Author: Iain Staffell

Iain Staffell is a multi-disciplinary scientist holding degrees in Physics, Chemical Engineering and Economics. He is a lecturer in Sustainable Energy at the Centre for Environmental Policy with ten years’ experience in energy R&D.

How to count carbon emissions

Iain Staffell, Imperial College London

31 August 2020

Opinion

Reduced demand, boosted renewables, and the near-total abandonment of coal pushed last quarter’s carbon emissions from electricity generation below 10 million tonnes.

Emissions are at their lowest in modern times, having fallen by three-quarters compared to the same period ten years ago.  The average carbon emissions fell to a new low of 153 grams per kWh of electricity consumed over the quarter.

The carbon intensity also plummeted to a new low of just 18 g/kWh in the middle of the Spring Bank Holiday.  Clear skies with a strong breeze meant wind and solar power dominated the generation mix.

Together, nuclear and renewables produced 90% of Britain’s electricity, leaving just 2.8 GW to come from fossil fuels.

The generation mix over the Spring Bank Holiday weekend, highlighting the mix on the Sunday afternoon with the lowest carbon intensity on record

National Grid and other grid-monitoring websites reported the carbon intensity as being 46 g/kWh at that time.  That was still a record low, but very different from the Electric Insights numbers.  So why the discrepancy?

These sites report the carbon intensity of electricity generation, as opposed to consumption.  Not all the electricity we consume is generated in Britain, and not all the electricity generated in Britain is consumed here.

Should the emissions from power stations in the Netherlands ‘count’ towards our carbon footprint, if they are generating power consumed in our homes?  Earth’s atmosphere would say yes, as unlike air pollutants which affect our cities, CO2 has the same effect on global warming regardless of where it is produced.

On that Bank Holiday afternoon, Britain was importing 2 GW of electricity from France and Belgium, which are mostly powered by low-carbon nuclear.  We were exporting three-quarters of this (1.5 GW) to the Netherlands and Ireland.  While they do have sizeable shares of renewables, they also rely on coal power.

Britain’s exports prevented more fossil fuels from being burnt, whereas the imports did not as they came predominantly from clean sources.  So, the average unit of electricity we were consuming at that point in time was cleaner than the proportion of it that was generated within our borders.  We estimate that 1190 tonnes of CO2 were produced here, 165 were emitted in producing our imports, and 730 avoided through our exports.

In the long-term it does not particularly matter which of these measures gets used, as the mix of imports and exports gets averaged out.  Over the whole quarter, carbon emissions would be 153g/kWh with our measure, or 151 g/kWh with production-based accounting.  But, it does matter on the hourly timescale, consumption based accounting swings more widely.

Imports and exports helped make the electricity we consume lower carbon on the 24th, but the very next day they increased our carbon intensity from 176 to 196 g/kWh.

When renewable output is high in Britain we typically export the excess to our neighbours as they are willing to pay more for it, and this helps to clean their power systems.  When renewables are low, Britain will import if power from Ireland and the continent is lower cost, but it may well be higher carbon.

Two measures for the carbon intensity of British electricity over the Bank Holiday weekend and surrounding days

This speaks to the wider question of decarbonising the whole economy.

Should we use production or consumption based accounting?  With production (by far the most common measure), the UK is doing very well, and overall emissions are down 32% so far this century.  With consumption-based accounting it’s a very different story, and they’re only down 13%*.

This is because we import more from abroad, everything from manufactured goods to food, to data when streaming music and films online.

Either option would allow us to claim we are zero carbon through accounting conventions.  On the one hand (production-based accounting), Britain could be producing 100% clean power, but relying on dirty imports to meet its entire demand – that should not be classed as zero carbon as it’s pushing the problem elsewhere.  On the other hand (consumption-based accounting), it would be possible to get to zero carbon emissions from electricity consumed even with unabated gas power stations running.  If we got to 96% low carbon (1300 MW of gas running), we would be down at 25 g/kWh.  Then if we imported fully from France and sent it to the Netherlands and Ireland, we’d get down to 0 g/kWh.

Regardless of how you measure carbon intensity, it is important to recognise that Britain’s electricity is cleaner than ever.

The hard task ahead is to make these times the norm rather than the exception, by continuing to expand renewable generation, preparing the grid for their integration, and introducing negative emissions technologies such as BECCS (bioenergy with carbon capture and storage).

