Emissions from electric vehicles fall by two thirds thanks to greener electricity generation

As more renewables replace coal on the power system – the electricity we use is getting cleaner, making electric cars and SUVs better than ever for lowering our carbon emissions.

The latest Electric Insights report, produced by researchers at Imperial College London, in collaboration with Drax, analysed electricity generation data from April to June this year. It showed that the power produced during this quarter contained 199g of CO2 per kWh – 10% lower than the previous minimum set last year.

Dr Iain Staffell from Imperial College London explained: “It is widely accepted that electric cars dramatically reduce air pollution in cities, but there is still some debate about how clean they actually are – it varies depending on where the electricity to charge them with comes from.

“According to our analysis, looking at a few of the most popular models – they weren’t as green as you might think up until quite recently, but now, thanks to the rapid decarbonisation of electricity generation in the UK, they are much better.

“For example, producing the electricity to charge a Tesla Model S back in 2012 would have created 124g of carbon per km driven. Nowadays emissions from charging the same car have halved to 74g per km driven in winter and just 41g per km in summer – thanks to the decarbonisation of electricity generation in the UK.

“Smaller electric cars like the Nissan Leaf and BMW i3 can be charged for less than half the CO2 of the cleanest non-electric car on the market – the Toyota Prius hybrid.”

In the UK there are now more than 100,000 electric vehicles on the roads – pure electric and plug-in hybrid numbers have grown 30-fold in four years, representing 1.8% of new car registrations.

The following table shows the change in carbon intensity of electricity for some of the most popular models of electric vehicle:

Make and modelWinter 2012/13Winter 2016/17Summer 2017
Tesla Model S124g/km74g/km41g/km
Nissan Leaf97g/km58g/km32g/km
Mitsubishi Outlander PHEV87g/km52g/km29g/km
BMW i381g/km48g/km27g/km

For context, a 2L Range Rover Evoque emits 125g/km  and a Toyota Prius emits 70g/km based on data from the government’s Vehicle Certification Agency.

At the same time as electric car numbers are increasing, Britain’s electricity has been decarbonising.

Andy Koss, Drax Power CEO, said: “It’s very exciting to see from this analysis by Dr Staffell and the team at Imperial how we at Drax are contributing to helping the UK to decarbonise.

“Our biomass generating units deliver carbon savings of 68% compared to gas power stations and more than 80% compared to when they used coal.

“Biomass is cost effective, reliable and flexible – this is important not just in terms of reducing emissions in the energy sector, but also the far reaching impacts this can have in transforming other sectors like the automotive and rail industries. The need for more flexible renewable power generation is a real example of the challenges Dieter Helm’s review for BEIS must address.”

Since upgrading half of the power station at Drax to sustainable biomass, more than two thirds of the power produced is renewable. In the first half of this year Drax produced 17% of the UK’s renewable electricity – enough for four million households.

Electric Insights is published once a quarter, and is supported by an interactive website – www.ElectricInsights.co.uk – which provides live data from 2009 until the present. The data sources and methodology used in Electric Insights are listed in full on the website.

Commissioned by Drax Group, owner and operator of the UK’s largest power station and Europe’s biggest biomass-fuelled power plant, the report is delivered independently by Dr Iain Staffell from Imperial College London, facilitated by the College’s consultancy company – Imperial Consultants.

The full report can be read here [PDF here].


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Ali Lewis

Drax Group Head of Media Relations

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Editor’s Notes

  • The calculation to determine the carbon emissions from electric vehicles relies on a number of variables, including the time of day or night a vehicle is charged, and which power stations increase their output to meet additional demand. Electric Insights has illustrated how these emissions have changed recently by assuming that vehicle charging is spread evenly across the day and uses the average electricity mix during each period.
  • The average electricity consumption was averaged across five variants of Tesla Model S which achieve over a 300 mile driving range (75D, 90D, 100D, P90D, P100D). These average 3.22 miles per kWh.  This was converted to 0.194 kWh per km driven.  The data was taken from the Vehicle Certification Agency.
  • Direct CO2 emissions are listed as 0 g/km. Emissions from electricity production were taken from Electric Insights, averaging all half-hourly periods in March 2012.  The carbon intensity of production was 569g/kWh.  We assume 7.5% of electricity is lost in transmission and distribution, and 4% in charging the electric vehicle.  The carbon intensity of electricity consumed was 641g/kWh.  641 x 0.194 = 124.4g/km CO2.
  • Fuel economy listed for a 2016 model year Toyota Prius Active8 with 15” wheels, E-CVT: 94.1 mpg, 70 g/km CO2. Other model variants have different fuel economy and carbon emissions.
  • The disclaimer from the Vehicle Certification Agency applies to the data used.
  • The carbon intensity data for the Mitsubishi is for when that SUV is driven in electric-only mode, not when driven in hybrid mode.

