I

n pursuit of the goals of the Paris Agreement on climate

change, now in force, the 2°C scenario of the Interna-

tional Energy Agency attributes more than 300 Gt of

avoided carbon dioxide emissions by 2050 to a revolu-

tion in electricity generation. Industry is supposed to

contribute about 150 Gt, with transport just behind at about

140 Gt.

The challenge to meet the goals in all sectors is immense,

especially in electricity generation, so is it a good idea to add to

the demand for electricity by a global rollout of vehicles powered

by electricity?

Battery-Electric Vehicles

When most people think of an electric vehicle, they imagine a

battery-powered car that is plugged into the electricity mains

to recharge the battery. In these battery-electric vehicles (BEV),

an on-board battery provides electricity to run the electric

power train. In its May 2016 summary of the global electric

vehicle outlook, the International Energy Agency reported that

the number of BEVs had passed 750,000 (http://tinyurl.com/

IEA-2016-EV-outlook). More than 20 manufacturers now

offer highway-capable BEVs.

Most people also know about range anxiety – that awful feeling

that you will run out of fuel before reaching the next refuelling

station – in relation to BEVs because most BEVs have much

shorter ranges than the vehicles we are used to (typically 150–200

km). The Tesla Model S is a notable exception.

At first glance, the replacement of our current petroleum-

burning vehicles by BEVs that don’t produce CO 2 or other pollu-

tants during their operation is a great idea, but only if we consider

the vehicle in isolation. Following the energy back to its source,

we should ask how the electricity is generated, and 67% of the

world’s electricity is still generated from fossil fuels

(http://tinyurl.com/IEA-2016-key-world-stats). Consequently

we should ask whether replacing an internal combustion engine

vehicle (ICEV) with a BEV actually reduces CO 2 emissions.

A BEV doesn’t avoid the pollution from electricity produc-

tion – it is released at the power station rather than on the

highway. Even worse, more BEVs will increase the demand for

electricity from a grid that already can’t cope, unless the demand

is managed to be outside peak periods. If the electricity comes from

burning coal, the reduction in CO 2 emissions from taking an

ICEV off the road is offset by the increase from burning extra coal.

So thinking a little about the proposal to replace ICEVs with

BEVs raises a number of very important issues to resolve.

This is a complex matter, but a back-of-the-envelope calcu-

lation helps to sort it out. Let’s take a small-ish BEV with a

50 kWh battery pack and a fairly generous 300 km range. If it

28 ||MAY/JUNE 2017

EVAN GRAY

How much can electric vehicles reduce Australia’s carbon emissions, and what are the factors

limiting the transition from Australia’s fleet of conventional combustion engines?

Speed Bumps Slow

Electric Vehicles

Speed Bumps Slow

Electric Vehicles

asadykov/Adobe