Modelling GIC in the UK

Although the UK is not normally considered to be at risk from geomagnetically induced currents (GIC, see page 5.23), recent severe geomagnetic storms driven by solar activity have resulted in large GIC being observed in Scotland. Although not large enough to cause blackouts such as those in Sweden and Canada, they are indicative of the potential problems during large geomagnetic storms, which can occur with little warning. As society becomes ever more dependent on technology, the space-weather hazard should be assessed for mid-latitude countries such as the UK. As this is a relatively small country, its power network (the National Grid) does not contain the long power lines present in countries such as Canada, which can produce large GIC. However, the UK grid is complex and with the future possible inclusion of, for example, isolated wind farms, may soon include longer lines. The UK also has a complicated geological structure and is surrounded by a shallow sea shelf, with the deep ocean on one side and continental Europe on the other — factors that play a role in the production of GIC during geomagnetic storms. In addition, the National Grid is not isolated; it is connected to Northern Ireland and France by undersea direct current power transmission lines. In the long term this means that the effect of GIC in Europe needs to be considered. For the time being, we have studied the UK in isolation.