Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.
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Does reducing speed reduce emissions from the average car?
Every car has an optimal speed range that results in minimum fuel consumption, but this range differs between vehicle types, design and age.
Typically it looks like this graph below: fuel consumption rises from about 80km/h, partly because air resistance increases.
But speed is only one factor. No matter what car you are driving, you can reduce fuel consumption (and therefore emissions) by driving more smoothly.
This includes anticipating corners and avoiding sudden braking, taking the foot off the accelerator just before reaching the peak of a hill and cruising over it, and removing roof racks or bull bars and heavier items from inside when they are not needed to make the car lighter and more streamlined.
In New Zealand, EnergyWise rallies used to be run over a 1200km course around the North Island. They were designed to demonstrate how much fuel could be saved through good driving habits.
The competing drivers had to reach each destination within a certain time period. Cruising too slowly at 60-70km/h on straight roads in a 100km/h zone just to save fuel was not an option (also because driving too slowly on open roads can contribute to accidents).
The optimum average speed (for both professional and average drivers) was typically around 80km/h. The key to saving fuel was driving smoothly.
In the first rally in 2002, the Massey University entry was a brand new diesel-fuelled Volkswagen Golf (kindly loaned by VW NZ), running on 100% biodiesel made from waste animal fat (as Z Energy has been producing).
A car running on fossil diesel emits about 2.7kg of carbon dioxide per litre and a petrol car produces 2.3kg per litre. Using biofuels to displace diesel or petrol can reduce emissions by up to 90% per kilometre if the biofuel is made from animal fat from a meat works. The amount varies depending on the source of the biofuel (sugarcane, wheat, oilseed rape). And of course it would be unacceptable if biofuel crops were replacing food crops or forests.
Regardless of the car, drivers can reduce fuel consumption by 15-20% by improving driving habits alone – reducing emissions and saving money at the same time.
When you are thinking of replacing your car, taking into account fuel efficiency is another important way to save on fuel costs and reduce emissions.
Many countries, including the US, Japan, China and nations within the European Union, have had fuel efficiency standards for more than a decade. This has driven car manufacturers to design ever more fuel-efficient vehicles.
Most light-duty vehicles sold globally are subject to these standards. But Australia and New Zealand have both dragged the chain in this regard, partly because most vehicles are imported.
New Zealand also remains hesitant about introducing a “feebate” scheme, which proposes a fee on imported high-emission cars to make imported hybrids, electric cars and other efficient vehicles cheaper with a subsidy.
In New Zealand, driving an electric car results in low emissions because electricity generation is 85% renewable. In Australia, which still relies on coal-fired power, electric cars are responsible for higher emissions unless they are recharged through a local renewable electricity supply.
Fuel and electricity prices will inevitably rise. But whether we drive a petrol or electric car, we can all shield ourselves from some of those future price rises by driving more efficiently and less speedily.
Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.
If you have a question you’d like an expert to answer, please send it to email@example.com
There is a lot of discussion on the benefits of electric cars versus fossil fuel cars in the context of lithium mining. Please can you tell me which one weighs in better on the environmental impact in terms of global warming and why?
Electric vehicles (EVs) seem very attractive at first sight. But when we look more closely, it becomes clear that they have a substantial carbon footprint and some downsides in terms of the extraction of lithium, cobalt and other metals. And they don’t relieve congestion in crowded cities.
In this response to the question, we touch briefly on the lithium issue, but focus mainly on the carbon footprint of electric cars.
The increasing use of lithium-ion batteries as a major power source in electronic devices, including mobile phones, laptops and electric cars has contributed to a 58% increase in lithium mining in the past decade worldwide. There seems little near-term risk of lithium being mined out, but there is an environmental downside.
The best comparison is based on a life cycle analysis which tries to consider all the emissions of carbon dioxide during vehicle manufacturing, use and recycling. Life cycle estimates are never entirely comprehensive, and emission estimates vary by country, as circumstances differ.
A life cycle analysis of emissions considers three phases: the manufacturing phase (also known as cradle-to-gate), the use phase (well-to-wheel) and the recycling phase (grave-to-cradle).
The manufacturing phase
In this phase, the main processes are ore mining, material transformation, manufacturing of vehicle components and vehicle assembly. A recent study of car emissions in China estimates emissions for cars with internal combustion engines in this phase to be about 10.5 tonnes of carbon dioxide (tCO₂) per car, compared to emissions for an electric car of about 13 tonnes (including the electric car battery manufacturing).
