By John Kemp
LONDON, June 28 For a few hours in the dark,
cold winter evenings between October 2015 and March 2016,
Britain's National Grid may come uncomfortably close to being
forced to disconnect some electricity customers as demand
Before resorting to disconnections, the grid operator and
the power utilities will do everything possible to keep the
lights on - reducing customer voltages, ordering generators to
run flat out and introducing emergency restrictions on
electricity exports to France and Ireland.
Nonetheless, there is a one-in-12-year risk that power
utilities will begin controlled disconnections at some point in
the winter of 2015/16, according to a new report from the
government's Office of Gas and Electricity Markets (Ofgem).
The threat could be even higher if there is a period of
unusually cold weather or if power demand does not continue to
fall as National Grid expects. In the worst scenario, the risk
of controlled disconnections could be as high as one-in-two.
That would represent a sharp increase from last winter, when the
risk of disconnections was just one-in-47.
In a touch of irony, the faster the economy recovers, the
greater the risk of power shortages in 2015.
Spare capacity is shrinking to dangerously low levels, Ofgem
explained in its "Electricity Capacity Assessment Report 2013"
published on Thursday.
Tables 10 and 11 in the report show just how close Britain
could come to controlled disconnection in the next few years ()
Under the grid code, if electricity starts to run short,
power distributors first appeal to large industrial and
commercial customers to reduce demand voluntarily, then extend
the appeal to residential customers, urging them to avoid using
appliances at peak times.
If voluntary conservation is not enough, distributors start
forcible disconnections, beginning with the largest industrial
users and cutting power supplies to households only as a last
For residential customers, blackouts remain highly unlikely.
But there is a real risk that industrial and commercial users
will be asked to undertake voluntary conservation or be forcibly
disconnected on some of the coldest days in the winter of
Beyond 2015/16, capacity margins should improve again and
the risk of disconnection fall as more wind farms are connected
to the grid and at least some new gas-fired and biomass-powered
generating units are added.
UNREALISTIC ENERGY TARGETS
If the lights are extinguished in 2015/16, the blame will
fall squarely on the European Union, which has forced more than
8 gigawatts of coal-fired generation capacity (more than 10
percent of Britain's total generating potential) to close since
2008, and with poor implementation by the British government,
which has failed to plan for adequate and timely replacements.
Green campaigners often emphasise the importance of
"technological forcing" - using ambitious regulations to force
industry to ditch old and polluting systems and deploy cleaner
new technology. But the threat to Britain's power supplies shows
what happens when the single-minded pursuit of clean energy
comes at the expense of other important objectives such as
controlling costs and ensuring reliability.
If parts of the country are plunged into chilly darkness in
the winter of 2015/16 while the landscape is dotted with large
coal-fired power plants sitting idle because they cannot operate
because of emissions regulations, it will trigger a ferocious
Ministers and power companies urgently need to find some way
to allow some coal-fired plants to remain on stand-by at least
In the longer term, the government must show that its plans
for capacity provide a realistic mix of fossil fuel generation,
renewables and demand response to ensure that service quality is
maintained at an acceptable cost, even as greenhouse emissions
POORLY DESIGNED POLICIES
Ministers and power market regulators often seem surprised
by the looming electricity crunch. But it stems directly from
policies crafted by the government in London and the European
Commission in Brussels and could have been entirely avoidable.
The EU's Large Combustion Plant Directive (LCPD) will force
12 GW of coal and oil-fired generating capacity to close by the
end of 2015, according to Ofgem. Some older, combined cycle gas
turbine (CCGT) plants are also likely to close around the middle
of the decade as they reach the end of their technical
In their place, Britain has installed a huge number of wind
turbines. Wind capacity has been growing for more than a decade
and is set to double again from 10 GW in 2013/14 to 20 GW by
The problem is that wind is much less reliable because it is
not necessarily available when needed most. Coal, gas and
oil-fired generating units are assumed to be able to produce 85
to 90 percent of their rated capacity on demand (allowing for
maintenance and unplanned outages). The grid can rely on wind
farms to produce only about 17 to 24 percent.
New wind capacity is therefore a poor replacement for the
coal and gas-fired plants that are retiring.
Declining demand, meanwhile, has helped offset the loss of
coal generating capacity. Electricity consumption has been
falling since 2008, partly as a result of the recession and
partly because of the implementation of energy efficiency
measures, such as a ban on the sale of incandescent light bulbs.
Regulators and the grid are relying on demand response
later in the decade to help offset the increased variability of
the power supply caused by the rising share of renewables on the
Demand response is expected to increase once smart meters
have been rolled out and customers have been moved onto
time-of-use tariffs, which charge them more for using
electricity at peak times such as winter evenings.
In the meantime, though, neither Ofgem nor the grid operator
is certain how demand will change over the next three to four
"A DAMNED CLOSE-RUN THING"
Demand is likely to start rising as the economy continues to
recover from the recession. Ofgem and the grid operator say,
however, that energy efficiency measures could trim peak power
consumption during an average cold spell by around 0.7 percent
by 2015/2016. Demand response could shave another 0.6 percent
from the peak.
Power consumption during 2015/16 cold spell peak could be
anywhere from 1.5 percent higher to 0.4 lower than in 2012/2013,
according to Ofgem.
Ofgem is unsure how much spare generating capacity might be
available to meet that peak demand, but it could be as little as
2 percent in 2015/16, compared with 6 percent now.
Under normal grid operating conditions, generation could
fall short of demand for three hours in 2015/2016, compared with
just one hour last winter, a metric that grid operators call
"loss of load expectation".
But because of the tremendous uncertainty about demand,
energy efficiency and demand response, the loss of load
expectation could range anywhere from two hours to nine hours in
The nightmare scenario is that an area of high pressure
lingers over the UK for several days, bringing cold weather and
clear skies, which would maximise heating demand but idle the
fleet of wind turbines.
At around 1730 GMT, as some customers arrive home and turn
on the heating and start preparing the evening meal while
industrial and commercial buildings are still in use, capacity
could be stretched to breaking point.
The loss of load expectation does not automatically mean
customers will be disconnected. The grid can cope with a
generation shortfall of up to 500 MW by turning down the
voltage. Another 250 MW can be bridged by ordering all
generators to run absolutely flat out, exceeding their normal
In a last desperate bid to keep the lights on, the grid can
halt all power exports to Ireland and France and request
emergency imports via the interconnectors, making up perhaps
another 2,000 MW.
But if power demand exceeds generation by more than around
2,750 MW, the grid would have no option but to ask power
distributors to start the controlled disconnection process. It
could get very close for a few hours in 2015/16.