Analysis: Fuel-duty freeze has increased UK CO2 emissions by up to 5% - Carbon Brief (2022)

The freeze in fuel duty since 2010 means the UK’s CO2 emissions are as much as 5% higher than they would have been, Carbon Brief analysis shows.

The analysis comes amid widespread lobbying and speculation over the future of fuel duty in the UK’s next budget, due to be announced by the new chancellor Rishi Sunak on 11 March.

Fuel duty is currently applied to petrol and diesel sales in the UK at a rate of 58 pence per litre, plus VAT. Instead of rising with inflation, this rate has been frozen since 2010, meaning motorists have enjoyed a large price cut in real terms, even as public transport fares have risen faster than inflation.

If fuel duty had increased each year as planned in the June budget 2010, then pump prices would have been a fifth higher than they are today. Higher prices would have cut CO2 in 2019 by 2-18 million tonnes of CO2 (MtCO2), some 0.5-5.0% of overall UK carbon emissions, Carbon Brief analysis shows.

Instead, transport is now the largest contributor to the UK’s carbon emissions, having overtaken the power sector in 2015. Road transport emissions rose by around 3% over the past decade and cars alone are now responsible for a larger share of the total than all of the country’s power stations put together.

Fuel-duty freezes

According to the Institute of Fiscal Studies (IFS), the respected economic thinktank, forecasts of UK government finances assume that fuel duty will increase in line with inflation at the start of each financial year.

But successive governments have frozen the rate of fuel duty each year since 2010, meaning motorists have enjoyed a significant tax cut in real terms.

The chart below shows how the rate of fuel duty, in pence per litre of petrol or diesel, has been frozen at the same level since 2010 (thick red line, nominal prices). Planned increases are shown in shades of blue, corresponding to budgetary forecasts in 2010 onwards.

Analysis: Fuel-duty freeze has increased UK CO2 emissions by up to 5% - Carbon Brief (1)

The actual rate of fuel duty, in pence per litre not adjusted for inflation, between 2008 and today (thick red line). Planned increases, cancelled at successive budget statements over the period, are shown in shades of blue. Note the truncated y-axis. Source: Institute for Fiscal Studies and Department for Business, Energy and Industrial Strategy. Chart by Carbon Brief using Highcharts.

According to the IFS, the ongoing fuel-duty freeze is costing the exchequer some £11.2bn in the current financial year 2019-20 alone, rising to £13.9bn in 2022-23 if the freeze continues.

(These figures are relative to the planned fuel duty “escalator”, as of June 2010, inherited from the outgoing Labour government. This would have seen the level of fuel duty go up by 1p above inflation each year.)

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As of March 2020, the fuel-duty freeze means that pump prices for petrol and diesel are some 28p per litre lower (23%) than they would have been, if the June 2010 plans had gone ahead.

In an October 2019 report on the taxation of motoring, the IFS notes that UK rates of fuel duty are “high by international standards” and that low-income car-owning households are particularly vulnerable to even higher rates. (It adds that, since low-income households are much less likely to own a car, fuel duties are not regressive overall.)

The thinktank also says: “Fuel duty rates are set higher than can be justified by emissions alone, but are much too low – and too poorly targeted – to reflect the costs of congestion.

It adds that the £28bn due to be collected via fuel duties in 2019-20 will “all but disappear” as drivers shift to zero-carbon transport, if the UK’s target to reach net-zero emissions by 2050 is to be met.

Nevertheless, the IFS concludes by arguing that fuel duties should once again start rising in line with inflation. It says: “There is no case for the recurrent ritual…when planned inflation uprating of fuel duties has been repeatedly cancelled for one more year.

This week’s budget comes amid tumbling oil prices, after the breakdown of a deal between Russia and OPEC, the oil producers’ cartel, as well as the hit to demand from the coronavirus outbreak.

In 2012, then-chancellor George Osborne introduced a “fair fuel stabiliser”, later ignored, designed to raise fuel duties when oil prices were low and postpone increases if oil prices were high.

Emissions effect

Regardless of the merits of current fuel duty rates, there is strong economic evidence that higher pump prices would have reduced demand and, consequently, CO2 emissions.