Emissions from the manufacturing of a lithium-nickel-manganese-cobalt-oxide battery alone were estimated to be 3.2 tonnes. If the vehicle life is assumed to be 150,000 kilometres, emissions from the manufacturing phase of an electric car are higher than for fossil-fuelled cars. But for complete life cycle emissions, the study shows that EV emissions are 18% lower than fossil-fuelled cars.
In the use phase, emissions from an electric car are solely due to its upstream emissions, which depend on how much of the electricity comes from fossil or renewable sources. The emissions from a fossil-fuelled car are due to both upstream emissions and tailpipe emissions.
Upstream emissions of EVs essentially depend on the share of zero or low-carbon sources in the country’s electricity generation mix. To understand how the emissions of electric cars vary with a country’s renewable electricity share, consider Australia and New Zealand.
In 2018, Australia’s share of renewables in electricity generation was about 21% (similar to Greece’s at 22%). In contrast, the share of renewables in New Zealand’s electricity generation mix was about 84% (less than France’s at 90%). Using these data and estimates from a 2018 assessment, electric car upstream emissions (for a battery electric vehicle) in Australia can be estimated to be about 170g of CO₂ per km while upstream emissions in New Zealand are estimated at about 25g of CO₂ per km on average. This shows that using an electric car in New Zealand is likely to be about seven times better in terms of upstream carbon emissions than in Australia.
The above studies show that emissions during the use phase from a fossil-fuelled compact sedan car were about 251g of CO₂ per km. Therefore, the use phase emissions from such a car were about 81g of CO₂ per km higher than those from a grid-recharged EV in Australia, and much worse than the emissions from an electric car in New Zealand.
The recycling phase
The key processes in the recycling phase are vehicle dismantling, vehicle recycling, battery recycling and material recovery. The estimated emissions in this phase, based on a study in China, are about 1.8 tonnes for a fossil-fuelled car and 2.4 tonnes for an electric car (including battery recycling). This difference is mostly due to the emissions from battery recycling which is 0.7 tonnes.
This illustrates that electric cars are responsible for more emissions than their petrol counterparts in the recycling phase. But it’s important to note the recycled vehicle components can be used in the manufacturing of future vehicles, and batteries recycled through direct cathode recycling can be used in subsequent batteries. This could have significant emissions reduction benefits in the future.
So on the basis of recent studies, fossil-fuelled cars generally emit more than electric cars in all phases of a life cycle. The total life cycle emissions from a fossil-fuelled car and an electric car in Australia were 333g of CO₂ per km and 273g of CO₂ per km, respectively. That is, using average grid electricity, EVs come out about 18% better in terms of their carbon footprint.
Likewise, electric cars in New Zealand work out a lot better than fossil-fuelled cars in terms of emissions, with life-cycle emissions at about 333 g of CO₂ per km for fossil-fuelled cars and 128g of CO₂ per km for electric cars. In New Zealand, EVs perform about 62% better than fossil cars in carbon footprint terms.
When it comes to road transport, Australia is at risk of becoming a climate villain as we lag behind international best practice on fuel efficiency.
Road transport is one of the main sources of greenhouse gas emissions and represented 16% of Australia’s total carbon dioxide emissions in 2000, growing to 21% in 2016. Total CO₂ emissions from road transport increased by almost 30% in the period 2000-16.
Fuel efficiency (CO₂ emission) standards have been adopted in around 80% of the global light vehicle market to cap the growth of transport emissions. This includes the United States, the European Union, Canada, Japan, China, South Korea and India – but not Australia.
If Australia had introduced internationally harmonised emissions legislation three years ago, households could have made savings on fuel costs to the tune of A$1 billion.
This shocking figure comes from our preliminary calculations looking at the effect of requiring more efficient vehicles to be sold in Australia.
A report, published yesterday by Transport Energy/Emission Research, looked at what Australia has achieved in vehicle fuel efficiency and CO₂ standards over the past 20 years. While Australia has considered and tried to impose standards a number of times, sadly these attempts were unsuccessful.
Legislative action on vehicle CO₂ emissions is long overdue and demands urgent attention by the Australian government.