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Front cover of Drax Electric Insights Q2 2020 report

Electric Insights Q2 2020 report [click to view/download]

The cost of staying in control

Iain Staffell, Imperial College London

Opinion
What: Industrial landscape with cables, pylons and train at sunset Where: Somerset, UK When: January 2016

The cost of keeping Britain’s power system stable has soared, and now adds 20% onto the cost of generating electricity.

The actions that National Grid takes to manage the power system have typically amounted to 5% of generation costs over the last decade, but this share has quadrupled over the last two years.  In the first half of 2020, the cost of these actions averaged £100 million per month.

Supplying electricity to our homes and workplaces needs more than just power stations generating electricity.

Supply and demand must be kept perfectly in balance, and flows of electricity around the country must be actively managed to keep all the interconnected components stable and prevent blackouts.  National Grid’s costs for taking these actions have been on the rise, as we reported over the previous two summers; but recently they have skyrocketed.

At the start of the decade, balancing added about £1/MWh to the cost of electricity, but last quarter it surpassed £5/MWh for the first time (see below).

Balancing prices have risen in step with the share of variable renewables.  The dashed line below shows that for every extra percent of electricity supplied by wind and solar adds 10 pence per MWh to the balancing price.  Last quarter really bucks this trend though, and balancing prices have risen 35% above the level expected from this trend.  The UK Energy Research Centre predicted that wind and solar would add up to £5/MWh to the cost of electricity due to their intermittency, and Britain has now reached this point, albeit a few years earlier than expected.

This is partly because keeping the power system stable is requiring more interventions than ever before.  With low demand and high renewable generation, National Grid is having to order more wind farms to reduce their output, at a cost of around £20 million per month.  They even had to take out a £50+ million contract to reduce the output from the Sizewell B nuclear reactor at times of system stress.

Two charts illustrating the costs of balancing Great Britain's power system

[Left] The quarterly-average cost of balancing the power system, expressed as a percentage of the cost of generation. [Right] Balancing price shown against share of variable renewables, with dots showing the average over each quarter

A second reason for the price rise is that National Grid’s costs of balancing are passed on to generators and consumers, who pay per MWh.  As demand has fallen by a sixth since the beginning of the coronavirus pandemic, the increased costs are being shared out among a smaller base.  Ofgem has stepped in to cap the balancing service charges at a maximum of £10/MWh until late October.  Their COVID support scheme will defer up to £100 million of charges until the following year.

For a quarter of a century, the electricity demand in GB ranged from 19 to 58 GW*.  Historically, demand minus the intermittent output of wind and solar farms never fell below 14 GW.  However, in each month from April to June this year, this ‘net demand’ fell below 7 GW.

Just as a McLaren sports car is happier going at 70 than 20 mph, the national grid is now being forced to operate well outside its comfort zone.

This highlights the importance of the work that National Grid must do towards their ambition to be ready for a zero-carbon system by 2025.  The fact we are hitting these limits now, rather than in a few years’ time is a direct result of COVID.  Running the system right at its limits is having a short-term financial impact, and is teaching us lessons for the long-term about how to run a leaner and highly-renewable power system.

Chart: Minimum net demand (demand minus wind and solar output) in each quarter since 1990

Minimum net demand (demand minus wind and solar output) in each quarter since 1990

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Front cover of Drax Electric Insights Q2 2020 report

Electric Insights Q2 2020 report [click to view/download]

Under lockdown, every day is a Sunday

Iain Staffell, Imperial College London

21 May 2020

Opinion
empty UK motorway in England at sunset with no traffic

On March 23rd the UK took an unprecedented move to tackle the coronavirus. Most business that had not already closed moved online, with millions of people now working from home. This had a huge impact on electricity demand: consumption on weekdays fell by 13% to its lowest levels since 1982 – a time when there were 10 million fewer people in the country, and GDP was a third lower than today.

Other regions have seen a similar collapse in electricity demand. Spain, Italy and France have all seen electricity demand fall by 10-15% according to analysis by Ember. Across the Atlantic, New York City has seen similar reductions.

