ESEGH key terms

The average revenue per unit of electricity needed over a plant's lifetime to recover all build and operating costs, discounting future cash flows. Used to compare generation options of differing size, fuel, and lifespan.

Actual electricity produced over a period divided by the output if the plant ran at full rated power continuously. Wind and solar have low values; nuclear and baseload gas have high ones.

The ranking of generating units by ascending marginal cost that dispatch models use to meet demand. Renewables with near-zero marginal cost sit at the bottom and push expensive plants out.

Plants whose output can be raised or lowered on command to follow demand, such as gas turbines, hydro with storage, or batteries. Contrasts with variable wind and solar output.

Deliberate reduction of available renewable output because of network limits, oversupply, or system security constraints. It wastes clean energy and is a key indicator of grid flexibility gaps.

The ability of a power system to balance supply and demand across timescales using storage, flexible demand, interconnection, and fast-ramping plants. Becomes more valuable as variable renewable shares rise.

Support services that keep a grid stable, including frequency regulation, voltage support, spinning reserve, and black-start capability. Often procured separately from energy in organized markets.

A mechanism that pays generators or storage to be available to meet future peak demand, separate from payment for energy delivered. Aims to ensure adequacy as fixed-cost plants earn less energy revenue.

Voluntary or contracted changes in end-user electricity use in response to price signals or grid operator requests. Shifts or reduces load during peaks and can substitute for peaking generation.

Average load divided by peak load over a period. A high value means steady consumption and better asset utilization; a low value signals spiky demand that raises system costs.

The maximum power drawn from a system during a defined period. Drives network sizing and expensive peaking capacity, so reducing it is a core efficiency and demand-management goal.

Energy consumed per unit of economic output or physical product, such as joules per dollar of GDP. A fall indicates decoupling of growth from energy use through efficiency or structural change.

The observed shortfall between cost-effective efficiency measures available and those actually adopted. Explained by split incentives, hidden transaction costs, information gaps, and risk aversion.

A situation where the party paying for an efficiency upgrade differs from the party receiving the savings, such as landlord versus tenant. Suppresses investment in cost-effective measures.

The share of a generator's nameplate capacity that can be relied on to meet peak demand with high probability. Low for solar in winter-peaking systems; higher for wind with broad geographic spread.

Actual electricity produced over a period divided by the output if the plant ran at full rated power continuously. Wind and solar have low values; nuclear and baseload gas have high ones.

Power electronics that convert direct current from solar panels or batteries into grid-compatible alternating current. Modern units also provide voltage and frequency support and can ride through disturbances.

The number of hours a storage system can discharge at rated power before emptying, computed as energy capacity divided by power rating. Distinguishes short-duration shifting from long-duration firming.

The share of electricity put into a storage system that is recovered on discharge, accounting for conversion and standby losses. Lithium-ion is typically high; hydrogen pathways are much lower.

Hydrogen produced by electrolysis powered by renewable electricity, splitting water into hydrogen and oxygen. Seen as a route to decarbonize industry and long-distance transport, though conversion losses are large.

Conversion of electricity into other energy carriers or products, such as hydrogen, synthetic methane, ammonia, or heat. Enables sector coupling and long-term storage of surplus renewable power.

Linking electricity with heating, transport, and industry so that low-carbon power can displace fossil fuels in those sectors. Increases overall demand for electricity but enables deeper emissions cuts.

Replacing fossil-fuel end uses with electricity-powered alternatives such as heat pumps and electric vehicles. Effective for decarbonization only where the power supply itself is low-carbon.

A device that moves heat using a refrigeration cycle, delivering several units of heat per unit of electricity. Efficiency drops as the source-to-delivery temperature difference grows.

Heat or cooling delivered divided by electrical energy consumed by a heat pump or chiller. Values above one reflect heat moved from the environment rather than generated.

Breaking the historical link between economic growth and energy use or emissions, so output rises while resource consumption or pollution falls. Measured by comparing growth rates of GDP and emissions.

Emissions of carbon dioxide equivalent per unit of electricity, energy, or output. Grid averages fall as renewables displace fossil generation and are used to value electric vehicles and heat pumps.

A coefficient converting activity data, such as fuel consumed or electricity used, into greenhouse gas emissions. Quality and boundary choice strongly affect the resulting inventory.

Direct greenhouse gas emissions from sources owned or controlled by the reporting entity, such as on-site fuel combustion, process reactions, and company vehicles.

Indirect emissions from purchased electricity, heat, steam, or cooling consumed by the reporting entity. Can be calculated with location-based or market-based methods.

All other indirect emissions in a company's value chain, including purchased goods, business travel, and use of sold products. Typically the largest share and the hardest to measure.

A credit representing a verified reduction or removal of greenhouse gases elsewhere, used to compensate for an entity's own emissions. Quality depends on additionality and permanence.

The test of whether an emissions reduction would have occurred without a project or policy intervention. Central to the integrity of offsets, carbon markets, and baseline setting.

A state where anthropogenic greenhouse gas emissions to the atmosphere are balanced by removals over a defined period. Requires deep cuts first, with residual emissions neutralized by durable removals.

The cumulative amount of carbon dioxide that can still be emitted while keeping warming below a specified limit with a given probability. Translates temperature goals into a finite quantity.

The cost of reducing one additional tonne of emissions using a given measure. Ranking measures by this value produces abatement cost curves used to design policy and investment priorities.

A policy that puts a monetary cost on greenhouse gas emissions, through a tax or a cap-and-trade market. Aims to internalize the climate externality and shift investment toward low-carbon options.

A regulation requiring electricity suppliers to source a minimum share of their sales from renewable generation, tradable certificates often tracking compliance. A quantity-based alternative to carbon pricing.

A guaranteed long-term price paid per unit of renewable electricity fed into the grid, typically differentiated by technology. Reduces revenue risk and has driven early solar and wind deployment.

The potential for harm to assets, operations, and people from climate hazards such as heat, flooding, drought, and storms. Assessed through hazard, exposure, and vulnerability.

Financial and operational risk arising from the shift to a low-carbon economy, including policy change, technology substitution, and reputational or litigation pressure. Distinct from physical climate risk.

An asset that loses value ahead of schedule because of market, policy, or technology change, such as fossil fuel reserves unusable under a carbon budget. A key transition risk for investors.

Adjustments in systems or behavior to reduce harm from actual or expected climate impacts, such as flood defenses, cooling, or drought-resistant crops. Complements mitigation, which addresses causes.

The capacity of a system to absorb climate or other shocks and keep functioning, and to recover and adapt afterward. In grids, relates to redundancy, islanding capability, and restoration speed.

Structured exploration of plausible future pathways, such as warming levels or policy trajectories, to test how strategies perform under uncertainty. Common in climate risk disclosure.

The reference level of emissions or energy use against which a project, policy, or target is measured. Baseline choice determines the claimed savings and is a frequent source of dispute.