2 Background
What is a supergrid?
9. The term "super grid" was first
used to describe the unified British national electricity transmission
system over fifty years ago. The concept of a UK supergrid is
defined in the British Grid Code as a transmission system operating
at voltages above 200 KW. In the 21st Century, however,
the term "supergrid" is used to describe a number of
different kinds of interconnection between international electricity
systems, often incorporating generation assets as part of the
system. In other words, the same transmission lines would connect
up different countries' electricity systems as well as a variety
of power generators such as offshore wind farms. Ideas range from
a more integrated offshore grid in the North and Irish Seas to
a network of "super highways" across Europe and into
Africa and Asia.
10. A supergrid was defined by the Friends of
the Supergrid as an electricity transmission system, mainly based
on high voltage direct current (HVDC), designed to facilitate
large-scale sustainable power generation in remote areas for transmission
to centres of consumption, one of whose fundamental attributes
would be the enhancement of the market in electricity.[6]
As well as enabling the transmission of electricity from areas
of excess supply to where it is needed, a supergrid could also
enable wider access to physical electricity storage options, such
as pumped storage in Scandinavia and the Alps. This could help
to balance out fluctuations in intermittent renewables supply
with affordable, low-carbon generation.[7]
11. Friends of the Supergrid have set out suggestions
for Phase I of a supergrid, which would integrate the UK's offshore
renewables resources with interconnection with Germany and Norway.
Figure
1: Friends of the Supergrid, Phase 1
Source: Ev 68 (Friends of the Supergrid),
section 3
12. A supergrid could represent a revolution
in the scale and ambition of interconnection and offshore grid
integration. At the moment, national electricity systems remain
largely separate, each state providing for its own supply to meet
demand. The UK is particularly insulated from its neighbours.
A supergrid implies that a much greater degree of interconnection
between national electricity systems would be possible, allowing
them to draw on shared resources to meet demand. John Scott, of
the Institute of Engineering and Technology, told us that whilst
the UK currently had a 2 GW link with France, a 20 GW link could
be possible.[8] He suggested
that "you have to think of [a supergrid] as a system, not
as a series of electrical pipes. It has to become a system, which
means that it has to be balanced in real time between generation
and demand". [9] In
other words, a supergrid could be a complex transmission network,
potentially coordinating dispatch and supply of electricity across
several jurisdictions.
13. However a supergrid is not just about increased
interconnection, it is also about integrating offshore renewable
generation into the transmission system in order to optimise the
output of technologies like offshore wind, marine and tidal energy.
At the moment, these resources are connected to the onshore system
individually by "radial" or "point-to-point"
connections.[10] A supergrid
could integrate these connections into the transmission system
itself, saving money, reducing the need for new connections and
enabling more efficient sharing of resources.
14. Stuart Cook, from Ofgem, explained that a
supergrid could entail different mixes of interconnection and
integration of offshore renewables within the transmission system:
The range of options that the transmission companies
in Europe have looked at span from, at one end, something that
simply is point-to-point, which is more or less the way that the
system has evolved so far; to a system that involves optimisation
of the onshore connection; to a system that involves the optimisation
of the onshore connections and the interconnections across countries;
to something that, at the extreme, is a meshed system looking
like a grid on the sea.[11]
15. In this Report, we will refer to an offshore
grid, integrating renewable generation and interconnection, as
a kind of "supergrid". Further details of the different
visions for a supergrid currently under development can be found
in Annex II.
6 Ev 68 (Friends of the Supergrid) Back
7
Ev 47 (DECC), section 17; Ev 56 (Ofgem), section 1.12 Back
8
Q 2 [John Scott]; Ev w32 (Centrica), section 14 Back
9
Q 2 Back
10
Q 1 [Eddie O'Connor] Back
11
Q 62 Back
|