Demand has fallen for a simple reason: with schools and workplaces now closed or running with a greatly reduced staff – machinery, computers, lights and heaters are not drawing power. Electric rail, tram and tube systems are also running a reduced service. On the contrary, with more people at home, household electricity consumption has increased. Octopus Energy estimate that during social distancing (before the stricter lockdown came into effect) homes were consuming up to a third more electricity, adding £20 per month to the typical bill.

The impact of lockdown on Britain’s electricity demand is much like living through a month of Sundays. The average profile for a March weekend day in previous years looks very similar to the daily profile for weekdays since lockdown begun – both in the amount of electricity consumed and the structure. Post-lockdown weekends have even lower demand, tracking 11% below weekday demand.

People no longer have to get up at the crack of dawn for work. On a typical weekday morning, demand would rise by 10 GW over two hours from 5:30 to 7:30 AM. Now it takes more than twice as long – until midday – for this rise to occur. At the other end of the day, there would normally be a small peak in demand around 8 PM from people gathering in pubs and restaurants up and down the country. Both on weekdays and weekends, demand begins falling earlier in the evening as the sofa has become the only available social venue.

urban street cafe empty without visitors

With lower demand comes lower power prices. Wholesale electricity prices are typically 7% lower on Sundays than on weekdays for this reason. March saw the lowest monthly-average power price in 12 years, down one-third on this month last year. Prices were already heading downwards because of the falling price of gas, but the lockdown has amplified this, and negative prices have become commonplace during the middle of the day. There was not a visible impact on carbon emissions during the first quarter of the year, as only the last week of March was affected. However, as lockdown continued into April and May, emissions from power production in Britain have fallen by 35% on the same period last year. The effect is slightly stronger across Europe, with carbon emissions falling almost 40% as dirtier coal and lignite power stations are being turned down.

Will some of these effects persist after lockdown restrictions are eased? It is too early to tell, as it depends on what long-lasting economic and behavioural changes occur. Electricity demand is linked with the country’s GDP, which is set to face the largest downturn in three centuries. Whether the economy bounces back, or is afflicted with a lasting depression will be key to future electricity demand. It will also depend on behavioural shifts. People are of course craving their lost freedoms, many may appreciate not going back to a lengthy daily commute – and the rise of video conferencing and collaboration apps has shown that remote working may finally have come of age. With even a small share of the population continuing to work from home on some days, there could be a lasting impact on electricity demand for years to come.

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How clean is my electric car?

Iain Staffell, Imperial College London

29 August 2019

Opinion
Birmingham UK Spaghetti Junction aerial with city centre background

Electric vehicles are fast becoming mainstream. There are now well over 200,000 on Britain’s roads, and this number is growing by 30% per year. 1 in 40 cars sold in Britain is now electric, around one third of which are pure battery models, and two thirds are plug-in hybrid.[1]

This radical shift is just beginning though. Britain’s electric vehicle fleet is expected to expand ten-fold over the next five to ten years. In more optimistic scenarios, half of all vehicles on the road could be electric just fifteen years from now.[2]

While many see EVs as the cleanest way to drive, they are still the subject of much speculation. Recent criticisms range from a UK government report saying they won’t end air pollution[3] to a string of studies (often debunked) claiming they emit more CO2 than diesel equivalents.[4]

The arguments are simple: how can it be cleaner to swap a petrol car for electric if it is recharged using electricity from dirty coal or gas? Secondly, how can electric vehicles ‘repay’ the energy needed for mining lithium and to assemble the huge batteries that power them?

We review academic studies of battery manufacture and use data from Electric Insights to answer these questions.  On average Britain’s EVs emit just one quarter the CO2 of conventional petrol and diesel vehicles. If the carbon emitted in making their battery is included, this rises to only half the CO2 of a conventional vehicle. Electric vehicles bought today could be emitting just a tenth that of a petrol car in five years’ time, as the electricity system is widely expected to continue moving towards low-carbon sources.

Manufacturing each kWh of battery emits a similar amount of carbon as burning through one full tank of petrol.[5] Electric vehicles typically have a battery capacity ranging from 30 kWh for small city hatchbacks up to 100 kWh for top-end models – manufacturing the latter emits as much carbon as three round-the-world flights. More CO2 is emitted in building the battery for premium EV model than from the recharging it over a 15-year lifetime.[6]

However, the most efficient EV models could need just two to three years of driving to save the amount of carbon emitted in producing their batteries. Smaller EVs with modest battery sizes are better for the environment; whereas the largest luxury EV models could need three times longer to pay back their carbon cost.

