You’re just moving the pollution somewhere else, aren’t you?

Otherwise known as the the “long tailpipe” argument

For some time it’s been argued by some that electric cars simply displace the pollution to power stations, so electric cars can’t possibly be any better than petrol cars. I used to believe this.

While this is true, in that electricity has to be generated somewhere, there are a number of arguments that this ignores:

1 The electricity grid worldwide is being decarbonised as renewable energy is deployed. In the UK coal power stations are now a “last resort”; and batteries are being used to store renewable energy generation- it’s happening today. A petrol car can’t use renewable energy.

Sometimes the car owner has solar PV panels on their property and can charge the car from them directly! To be fair though, the sun usually comes out when you’re already at work…

2 The gross inefficiency of an IC engine is easy to beat. Over ¾ of the energy in petrol is wasted as heat. I’ll say that another way – in the UK with petrol at £1.20 a litre, over £1 of that is wasted. Only 19p of your £1.20 is used to push you down the road. In contrast the vast majority of the energy you buy from the the plug hits the road in an EV: around 30% is wasted in system losses from the plug to the road.  There are still some losses from charging and the drivetrain for example, but comparatively little.

3 Electric cars make use of regenerative braking to recover energy instead of, again, turning it into heat (and dust). Over a hilly country route this can be a 20% contribution. This also helps the “hybrid” car case as they can also brake using regen.

4 EVs are usually (at least 81%) charged overnight in periods of low demand and so renewables such as wind power can be used, along with cheap off-peak power from other sources

5 EVs can be part of the solution with vehicle-to-grid, V2G, this is being trialled in the UK and has been in use in Japan for some years. This helps stabilise the grid by providing a large amount of storage when cars are parked and plugged in (which can be 95% of the time).

6 Anyone (in the UK at least) can buy electricity from a green supplier, such as Ecotricity. Then the car will be powered by sun and wind. Even if you don’t “buy” this argument then you’re at least investing in the future – of a greener energy network.

 

In terms of some numbers,

Petrol car at 40mpg

1 Imperial gallon is 4.5 litres, or roughly 45kWh

=1.125kWh/mile

EV at 4m/kWh

=0.25kWh/mile

The EV is 4.5 times more energy-efficient

Add into that the difference in taxation and it’s easy to see why electric cars are cheaper to run…

Air quality

Local air quality in towns and cities stands to be improved immensely by the adoption of EVs:

1 No exhaust emissions

2 Little or no emissions from clutches, or brakes (these can be 55% of the total particulate vehicle emissions, so not easily ignored).

Mean (tyre+brakes) PM10 emissions are 0.04g/km (Nicholson, 2000). This level of 0.04g/km is more than the 2005 “EU4” diesel exhaust emissions limit!

 

My only area of concern would be tyres: the instant acceleration of an EV could lead to higher local emissions from tyres! Those tyres wear out, and guess where they end up? Perhaps we need acceleration limits in towns as well as speed limits  🙂