Climate explained: why switching to electric transport makes sense even if electricity is not fully renewable



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Robert McLachlan, Massey University

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 climate.change@stuff.co.nz

I have a question about the charging of electric cars. I understand New Zealand is not 100% self-sufficient in renewable energy (about 80%, supplemented by 20% generally produced by coal-fired stations). If I were to buy an electric vehicle it would add to the load on the national grid. Is the only way we are currently able to add the extra power to burn more coal? Does this not make these vehicles basically “coal fired”?

New Zealand is indeed well supplied with renewable electricity. In recent years, New Zealand has averaged 83% from renewable sources (including 60% hydropower, 17% geothermal, and 5% wind) and 17% from fossil fuels (4% coal and 13% gas).

In addition to being cheap and renewable, hydropower has another great advantage. Its production can ramp up and down very quickly (by turning the turbines on and off) during the day to match demand.

Looking at a typical winter’s day (I’ve taken July 4, 2018), demand at 3am was 3,480 megawatts (MW) and 85% was met by renewable sources. By the early evening peak, demand was up to 5,950MW, but was met by 88% renewable sources. Fossil fuel sources did ramp up, but hydropower ramped up much more.

Flipping the fleet

Even during periods of peak demand, our electricity is very clean. An electric vehicle (EV) charged during the evening would emit about 20 grams of carbon dioxide per kilometre.

Even an EV charged purely on coal- or gas-fired electricity still has lower emissions than a petrol or diesel car, which comes to around 240g CO₂/km (if one includes the emissions needed to extract, refine, and transport the fuel).

An EV run on coal-fired electricity emits around 180g CO₂/km during use, while the figure for gas-fired electricity is about 90g CO₂/km. This is possible because internal combustion engines are less efficient than the turbines used in power stations.




Read more:
Climate explained: the environmental footprint of electric versus fossil cars


Looking longer term, a mass conversion of transport in New Zealand to walking, cycling and electric trains, buses, cars and trucks is one of the best and most urgent strategies to reduce emissions. It will take a few decades, but on balance it may not be too expensive, because of the fuel savings that will accrue (NZ$11 billion of fuel was imported in 2018.)

This conversion will increase electricity use by about a quarter. To meet it we can look at both supply and demand.

More renewable electricity

On the supply side, more renewable electricity is planned – construction of three large wind farms began in 2019, and more are expected. The potential supply is significant, especially considering that, compared to many other countries, we’ve hardly begun to start using solar power.

But at some point, adding too much of these intermittent sources starts to strain the ability of the hydro lakes to balance them. This is at the core of the present debate about whether New Zealand should be aiming for 100% or 95% renewable electricity.

There are various ways of dealing with this, including storage batteries, building more geothermal power stations or “pumped hydro” stations. In pumped hydro, water is pumped uphill into a storage lake when there is an excess of wind and solar electricity available, to be released later. If the lake is large enough, this technology can also address New Zealand’s persistent risk of dry years that can lead to a shortage of hydropower.




Read more:
Climate explained: why don’t we have electric aircraft?


Smarter electricity use

On the demand side, a survey is under way to measure the actual charging patterns of EV drivers. Information available so far suggests that many people charge their EV late at night to take advantage of cheap night rates.

If demand gets too high at certain times, then the cost of both generation and transmission will likely rise. To avoid this, electricity suppliers are exploring smart demand responses, based on the hot water ripple control New Zealand began using in the 1950s. This allows electricity suppliers to remotely turn off hot water heaters for a few hours to limit demand.

In modern versions, consumers or suppliers can moderate demand in response to price signals, either in real time using an app or ahead of time through a contract.

New Zealand’s emissions from land transport continue to rise, up by another 2% in 2018 and almost double on 1990 levels.

To address climate change, we have to stop burning fossil fuels. Passenger cars are among the biggest users and also one of the easiest to change. Fossil fuel cannot be recycled or made clean. In contrast, electricity is getting cleaner all the time, both in New Zealand and in car factories.

If you switch to an EV now, your impact is far greater than just your personal reduction in emissions. Early adopters are vital. The more EVs we have, the more people will get used to them, the easier it will be to counter misinformation, and the more pressure there will be to cater for them.

Many people have found that switching to an electric car has been empowering and has galvanised them to start taking other actions for the climate.The Conversation

Robert McLachlan, Professor in Applied Mathematics, Massey University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

These 5 images show how air pollution changed over Australia’s major cities before and after lockdown



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Elena Sánchez-García, Universitat Politècnica de València and Javier Leon, University of the Sunshine Coast

Have you recently come across photos of cities around the world with clear skies and more visibility?