Hatchbacks

Small hatchbacks are the best-selling type of electric vehicles, led by the Nissan Leaf. They are also the cleanest to drive as they are small and light. Electric models currently emit around 33 grams of CO2 per km driven, which is one quarter that of the most popular conventional vehicle, a 2019 Ford Fiesta.

Volkwagen e-up! electric car showcased at the Frankfurt IAA Motor Show 2017.

These electric models typically come with a 30-45 kWh battery, which pushes their lifetime emissions up around 60 g/km. This is still less than half the emissions of a petrol or diesel car. With the projected changes to the grid mix, this will fall to less than one third of a standard car in just five years’ time.

EV models: Nissan Leaf, Renault Zoe, Volkswagen e-Golf and e-Up, Hyundai Kona and BMW i3

Battery size: 39 kWh on average (31–46 kWh central range)

Lifetime carbon content of the battery: 26 g/km driven on average (18–34 g/km central range)

Emissions with 2018/19 grid mix: 28–38 g/km from recharging, 45–72 g/km including battery

Emissions with 2025 grid mix: 12–20 g/km from recharging, 28–52 g/km including battery

Luxury

Luxury saloons and SUV models include the iconic Tesla Models S and X, and the new Jaguar i-Pace. These are much larger and need more energy to move, meaning they have higher emissions than hatchbacks, at 44-54 g/km. This is still just a quarter of the emissions from a comparable conventional car (a top of the range Mercedes S-Class).

Jaguar I Pace EV

The lifetime emissions of these luxury EVs are notably higher though, pushed up by the enormous 90-100 kWh batteries they use to provide a driving range of over 250 miles. These batteries are responsible for more CO2 emissions than driving the car over its entire lifetime.

Models considered: Jaguar i-Pace, Tesla Model S and Model X

Battery size: 97 kWh on average (90–100 kWh central range)

Lifetime carbon content of the battery: 63 g/km driven on average (47–80 g/km central range)

Emissions with 2018/19 grid mix: 44–54 g/km from recharging, 92–133 g/km including battery

Emissions with 2025 grid mix: 19–29 g/km from recharging, 63–103 g/km including battery

Vans

Electric vans are quickly taking off, with over 8,000 sold in Britain to date. Their performance is comparable to small hatchbacks, and they also currently emit around a quarter of the CO2 of the most popular conventional van, with around 40 g/km.

A white Nissan e-NV200 electric van makes deliveries in London.

With their 30–40 kWh battery pack included, this rises to just below half the CO2 of a small Ford Transit.

Models considered: Nissan e-NV200 and Renault Kangoo

Battery size: 37 kWh on average (33–40 kWh central range)

Lifetime carbon content of the battery: 24 g/km driven on average (18–31 g/km central range)

Emissions with 2018/19 grid mix: 37–43 g/km from recharging, 54–74 g/km including battery

Emissions with 2025 grid mix: 15–23 g/km from recharging, 32–52 g/km including battery

Payback time

A typical driver filling their car up once a month and driving around 7,500 miles per year will produce one and a half tonnes of CO2 per year in a modern petrol or diesel hatchback. An electric vehicle doing the same mileage would take 4 years to produce this amount.

With a conventional vehicle, there is no scope for reducing emissions over its lifetime, as petrol and diesel fuels cannot become carbon-free.  On the contrary, National Grid expect the carbon content of Britain’s electricity to continue falling, so that an electric vehicle bought now will be emitting half as much CO2 in 2025 as it does today.

It is inconceivable that an electric vehicle in the UK could be more polluting than its conventional equivalent.  This would require electricity to have a carbon intensity of around 850–950 g/kWh, values not seen since the 1960s.[7]

Electric vehicles can be thought of as having an upfront ‘carbon cost’ for manufacturing the battery, which can then be ‘repaid’ through lower emissions as they are driven.  With Britain’s current grid electricity (producing 205 g/kWh), smaller electric cars and vans will take between 2 and 4 years to have saved the amount of CO2 than was emitted in making their batteries.  For the larger luxury models, it will take more like 5–6 years of driving to pay back that carbon.

