Positive Energy: how renewable electricity can transform ... - WWF UK

GLOSSARY
Anticyclone – A weather condition involving large-scale circulation of winds around a
central region of high atmospheric pressure. Effects of surface-based anticyclones include
clearing skies and low wind speeds.
Arbitrage – The practice of taking advantage of a price difference between two or more
markets: striking a combination of matching deals that capitalise on the imbalance, the
profit being the difference between the market prices.
Back up plant – Electricity generation capacity kept in reserve to maintain system
security and only used infrequently at times of high demand.
Capacity mechanism – A mechanism to ensure security of supply by paying for
capacity (generators, for example) to be available.
Combined Cycle Gas Turbine (CCGT) – A form of power generation with higher
levels of efficiency than OCGT (see below).
Committee on Climate Change (CCC) – An independent body set up to monitor the
UK’s progress towards the Climate Change Act targets and advise the government on how
to meet these targets.
Curtailment – The practice of reducing the output of a generator to below what it is
capable of producing.
Decarbonisation – The practice of reducing the volume of carbon dioxide emitted per
kWh of electricity produced.
Demand side management – The practice of encouraging consumers to use less
energy during peak hours through methods such as financial incentives. This may be
done through ex ante tariffs which are fixed in advance based on expected demand at
different times of day (Economy 7 tariffs work in this way) or ‘active’ pricing based on real
time fluctuations in actual supply and demand patterns.
Dispatchable generation – Electricity generation which can be turned on or off at any
time in response to demand.
WWF-UK 2011 Positive Energy page 58