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The Changing Face Of UK Electricity Supply

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Euan Mearns, Energy Matter

Natural gas, which produces less CO2 per GWh than coal, is being squeezed out of the UK generating mix

Figure 1 Stacked area chart showing the contributions to the UK grid from various generating sources for March 2013. Similar charts for January, February and April can be found in an earlier post. With 9000 lines of data, it is not easy to display a time scale on the x-axis. The peaks represent days with the 1st of March to the left of the chart. The “Other” category includes French, Dutch, Irish and EW imports / exports via inter-connectors, pumped storage, conventional hydro, oil, open cycle gas turbines and “other”. Data from BM reports as reported by Gridwatch.

Balancing Mechanism (BM) reports as recorded by Gridwatch provide insight to exactly how the UK grid is coping with and responding to the ever growing amount of intermittent wind energy. The key observations are detailed below, the evidence is below the fold.

  • There is no evidence that integrating wind has impaired the efficiency of combined cycle gas turbine (CCGT) or coal fired generation.
  • The rate of load change to accommodate wind is no greater than the diurnal load cycle to accommodate demand.
  • Wind is variable and is just as likely to be blowing at night when demand is low as during the day when demand is high (Figure 1).
  • CCGT (gas) bears the brunt of load balancing in the UK for both diurnal demand and wind variability.
  • A consequence of this is that CCGT is losing market share to wind whilst providing an ever larger and more valuable load balancing service.
  • Reduction in coal generating capacity meant that coal fired power was running at capacity for periods last winter.
  • Nuclear was also running at capacity for periods during the winter months.
  • UK gas storage was run down to near zero April 2013 (source Rune Likvern atFractional Flow), the result of a colder than normal winter and competition for LNG from Japan (Source National Grid).
  • Continued growth of wind is going to squeeze CCGT (gas) out of the system – which is a consequence of the 2008 Climate Change Act. At some point CCGT generation may become unprofitable, but since it also provides essential grid balancing service, the industry may have to transfer to state ownership.
  • Wind electricity displacing imported gas has a positive impact upon UK trade balance.
  • Within a  tight European gas market, wind power is making a contribution to keeping the UK grid operational. Without wind, the UK gas and electricity security situation would have been worse last winter
  • Had the UK government commissioned 20GW of nuclear power 10 years ago, this situation could have been avoided.

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