With each passing year as the electricity mix gets cleaner, this payback time will continue to fall, and the environmental credentials of electric vehicles will keep growing stronger.

About this study

The fuel economy and climate impact of vehicles are measured by the government through the amount of CO2 they release for every kilometre driven. The UK’s most popular car, the Ford Fiesta, emits around 120 g/km in its cleanest models and 160 g/km in the sportier versions.[9]  Electric vehicles don’t emit any CO2 while driving, but the power system does when producing the electricity needed to recharge them.

Britain’s power system has changed dramatically over the last five years, with carbon emissions halving and the share of coal generation falling from 36% to just 3%. One kWh of electricity in Britain is now contains 204 grams[10] of CO2, less than the carbon released from burning one kWh of petrol. An electric vehicle can drive up to four times further on 1 kWh than a petrol or diesel car could, because electric motors are so much more efficient.

The charts above look at three categories of vehicle – small hatchbacks, luxury saloons and SUVs, and small commercial vans. Each chart shows how the carbon emissions from an electric vehicle have fallen over the past decade, and how they are expected to continue falling in the years to come. The charts consider changes to the electricity generation mix used for recharging,[11] and a gradual reduction in emissions from battery manufacture as the electricity mix changes in other countries.[12]

The range in direct emissions from recharging (the dark blue bands) covers the main EV models currently on sale in each segment, and variants on each model available.  The top of each band (highest emissions) shows the least efficient EV model, the bottom of each band (lowest emissions) shows the most efficient. In the forecast, these bands also include the range of emissions factors for electricity production coming from National Grid’s scenarios.

There is a larger range in the estimated whole-lifecycle emissions (the lighter blue bands) due to the additional uncertainty in the emissions caused by manufacturing 1 kWh of battery capacity, and the range of battery sizes seen across EV models.

Studies have estimated a wide range of emissions, depending on the type of battery type, its design, where it is manufactured and how old the study is.  Current estimates range from 40 up to 200 kg of CO2 emitted per kWh of battery capacity.[13] We take the average across eight studies and assume 75–125 kgCO2 per kWh. The true value may be less than this, as end-of-life batteries could be recycled,[14] or could be repurposed as a second-life home or grid storage batteries. It will also reduce in future as the electricity used to make batteries is decarbonised, or as more factories switch to 100% renewable energy (as has the US Tesla Gigafactory).

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Britain’s power system has never been closer to being fossil-free

Iain Staffell, Imperial College London

23 July 2019

Opinion
Drax EI header

Electricity generation is decarbonising faster in Britain than anywhere else in the world.[1] Changes to the way we produce power over the last six years have reduced carbon emissions by 100 million tonnes per year.[2]

The carbon savings made in Britain’s power sector are equivalent to having taken every single car and van off our roads.[3]

This puts Britain at the forefront of the wider trend towards clean electricity. Coal generation is collapsing in Germany, having fallen 20% in the last year due to rising carbon prices. Renewables have beaten fossil fuels as the largest source of generation in Europe. A third of America’s coal power stations have retired over the last decade as they switch to cleaner natural gas.

Britain’s coal power stations made international headlines in May for sitting completely idle for two full weeks. But coal is only part of the story.

The second quarter of 2019 saw three major milestones that signal Britain’s progress towards a clean power system:

  1. The carbon content of electricity hit an all-time low, falling below 100 g/kWh across a whole day for the first time;
  2. Renewables hit an all-time high, supplying more than half of Britain’s electricity over a full day; and
  3. For the first time ever, less than a tenth of electricity was produced from fossil fuels.

Going below 100 grams

100 grams of CO2 per kWh is an important number. Two years ago the Committee on Climate Change recommended it as the target for 2030 that would mean our electricity system is in line with the national commitment to decarbonise.

Britain’s electricity has dipped below 100 grams for single hours at a time, but until now it had never done so for a full day.

June 30th was a sunny Sunday with a good breeze that brought a 33°C heatwave to an end. Electricity demand was among the lowest seen all year while wind output was at a three-month high.   The carbon intensity of electricity sat below 100 g/kWh for half of the day, falling to a minimum of just 73 g/kWh in the mid-afternoon. Carbon emissions averaged over the day were 97 g/kWh, beating the previous record of 104 g/kWh set a year ago.

