Just how low can Britain’s power system go in terms of fossil fuels and carbon emissions?
Does Britain’s geography necessitate a minimum amount of dispatchable, flexible and thermal power on the system? Being an island, it is more expensive for us to build electrical links to other countries, than it is for example Germany to build them across its land borders. Similarly, our lack of mountains means that pumped hydro is never going to provide weeks or months of storage. Britain faces more challenges than most in this area, but that does not dampen the ambition for zero carbon electricity.
Some call it intermittency, some call it variability; the simple fact is we cannot control the wind.
Britain’s wind farm output swings widely from one week to the next, caused by high- and low-pressure weather systems passing over the country.
Wind output can vary from 2 GW one day to 12 GW the next1, and Britain can experience long lulls in wind output. For example, the mini heatwave at the end of February saw a 6-day long collapse in wind output. So, how can Britain balance out the variability that wind power brings?
From the chart below it is clear that gas is the main source of flexibility at the moment. We have sufficient capacity, and it is sufficiently flexible to ramp up or down by 10+ GW when needed. Nuclear output is stable over the course of the year, only varying due to maintenance. Coal provides extra balancing during the coldest weather (when gas prices are higher), but at most it flexed up and down by 5 GW (daily average) during January. Hydro and biomass also provide flexibility, but together they are dwarfed by the swings in wind power. Finally, interconnectors ought to provide flexibility, but at the moment it is more profitable to import at full power regardless of what the wind is doing.
Daily average output from wind farms (top) and other generating technologies (below) over the first three months of 2019
Britain has around 20 GW of wind capacity today, but National Grid and BEIS expect this could double to 40 GW in as little as seven years2. Doubling the current levels of volatility at a time when coal capacity is retiring will test the whole electricity system, and likely require new sources of flexibility. Three key options are available to us: (1) more interconnection, (2) energy storage, (3) new fuels such as hydrogen, or (4) using existing fuels to back up wind farms.
Balancing the wind with energy storage would need radically different technologies to those we have today. Britain’s pumped hydro storage plants usually operate on a daily cycle, charging up overnight and discharging during the day (although they are increasingly used to provide rapid response to grid fluctuations). Lithium ion batteries are for even shorter durations, typically holding less than 4 hours of charge, rather than the several days needed to balance out wind lulls. Electric vehicles, homes and offices could provide a large new source of flexibility in the near future, through vehicle-to-grid(V2G) and demand-side response (DSR).
Sticking to the present day, fossil fuels provide an almost-ideal counterbalance. They have a high energy density, are easy to store, and we already have the infrastructure in place to transport and use them. However, in a carbon-constrained world, we cannot continue indefinitely using unabated coal or gas to backup renewables. Biomass is an alternative, but we only have 3.2 GW today, and this is not expected to grow significantly over the coming decades. Ultimately, a mix of all these solutions will likely be the best route forwards.
A new interconnector to Belgium has pushed British electricity imports to record highs.
At the start of this year, the £600m Nemo link between Kent and Zeebrugge in Belgium came online. It adds 1 GW – or 25% – to Britain’s connections with neighbouring countries. The link has imported power to Britain every day it has been in operation, exploiting the price differential between electricity markets on either side of the channel.
As Britain’s electricity imports are on the rise, we look at how our neighbouring countries generate their electricity.
Europe’s electricity mix is diverse, ranging from fully-renewable through to heavy reliance on coal and gas. The graphic below details where our imported electricity comes from – mapping the current and proposed interconnectors to Britain, and the makeup of each of our neighbours’ power systems.
This quarter saw some significant changes from the first three months of 2018.
Winter was particularly mild, with average temperatures 2°C higher than last year, meaning demand was down by 6%. Nuclear output is 16% lower than last year as five reactors are down for maintenance, including two extended outages due to cracks being found.
This year we have begun keeping track of all the record highs and lows on Britain’s power system.
The tables below look over the past decade (2009 to 2019) and report the record output and share of electricity generation, plus sustained averages over a day, a month and a calendar year1. Cells highlighted in blue are records that were broken in the first quarter of 2019. Each record links to the date it occurred on the Electric Insights website, allowing the data to be explored visually.