In an unexpected silver lining to this tragic crisis, urban centres, such as around Wuhan in China, northern Italy and Spain, have recorded a vastly lower concentration of air pollution since confinement measures began to fight the spread of COVID-19.

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Likewise, the Himalayas have been visible from northern India for the first time in 30 years.

But what about Australia?

Researchers from the Land and Atmosphere Remote Sensing group at the Physical Technology Center in the Polytechnic University of Valencia – Elena Sánchez García, Itziar Irakulis Loitxate and Luis Guanter – have analysed satellite data from the new Sentinel-5P satellite mission of the Copernicus program of the European Space Agency.

The data shows a big improvement to pollution levels over some of our major cities – but in others, pollution has, perhaps surprisingly, increased.

These images measure level of nitrogen dioxide in the atmosphere, an important indicator of air quality. They show changes in nitrogen dioxide concentrations between March 11 to March 25 (before lockdown effectively began) and March 26 to April 11 (after lockdown).

Why nitrogen dioxide?

Nitrogen dioxide in urban air originates from combustion reactions at high temperatures. It’s mainly produced from coal in power plants and from vehicles.

High concentrations of this gas can affect the respiratory system and aggravate certain medical conditions, such as asthma. At extreme levels, this gas helps form acid rain.

Coronavirus: nitrogen dioxide emissions drop over Italy.

Declining nitrogen dioxide concentrations across Europe in the northern hemisphere are normally expected around this time – between the end of winter and beginning of spring – due to increased air motion.

But the observed decreases in many metropolises across Europe, India and China since partial and full lockdowns began seem to be unprecedented.

Nitrogen dioxide levels across Australia

Preliminary results of the satellite data analysis are a mixed bag. Some urban centres such as Brisbane and Sydney are indeed showing an expected decrease in nitrogen dioxide concentrations that correlates with the containment measures to fight COVID-19.

On average, pollution in both cities fell by 30% after the containment measures.

Like a heat map, the red in the images shows a higher concentration of nitrogen dioxide, while the green and yellow show less.



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On the other hand, nitrogen dioxide concentrations have actually increased by 20% for Newcastle, the country’s largest concentration of coal-burning heavy industry, and by 40% for Melbourne, a sprawling city with a high level of car dependency. Perth does not show a significant change.



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We don’t know why pollution has increased in these cities across this time period, as 75% of Melbourne’s pollution normally comes from vehicle emissions and most people are travelling less.

It could be because the autumn hazard reduction burns have begun in Melbourne. Or it may be due to other human activities, such as more people using electricity and gas while they stay home.

Pollution changes with the weather

Understanding how air pollution changes is challenging, and requires thorough research because of its variable nature.

We know atmospheric conditions, especially strong winds and rain, are a big influence to pollution patterns – wind and rain can scatter pollution, so it’s less concentrated.

Blue skies over Chinese cities as COVID-19 lockdown temporarily cuts air pollution.

Other factors, such as the presence of additional gases and particles lingering in the atmosphere – like those resulting from the recent bushfires – also can change air pollution levels, but their persistence and extent aren’t clear.




Read more:
Even for an air pollution historian like me, these past weeks have been a shock


Changes should be permanent

If the decrease in nitrogen dioxide concentration across cities such as Brisbane and Sydney is from containment measures to fight COVID-19, it’s important we try to keep pollution from increasing again.

We know air pollution kills. The Australian Institute of Health and Welfare estimates around 3,000 deaths per year in Australia can be attributed to urban air pollution.

Yet, Australia lags on policies to reduce air pollution.




Read more:
Australia needs stricter rules to curb air pollution, but there’s a lot we could all do now


COVID-19 has given us the rare opportunity to empirically observe the positive effects of changing our behaviours and slowing down industry and transport.

But to make it last, we need permanent changes. We can do this by improving public transport to reduce the number of cars on the road; electrifying mass transit; and, most importantly, replacing fossil fuel generation with renewable energy and other low-carbon sources. These changes would bring us immediate health benefits.The Conversation

Elena Sánchez-García, Postdoctoral researcher at LARS group, Universitat Politècnica de València and Javier Leon, Senior lecturer, University of the Sunshine Coast

This article is republished from The Conversation under a Creative Commons license. Read the original article.