Fig 1 – Britain’s generation mix during June 30th that delivered electricity for less than 100g of carbon per kWh. Click to view/download.

Going above 50% renewables

June 30th was a record-breaker in a second way. Wind, solar, biomass and hydro supplied 55% of electricity demand over the day – smashing the previous daily record of 49% set last summer.

For the first day in the national grid’s history, more electricity came from renewables than any other source.

That day, Britain’s wind farms produced twice as much electricity as all fossil fuels combined. A quarter of the country’s electricity demand was met by onshore wind farms, and 15% from offshore.[4]

Despite several reactors being offline for maintenance, nuclear power provided nearly a fifth of electricity; again, more than was supplied by all fossil fuels.

Heading towards fossil-free electricity

The rise of renewable energy has been a major factor in decarbonising Britain’s electricity, complemented by the incredible fall in coal generation.

Every single coal plant in Britain has sat idle for at least two days a week since the start of spring.

It has been three years since Britain’s first zero-coal hour. A year later came the first full day, and earlier this year we saw the longest coal-free run in history, lasting 18 days. This summer could see the first full month of no coal output if this trend continues.

Fig 2 – Number of hours per week with zero generation from Britain’s coal power stations. Click to view/download.

Attention must now shift from ‘zero coal’ to ‘fossil free’.

Unabated natural gas (without carbon capture and storage) needs to be removed from the grid mix by 2050 to tackle the climate crisis and ensure the UK hits net-zero emissions across the whole economy.

At the start of this decade, Britain’s power system had never operated with less than half of electricity coming from fossil fuels.

As renewables were rolled out across the country the share of fossil fuels has fallen dramatically. By 2014, the grid was able to operate with less than one-third from fossil fuels, and by 2016 it had gone below one-fifth.

On May 26th, the share of fossil fuels in Britain’s electricity fell below 10% for the first time ever.

Fig 3 – The record minimum share of fossil fuels in Britain’s electricity mix over the last decade, with projections of the current trend to 2025. Click to view/download.

This record could have gone further though. During the afternoon, 600 MW of wind power was shed – enough to power half a million homes.

National Grid had to turn off a tenth of Scotland’s wind farms to keep the system stable and secure.

This wind power had to be replaced by gas, biomass and hydro plants elsewhere in the country, as these were located closer to demand centres, and could be fully controlled at short notice. This turn-down coincides with ten straight hours where power prices were zero or negative, going down to a minimum of –£71/MWh in the afternoon. National Grid’s bill for balancing the system that day alone came to £6.6m.

If the power system could have coped with all the renewable energy being generated, fossil fuels would have been pushed down to just 8% of the generation mix.

This highlights the challenges that National Grid face in their ambition to run a zero carbon power system by 2025 – and the tangible benefits that could already be realised today. If the trend of the last decade continues, Britain could be on course for its first ‘fossil-free’ hour as early as 2023. This will only be possible if the technical issues around voltage and inertia at times of high wind output can be tackled with new low-carbon technologies.

Other countries are grappling with questions about whether renewables can be relied on to replace coal and gas. Britain is proof that renewables can achieve things that weren’t imaginable just a decade ago.

Zero carbon electricity is “the job that can’t wait”. Britain only has a few more years to wait before the first “fossil-free” hours become a reality.

[1] Over the last decade, the carbon intensity of electricity generation in Britain has fallen faster than in any other major economy. Source: Energy Revolution: Global Outlook.

[2] In the 12 months to July 2019 carbon dioxide emissions from electricity generation totalled 60.5 million tonnes. In the 12 months to July 2013 these emissions were 160.2 million tonnes. Both figures include emissions from imported electricity, and from producing and transporting biomass. See Electric Insights and our peer-reviewed methodology paper for details of the calculation.

[3] In 2017 the UK’s cars emitted 70 million tonnes of CO2 and light-duty vehicles emitted 19 million tonnes. Source: BEIS Final greenhouse gas emissions statistics.

[4] Electric Insights now provides data on the split between onshore and offshore wind farms. Typically, around 2/3 of the country’s wind power comes from its onshore wind farms.

Coal comeback pushes up UK’s carbon emissions

Iain Staffell, Imperial College London

17 September 2018

Opinion
UK coal production

10-year high gas prices1 have prompted a resurgence in coal-fired power across Britain – and with it a 15% increase in carbon emissions from electricity generation.