The key determinant of this effect is the “elasticity of demand”, which measures how sensitive consumers are to changes in price. If elasticity is high, then a rise in prices will have a relatively larger impact on demand. If elasticity is low, then demand may not change much.

The elasticity of demand is usually understood to increase over time, as consumers are able to adjust by changing their habits or buy more efficient cars. See below for further discussion.

Any change in the amount of CO2 released by burning petrol and diesel could have had a significant impact on the national total. This is because the transport sector is now the single-largest contributor to UK greenhouse gas emissions, accounting for a quarter of the total.

While the UK overall has cut its CO2 output by 29% over the past decade, emissions from road transport have increased by 3%. And emissions from cars alone, at around 70MtCO2 in 2019, are now far ahead of the nation’s power stations, which collectively emitted less than 60MtCO2.

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Against this backdrop, Carbon Brief’s new analysis shows that road-transport emissions would have been some 2-18MtCO2 lower in 2019, if fuel duty increases had gone ahead as planned. (The range reflects different estimates of the elasticity of demand, explored in more detail below.)

Instead of road-transport emissions rising by 3% between 2010 and 2019, planned fuel-duty increases could, therefore, have cut CO2 output by as much as 13%, as the chart below shows.

Analysis: Fuel-duty freeze has increased UK CO2 emissions by up to 5% - Carbon Brief (2)

Change in CO2 emissions from road transport between 2010 and 2019, per cent. The estimated change in actual emissions is shown in blue while the hypothetical effect of higher fuel duties is shown in red. Source: Carbon Brief analysis. Chart by Carbon Brief using Highcharts.

These figuresshow that planned fuel-duty increases could have cut overall UK CO2 emissions by between 0.5 and 5.0% in 2019, depending on the elasticity of demand.

The figures above exclude CO2 emissions from refineries, which stood at 13MtCO2 in 2018. If fuel-duty increases had cut refinery output in line with falling demand for petrol and diesel, then the overall impact on UK emissions could have reached 2-20MtCO2 in 2019.

Note that Carbon Brief’s analysis does not distinguish between petrol and diesel sales subject to the standard rate of fuel duty, versus tax exempt sales of “red diesel”, which account for 15% of all diesel use. Permitted uses of red diesel include farm vehicles, heating oil, generators and railways.

Elasticity of demand

The main uncertainty in Carbon Brief’s analysis, as mentioned above, is the elasticity of demand. A 2014 report from the Treasury and HMRC looked at a range of estimates for the impact of fuel-duty changes on demand, including those from within government and shown in the table, below.

For comparison, an elasticity of -1 means that a 10% increase in prices would translate into a 10% reduction in demand. The figures in the table below are lower than this, often substantially so.

SourceDescriptionPrice Elasticity
HMRC indirect taxes forecasting modelThese elasticities underlie the ORB's forecast of fuel duty receipts.-0.07 in the short term

-0.13 in the medium-term

Dahl (2019)A meta study examining the elasticities for petrol and diesel for various countries-0.11 to -0.33 for petrol

-0.13 to -0.38 for diesel

Brons et al A meta study exploring both short-run and long-run elasticities. -0.34 in the short-term

-0.84 in the long-term

Parry and SmallA study exploring the ideal fuel tax for the UK and the US.-0.55 with a range of -0.3 to -0.9

Researchers agree that the short-term elasticity of fuel demand is relatively low, perhaps around -0.1, says Hector Pollitt, head of modelling at consultancy Cambridge Econometrics. This is because consumers may have few immediate ways to cut car use for their commute, for example.

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But higher prices can have much larger impacts on demand if sustained over longer periods, Pollitt tells Carbon Brief. This is because there is time for society to adapt, he explains: consumers may decide to change travel habits by using alternative modes of transport, or their next car may be more fuel efficient. In turn, car manufacturers may be encouraged to develop cleaner models.

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In its own modelling work, Cambridge Econometrics has used a figure of -0.7 as the long-run elasticity of fuel demand, Pollitt says. He adds that there is the potential for even larger, non-linear effects now that hybrid and electric vehicles are widely available.

(If a consumer replaces a combustion car with an electric vehicle, at least in part because fuel is expensive, then their personal demand for petrol or diesel will fall to zero.)

