In July 2018 National Grid stated that widespread power outages were a risk that occurred only once every 12 years. The events on Friday 9th August that led to one million people losing power as well as transport being disrupted for around two hours is evidence that the Grid is more vulnerable today than it was in the past as traditional thermal plants have been closed and we rely more on renewables. It was fortunate this power cut was not in the winter when demand is typically at its highest.
The August Power Outage
The problems on Friday are still being analysed but two contributory factors were evident. Firstly, the Hornsey wind farm failed quickly followed by a gas fired power station, which collectively meant a sudden loss of around 5% of the grid’s electricity (around 1.4 GW of power).
Secondly, as a result of these power outages, and the fact that around 30% of the power being supplied to the grid was from wind, there was less inertia within the grid to protect against sudden frequency changes. The grid frequency dropped below 49Hz which automatically triggered the disconnection of certain parts of the network, causing power cuts until the system came back into balance and frequency stabilised.
How do we plan for the future and manage potential power outages?
It is rare that two key sources of power fail almost simultaneously but it is not unheard of, and with the increasing reliance on wind and solar in particular, new stability and reliability problems can be expected in the future.
Although the position is complex and there are still questions to answer, there are three considerations for the future:
1. Natural gas will play a critical role in providing ‘back-up’ power for decades to come. Indeed, without it this country will not have a reliable energy system. The faster the response, the lower the cost and the smaller the carbon footprint of providing this back-up power of course the better;
2. We will become more dependent on electricity than we probably realise as we aim to electrify more of our heating systems and transport, particularly electric vehicles; and
3. The need to manage the grid itself has certainly become more complex as the country becomes more reliant on wind and other renewables with significantly less inertia on the system. Here batteries and the use of innovative ways of maintaining inertia will need to play a role.
Friday’s power outages provide a useful impetus to the efforts of Government, Ofgem, National Grid and the DNO’s to keep working at this. For Statera’s part we are pleased to be at the centre of this making a real contribution to this transition by two means:
1. Battery storage: They can respond to a crisis like the one on Friday in milliseconds, to counter the frequency drop by exporting power to the grid. Statera operates two of the largest battery sites in the UK which provided around 100 MW in capacity throughout the stress event. More batteries will mean a greater ability to counter similar frequency drops.
2. Natural gas back-up generation: While batteries can help with the need to instantaneously stabilise frequency, this technology and its finite capacity ultimately limit the extent of the services it can provide. Batteries cannot therefore replace substantial lost generation for sustained periods. Using natural gas to generate electricity quickly to cover lost supply is therefore critical. As the last of the coal plant are decommissioned, and the older nuclear and gas plant come to the end of their lives, we must have the right back-up power sources in place to cover the intermittency of wind and solar, the increased demand for electricity and to ensure we ‘keep the lights on’.
Clear policy support is needed from Government to build-up the country’s back-up provision but at Statera the sense is that we have proved the technology, the finance is available and with others in this space answers can be provided quickly, effectively and reliably.