It is a well-reported fact that electricity margins are tighter than they have been for years and, as we move towards winter, talk will increasingly turn to the need to balance energy supply and demand to mitigate the risk of blackouts in the UK.
Almost all of the UK’s grid balancing has traditionally been done by coal and gas. But the EU’s Large Combustion Plant Directive has limited running hours at a number of plants, and in the past 12 months both Longannet and Eggborough power stations, which currently provide around 5 per cent of the UK’s capacity, have announced they will be closing their doors in 2016.
Add to this the solar and wind explosion – experts predict that by the end of 2015 the UK will have 10GW of solar capacity, a benchmark most thought would not be reached until 2020. By 2020, National Grid’s future energy scenarios indicate that small-scale, distributed generation will represent a third of total capacity in the UK.
The transformation of the energy system from centralised generation to small-scale, distributed power means that speed of response to changes in energy supply and demand will be more important than ever.
Indeed, although most people are focusing on the tight capacity margin between supply and demand, the real blackout threat could come from generators unable to respond within the required window to balance instantaneous shifts on the grid.
For more than 12 months, energy data analysts at EnAppSys have been monitoring grid frequency and analysing large deviations that, if not managed, can lead to instability. Paul Verrill, director of EnAppSys, says that although we must ensure the system has sufficient supply to meet demand, the real risk of blackouts could come from this second issue that often falls under the radar: a lack of capacity able to deliver extra power in the required timeframe.
Grid agility and flexibility will be essential as we move away from models of centrally dispatched generation, and National Grid, through its Power Responsive campaign, has already asserted that demand-side response (DSR) will play an increasingly vital role in building a resilient, sustainable and affordable electricity system for the future.
This is especially pertinent given the results of new research by Open Energi, National Grid and Cardiff University, which suggests that smart demand-side response technology can meet the UK’s crucial grid-balancing requirements faster than a conventional power station.
The paper, part of the ongoing collaborative research programme between Open Energi, National Grid and Cardiff University, is titled Power System Frequency Response from the Control of Bitumen Tanks, and looks at the feasibility of DSR to provide a significant share of frequency-balancing services.
To test the scale of the opportunity for industrial heating loads to balance the power system, bitumen tanks (which contain the glue that binds our roads together) equipped with dynamic demand technology were tested in combination with National Grid’s model of the GB transmission system.
Dynamic demand deployed on a large scale can contribute to grid frequency control in a manner similar to and, crucially, faster than traditional peaking power generation – and more cleanly and cheaply.
Field tests showed that full response could be achieved in less than two seconds, compared with 5-10 seconds for a thermal generator. Large-scale deployment of dynamic demand will reduce dependence on frequency-sensitive generators and ensure the grid stays balanced.
The simulations help shape National Grid’s understanding of DSR as a replacement for frequency-sensitive generation and will be used when it is planning its requirements for future grid network operation.
When National Grid chief executive Steve Holliday launched Power Responsive, he said: “Supply is only half the story. The challenge now is to exploit new opportunities to radically evolve our energy system by changing the way we use electricity.”
This is why the research is so significant.
With more renewables and decreased thermal generation, “inertia” on the grid will decrease, making frequency more unstable. To counteract this effect we need faster response, so by rolling out dynamic demand today we are future-proofing the grid.
With its Power Responsive campaign, National Grid has recognised the need for a new kind of flexibility and has said it is committed to scaling up the smart DSR industry.
By knowing when to increase, decrease or shift their electricity consumption, businesses and consumers will save on total energy costs and can reduce their carbon footprints. It is the smart way to create new and efficient patterns of demand.
Chris Kimmett, commercial manager, Open Energi