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For the analysis of fuel-duty impacts on road-transport emissions, Carbon Brief has provided a range of estimates based on the short-term elasticity estimate from HMRC at the low end and on Cambridge Econometrics’ long-run figure at the high end.

Pollitt also points to research, published in 2018 by Prof Michael Grubb and colleagues, which finds that long-run energy expenditure is constant, relative to GDP. This report says:

“A constant level of energy expenditure, ceteris paribus [if other things are equal], would imply an elasticity of (minus)1 – considerably higher than classical time-series measures of energy demand-price elasticity (which point to long-run elasticities of (minus) 0.6-0.7 at most)…[T]he data clearly imply that energy systems have a large capacity to adapt to higher prices and other pressures, given time.”

Noting the potentially regressive nature of higher fuel duties, the Grubb research report adds:

“[S]imply imposing higher prices can carry a significant welfare cost, particularly on poorer households…To combine regulatory certainty with flexibility, it is also possible that price-based instruments (such as fuel duties or environmental pricing) could be designed with escalators that are automatically paused if expenditure thresholds are exceeded and resume when expenditure falls.”


Carbon Brief’s estimate of the CO2 impact of fuel-duty freezes is based on increases recorded by the IFS as having been planned in June 2010. If these increases had gone ahead, then pump prices would have been some 23% higher than they were, as of the most recently weekly data, or 22% based on the 2019 average figures.

These figures are converted into changes in demand and CO2 emissions using a range of estimates for the elasticity of demand, discussed above. For example, if the price elasticity is -0.7 then a 22% increase in price would have caused a 15% decrease in demand. The demand reduction is assumed to correspond directly to a reduction in emissions.

Road transport and refinery emissions are based on the 2018 final greenhouse gas emissions figures published by the Department for Business, Energy and Industrial Strategy. Figures for 2019 are estimated using the latest quarterly traffic statistics, published by the Department for Transport.

The UK’s CO2 emissions in 2019 are taken from Carbon Brief estimates published last week.


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What was the fuel duty escalator? ›

The Fuel Price Escalator (later Fuel Duty Stabiliser), a fuel duty policy in the United Kingdom ahead of inflation, was introduced in March 1993 as a measure to stem the increase in pollution from road transport and cut the need for new road building at a time of major road protests, at Twyford Down and other locations ...

How much CO2 does a litre of petrol produce? ›

CO2 from fuel use:

The CO2 emissions from petrol and diesel are around 2.4 kg per litre [1], i.e. 10.9 kg per gallon (since 1 gallon is 4.546 litres).

How much CO2 is produced per litre of diesel UK? ›

One litre of diesel corresponds to 2.68kg of CO2. So you can simply multiply your litres by 2.68 to get to your kilograms of CO2. Most of our customers' fleets run on diesel, but if you have a mixed fleet you can also use the emissions number for petrol (2.31 kg/l) or something in between.

How much CO2 does a litre of diesel emit? ›

Another way to relate carbon dioxide emissions intensity to fuel is per litre of fuel consumed. For example, 1 litre of petrol will produce about 2.3 kg of carbon dioxide and 1 litre of diesel will produce about 2.7 kg of carbon dioxide.

Why is fuel duty so high in the UK? ›

Fuel prices have increased sharply because the price for crude oil, which is used to make petrol and diesel, has gone up. Crude oil was cheaper at the beginning of the Covid pandemic, because many businesses temporarily closed and demand for energy collapsed. As life returned to normal, the demand for energy increased.

How much does fuel duty raise? ›

They represent a significant source of revenue for government. In 2022-23, we expect fuel duties to raise £26.2 billion. That would represent 2.7 per cent of all receipts, and is equivalent to around £930 per household and 1.0 per cent of national income.

How do you calculate CO2 emissions from fuel consumption? ›

The simplest way to calculate tailpipe emissions of CO2 is to measure fuel consumption. Just add your fuel bills each period to see how much CO2 you have produced. Burning a litre of diesel produces around 2.62 kgs of carbon dioxide, whereas petrol has a lower carbon content and produces about 2.39 kgs.

What fuel produces the most CO2? ›

Coal is the dominant CO2 emissions source related to electricity generation.

