Transport has for some time been the second-largest and fastest-growing source of carbon emissions in Australia, as is the case in many other nations, owing to the sheer growth in car and truck use over recent decades coupled with the unyielding trend toward larger and heavier vehicles.
With Australia’s largest emission source (electricity generation) now having turned the corner thanks to the boom in solar and wind energy, attention has rightly turned to transport as the next highest priority for urgent reductions.
For decades, the evident solution for transport’s excessive carbon emissions has been to boost, via policy, those methods of transport that involve the smallest energy use per passenger or per tonne of goods—walking and cycling first, then mass public transport via trains, trams and buses, and rail for bulk freight transport.
But thanks to the rapid take-up of renewable electricity generation, including by individual households, there can appear to be an alternative prospect, a ‘technical fix’ that maintains the status quo exactly as-is while, in theory, making the carbon emissions disappear. It’s enough, the argument goes, simply to electrify everything—and in the case of transport, this could just mean replacing petrol and diesel vehicles with cars and trucks that look virtually identical to today’s, but run on electricity.
Here for example is Bill Gates’ version of the siren song (in a book that contains one mention of “alternative modes, like walking, biking and carpooling” but fails to mention public transport at all):
It’s rare that you can boil the solution for such a complex subject down into a single sentence. But with transportation, the zero-carbon future is basically this: Use electricity to run all the vehicles we can, and get cheap alternative fuels for the rest.
—Bill Gates, How to avoid a climate disaster (Penguin, 2021)
Of course, all this promises to do is (eventually) eliminate the carbon emission footprint from transport, as part of the fight against dangerous climate change. Because it just replaces cars and trucks with better cars and trucks, it won’t make any difference to traffic congestion, to death and injury on the road, or to the factors driving urban sprawl and undermining walkable communities. It won’t even fully solve pollution problems, because many of the most dangerous ‘PM2.5’ particulate emissions actually come from tyres or road dust. In the worst case, the perception of better vehicle technology that is cheaper to operate could make these problems worse by increasing overall levels of car and truck travel.
Nonetheless, the magnitude and urgency of climate change action by itself weighs in favour of the zero-emission vehicle solution, even if carbon emissions are the only problem solved. So it’s worth considering the electric vehicle solution on its own merits solely as an emission-reduction measure.
EVs can be zero-emission…in the fullness of time
Considered on their own merits, and despite their ultimate promise, zero-emission vehicles relying on renewable electricity have a key drawback. While it’s easy to picture the endpoint—a fully-electric vehicle fleet with a 100% renewable electricity grid, all the technology for which already exists today—that endpoint with its promised emission reductions simply won’t be achieved as fast as is needed.
As 2021’s Glasgow climate conference (‘COP26’) made clear, it’s no longer sufficient to target emission reductions by 2040 or 2050 in order to avoid an increase in average global temperatures above 2 degrees, let alone the Paris target of 1.5 degrees. Avoiding the most dangerous effects of climate change (extreme weather, heat-related death and crop losses, the end of coral reefs, submerging of Pacific island nations) makes it necessary to achieve reductions of at least 50 to 60 per cent of 2005 levels by 2030. Indeed, calculations by Environment Victoria, based on the Combet Report to the Victorian Government on decarbonisation, suggest that a 67 per cent reduction on 2005 levels by 2030, at least, is needed to keep us on track for a 1.5 degree reduction.
The electric-vehicle pathway to emission reductions proceeds in three logical steps:
- Replace the current Australian fleet of petrol and diesel vehicles with an equivalent electric fleet.
- Provide the electrical infrastructure to meet the road transport task from the existing power grid.
- Develop renewable energy sources to make the power grid 100% renewable.
Of these three steps, only the last has currently proceeded to any substantive extent: as of 2020, the Australian grid is about 24% renewable. But all three steps are necessary to getting big reductions in transport emissions via EVs, and none of them are likely to be as fast as (for example) the one decade it took to replace landlines with mobile phones, or CRT with LCD televisions. Both cars and power stations are much larger and longer-lived than typical household appliances.
