Blackout Britain is a headline which has become increasingly common over recent years. Many argue that decades of under investment in generation infrastructure has left the margin between demand and supply in the UK desperately short, raising the possibility of network outages at times of high power demand. Given the blame that would be landed at the government’s feet were the lights to go out, energy security has been given top priority over the other facets of the energy trilemma; decarbonisation and affordability.
The government’s solution to this was to devise the Capacity Market as a mechanism to encourage investment in new power plants, with yearly auctions for participants who can provide capacity over the winter peak. Crucially, auctions are held four years in advance of the capacity ‘go live’ date, to guarantee revenue and give investors the confidence they need to build new power stations.
There are, however, major flaws in the thinking behind such an approach. There is much evidence to suggest that the UK is in fact well supplied with power station capacity, that building more stations is unnecessary and that running the system more efficiently on tighter margins is a good thing. And by ensuring there is sufficient power plant capacity to meet the instance of highest demand in the year other potentially greater threats to security of supply are being ignored.
The graph below shows the frequency of the UK grid, which is the primary indicator of the system stability. The network is in balance when the frequency is hovering around the 50Hz mark, however any significant variation either side is a sign of a serious imbalance between generation and demand and could result in a potential shutdown of the network. This isn’t a distant threat: whole towns had to be shut off as an emergency measure in 2008 when grid frequency dropped to 48.8Hz.
In this case, we can see what happed to the frequency when a large supply source – an interconnector between the UK and France – failed, leading to more power being drawn by consumers than was being supplied to the grid. To counteract the resulting frequency drop and avoid a system shut down, a series of automatic measures kicked into action, including turning up thermal power plants (coal and gas) and sending water reserves cascading through turbines of hydroelectric plants.
More recently on 9 May 2016 there were 37 significant failures across 27 different coal and gas plants as well as the France interconnector; with each one disrupting frequency and testing the grid’s resilience. At one point in the day National Grid issued a warning that insufficient spare capacity would be available in an hour’s time. This is too short notice for a thermal plant to start up (which takes around four hours) so not something the Capacity Market would have helped with.
National’s Grid’s Head of Commercial Operation Cathy McClay has said managing the grid frequency is becoming an increasing headache for our island system. However, the technologies traditionally used to respond in these situations look increasingly unfit for the role. The best new candidate is demand side flexibility – in the form of batteries and demand side response – which offers numerous benefits.
Energy storage and demand side response offer five core advantages over traditional solutions
- Speed of response: Demand side response and batteries can deliver their full power in under 1 second from receiving a request from the network. By comparison thermal plants and hydroelectric generators need around 10 seconds. As the interconnector example shows, this difference is crucial for avoiding a potential network shutdown and will be needed more and more due to continued reductions in system inertia.
- Decentralisation: Demand side response and batteries are distributed technologies meaning a required level of response can be made up from aggregating together many smaller sites. We have seen how relying on large centralised technologies (like the undersea link to France) poses increased risk to system stability as they represent significant single points of failure. Thermal power stations fail on a daily basis so individual plants cannot be relied upon for response; whereas with distributed technologies this risk is shared across many assets; if one fails the whole service is not compromised.
- No need for spinning reserve: Traditional providers are only able to achieve the 10 seconds or so when starting from an already running position, hence the generators must be operating at some partial output to provide the quick response. This impacts fuel efficiency by around 10-20%, greatly increasing costs and CO2 emissions.
- Flexibility: The network can only absorb as much power as there is demand, so at times of low demand, National Grid must turn down clean and zero marginal cost power from renewable sources like wind to accommodate the thermal generators which must be kept running for frequency response. Demand side response and batteries overcome this problem.
- Low carbon: By maximising the use of demand side response and energy storage technologies, the UK will be able to achieve further growth in renewable generation; while reducing its reliance on interconnectors and its exposure to volatile gas prices.
The high capacity fossil fuel plants which have historically been used to respond to the demands of the grid are increasingly unfit for purpose in a modern electricity network, yet the Capacity Market fails to encourage the development or implementation of smarter, cleaner and decentralised solutions which would provide a more efficient means of addressing both our energy security and other elements of the trilemma.
Neglecting these alternative solutions via the Capacity Market will undermine exactly the thing Government is trying to advance: security of supply. National Grid should be applauded for its efforts to implement change through its Power Responsive campaign – designed to encourage demand side participation in the balancing markets – but many policy makers remain locked into the old paradigm of an archaic industry; no doubt weighed down by the stranglehold of well-established energy incumbency (better known as the Big Six).
For these parties, using distributed assets to balance the system still represents a significant departure from the orthodoxy of constructing and operating a few large centralised assets like Hinkley Point C, which will deliver 7% of all UK electricity when completed.
To achieve a real paradigm shift towards a secure, affordable and low carbon economy, we don’t even need to find new solutions. Distributed and demand side technologies are ready to deliver; we now need to change the supply-focused mind set of our policy makers and operators.