We are responsible for managing the flows of electricity to
homes and businesses on a real time basis. Once electricity is generated and
enters our network, our job is to ‘balance’ the network, ensuring supply and
demand are matched second by second.
Balancing the system to make sure that demand is met by supply
is one of the most important things we do, and it is becoming more challenging
as intermittent generation – such as wind power – becomes a bigger part of the
overall energy mix.
As we continually work to balance the system, we can ask
generators of all kinds – not just wind farms – to come on or off the grid to
help us balance supply and demand, or to manage ‘constraints’ – effectively
bottlenecks – in the network.
This is something we do many times every day, and have done for
many years. It is a normal part of our job, and we have a number of well-proven
tools to help us do it, including buying generation onto or off the network one
or two days ahead of real time, and bids on the balancing mechanism within one
or two hours of when the energy is needed.
Our demand forecasting team is always planning ahead, so we can
make sure there is enough back-up power available to cover any potential
shortfall, whether that’s due to a power station breakdown or an unexpected
For instance, in very high winds, many wind farms will shut down
their turbines for their own protection, often automatically. When that happens,
we can use our backup generation to balance the system.
Sometimes it works the other way too. In early January 2012, we
asked some wind farms in Scotland to stop generating for a few days. This was
for two reasons.
First, the very high winds were affecting the transmission
network, causing constraints. Also, demand in Scotland was low because of the
New Year Bank Holidays, so that additional energy wasn’t
There is a cost in this balancing activity, but it is very low
for consumers - no more than a few pence a year on a typical electricity bill.
As part of a ‘balancing mechanism’, each power station makes a ‘bid’ that
reflects what they are willing to be paid – or to pay – to be taken off or moved
on to the network.
In 2012/13, the total cost of balancing the network was
£803million which makes up around 1 per cent of consumer bills. Ofgem regulates
these balancing costs and gives us incentives to keep them down.
The balancing costs are made up of a number of elements and one
of these is constraint costs.
The total cost of constraints in 2011/12 was £324million. Of
this amount, £31million was for wind constraints.
The total cost of constraints in 2012/13 was £170million. Of
this amount, £7million was for wind constraints.
Wind constraints reduced because of the investment made in
reinforcing the transmission network. The reinforcements increase the capacity
to transport more energy, but while doing the work, we need to take parts of the
network out of service which reduces the capacity and leads to us needing to
constrain some energy in the interim.
Of course, more generation is connecting to the system so there
will continue to be outages to aid the investment of new transmission
infrastructure, which means we will still be managing wind constraints but not
proportionally to the capacity of installed wind.
We expect that new technology, from smart meters to innovative
forms of electricity storage, could offer new opportunities for large and small
consumers to help us balance the system.
We also carry out a number of consultations to give the rest of the industry an opportunity to
contribute to the debate.
Balancing the network FAQs