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 firstname.lastname@example.org
Why can’t I use the battery from my electric car to export solar power to the grid when I don’t need it?
Technically it is possible. You could charge your electric vehicle (EV) with solar photovoltaic panels (or any other means), and if the EV is not used, the stored energy could be pushed back into the grid, especially during hours of peak demand for electricity when market prices are high.
This is known as vehicle-to-grid technology and is seen as the future as we move towards more electrification of transport and a smart grid.
But manufacturers of electric vehicles have been reluctant, at first, to allow the bidirectional flow of power, for two reasons.
First, it could accelerate the degradation of batteries, which means they would need to be replaced more often. Second, the EV has to connect to the grid in the same way a solar photovoltaic system does, complying with standards to protect line operators and maintenance personnel working on the grid.
Such advanced bidirectional charge controllers come at an additional cost. Nevertheless, EV manufacturers such as Audi and Nissan have now taken steps to enable vehicle-to-grid connection with some of their models.
For EV models that do not have onboard inverters (to convert the DC electricity in the electric car to AC electricity we use in our homes), there are now bidirectional inverters available to connect any electric car. But the issue of battery life remains.
The continual charging and discharging through a 90% efficient converter shortens the life of the battery, and depending on brand and model, it may need replacing every five years. At more than NZ$5,000, this is a significant price tag for “energy prosumers” – people who both produce and consume energy.
There are other considerations that are very context-specific. These relate to the additional charges for enabling the export of electricity from households, which vary between lines companies and retailers (or local authorities), as well as the buy-back rate of the electricity, which again depends on the purchaser of the electricity.
At the moment, these specific circumstances are seldom favourable to justify the additional cost of the infrastructure needed to connect an electric car to the grid.
There are also practical considerations. If the EV is used for the morning and evening commute, it is not at the home during the day to be charged with a solar system. And if it is (hopefully) not charged during peak demand hours, but mostly in off-peak hours at night, then the vehicle-to-grid route makes less sense.
It only starts to make sense if an EV is not used daily, or if EVs are available to a larger network than just one household. There are major opportunities for EVs to be used in communities with microgrids that manage their own generation and consumption, independent of the larger grid, or if large smart grid operators can manage distributed EVs remotely and more efficiently.
What we suspected is now official: 2019 was Australia’s hottest year on record. The country’s average maximum temperature last year (30.69℃) was a scorching 2.09℃ hotter than the 1961-1990 average.
For the whole planet, 2019 is expected to come in second (behind 2016) making the last five years the hottest on record since 1880.
As we brace for increasingly hot summers, we are mindful extreme heat can pose significant health risks for vulnerable groups. But the effects of heat on the incidence of accidents and injury are less clear.
In research published today in Nature Medicine, researchers in the United States looked at the impact warmer temperatures will have on deaths from injury. They found if average temperatures warmed by 1.5℃, we could expect to see 1,600 more deaths each year across the US.
Given Australia is ahead of the global temperature curve, we could see an even greater number of deaths from injury per capita as a result of rising temperatures.
The researchers analysed death and temperature data collected from 1980 to 2017 across mainland United States (so their results excluded the states of Alaska and Hawaii).
They looked at records from more than five million injury deaths from this 38-year period. They also identified temperature anomalies by county and by month, to understand how these deaths could relate to spikes in the weather.
Using a method called Bayesian Spatio-temporal modelling, the authors combined this information to estimate the rates at which injury deaths would rise with a 1.5℃ temperature increase.
They categorised injury deaths as either unintentional (transport, falls and drownings) or intentional (assaults and suicides), and stratified results further by gender and age group.
They found deaths from drownings would increase by as much as 13.7% in men aged 15-24 years, whereas assaults and suicides would increase by less than 3% across all groups. Transport deaths would rise by 2% for men aged 25-34 years and 0.5% for women in the same age group.
Overall, these increased risks would account for 1,601 additional deaths per year from injury across the US, an annual rise of 0.75% in overall deaths from injury in the population. They indicate 84% of these deaths would occur in males.
Although the primary focus was on 1.5℃ warming, the researchers also looked at a rise of 2℃. The found this would result in 2,135 additional deaths from injury (a 1% increase).
Why do deaths from injury increase in hot weather?
Higher temperatures are associated with irritability, and increases in conflict and interpersonal violence.
