But concern is voiced for the longer term as the government admits that replacement nuclear capacity has slipped. It now estimates new plant will not be online until "around 2025.' The estimate of 2020 was the official date two years ago.

With the recent German nuclear closure, losing it approximately 8GW may have a knock-one effect to the UK electricity market, impacting imports and exports and possibly at peak demand, as Germany, once a net electricity exporter becomes a net importer.


UK  GRID INTERCONNECT
Given that the UK is interconnected with France and The Netherlands, this could result in demand for GB electricity increasing at periods of high demand.

The UK currently has a 2GW link to France, a 500MW link between Northern Ireland and Scotland (max low into GB is 295MW) and a 1GW connection with The Netherlands, which became operational in April 2011. (This inter-connector can run harder (up to 1.2GW) in exceptional circumstances).

Increased interconnection may provide important security of supply benefits, as access to additional power supplies could help manage fluctuating supply. But tighter markets and higher prices outside UK means exported electricity and tightening the UK market.

Evidence from the US and Europe is that extensive interconnection across System Operator boundaries can lead to difficulties in predicting power lows, particularly when faults occur and circuits trip. However, this can be managed through close cooperation and information exchange between System Operators and is less of a problem with direct current interconnection, as power lows can be controlled.

National Grid accordingly is a member of the CORESO grouping of European TSOs. CORESO is a coordinating body that gathers real-time system information from all member TSOs and assists with system planning to avoid/mitigate such emergency situations and maximise the use of cross border capacity.

In September 2012 the 500MW East-West Interconnector (linking the UK and Irish electricity grids) goes live. In addition, National Grid Interconnector Limited (NGIL) a National Grid subsidiary) has several planned further links, with Belgium, Norway and France and a number of other third party developers have also expressed an interest in building links between GB, Norway, Denmark, France, Spain and Iceland.

It is not clear which links will be realised; but a conservative estimate is that by 2020 an additional
2-3GW of interconnection will be built, just less than 10% of installed generation.

NUCLEAR CLOSURE

Existing generating capacity in the UK stands at 90.2GW. Closure of a number of coal and oil fired plant considered polluting and nuclear plant scheduled to end their working lives will lose around 12GW of coal and oil fired generated by end of 2015 at the latest with further possible closures by 2023.  

Also 7.1GW of nuclear power will close by 2020, meaning a total 19.1GW will be closed by 2020 and more by 2023.

Around 8.3GW new plant will connect to the National Grid and is already being built. 4.3GW is gas plant and 3.6GW is renewable. A further 13.2Gw has permission, of which 8.7GW is gas fired generation and 3.7GW renewable. Total new and consented plant is 21.5GW replacement, and nuclear may be constructed by 2025.

National Grid's seven year statement shows that 3.6GW of transmission connected renewable electricity projects are under construction. An additional 7.3GW renewables that will connect are under construction or consented, and a further 5.7Gw submitted planning applications, predominantly off-and-onshore wind and biomass generation with majority capacity being over 50MW.

The schedule nuclear slippage is in line with recent pull-outs by some nuclear power developers afterFukushima, and delays in construction of Areva's Pressurised Reactor type Olkiluoto plant in (right) Finland, where completion is now put at 2014.

Expected to be built in the UK, this type is lagging its schedule by five years. New nuclear plant can not now help the UK to meet its 2020 carbon emission reduction targets.

Ofgem's estimate last year that the gas and electricity markets need ￡200bn investment between now and 2020 to meet the challenge of keeping power available, while reducing emissions, is re-confirmed in the current report.