How did Australia get here?
The most efficient versions of vehicle models offered in Australia are considerably less efficient than similar vehicles in other markets.
Australia could increasingly become a dumping ground for the world’s least efficient vehicles with sub-par emissions performance, given our lack of fuel efficiency standards. This leaves us on a dangerous path towards not only higher vehicle emissions, but also higher fuel costs for passenger travel and freight.
Australia has attempted to impose CO₂ or fuel efficiency standards on light vehicles several times over the past 20 years, but without success. While the federal government was committed to addressing this issue in 2015, four years later we are still yet to hear when – or even if – mandatory fuel efficiency standards will ever be introduced.
The general expectation appears to be that average CO₂ emission rates of new cars in Australia will reduce over time as technology advances overseas. In the absence of CO₂ standards locally, it is more likely that consumers will continue to not be offered more efficient cars, and pay higher fuel costs as a consequence.
Using an Australian fleet model described in the TER report, we can make a conservative estimate that the passenger vehicle fleet uses about half of this fuel: 16 billion litres per year. New cars entering the fleet each year would represent about 5% of this: 800 million litres per year.
So assuming that mandatory CO₂ standards improve fuel efficiency by 27%, fuel savings would be 216 million litres per year.
In the last three years, the average fuel price across Australia’s five major cities is A$1.33 per litre. This equates to a total savings of A$287 million per year, although this would be about half the first year as new cars are purchased throughout the year and travel less, and would reduce as vehicles travel less when they age.
The savings are accumulative because a car purchased in a particular year continues to save fuel over the following years.
The table below shows a rough calculation of savings over the three year period (2016-2018), for new cars sold in the same period (Model Years 2016, 2017 and 2018).
As a result, over a period of three years, A$1.3 billion in potential savings for car owners would have accumulated.
Policy has come close, but what are we waiting for?
The Australian government is not progressing any measures to introduce a fuel efficiency target. In fact, it recently labelled Labor’s proposed fuel efficiency standard as a “car tax”.
But Australia has come close to adopting mandatory vehicle CO₂ emission standards in the past.
In late 2007, the Labor government committed to cutting emissions to achieve Australia’s obligations under the Kyoto Protocol. The then prime minister, Kevin Rudd, instructed the Vehicle Efficiency Working Group to:
… develop jointly a package of vehicle fuel efficiency measures designed to move Australia towards international best practice.
Then, in 2010, the Labor government decided mandatory CO₂ emissions standards would apply to new light vehicles from 2015. But a change in government in 2013 meant these standards did not see the light of day.
The targets for adopting this policy in 2025, considered in the draft statement, were marked as “strong” (105g of CO₂ per km), “medium” (119g/km) and “mild” (135g/km) standards.
Under all three targets, there would be significant net cost savings. But since 2016, the federal government has taken no further action.
It begs the question: what exactly are we waiting for?
The technical state of play
Transport Energy/Emission Research conducted preliminary modelling of Australian real-world CO₂ emissions.
This research suggests average CO₂ emission rates of the on-road car fleet in Australia are actually increasing over time and are, in reality, higher than what is officially reported in laboratory emissions tests.
In fact, the gap between mean real-world emissions and the official laboratory tests is expected to grow from 20% in 2010 to 65% in 2025.
This gap is particularly concerning when we look at the lack of support for low-emissions vehicles like electric cars.
Given that fleet turnover is slow, the benefits of fuel efficiency standards would only begin to have a significant effect several years into the future.
With continuing population growth, road travel will only increase further. This will put even more pressure on the need to reduce average real-world CO₂ emission rates, given the increasing environmental and health impacts of the vehicle fleet.
Even if the need to reduce emissions doesn’t convince you, the cost benefits of emissions standards should. The sale of less efficient vehicles in Australia means higher weekly fuel costs for car owners, which could be avoided with the introduction of internationally harmonised emissions legislation.
Australian cars are using 23% more fuel than advertised, according to a report from the Australian Automobile Association, which also claims that eco-friendly hybrid electric cars emit four times more greenhouse gas than the manufacturers advertise.
The report on real-world (that is, on-road) emission testing was commissioned by consultancy firm ABMARC to test 30 cars twice on Melbourne roads. The method used to measure both the emissions and the fuel consumption was a so-called Portable Emissions Measurement System (PEMS).