Hyperthermia (abnormally high body temperature) can also lead to symptoms such as loss of concentration and fatigue. These factors can trigger incidents such as car accidents and faults operating mechanical equipment. So we can expect injuries to increase as we face more hot days.
A South Australian study of workers’ compensation claims found for every degree above 14℃, occupational injuries requiring more than three days off work increased modestly (0.2%).
Increases in drowning might occur due the higher proportions of people seeking relief in the water on hot days.
We must strengthen the nation’s climate change and human health research to provide specific details on when, where and how we can best ameliorate heat harm.
We need to ramp up our prevention efforts in this space. All Australians should be made aware of the dangers of a hotter world through a federally funded public education strategy, akin to the successful “Life. Be in it” campaign, which successfully promoted the importance of being active.
Most urgently, we must focus on prevention through climate change mitigation, which will be the best and most far-reaching prevention strategy we can deliver.
The long-awaited proposed changes would bring New Zealand in line with most other developed countries; apart from New Zealand, Russia and Australia are the last remaining OECD nations without fuel efficiency standards.
New Zealand’s long tradition of not regulating its car market, combined with substantial indirect subsidies for private cars, makes addressing emissions from the transport sector both challenging and highly significant.
Land transport emissions – the single largest source of fossil carbon dioxide in New Zealand – grew 93% between 1990 and 2017. There are multiple causes. The population grew 44% during this period, mostly through immigration. The car ownership rate also grew rapidly, partly due to economic growth and deficiencies in public transport in the main cities. Car ownership in New Zealand is now the highest in the OECD and there are more motor vehicles than adults.
Fuel efficiency improved only slowly over this period, before stalling in recent years: at 180g CO₂/km, the emissions of newly imported vehicles in New Zealand are 50% higher than in Europe. Because of the lack of a fuel efficiency standard, importers provide less efficient versions of their bestsellers to the New Zealand market. Of the ten bestselling new vehicles, five are utes (which also benefit from a fringe benefit tax exemption, four are SUVs and one is a regular car.
In addition, half of all vehicles are imported secondhand, mostly from Japan. They are cheap, but less efficient than newer models. Emissions, and congestion, are likely to continue rising as the national vehicle fleet is increasing by 110,000 vehicles a year.
One bright spot in the present situation is the emergence of an electric vehicle segment, mostly driven by the availability of cheap second-hand Nissan Leafs from Japan and the construction of a fast-charging network by a private company. Although sales have stalled in the past year at a market share of 2%, there are now 15,000 electric vehicles in New Zealand. (Australia has around 10,000 electric vehicles.)
New Zealand’s history of fuel taxes
New Zealand does not have a strong record of taxing “bads”. The only goods subject to excise taxes are tobacco, alcohol and fuel. The fuel tax is moderate by international standards. Over the past decade, the fuel tax has been fully allocated to road construction and maintenance.
New Zealand has an emissions trading scheme. The current carbon price of NZ$25/tonne of carbon dioxide adds five cents per litre to the price of fuel. Clearly, any likely increases in the carbon price are not going to be enough to change car buying decisions. Research shows that consumers tend to focus on upfront costs, while underestimating future fuel and maintenance costs.
Despite that, a special Auckland fuel tax of 10 cents per litre that co-funds public transport investment provoked a brief but intense backlash from the public. Plans to extend the scheme to other centres were canned.
A two-pronged plan
The proposed fuel efficiency standard would require car importers to either meet it or pay a fine. The suggested standard is 150gCO₂/km in 2021, falling to 105gCO₂/km in 2025, with further falls thereafter. There are more than 3000 car importers in New Zealand, so this could prompt a major shakeup, including possible price adjustments.
The standards are similar to those proposed by the Australian Coalition government in 2016, which have not yet been taken any further. Internationally, fuel efficiency standards cover 80% of the light vehicle market.
But the second component of the proposal, the clean car discount, has attracted more attention. Cars emitting less than the current threshold would received a discount, initially up to NZ$1800 for an efficient petrol car, up to NZ$4800 for a hybrid and up to NZ$8000 for a battery electric car. Cars costing more than NZ$80,000 would not receive a discount.
Known as a “feebate scheme”, those rebates would be paid for by increased fees for high-polluting cars, of up to NZ$3000. The amounts are designed so that the entire scheme would be revenue neutral to the government. Modelling suggests that the proposed standard and discount combined would save motorists NZ$12,000 over the life of a vehicle.