This edition of Electric Insights also found:

  • Reduced carbon intensity is the new norm for Britain’s power system. It averaged 199g/kWh – 10% lower than the previous minimum set last year. This is down from 740g/kWh in the 1980s and 500g/kWh in the 2000s.
  • There are seasonal variations in the carbon intensity of the UK’s electricity generation – more power generation is required to meet higher demand in the darker, colder winter months than the summer, when there is more power available from low carbon, weather-dependent renewables like solar.
  • In the second quarter of this year weather-dependent renewables like solar and wind continued to grow, with solar breaking a number of records during the period including supplying 25% of demand on April 8 and producing 8.91GW on May 26. Over the quarter solar produced 4TWh of electricity – 12% above the previous maximum set in 2015.
  • There is a move towards a decentralised power system as 10% of June’s electricity did not use the national grid. Small renewables (particularly solar) make up a growing portion of the supply and are embedded into local distribution networks rather than connected to high-voltage transmission system. The rise of solar has given rise to the proportion of generation which is bypassing the grid reaching its highest ever level in June – more than 25% of demand was met by embedded generation for 41 hours over the quarter, primarily on sunny weekend afternoons.
  • Having more intermittent renewables on the system is also having an impact on prices. Prices spike when wind and solar output drops and other generators are needed to plug those gaps. The analysis by the team at Imperial College London found that balancing market prices leapt from around £40 per MWh up to as high as £1,500 on May 17 when solar and wind output fell sharply.

About Electric Insights

  • Electric Insights Quarterly was commissioned by Drax and is delivered independently by a team of academics from Imperial College London, facilitated by the College’s consultancy company – Imperial Consultants. The report analyses raw data that are made publicly available by National Grid and Elexon, which run the electricity and balancing market respectively. Released four times a year, it will focus on supply and demand, prices, emissions, the performance of the various generation technologies and the network that connects them.
  • Along with Dr Iain Staffell, the team from Imperial included Professors Richard Green and Tim Green, experts in energy economics and electrical engineering, and Dr Rob Gross who contributed expertise in energy policy. The work to date has revealed scope for further research in this area, to inform both government and organisations within the energy industry.
  • The Q2 2017 report has an additional co-author: Dr Jonathan Scurlock, National Farmers’ Union and The Open University.
  • The quarterly reports are backed by an interactive website electricinsights.co.uk which provides live data from 2009 until the present. It was designed by The Economist Group’s independent data design agency, Signal Noise.

About Drax

Drax Group plc plays a vital role in helping change the way energy is generated, supplied and used as the UK moves to a low carbon future. Drax operates the largest power station in the UK, based at Selby, North Yorkshire and supplies 7 percent of the country’s electricity needs. The energy firm converted from burning coal to become a predominantly biomass-fuelled electricity generator. Drax is the biggest single site renewable generator in the UK and the largest decarbonisation project in Europe.  Its 2,300-strong staff operate across three principal areas of activity – electricity generation, electricity sales to business customers and compressed wood pellet production.

The Group includes:

Drax Biomass, based in the US and manufactures compressed wood pellets produced from sustainably managed working forests.

Haven Power, based in Ipswich, providing businesses with electricity.

Opus Energy, based in Oxford, Northampton and Cardiff, providing electricity and gas to businesses.

Billington Bioenergy, based in Liverpool with depots across the UK, is one of the leading distributors of wood pellets for sustainable heating in the UK.

For more information visit www.drax.com