They found that when compared to the laboratory limits, on-road vehicle NOx (a toxic gas pollutant) emissions were exceeded for 11 out of 12 diesel vehicles, and carbon monoxide (also a toxic gas) emissions were exceeded by 27% of tested petrol vehicles.
However, the key consideration here is the phrase “comparison to the laboratory limits” because on-road tests can’t directly be compared to the laboratory test limits, for several key reasons.
How are emissions from vehicles measured?
Australian Design Rules (ADR) stipulate that before introducing a new vehicle model on the market, every car or truck manufacturer in Australia has to test one new car in the laboratory.
This is done by placing the vehicle on a chassis dynamometer, connecting the exhaust to highly accurate emissions-measurement equipment, and driving the vehicle according to a strictly defined routine.
The chassis dynamometer simulates the load conditions that the vehicle would experience if it were driven on a road. In current practice, the New European Driving Cycle (NEDC) is used. This defines the speed of the vehicle and rate of acceleration for every second of the 20-minute test.
There is strict control of the testing protocol, with stipulations on how and when the gears should be changed, right down to minute details such as turning off the radio while the headlights are on. This strict control enables testers to compare the performance of different vehicles measured in different laboratories around the world.
However, these highly defined conditions have led to certain manufacturers enabling the car’s engine management system to recognise when it is being tested and to adopt and produce cleaner exhaust emissions. The most famous example of this is the recent VW scandal that affected millions of vehicles worldwide.
Even though the driving cycle has “new” in its name, NEDC was designed in the 1980s and today can be considered outdated.
Real Driving Emissions
To address these challenges, Real Driving Emissions (RDE) tests were developed. RDE tests measure the pollutants emitted by cars while driven on the road. To run a RDE test, cars are fitted with a Portable Emissions Measurement System (PEMS).
A PEMS is a complex piece of equipment that sits in the back of the car and monitors key pollutants emitted by the vehicle in real time as it is driven on the road.
These tests have proved extremely useful in highlighting some of the shortfalls of the laboratory tests. They can be run for much longer periods (several hours as compared with 15-30 minutes in the laboratory) and can give us information on long-term emission performance of the vehicles. They will not replace laboratory tests, but can provide additional information.
RDE requirements will ensure that cars deliver low emissions during on-road conditions. In 2021, Europe will become the first region in the world to introduce such complementary on-road testing for new vehicles.
RDE tests still face several unresolved challenges. The first is that the PEMS are still being developed and are not as accurate as the lab measurement equipment. The second, and more important, is the variability that one encounters while driving in real-world road conditions.
In order to compare the RDE test results with the laboratory-based standards a “conformity factor” is defined as a “not to exceed limit” that takes into account the error of measurements. This error is due to the PEMS equipment being less accurate, the variability in road conditions and driving behaviour, and thus the fact that the RDE tests will not deliver exactly the same results for each run.
A conformity factor of 1.5 would mean that the emissions measured by the PEMS in an RDE test should not exceed the standard NEDC test by more than a factor of 1.5. This is exactly the value that European Union legislators want to introduce – but not before 2021.
Australia is years behind
Australia remains years behind the European Union when it comes to vehicle emission standards.
The Euro emissions standards define the acceptable limits for exhaust emissions of new vehicles sold in the EU. Australia introduced the Euro 5 emission standards in 2016 as compared to Europe, which introduced these in 2009. At that time EU abolished the Euro 5 standard for already new ones in 2015.
Australia needs to upgrade to meet Euro 6 standards in order to provide effective detection of new vehicles. These include measures such as remote sensing as part of a vehicles road-worthiness assessment. This would help to ensure the maintenance status of vehicles and deliver compliance with Euro 6 RDE legislation.
What the Australian Automobile Association report highlights most of all is that the in-use vehicles (whether or not they are hybrid vehicles), many of which fall under the Euro 5 standard (or older), have almost all failed emission tests.
Until Australia updates our vehicle testing regimes to meet international standards, it will remain extremely difficult for Australians who want to buy an energy-efficient vehicle to make an informed purchasing decision.
The cheapest way for Australia to cut greenhouse gas emissions is to put a cap on car emissions. It would be so cheap, in fact, that it will save drivers money.