But overall, the New Zealand proposal has been received positively by car makers and across political parties.
One possible weakness is that it is entirely based on carbon dioxide. Other pollutants, including nitrous and sulphur oxides and particulate matter (soot), that are responsible for most of the immediate health impacts of vehicle pollution and are worse in diesel than in petrol vehicles, are not targeted. Nor are the underlying subsidies to the car-based transport system, which make a transition to active and public transport more difficult.
Any decisions made now will have impacts for decades to come. Switching the fleet to electric is different from just switching to more fuel-efficient cars. It involves new charging infrastructure and some behavioural changes from the public, and these challenges (rather than simply cost) are stumbling blocks worldwide to more rapid adoption.
These arguments have persuaded many countries to bring in electric vehicle incentives beyond simply targeting carbon dioxide. Norway is a famous example, where electric vehicles avoidpurchase taxes and market share is already 60%. The UK has recently exempted electric company cars from fringe benefit tax.
As the global market share of electric vehicles still stands at only 2%, eight years after they became widely available, and the number of fossil-fueled vehicles is increasing by 48 million a year, stronger action on vehicle emissions is clearly needed worldwide.
Children today spend more time in cars than previous generations. They also spend less time playing on the streets and in unstructured and unsupervised activity outdoors. The lack of opportunities for physical activity and the loss of freedom to explore their local neighbourhood is bad news for children’s physical, social and mental well-being.
We know surprisingly little, however, about the detailed reasons for individual private car use. An international study highlights that households with children have higher rates of car ownership and use. In Australia, official statistics on transport pay a great deal of attention to the “journey to work”, but car travel that can be attributed to child-related activities has not been fully explored.
Research on children’s travel patterns tends to focus on the “journey to school”. While school trips are important, this provides only a narrow image of children’s actual travel patterns. They also make many trips to non-school destinations and extracurricular activities such as sport, music and dance classes.
We recently reviewed local government policies related to sustainable mobility and child-and-youth-friendly cities. Our review found little consideration of children and young people in transport planning policies across Australia. This is despite the fact that the decline in their walking and cycling rates was widely recognised.
All together, these suburban conditions add to the social disadvantage resulting from limited access to services and activities that are critical for families with children. This further encourages private car use.
Changing social structures mean families usually are on tight schedules. These changes include increases in employment for women and in the number of both single-parent families and families where both parents are in paid work. Because the car is relatively cheap and easy to use for individual mobility in Australian cities, it is generally the uncontested way to manage these schedules.
In addition, the increased individualisation as a common characteristic of Western societies usually means parents are expected to provide strict supervision of children’s movements. In the conditions described above, the most practical way to do this is usually to drive them in a car.
Of course this increases the number of cars on our streets, particularly around schools and other common destinations for children. This then perpetuates parents’ concerns about traffic safety, leading in turn to even more private car use.
What is perhaps most striking about the trend towards chauffeuring children is that these facts are seemingly becoming accepted as unavoidable outcomes of modern society. They are largely ignored in transport planning.
The importance of children’s role in sustainable mobility can be grouped under two themes.
First, children’s needs in today’s lifestyles mean they have an active role in contributing to increased private car use. The daily lives of families with children offer a good example of the context in which carbon-intensive travel patterns occur. If their mobility needs can be met more sustainably (even partially) we are likely to achieve significant carbon savings.
A better understanding of children’s travel patterns would provide a solid foundation for sustainable mobility policies. Planning and transport policies that are responsive to children’s specific needs are likely to have more effective and longer-lasting outcomes, with many related benefits for social sustainability and public health.
But just because there will be more cars, covering more ground, that doesn’t necessarily mean CO₂ emissions will continue to rise. It depends on a complex mix of population trends, income growth and the impacts of new policies and technologies.
It might therefore seem sensible to delay policy decisions until we can see what type of future emerges. However, our research found that a “wait and see” approach will dramatically increase our economic, social and environmental vulnerability.
Lower-income Australians are particularly at risk. This is because transport accounts for a greater proportion of their household income and they tend to live on the urban fringe where daily travel distances are necessarily higher.
Future-proofing our transport policy means we must engage with uncertainty, not ignore it. That means choosing policies that allow us to adapt to a range of technological or social developments.