If coal-fired electricity remains cheaper than gas-fired (as analysts predict), we could see the first year-on-year rise in carbon emissions from Britain’s power sector in six years. This highlights the importance of retaining a strong carbon price if we are to ensure the successful decarbonisation of the power system is not reversed.

After dropping to a historic low of just 0.2 GW during June and July, Britain’s coal power generation doubled in August, and has shot up to 2 GW during the first week of September.  The last time coal output was this high was during the Beast from the East, when temperatures plummeted in March.

With these coal power stations running instead of more efficient gas plants, Britain is producing an extra 1,000 tonnes of carbon dioxide (CO2) every hour.2  Carbon emissions from electricity generation are up 15% as a result.  These coal plants are not running solely because they are needed to meet peak demand, but because gas prices have risen sharply and carbon prices have not kept up, making coal power stations more economic to run than gas-fired ones.

It became cheaper to generate power from coal than from gas (see thick lines, chart below) in late August.  Even though carbon prices now double the cost of generating electricity from coal,3 coal plants are consistently “in the money” at the moment, meaning they can generate power profitably all day and night.

Estimated cost of generating electricity from coal and gas in Quarter 3 (thick lines), and the output from coal power stations in Britain (thin line)

Estimated cost of generating electricity from coal and gas in Quarter 3 (thick lines), and the output from coal power stations in Britain (thin line)

The cost of emitting CO2 has increased sharply, up 45% so far this year due to the ongoing rally in European Emissions Trading Scheme (EU ETS) prices.  Rising carbon prices should make gas more economical to burn as it emits less than half the CO2 of coal.

However, wholesale gas prices have also risen 40% since the start of the year, as supplies and storage are squeezed in the run up to winter.  Gas prices are at a ten-year high, currently 14% above their previous quarterly-average peak back in 2013 (see chart below).  These rising costs are feeding through into wholesale power prices, which have risen by a third over the past year to hit £60/MWh.

The cost of generating electricity and carbon cost

The estimated cost of generating electricity from fossil fuels over the last 20 years, along with the cost of emitting CO2.

Britain’s carbon price strengthened dramatically through 2014–15 due to the government implementing a Carbon Price Support scheme.  This caused gas to become competitive against coal for power generation, leading to carbon emissions from the power sector halving.  Unless Britain’s carbon price can once again make up the gap between coal and gas prices, we risk rolling back some of the world-leading gains made on cleaning up our electricity system.

The Committee on Climate Change has made it clear that power is the only sector that is pulling its weight when it comes to decarbonising the UK.  Clean electricity could power low-carbon vehicles and heating, but this opportunity will be wasted if the electricity comes from high-carbon coal.

UK electricity system

So what can be done?  The sharp rise in gas prices hints at a lack of flexibility in the energy system.  Britain came uncomfortably close to gas shortages in March, in part due to the closure of the country’s largest gas storage site.  With nearly half of the electricity generated in Britain coming from gas, plus five-sixths of household heat, diversifying into other – cleaner – energy sources would help insulate consumers and businesses from price spikes.

No one country has the power to determine international fuel prices.  Several factors have come together to push up gas prices, including a lack of transmission capacity, depleted stores of gas after the long hot summer and a lack of wind power increased output from gas-fired stations. Suppliers which don’t wish to be caught short after the Beast from the East, are also stocking up on gas.

Any knee-jerk reaction to try and lower the cost of electricity (for example, slashing the cost of carbon emissions) may only have a short-term impact, and could easily lead to longer-term damage (such as the resurgence of coal) which would require further interventions in the future.

Britain does have control over its carbon price. Its power stations and industry currently pay the Emissions Trading System price (determined on the Europe-wide market) which has fluctuated wildly over the past week between €25 (£22) and €19 (£17) per tonne, plus £18 per tonne in Carbon Price Support which goes to the Treasury.  This needs to be maintained or strengthened further to save the power system from backsliding, and to show strong climate leadership on the international stage.

Explore this data live on the Electric Insights website

View Drax Power CEO Andy Koss’ comment

Commissioned by Drax, Electric Insights is produced independently by a team of academics from Imperial College London, led by Dr Iain Staffell and facilitated by the College’s consultancy company – Imperial Consultants.