According to analysis from ClimateWorks, the toughest proposed standard would help Australia achieve about 6% of its 2030 emission reduction target, and save drivers up to A$500 each year on fuel.
The federal government is looking at policy options to meet Australia’s 2030 emissions target of 26-28% below 2005 levels. Last year it established a ministerial forum to look at vehicle emissions and released a draft Regulation Impact Statement for light vehicles (cars, SUVs, vans and utilities) in December.
There is no reason for the government to delay putting the most stringent emissions standard on cars.
Cars getting cleaner, but not in Australia
Australia currently does not have carbon dioxide emission standards on light vehicles. CO₂ standards work by improving the overall efficiency of the vehicle (the amount of CO₂ emitted per kilometre). These are different from fuel quality standards, which regulate the quality of fuels used by vehicles, and noxious emissions standards, which monitor a car’s emissions of noxious gases and particulates.
Currently, CO₂ emission standards cover over 80% of the global light automotive market. The lack of standards here means that Australia’s cars are less efficient than in many other countries, and this gap is set to widen.
In 2015, the average efficiency of new cars sold in Australia (in grams of CO₂ emitted per km) was 184g per km. In the European Union, the average efficiency of new cars was 120g per km for passenger vehicles and 168g per km for light commercial vehicles (such as vans used as couriers). In the United States – the spiritual home of the gas-guzzler – it is 183g per km and set to improve to 105g per km in 2025.
Australia’s cars account for about 10% of Australia’s greenhouse gas emissions, which are set to grow to 2030 if the market is left to its own devices.
Helping meet Australia’s climate target
In our submission to the draft Regulation Impact Statement, we confirmed that if the most stringent proposed target (105g per km) were introduced as proposed from 2020 to 2025, it would deliver 6% of Australia’s 2030 emissions reduction target. This would save A$49 per tonne of CO₂. Although there would be some costs in introducing the scheme, it would save A$13.9 billion by 2040 overall.
This saves an extra additional 41 million tonnes of CO₂ by 2030, 140 million tonnes by 2040, and an extra A$8.1 billion overall by 2040 compared with the least stringent proposed target (135g per km by 2025).
However, we found that a two-year delay would add an extra 18 million tonnes of CO₂ to the atmosphere, or 2% of the government’s 2030 carbon budget.
Any reductions not achieved in vehicle emissions will need to be made up in other sectors, or purchased through international carbon permits, most likely at a higher cost.
Savings on fuel and health
The most stringent target delivers A$27.5 billion in total fuel savings by 2040, A$16.7 billion more than the least stringent standard.
The draft regulations show that for an average car this is equal to a saving of A$197-295 a year for a driver doing 15,000km per year, and A$328-493 for a driver doing 25,000km per year.
To put this in context, based on 2012 household energy costs data, this would cut household energy costs by up to 10%, with even greater savings for low-income households.
But a two-year delay of the most stringent standard would also result in new car owners paying an extra A$4.9 billion in fuel costs by 2030, and an extra A$8.3 billion to 2040.
The reduction in fuel use will also potentially reduce air pollution, resulting in better health outcomes.
The most stringent standard will save deliver 2.6 times as much fuel as the least stringent standard, so should reduce health costs by a similar proportion. However, the introduction of emissions standards would need to occur in a way that does not increase noxious emissions such as nitrogen oxides.
No reason to delay
Given the enormous benefit of a more stringent standard, the government should also investigate an even more ambitious target.
Our research shows a standard of 95g per km by 2025 will deliver even greater benefits and is technically feasible based on achievements in other markets. The EU is aiming for this level by 2020.
While we also support improving fuel quality to reduce noxious emissions, research by the International Council on Clean Transportation (ICCT) shows that we do not need to improve Australia’s fuel quality standards before the introduction of standards to improve the overall efficiency of the vehicle.
Similarly, despite discrepancies between on-road and in-lab performance of vehicles as seen in the Volkswagen emissions scandal, a standard will still provide significant savings to consumers and the environment.
Standards alone are not the silver bullet. We’ll need a range of other measures to support emissions standards on cars to help improve efficiency and build consumer awareness of fuel-efficient vehicles.
With Australian car manufacturing due to cease by the end of 2017, it is an ideal time to ensure that new cars bought into Australia are the most efficient available. This will set us on the path towards lower vehicle emissions while reducing costs for motorists and improving health.