The most optimistic credible scenarios to date—completely setting aside current woeful Federal government policies—have EVs comprising around 85% of all new car sales by 2030. Some individual manufacturers such as Volvo, Fiat and Mercedes-Benz have committed to sell only electric cars by 2030. But it will take, at best, a further decade for the majority of the existing pre-2030 car fleet to be renewed, meaning the earliest credible date for internal-combustion engines to be relegated to an inconsequential minority is around 2040.
Most published forecasts have the EV transition proceeding much more slowly than this. The COP26 pledge, to which the NSW and Victorian governments signed up in 2021, is to transition to 100% new vehicles being EVs in ‘leading markets’ by 2035. To align with this, these states have officially targeted having 50% new car sales being EVs by 2030.
As the Appendix shows, even if one trusts to luck and proceeds with the heroic assumption that the entire Australian road transport fleet (existing and new) can be electrified by 2030, the maximum plausible reduction in emissions from the (combined) electricity generation and transport sectors is 44 per cent on 2005 levels by 2030.
Make no mistake: this is an impressive reduction, and more than ample justification for active policy measures to replace internal-combustion vehicles with EVs as fast as is practical. But it’s not enough by itself to achieve the 1.5 degree target in the transport sector as well as electricity.
In the all-electric-by-2030 scenario, a car with a peak-time average occupancy of 1.1 passengers still involves emission on average of around 80g CO2-e per passenger kilometre, compared with 200g per kilometre or more for an internal-combustion car and around 130g for an EV charged from the electricity grid in 2020. But with more plausible assumptions on the pace of electrification, average driving emissions will far exceed 80g/km. (And this considers just the emissions in operation, leaving aside the emissions generated by manufacturing a new fleet of electric vehicles.)
Unfortunately, it’s also not enough to argue that individual households can reduce these emissions to zero by relying on their own solar panel output to charge electric cars. Residential PV generation has been, and will continue to be, one of the largest contributors to decarbonising the entire power grid; but the same solar panel cannot be charging an EV and decarbonising Australia’s electricity at the same time. Meanwhile, not every household and business is going to be able to install sufficient on-site PV capacity to meet EV charging demands (or batteries, if they have to charge at night). No matter what individual households do, the climate only responds to emissions in the aggregate. Our 2030 scenario takes ambitious expansion of household solar panels into account alongside other renewables—exceeding even the impressive growth seen in the 2010s—but shows that even this level of ambition isn’t enough.
To have any chance of achieving the Paris target, we need to boost the use of other methods of transport that entail much less than 80g of carbon emissions per passenger-kilometre—and ideally also rely on a smaller number of vehicles needing to be manufactured.
Public and active transport are low-emission today
Public transport, even at moderately low levels of patronage, has an inherently low energy and emissions footprint per passenger relative to cars. As is detailed further on our energy and emissions pages, this holds true even when the public transport system operates from fossil-fuel sources.
While cars accounted for 185 billion vehicle-km in 2018–19, and trucks and utes another 73 billion, the total covered by buses was only 2.5 billion vehicle-km, or 1% of the total. So even if governments doubled the provision of bus services across the board (allowing Melbourne buses with a 20 minute frequency to run every 10 minutes instead, for example), this would only add another 1% to the overall road transport task.
At a moderate loading of 40 passengers, even a diesel bus generates emissions of 22gCO2-e per passenger-km: one-sixth that of an electric car on the 2020 power grid and just over one-quarter that of an electric car in the hypothetical all-electric-by-2030 scenario. An electric bus (as the Victorian and NSW governments will introduce progressively during the 2020s) even at a low loading of 10 passengers involves around one-third the energy and emissions per passenger compared with an electric car carrying 1.1 passengers, the two supplied from the same power grid.
These big reductions in emissions per passenger are available now, not in 2030. They do depend, of course, on people having access to public transport, and walking and cycling options, suitable to their needs.