How do you calculate CO2 emissions? ›

Carbon dioxide emissions per barrel of crude oil are determined by multiplying heat content times the carbon coefficient times the fraction oxidized times the ratio of the molecular weight of carbon dioxide to that of carbon (44/12).

How much CO2 is produced per kg of petrol? ›

What do I need to know? Burning 1 L of gasoline produces approximately 2.3 kg of CO2.

How many kg of CO2 does a car produce UK? ›

The average petrol car in the UK produced the equivalent of 174 grams CO2 per kilometer (g CO2e per km) in 2021, while diesel cars emitted roughly 168g CO2e per km. In comparison, the average battery electric vehicle (BEV) emits considerably less, at 57.77g CO2e per km.

What is the average CO2 emissions for a car UK? ›

Average CO2 Emissions per Car UK

In the UK, average CO2 emissions per car are 138.4 grams per km (or 221.4 grams per mile), according to latest 2020 data from the Department for Transport.

How do you calculate CO2 emissions per kg? ›

1 kg of L-gas consists for 61,4% of carbon, or 614 grammes of carbon per kg of L-gas. In order to combust this carbon to CO2, 1638 grammes of oxygen is needed. The sum is then 614 + 1638 = 2252 grammes of CO2/kg of L-gas. An average consumption of 5 kg / 100 km then corresponds to 5 kg x 2252 g/kg = 113 g CO2/km.

How much CO2 does a petrol car produce? ›

A typical passenger vehicle emits about 4.6 metric tons of carbon dioxide per year. This assumes the average gasoline vehicle on the road today has a fuel economy of about 22.0 miles per gallon and drives around 11,500 miles per year. Every gallon of gasoline burned creates about 8,887 grams of CO2.

Does diesel fuel produce CO2? ›

Diesel engine, like other internal combustion engines, converts chemical energy contained in the fuel into mechanical power. Diesel fuel is a mixture of hydrocarbons which—during an ideal combustion process—would produce only carbon dioxide (CO2) and water vapor (H2O).

Which country has the highest tax on petrol? ›

The DoE's graph shows that countries such as Indonesia, Brazil, the United States, Canada, Mexico, and China pay the least amount of tax on their fuel. Whereas countries such as the UK, the Netherlands, Turkey, and Italy pay the most.

What's the reason for high fuel prices? ›

Why the No. 1 oil country is producing less oil. Even before the invasion, prices of oil and gasoline were rising as the world gradually recovered from the Covid pandemic. For a brief moment in 2020, the cost of a barrel of oil fell below zero because storage tanks were full from the lack of demand.

Why is fuel getting more expensive? ›

The Pandemic Effect and Capacity

Refineries turn - or 'crack' - crude oil into products such as petrol, diesel and jet fuel, and the cost of this process is called the 'crack spread', which in turn is then factored into the wholesale, and therefore retail price of fuel.

How much does the UK make from fuel duty? ›

HMRC collected £25.9bn (1.1% of GDP) from fuel duty in the last tax year (2021/22).

How much does the UK government make from road tax? ›

Background. The UK government receives tax revenue from drivers of petrol and diesel cars via two key methods: fuel duty, which brings £28 billion a year into government coffers, and Vehicle Excise Duty (road tax), which nets roughly £7 billion.

How much does the government get from taxes UK? ›

In 2021/22, UK government raised over £915 billion a year in receipts – income from taxes and other sources. This is equivalent to around 39% of the size of the UK economy, as measured by GDP, which is the highest level since the 1980s.

How much carbon is in a litre of petrol? ›

1 liter of petrol weighs 750 grammes. Petrol consists for 87% of carbon, or 652 grammes of carbon per liter of petrol.

What produces more CO2 petrol or diesel? ›

Diesel engines emit less CO2 and greenhouse gases than petrol engines. This happens because of the particular type of fuel and the internal efficiency of the diesel engine. More specifically, the fuel used in diesel engines has a higher compression ratio than petrol and it also performs better than petrol engines.

What is 1 tonne of carbon emissions equivalent to? ›

That's equivalent to: Driving 23,000 miles in the average car (once around the world) 18 dairy cows in weight. 25 million plastic straws.

How much CO2 does 1kg of natural gas produce? ›

1 kg of natural gas releases 2.75 kg of CO2.


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