The difference between the highest and lowest prices recorded during a given trading period

Reactive Charges
Charges applied to a clients invoice in cases where certain suppliers and distribution companies enforce a penalty for Reactive Power use.

Reactive Power (kVAr)
This is the difference between the electricity supplied and the electricity converted into useful power. If the difference is large, i.e. there is a large amount of power being wasted, it puts an additional strain on the distribution network. This is measured via the Reactive register on a meter and is charged to the customer depending on how much they accumulate.

Reactive Power Charge (kVArh)
A charge levied by suppliers when the Power Factor falls below a given value.

The register is a series of dials (or digital displays) which record the amount of energy used. In CoP 5 meters, the meters can have up to 25 registers set up to provide information on, for example, demand peaks and totals.

Register Reads
These are the readings taken remotely of the various registers on a given meter.

Registered capacity
The full load capability of a generating unit less the energy consumed through the unit transformer.

All energy supply contracts must be registered by the proposed supplier. Registration can take from 3 to 6 weeks and it is, therefore, imperative that new supply contracts are agreed in sufficient time to avoid 'default charges' arising from late registration.

Remote Non Half Hourly Meters
These meters have a NHH set up but they are connected to a communication device.

Renewable Energy
Renewable energy is used to describe the energy produced using naturally replenishing resources. This includes solar power, wind, wave and tide and hydroelectricity. Wood, straw and waste are often called solid renewable energy, while landfill gas and sewerage gas can be described as gaseous renewables.

Renewable Energy And Energy Efficiency Partnership (REEEP)
An international partnership to promote the growth of renewable energy and energy efficiency systems, launched by the UK at the World Summit on Sustainability Development (WSSD).

Renewable Energy Certificates (REC's)
RECs, also known as Green Certificates, green tags, or tradable renewable certificates, represent the environmental attributes of the power produced from renewable energy projects and are sold separate from commodity electricity.

Renewable Energy Guarantee of Origin (REGO)
Electronic certificate used to provide evidence that a unit of electricity has been produced by a renewable generator. One REGO representing one kilowatt/hour of electricity. In some countries they are called Guarantees of Origin - GoOs.

Renewable Obligation (RO)
This is the main government market mechanism to support renewable energy. It is an obligation on all electricity suppliers to supply a certain amount of their electricity sales from accredited renewable sources under the Climate Change Levy exemption scheme.

Estimated volume of recoverable natural gas in a reservoir, based on drilling and geological/geophysical information.

Review of Gas Meter Arrangements (RGMA)
A project to determine industry wide business processes supporting data flows to underpin competition in gas metering services.

Roll Over
The transfer of a position from one futures period to another involving the purchase (sale) of the nearby month and simultaneous sale (purchase) of a further-forward month.

Roll-Over Clause
A clause inserted into some energy supply contracts which states that unless 'Termination Notice' is given prior to a set date the contract will continue for a further year.

The UK's main natural gas storage facility on the 'Rough Field in the North Sea.