Overview of energy for road transport
Battery electric vehicles (BEVs) store energy in lithium ion batteries. The electric motor produces no carbon emissions and is about three times as efficient as an internal combustion engine (ICE). Instead of filling your petrol tank, you charge up the batteries from the mains. The benefits of transitioning from ICEs to BEVs will only accrue if we are able to switch from fossil fuel electrical generation to other methods. The only feasible medium term substitute is nuclear power. This argument also applies, of course, in the wider energy context. Longer term views might forsee a reduced overall energy demand with a significant contribution from renewables. If nuclear fusion became practical it could provide limitless power.
Electric road vehicles – current technology
Although vans, lorries and buses can be electric-powered, I’ll concentrate on cars. There is a spectrum of technologies. Here are some broad categories:
1. Conventional ICE cars. Typically 20% efficient.
2. Hybrid electric vehicles (HEVs) (eg Toyota Prius) Have an ICE and a battery-powered electric motor. Slightly better efficiency than 1 above.
3. Plug-in hybrid electric vehicles (PHEVs). (eg Toyota Prius Plus) Have an ICE and a battery-powered electric motor. The battery can be charged by plugging it in to the mains supply. Better efficiency than 2 above.
4. BEVs (eg G-Wiz, Peugeot iOn, Nissan Leaf). Electric motor powered by lithium ion batteries. No ICE. Might incorprate additional energy-saving features (eg regenerative braking) Can be around 60% efficient.
Re-charging
Batteries in PHEVs and BEVs can be re-charged at home, although this is easier in a garage than on-street. There are publically accessible charging points around the country, but few in Wiltshire so far. (can be free or commercial) Here are some examples of charging points. Battery charging takes time (several hours for a full re-charge, little as half an hour for a quick “top-up”)
“Battery swapping” is being developed. Lithium ion batteries are large and heavy, so this needs lifting gear. If batteries become standardised battery-swapping stations might become a possibility.
Advantages of BEVs
1 No carbon emissions (at vehicle)
2 No other pollutants
3 Lower running costs
Current problems of BEVs
1 Limited range – typically 80-100 miles.
2 Long battery re-charge time (several hours).
3 High capital cost. Nissan Leaf - £30,000 (but £5,000 grant available)
Click here to find out what it's like to drive a BEV
Future prospects
Range will increase as batteries improve. Re-charging time will decrease significantly. Introduction of “battery swapping” technology might remove need for re-charging at home or in parking bays.
What can we do now?
So far Wiltshire has been excluded from the national charging network. Marlborough could take the lead and begin installing charging sites in the town centre. This would put us on the Eco-tourist map and enable businesses to reduce their carbon emissions.
This article was written by John Yates.