And to return to an earlier point: while it is quite technically feasible for electric vehicle chargers (including at the household level) to procure fully renewable electricity supplies by way of certificates, as is now being done for trains and trams in Victoria and NSW, there is a massive scale problem involved. As the appendix shows, the electricity required to operate today’s road transport sector using electric vehicles far exceeds all the electricity generated from renewable sources today. And even with a more than threefold increase in renewables to 2030, road transport would still use up more than half 2030’s total renewable generation, leaving less than half available to displace non-renewable sources in the traditional electricity sector. A 50% reduction in emissions across both sectors (let alone 67%) will remain well out of reach.
Trains and trams today, meanwhile, consume less than 5% of all energy used in transport in Australia, so impose a relatively small burden on renewable electricity supplies. Were all Melbourne’s train services upgraded to provide 10-minute frequencies throughout the day, for example, this would represent only a marginal increase on current consumption. The same goes for intercity freight: according to the Australasian Railway Association, each additional freight train avoids adding hundreds of B-double trucks to the roads, and generates 16 times less carbon pollution even when both run on fossil fuel.
An expansion in public transport and rail freight building on present-day resources, with a judicious rollout of electric buses over the coming decade, can generate and support large increases in patronage in a relatively short time. Nor will the cost be exorbitant, particularly compared with tax breaks and other subsidies for EVs likely to cost thousands of dollars per household.
Combined with measures to support a similar boost in walking and cycling, a major public transport boost will generate sufficient ‘mode shift’ away from cars to ensure, in tandem with the EV transition, a reduction in transport emissions by 2030 exceeding 50%, and (if pursued forthrightly enough) even exceeding the 67% considered necessary to hold us to the 1.5 degree target.
Irish researcher Vera O’Riordan, writing in The Conversation, sums up what is needed by referencing the Intergovernmental Panel on Climate Change’s “Avoid, Shift, Improve” framework for reducing transport intensity and emissions. In this framework ‘better cars and trucks’ have a key role, but only where car travel can’t readily be avoided through better planning or shifted to other modes of transport with lower energy intensity. It echoes the more familiar reduce–reuse–recycle approach to waste reduction, recognising that the most effective way to deal with the problem is to first make the size of the problem itself as small as practical.
Halving Australia’s transport carbon emissions in a 2030 time frame is eminently achievable—but only if a substantial shift away from low-occupancy car transport (however fuelled) is part of the plan. Since this also helps deal with all the other problems caused by too much dependence on cars—problems that persist whatever is under the bonnet—while avoiding billions of dollars of additional spending on roads, there appears little reason not to do this.
Technical appendix: a 2030 best-case EV scenario
Here we address the question of what reduction in carbon emissions could be achieved in 2030, assuming the status quo in transport but with the most favourable (indeed heroic) assumptions on the take-up of electric cars and trucks—in particular, that the entire Australian road transport fleet is electrified by 2030.
As set out above, official projections (as well as the policy taken by the ALP to the 2019 Federal election) have some 50% of new car sales being electric by 2030, meaning the 2030 fleet consists not only of a substantial number of pre-2030 internal combustion (IC) vehicles, but also many new IC vehicles that will remain in the fleet for most or all of the following decade. For the sake of argument, however, we will suspend disbelief and assume the entire fleet electric by 2030.
In the three-step pathway outlined above for EV emission reductions, Step 2—the translation of road transport to additional demand on the power grid—requires particular attention. Not so much because of the infrastructure challenge itself: car chargers can be rapidly deployed today, and intelligent control can ensure EVs don’t collapse the grid by all trying to charge at once. Rather, careful consideration is required because of the sheer amount the transport sector adds to current electricity demand if one assumes the status quo.
Rapid change scenarios for the power grid (such as the ‘step change’ scenario in AEMO’s Integrated System Plan) typically anticipate it being 70% renewable by about 2035. One highly optimistic scenario advanced by NSW operator Transgrid does suggest the eastern states grid (‘NEM’) could reach “91% as early as 2030”. However, on closer inspection this so-called Deep Decarbonisation scenario also assumes the size of the EV fleet in 2030 is 3.14 million, or just 18% of vehicles registered in NEM states in 2020.
