How Green are Electric Cars?
So is switching from ICEs to EVs really a greener option? We explore the question in this guide.
Last updated: Nov 16, 2022 • 4 min read
By moving from the internal combustion engine (ICE) to an equivalent electric car, you will significantly reduce your carbon footprint and air quality impacts. This guide explores:
- How green electricity actually is
- Which kinds of EV are the greenest
- How driving style affects emissions
- When charging is greenest
How green is using electricity as energy source?
While it is true that your electric car will be greener with specifically sourced renewable electricity, you may be surprised by how green it is when just plugged into the average UK gridmix.
Nissan LEAF vs Nissan Micra Example
|Nissan LEAF Acenta 40kWh||Nissan Micra VISIA|
|Efficiency||0.33 kWh/mile||52.3 miles per gallon|
|Direct emissions||0 gCO2/km||123 gCO2/km|
|Fuel production emissions||37 gCO2/km*||39 gCO2/km**|
|Total emissions||37 gCO2/km||162 gCO2/km|
* According to average UK grid emissions in 2020 - 180gCO2/kWh
** It is estimated that ~15-40% of total “well-to-wheel” emissions come from extraction and refinement of petrol. We’ve used 32% as a mid-point as an assumption.
The UK has dramatically decarbonised its power generation in recent years, mainly by replacing high emitting coal with less emitting natural gas and increasing the supply of renewable energy, like utilising solar panels. This process continues, as we look to remove the last of the coal, reduce our reliance on gas, and increase our reliance on renewable generation. As such the grid gets greener each year.
Tip: While EVs have continued to get more green in terms of CO2 emissions in recent years, in operational terms they are typically more efficient than equivalent internal combustion engine vehicles even when charged from coal-fired power! So EVs are always winning, but the winnings keep growing.
Not all EVs are equally green...
Much of the carbon dioxide released over the lifetime of an EV is a byproduct of its manufacturing processes and supply chain. At present firm values for the carbon footprint of EVs are hard to come by. A Ricardo report in 2011 estimated that BEVs have a ~30% carbon deficit in their manufacture when compared with an internal combustion engine car, but that deficit was typically comfortably overcome within the operational life of an EV.
More recently significant investments in renewable electricity sources at factories by the likes of BMW at its Leipzig plant and Tesla, particularly at its Gigafactory, have made an impact on the carbon intensity of their vehicle production. Meanwhile Volkswagen have made an incredible commitment to carbon neutral production of their ID range, with carbon off-setting for the shipment.
Generally RExs (range extenders) are greener to drive than PHEVs, while BEVs are the most efficient type of EV - as they use no petrol at all. But not all BEVs are equal!
Tip: Take a look at our vehicle guides and see the average efficiency of the different models - the most efficient are those that use the least “wh per mile”. You may be surprised at the differences.
Driving style affects how green a BEV is
Just like in a conventionally fuelled car, if you spend your time accelerating hard, you will use more energy than if you pull away more gently. And if you are using more energy per mile, then you are using more carbon per mile (unless you are charging from pure renewables).
Tip: How you configure your car can affect your efficiency. In particular, smaller wheels with larger profile tyres have less rolling resistance, leading to better efficiency and longer range.
Not all times are equally green
The UK’s carbon intensity varies depending on how much power is required and the grid mix at that time. For example, late on a windy night, the UK’s grid is very green, with demand almost all fulfilled by wind and nuclear (v low carbon).
There are several tools that show the carbon content of the grid, and even the types of generation both live and in recent days. We recommend:
- National Grid's Carbon Intensity Website
- Kate Morley's "National Grid: Live Status"
Tip: As a general rule, charging late at night has the lowest environmental impact, and is usually cheaper, as demand is lower. This may change as more cars become electric and the grid becomes more renewables based, but it is a good rule of thumb for the medium term.