We modelled different policy options in Western Australia, looking for options that reduced CO₂ emissions without creating social vulnerabilities. The most effective approach requires simultaneously improving fuel standards, making cars more efficient, and increasing city density to reduce both car ownership and the total distance we need to travel in cars.
However, CO₂ emissions alone don’t provide the full picture. Our model found that encouraging biofuels, for example, could mean increasing our agricultural footprint to grow feedstock.
Similarly, electric and hydrogen-fuelled vehicles require energy supplied by the electricity sector. As this sector itself decarbonises, technologies such as solar, hydro and wind will require greater areas of land than coal and gas technologies.
However, managing carbon dioxide emissions and demand on land is not necessarily mutually exclusive. Wind turbines can co-exist with grazing, and decentralised solar panels are already common on existing buildings. Offshore wind farms and solar installed on otherwise unproductive land can lessen impact. Targeted investment in technological efficiency can further reduce this impact.
Using land for both agriculture and energy production could actually give farmers greater economic resilience. Alternative fuels that use waste products or are low-impact (such as biofuel made from algae) are also promising avenues.
The economic case for expensive changes
Although the implementation of stringent transport policy will be costly – it requires massive changes in capital infrastructure and behaviour – it will open up other benefits and saving.
Changing the type of fuel used by cars, improving vehicle efficiency and increasing city density are all policy levers that can reduce the footprint of urban cars, but these must occur in tandem. To minimise costs and realise the potential savings, policymakers need to collaborate on finding policies that are flexible enough to adapt to an uncertain future.
Should we have the leadership to implement such sophisticated policy, we might accidentally design a future in which we are healthier and happier too.
Shopping can be confusing at the best of times, and trying to find environmentally friendly options makes it even more difficult. Welcome to the second instalment of our Sustainable Shopping series, in which we ask experts to provide easy eco-friendly guides to purchases big and small.
The harms of CO₂ emissions from fossil fuel burning have been hammered home time and time again: they are the main driver of global warming and sea level rise, and they harm vulnerable communities. So how can our choice of car minimise these devastating outcomes?
A simple way to reduce transport emissions significantly is to guide consumers towards more fuel-efficient vehicles. Many other countries have minimum national standards for new cars, but no such targets currently exist in Australia.
This means global car manufacturers can dump high-polluting cars, which can’t be sold in countries with stricter regulations, into the Australian market. The most fuel-efficient, low-emission vehicles offered in Australia are on average less efficient than those offered in other countries with fuel efficiency standards. Car manufacturers offer those vehicles that are cost effective to supply and maximise their profit in the Australian market.
Internationally, this makes Australia a laggard when it comes to energy efficiency in the transport sector, ranking last out of 16 major OECD countries.
The regulations will encourage car manufacturers to import and promote the most fuel-efficient models. Evidence shows that motorists’ vehicle choices play a key role in decarbonising the transport sector.
Unfortunately, current car labels can be very confusing, presenting numbers with very little context. There is a simple way to make this labelling more effective, which other countries have done very well: rate vehicles against a benchmark.
The Irish fuel label, for instance, includes colour-coded bands to rank CO₂ emissions, and an estimate of the amount of fuel needed to travel 18,000km. Buyers can tell at a glance if a score is good or bad, and thus easily compare models.
Irish car labels also tell buyers about the vehicle’s registration tax (stamp duty), which varies based on its CO₂ emissions.
What can Australians do?
The best starting point when buying a new car is the Green Vehicle Guide, which gives you the CO₂ emissions intensity for each model.
I can see that’s better than the other SUVs detailed in the guide, but I want some more context. My next step is to look at the Carbon Dioxide Emissions Intensity report by the National Transport Commission, which will give me an idea of how the Mitsubishi measures up against other new vehicles in Australia.
That report is a whopping 66 pages long, but the graph below is on page 21. It shows the range and average of CO₂ emissions of 2015 vehicle models, so I can see that the average medium SUV emits 175g per km, and the upper limit is over 250g per km. The Mitsubishi is therefore a pretty sound choice – it’s actually under the average emissions of all classes of new vehicles.
Ideally, finding a less environmentally damaging car would not take this much work.
