Peter McDonald

Shifting a fleet from ICE-powered vehicles to electric propulsion is one (big) thing, but there’s plenty more that can be done to reduce carbon footprints

For fleets wanting to reduce their carbon footprint, the single biggest thing they can do is switch from combustion vehicles to battery electric vehicles as quickly as possible. This transition appears to be happening at pace, with EV supply currently unable to keep up with demand. Where the transition is occurring, for an average vehicle – such as a mid-size SUV – the reduction in CO2 is about two tonnes for a year’s driving. Or, to look at it another way, 70% fewer emissions.

For sustainability-minded fleets, the opportunity to purchase ‘green’ energy can reduce the carbon footprint further, through the purchase of carbon credits or offsets.

You can’t change the electrons coming into your house or office – the carbon intensity is dictated by the National Grid energy mix – but you can offset the carbon generated through investing for instance in re-forestation programmes.

However, what’s lesser known is that the CO2 of the energy depends significantly on when and how the vehicle is being charged. If you charge your vehicle at 5pm whether it be through a rapid or home charger you’re taking energy at grid peak, on an average day that’s around 300g CO2/kWh. However, charging at sub-80g CO2/kWh is possible – and quite obtainable – with the right behaviour and hardware. It’s about charging when there’s a rich mix of renewables on the grid, predominately overnight.

Charging at sub-80g CO2/kWh is possible – and quite obtainable – with the right behaviour and hardware


The UK is generating lots of renewable energy – predominately wind – and, on a breezy day, the CO2 is up to 40% lower than usual. During lockdown, with some tariffs and smart charging platforms, customers benefited from negative costs – energy companies had more energy supply than demanded and were paying customers to store it in their electric vehicle.

Now, however, the world is quite a different place. Lockdowns were a unique event and energy prices have inflated massively, however the economic principles still hold true. Drivers can save CO2 by charging at better times and, when their hardware is integrated with smart tariffs that incentivise the charge at the best time for the grid, the savings can be very worthwhile.

Charging when best for the grid can reduce the battery electric vehicle carbon footprint by a further 70% compared to charging at grid peak.

Overall, the combination of switching to an EV and then charging it efficiently can make the CO2 only 1/10th of a combustion engine – now that’s a saving worth shouting about!

Peter McDonald is mobility director at Ohme. Prior to his current role, he spent two decades working for automotive manufacturers including Nissan, SEAT and the wider Volkswagen Group.

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