Energy transition explained

The amount of energy needed to meet consumers’ needs (i.e. energy consumption).

Measures to reduce overall energy consumption – often refers to physical material changes (insulation and technology) but can also refer to behavioural changes of the customers or improved control of existing equipment.

A form of contract used to undertake construction works by the private sector on large-scale and complex infrastructure projects. The companies that undertake these projects are called EPC contractors. 

Flexibility is the ability of electrical generators and consumers to alter their output or consumption on demand. It can be provided by assets ranging from large front-of-meter generation to residential appliances.

Reserves which are constantly used by the system operator to maintain system frequency as supply and demand constantly changes. It is automatically activated and is the fastest response possible once deviation from the reference frequency has been detected. It is sometimes called primary reserve. In the UK, the term firm frequency response (FFR) is used. 

Frequency is a crucial parameter in an AC electric power system. Deviations from the design frequency are a consequence of imbalances between supply and demand. Frequency response (FR) is a necessary part of any AC power system to keep the system operating at its design frequency. FR is usually procured via ancillary service markets.

This reserve includes both automatic (aFRR) and manual (mFRR). It restores frequency after an unexpected event. It is slower acting and longer duration than FCR. aFRR is secondary reserve and mFRR is tertiary reserve. 

An asset connected directly to the electricity transmission or distribution network, instead of behind a customer meter.

A gas transportation system that delivers gas to industrial, commercial and domestic customers.

Geothermal energy is the thermal energy generated and stored inside the earth. This can be recovered and used to raise steam to produce electricity. Note that this does not refer to the heat stored in shallow ground, which can be used as a heat source for ground source heat pumps. 

Green gases, mainly agricultural waste and residues and food wastes, which are used to produce renewable gas to inject into the gas grid or are burnt to produce electricity. Biomethane is commonly purchased as a vehicle fuel for buses and lorries at a refuelling station connected to another part of the gas grid.

A business model for how businesses sell heating, where customers pay for an outcome, such as feeling warm and comfortable in their homes at a time that suits them, rather than paying for kilowatt-hours of energy.