In the (pre-pandemic) 2018–19 financial year, cars and trucks clocked up a total of 261 billion vehicle-kilometres in Australia. If all of these were electric (and conservatively assuming every one consumed the 200Wh/km typically assumed for a medium sized electric car), this would have demanded 52TWh (terawatt-hours, or trillion watt-hours) of electricity. By sheer coincidence, this is exactly equal to the total electricity generated from all renewable sources across Australia in 2018–19—including residential solar panels—out of a total of 264TWh, or about 230TWh final demand after losses.
But it’s unrealistic to assume electric SUVs, utes and trucks can all achieve the passenger car average consumption of 200Wh/km. Conservatively, light commercial vehicles (‘pickups’ in American vernacular) are typically likely to require at least 320Wh/km, while estimates for trucks (rigid or articulated) range from 1200 to 1900Wh/km, so that 1500Wh/km might be taken as a suitable estimate. A more realistic calculation now arrives at a figure of 83TWh, not 52TWh, as this table sets out:
|2018–19 vehicle km|
Source: Vehicle-kilometres from BITRE Infrastructure Statistics Yearbook, 2020; PTUA calculations from consumption estimates as above.
So hypothetically, adding 83TWh of EV charging demand to the actual 2019 grid would raise final demand to 313TWh, with the 52TWh of renewable generation accounting for 17% of demand rather than the actual figure of 23% for 2018–19.
How does this map out to 2030, assuming that established trends continue? On the one hand there are grounds for optimism, given that renewable electricity is growing strongly while (non-transport) electricity demand has been essentially static for most of this century. Against this, one must account for trend growth in vehicle-kilometres assuming ‘business as usual’ in the transport sector (and conservatively, the same proportions of cars and trucks as in 2018–19). The following table provides the calculation:
|Renewable generation (TWh)||52||181|
|Non-transport electricity demand (TWh)||230||248|
|Total road travel (billion km)||261||311|
|Road transport electricity (TWh)||(83)||(99)||99|
|Total electricity demand (TWh)||230||248||347|
|Renewables as % of demand||23||73||52|
|Implied non-renewable generation (TWh)||178||67||166|
|Electricity carbon emissions (Mt CO2-e)||166||62||155|
|Electricity emissions intensity (gCO2-e/kWh)||722||250||447|
|Electric car emissions intensity (gCO2-e/km)||(144)||n/a||89|
(Notes: assumed annual growth rates of 1.6% for vehicle kilometres and 0.7% for non-transport electricity demand are based on the average trend from 2009 to 2019. Annual growth rate of 12% for renewable electricity is assumed, exceeding the 10% average trend from 2009–2019 in order to achieve greater than 70% penetration in 2030 excluding transport. Electricity carbon emissions for 2018–19 taken from Clean Energy Regulator figures, and for 2029–30 are scaled pro-rata based on implied non-renewable generation. Figures in parentheses are notional calculated values that do not contribute to totals.)
Should all assumptions favourably align, the projection is that electricity and transport sector emissions will total around 155Mt of CO2 equivalent. Comparing with the 2005 emissions totals of 278.5Mt (comprising 196.8Mt from electricity and 81.7Mt from transport), this represents a 44 per cent decrease.
The 44% reduction in electricity-plus-transport emissions to 2030 is well short of the 67% minimum considered necessary by Environment Victoria, and short even of the 50% expected on more modest ambitions. This is despite assuming the entire road transport sector is electric by 2030, and despite a more than threefold expansion of renewable electricity generation. Notice that on this scenario, adding the road transport sector to aggregate electricity demand means total non-renewable generation (hence emissions) in 2029–30 is only 7% less than in 2018–19, compared with 62% less if transport demand is excluded.
On less favourable assumptions—in particular, that electrification proceeds only partially to 2030, or that electrification generates a new boom in road transport vehicle-kilometres by more than 1.6% per year, or that non-transport electricity use starts growing noticeably in the next decade—the expected reduction in emissions will be well short even of the 44 per cent found in this scenario. Getting to more than 44 per cent, meanwhile, will require a change from the status quo, as the main text sets out.
Last modified: 27 November 2021