasks. Power plants can contribute to voltage control, frequency stabilisation, the provision of reactive power and redispatch. According to EU law, redispatch is a measure by transmission or distribution system operators that alters the generation or load pattern. In this way, physical load flows are shifted, congestion is reduced or system security is maintained. Redispatch is therefore not limited to dispatchable power plants, since loads and curtailable renewable plants can also be included. However, increasing feed-in beyond a bottleneck is usually done by dispatchable plants. Dispatchability is not spatially neutral here: a plant can be economically cheap and still be located in the wrong place in the grid. This is why the StromVKG also contains regional requirements for sites in the grid-technical north and south.

Climate impact and assessment

Dispatchable generation must not be equated with fossil generation. Historically, many dispatchable power plants were coal- or gas-fired. This is why the term is often associated with conventional electricity generation in political debates. That describes the past, but not the category itself. Renewable or low-emission plants can also be dispatchable, for example reservoir hydropower, biogas, to a limited extent geothermal energy, battery storage or, in the future, power plants operated with renewable hydrogen.

The opposite assumption would be just as wrong, namely that every dispatchable plant is climate-compatible simply because it is needed for security of supply. A coal-fired power plant is dispatchable but very emission-intensive. Coal-fired power plants are, as a rule, well above the stated limit of 550 grams of CO₂ per kilowatt hour and are therefore excluded from capacity payments under the StromVKG. A gas-fired power plant causes less CO₂ than coal but remains fossil as long as it runs on natural gas. A hydrogen power plant can be low-emission if the production, origin and transport of the hydrogen are organised accordingly. Dispatchable generation should therefore be assessed separately by several criteria: technical availability, emissions, fuel risks, costs and role in the system.

The term makes visible that a power system does not function on annual energy volumes alone. A country can, on an annual average, calculably generate enough renewable electricity and still need dispatchable capacity in certain hours. Conversely, a need for dispatchable capacity does not mean that large quantities of fossil energy must be generated permanently. In a well-organised system, many dispatchable plants can run rarely and still be very important for the stability of the overall system.

Dispatchable generation thus describes the callable side of electricity generation. The term says nothing about whether a plant is clean, cheap or available at all times. It clarifies whether and to what extent power can be provided in a targeted way. In a power system with a growing share of weather-dependent generation, this capability does not become superfluous. But it must be described more precisely: by response time, location, energy reserve, emissions, costs and the rules under which a plant is actually deployed.

Sources

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Edited by eCMS on 11.11.2026 19:24

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