Glossary

26 terms:

Cap and trade schemes

Cap and trade schemes establish binding controls on the overall amount of emissions from participants. Within this quantity ceiling, entities covered by the scheme are then free to choose where best to deliver emission reductions within the scheme by trading units which correspond to quanities of abatement.

Capacity factor

Energy produced by an electricity generator as a percentage of that which would be achieved if the generator were to operate at maximum output 100% of the time. E.g. the capacity factor of a 1 GW offshore wind farm may be 40%, which means over a year (8,760 hours) it would generate 40% * 1 GW * 8,760 = 3,504 GWh.

Capacity payment

Payment to energy supplier for providing a guaranteed level of capacity over a period of time

Carbon Capture and Storage (CCS)

Set of technologies to capture the carbon dioxide emitted from industrial processes or from burning fossil fuels or biomass, transport it, and store it in secure spaces such as geological formations, including old oil and gas fields and aquifers under the seabed.

Carbon credits

Carbon credits purchased in international carbon markets, generally corresponding to 1 tCO2e per credit. Also referred to as 'carbon units' in the Climate Change Act. It is not clear how carbon markets will develop in the future; however currently credits include allowances purchased in schemes such as the current EU ETS, or offset credits from project-based schemes (e.g. such as those generated under the Kyoto treatyÕs project-based flexibility mechanisms, Joint Implementation and Clean Development Mechanism).

Carbon Cycle

The global flow of carbon (in various chemical forms such as carbon dioxide) through the atmosphere, ocean, terrestrial biosphere and lithosphere.

Carbon dioxide equivalent (CO2e) concentration

The concentration of carbon dioxide that would give rise to the same level of radiative forcing as a given mixture of greenhouse gases.

Carbon dioxide equivalent (CO2e) emission

The mass of carbon dioxide emission that would give rise to the same level of radiative forcing, integrated over a 100-year time period, as a given mixture of greenhouse gas emissions.

Carbon Emissions Reduction Target (CERT)

CERT is an obligation placed by Government on gas and electricity suppliers to deliver household carbon savings across England, Scotland and Wales.

Carbon leakage

Carbon leakage occurs when there is an increase in emissions in one country/region as a result of emissions reduction by a second country/region with a strict climate policy.

Carbon price

The price at which 1 tCO2e emissions can be purchased. We use projections for the carbon price as a comparator for judging cost-effectiveness of potential emissions reduction measures.

Carbon price underpin / floor

Policy to ensure a set minimum amount is paid for every unit of carbon dioxide emitted.

Carbon Reduction Commitment (CRC)

A mandatory carbon reduction and energy efficiency scheme for large non-energy intensive public and private sector organisations. The CRC captures CO2 emissions not already covered by Climate Change Agreements and the EU Emissions Trading System.

Carbon sink

An absorber of carbon (usually in the form of carbon dioxide). Natural carbon sinks include forests and oceans.

Climate

The climate can be described simply as the 'average weather', typically taken over a period of 30 years. More rigorously, it is the statistical description of variables such as temperature, rainfall, snow cover, or any other property of the climate system.

Climate objective

To keep central estimates of global mean temperature change as close to 2 degrees as possible, and to limit the likelihood of temperature change above 4 degrees to very low levels.

Climate sensitivity

The response of global mean temperatures to increased concentrations of carbon dioxide in the atmosphere. It is typically defined as the temperature increase that would occur at equilibrium after a doubling of carbon dioxide concentration above pre-industrial levels.

Co-firing

Combustion of two different materials at the same time

Coefficient of performance

The amount of heat a heat pump produces compared to the total amount of electricity needed to run it.

Combined Cycle Gas Turbine (CCGT)

A gas turbine generator that generates electricity. Waste heat is used to make steam to generate additional electricity via a steam turbine, thereby increasing the efficiency of the plant.

Combined Heat and Power (CHP)

The simultaneous generation of heat and power, putting to use heat that would normally be wasted. This results in a highly efficient way to use both fossil and renewable fuels. Technologies range from small units similar to domestic gas boilers to large scale CCGT or biomass plants which supply heat for major industrial processes.

Community Energy Saving Programme (CESP)

CESP targets households across Great Britain, in areas of low income, to improve energy efficiency standards and reduce fuel bills. The programme is delivered through the development of community-based partnerships between local authorities, community groups and energy companies, via a house-by-house, street-by-street approach.

Contract for Difference (CfD)

Form of hedging on the future price of a commodity in which a strike price is pre-specified. Payments are made between counterparties depending on the difference between the strike price and the market price at the time.

Contrail

A line of cloud caused by aircraft flying through supersaturated air. Contrails have a significant warming effect on surface temperatures but this only lasts up to a few hours.

Copenhagen Accord

The document that delegates of the 15th Conference of Parties to the UNFCCC agreed to 'take note of' in December 2009. The text endorsed the continuation of the Kyoto Protocol, but is not legally binding.

Credits

Emissions credits purchased in international carbon markets, generally corresponding to 1 tCO2e per credit. Also referred to as 'carbon units' in the Climate Change Act. It is not clear how carbon markets will develop by the 2020s. Therefore, where we refer to credits for the 2020s these could be allowances purchased in schemes such as the current EU ETS, or offset credits from project-based schemes (e.g. such as those generated under the Kyoto ProtocolÕs project-based flexibility mechanisms, Joint Implementation and Clean Development Mechanism).