The Green Vehicle Guide should compare all categories of new vehicles against the “best in class” chart on page 22 of the Carbon Dioxide Emissions Intensity report. Better still, manufacturers should have to provide this information in an easily understood way on each car they sell.
Such rankings would inform people whether the vehicle they are choosing is an eco-friendly brand, and put pressure on manufacturers to improve their Australian offerings.
Making it easy to find greener cars can have a big impact. If all Australians buying a new vehicle in 2015 had picked the “best in class” for their model, the national average for new car CO₂ emissions that year would have been 55% lower.
The government can help the environment and consumers by following the European Union’s example. This would mean imposing better industry standards and raising consumer awareness by providing information on car labels that is easily understood and transparent, such as ranking vehicles against colour coded CO2 emission bands. Until then, a little information and some homework can help you find the most eco-friendly vehicle for your needs.
I have had a most interesting couple of days on the road and in the bush. Currently I’m in a motel room at Woolgoolga, near Coffs Harbour on the mid-north coast of New South Wales, Australia. ‘Hardly the wild,’ I hear you say, and you’re quite right – it isn’t. The weather was beginning to change I noticed on the final leg of my day’s itinerary, so I decided to hide out in a motel room for the night – good decision, it’s pouring outside.
I won’t give all away – I’ll leave the main description of the holiday to the website – but just some of the ‘downlights’ of the first couple of days for this post.
I didn’t arrive at Cathedral Rock National Park until just on dark, but did get the tent up prior to darkness arriving – when it did, it was dark! The campfire took an eternity to get going as all of the timber was damp and by the time I got it started it was time for bed – all-be-it an early night (7.30pm). I had decided to not spend the money on replacing all of the gear I needed to replace for camping, following the loss of a lot of gear over the years due to storage, etc. I hadn’t done much in the way of bushwalking or camping for years due to injuries sustained in my car crash and a bad ankle injury, so I left it all a bit late. I figured that for this holiday I’d make do and replace the gear with quality gear before the next trip. In short, I’ll get by – but it would have been nice to have some good gear just the same. It was a very cold night let me tell you – and long.
When I reached the heights of my first walk today, standing on top of Cathedral Rock National Park, my digital camera decided to die on me. I knew there was something wrong with it during the ascent as it was really chugging away taking pictures. I did get a couple of reasonable panoramic shots on the top of Cathedral Rock before it died, so that was good. I took stills with the video camera I was using, so it wasn’t a complete loss. When I completed the Woolpack Rocks walk I made the trip to Coffs Harbour to seek a replacement and got one for a reasonable price. It’s just another compact and so I will also buy a digital SLR prior to my next trip I hope. My previous SLR was basically destroyed when the camera cap came off during a multiple day bushwalk and all manner of stuff got into it. It wasn’t digital so I didn’t bother repairing it.
So tomorrow – off to Dorrigo National Park I hope and several lengthy walks I haven’t done before. Hopefully the rain will clear.
My latest holiday plan has gone flop – the back packing holiday is a no-goer. Reason? It would seem from all reports that the Tops to Myalls Heritage Trail has been abandoned, with parts of the route now so overgrown as to be unrecognizable. I have been told of walkers in recent times having to back track a fair distance when the way ahead was no longer able to be walked. So as disappointing as it is I have abandoned the trail myself and will now do something else.
With time running out for a settled option, I have decided to fall back on an earlier idea and that is to visit the Cathedral Rocks National Park and possibly do some further walks at the Dorrigo National Park. I have booked a vehicle (car rental) for the trip so things are fairly settled now as far as the destination is concerned. I am now going to put some meat on the bones of my idea and draw up an itinerary, Google Map, etc. So some real detail of what I plan to do will be coming over the next few weeks.
This isn’t going to be an expensive holiday or a long one, but is mean’t to be a simple time-out break and one that will allow me to plan some much bigger holidays for later in the year and into the coming year also.
It is time to start planning my next holiday. First step in the process was to settle on a date for it – this has been done and I have booked in two weeks annual leave for it.
The second stage is now to establish a location for the holiday. I’m toying with a couple of ideas at the moment. The first is to travel to Cathedral Rocks National Park and do some walks in that area. The second idea is to do some overnight walks through the Myall Lakes National Park through to the Gloucester area. I ruled out the possibility of travelling to the red centre due to rental car restrictions, so it is down to these two possibilities at this stage. I am leaning towards the latter at this stage however.