[1] The three-month average cost of generating electricity from gas exceeded £60/MWh for the first time since 2009.  Short-term price spikes have been higher than this, such as the first week of March during the Beast from the East.↩

[2] Extra generation from coal reduces the output from gas plants, which are their main competitors, as nuclear, wind and solar already run as much as possible.  Calculation based on 1934 MW of coal generation (the average during the first week of September) emitting 937 gCO2 per kWh (1812 tonnes per hour) instead of gas generation which would have emitted 394 gCO2 per kWh (762 tonnes per hour).↩

[3] The coal that must be burnt to produce 1 MWh of electricity now costs around £31, and the CO2 pollution costs an extra £31 on top.  For comparison, producing 1 MWh of electricity from gas costs £50 for the fuel and £15 for the CO2.↩

How the heatwave affects electricity demand

Iain Staffell, Imperial College London

27 July 2018

Opinion

16.5 degrees is the Goldilocks temperature for the Brits – not hot enough for air-con, not too cold to put the heating on. In March we saw how the Beast from the East caused a surge in demand, now the long summer heatwave is doing the same.

June 23rd marked the start of the heatwave, with daytime temperatures surpassing 30°C in Scotland and Wales. The last week of June was 3.3°C warmer than the previous week, and demand was 860 MW higher (see chart below). This rise is equivalent to power demand from an extra 2.5 million households.

This reflects the growing role of air conditioning and refrigeration in shops, and cooling for data centres. Global electricity demand from cooling is rising dramatically, and is seen as a ‘blind spot’ in the global energy system.  This will become more important as global temperatures, and more importantly, global incomes rise. However, it is easier to deal with than cold spells during winter because demand is low and solar PV output is high.

Below 14°C, demand increases by 750 MW for every degree it gets colder as buildings need more heating. Around a tenth of British homes have electric heating, as do half of commercial and public buildings. And while the UK is not synonymous with air conditioners, demand rises by 350 MW for each degree that temperature rises above 20°C.

This effect may well grow stronger in the coming years. National Grid expect that the peak load from air conditioners will triple in the coming decade. Perhaps events such as the current prolonged heatwave may spur more households to invest in air conditioning.

Read the press release

Explore power grid data during the heatwave beginning 23rd June

Commissioned by Drax, Electric Insights is produced independently by a team of academics from Imperial College London, led by Dr Iain Staffell and facilitated by the College’s consultancy company – Imperial Consultants.

The Beast from the East

Iain Staffell, Imperial College London

18 April 2018

Opinion

Thursday 1 March was the coldest spring day on record, averaging –3.8°C. The six days from 26 February to 3 March (highlighted in blue) were the coldest Britain has been since Christmas 2010.

This pushed electricity demand up 10%, as people used more electric heating to keep warm. The evening peak demand on 1 March was the highest in three years, and so was not stretching the system to its limits.

Electricity prices rose to five times the average for the quarter. They peaked at £990 per megawatt hour (MWh) for half an hour, and also fell to –£150 per MWh as the market became volatile.

Coal generation surged for the weeks surrounding the cold spell. Not because more output from conventional plants was needed, but rising gas prices made it more economical to burn than gas. Total generation from fossil fuels remained around 20–25 GW.

Biomass and hydro ran solidly throughout the cold spell. Wind output was particularly high when it was most needed, ranging from 11.8 to 13.8 GW during 1 March. Whilst wind certainly helped, the lights would not have gone off without it, as up to 19 GW of spare gas capacity was available if needed.

Britain’s links to other countries were not so helpful. We exported to France through much of the cold spell. French electricity demand is more impacted by temperature than British, as more French homes use electric heating.

Looking in more detail at the UK’s links to other countries:

  • Britain had been largely importing from France all year, but then exported solidly through 27–28 February, when power prices were higher in France.
  • Prices remained lower in the Netherlands, so Britain continued importing from them.
  • Britain and Ireland traded power back and forth to help balance their systems. On 3 March the East-West link between North Wales and Dublin was taken offline for (unrelated) maintenance.

Download the PDF version

Read the press release

Explore this data live on the Electric Insights website

Commissioned by Drax, Electric Insights is produced independently by a team of academics from Imperial College London, led by Dr Iain Staffell and facilitated by the College’s consultancy company – Imperial Consultants.