We’re spectating a technological revolution. The guts of our vehicles are on the cusp of a major shift - the eradication of the combustion engine, and the spread of electric motors. Elon Musk’s vision of electric transport just had a genuinely thrilling boost with the introduction of semi-autonomous ‘autopilot’ software upgrades, and the launch of the falcon-wing’d Model X.
But we’re also steeped in the aftermath of Volkswagen’s catastrophic ‘Dieselgate’ scandal, in which vehicles were designed to cheat emissions tests, spewing dangerously high levels of nitrogen oxides - emissions that contribute to particulate levels, smog and a range of respiratory health problems.
A common argument raised against electric vehicles (EVs) is that the electricity they rely on is generated by carbon-intensive fossil fuel generation. Some even argue that this makes EVs worse for the environment. These aren’t valid criticisms. EVs are very shiny, and very cool, but these environmental questions matter, particularly in the face of flailing diesel technology. It’s clear that the electrification of our vehicle fleet means a lesser impact on the environment.
Imagine you bought a Tesla Model S, and plugged it directly into Hazelwood, Australia’s most carbon-intensive generator, which has an emissions intensity of around 1.5 tonnes of CO2 per MWh of generation. For a fully charged Tesla Model S with an 85 KWh capacity, that’s around 130 kilograms per full charge, which gets you about 426 kilometres of range - around 300 grams per kilometre (if you take the upper estimates of the Model S range, of around 510 km, this brings it down to 253 grams per kilometre).
According to the government’s Green Car Guide, that’s at the higher end of emissions scale, but it’s not the worst, which would be around 385 g/km.
It’s amazing that plugging a supercar into Australia’s worst power station still puts you ahead of a big chunk of Australia’s vehicle fleet. With that in mind, let’s compare the Tesla Model S to similar petrol cars. Car Advice suggests two candidates - the Audi RS7 or the Mercedes CLS 63 AMG S, which come in at 221 and 233 grams per km, respectively. Certainly lower than the Tesla, but remember we’ve plugged it directly into the worst possible power station. Using the Tesla’s higher range estimate, it manages to be competitive with these new, efficient, expensive cars.
Proud Tesla owner Mat Peterson, who has embarked on a few real-world road-trips in his Model S and has some great data on performance, came up with some similar estimates during a trip between Sydney and Melbourne - his real world data show that the environmental impact of his EV is lower than a comparative Audi RS7, and more so when he accounts for the refining emissions of petroleum (Peterson recently took the trip again and only used Tesla’s burgeoning supercharger network, which is 100% emissions free).
So, what if mass-market EVs are plugged into household power, rather than Australia’s dirtiest power station? If you just buy standard grid power, you already get some clean energy. Some of this is hydro power. Some of it is new wind and large-scale solar, which varies in output level much more than other generators (you can check current levels of output here).
On Australia’s eastern seaboard, the states are interconnected into a single large network known as the National Electricity Market, or NEM. It’s not hard to obtain and analyse NEM data, so we can visualise what our Model S emissions might look like charged in different states, based on the emissions intensity (year to date) of each state. I’ve also included the NEM grid average.
Technologies like wind and solar also vary in output. A windy night in SA would mean near-zero emissions charging, but you might not get the same the next night. The emissions intensity of our grid changes every five minutes, because different technologies are dispatched the grid operator based on a range of variables - here’s the last two weeks, by technology:
The environmental friendliness of your EV shifts every five minutes, and it’ll (hopefully) get better as more zero-emissions technology is added to the grid. Imagine, in the future, software that changes charging habits according to the live emissions intensity of the grid - pushing demand up when clean resources are available. It’d be a simple way of reducing the g/km carbon emissions of EVs, and we’d also see a cleaner grid because of it.
Consumers also have the option of buying 100% green power - an accreditation scheme that allows your retailer to guarantee the purchase of a certain quantity of clean energy. Alternatively, solar power can be used to charge electric vehicles. Both options remove the spatial and temporal variability of emissions intensity - you know you’re getting near-zero emissions electricity, all the time. In these cases, there is absolutely no question about the environmental benefits of EVs.
There’s also the issue of embedded energy - the emissions generated through manufacture of the vehicle. If you use a suspiciously short mileage comparison, like the 50,000 miles in this piece critical of EVs, then it seems like electric cars aren’t the better choice. But when you consider the whole lifespan of the vehicle, EVs come out quite conclusively on top. As Mat Peterson did, adding in the emissions from refining petroleum also tips the scales further in favour of EVs. And, before you ask, no, rare earths aren’t used in modern EVs, and yes, their batteries can be recycled.
I’ve also seen a few people point out that perhaps we ought to focus our energy on increasing uptake of public transport rather than EVs, but I think both ventures are complementary. In Sydney, for instance, 4.8% of weekday trips are on fossil-fuel powered buses, and 4.2% are on electrified trains. Though our bus fleet is lowering its emissions, imagine a fleet of electrified, autonomous (why not) public buses powered by wind and solar. A booming personal EV industry would almost certainly see this goal realised.
Companies like Tesla don’t make environmental issues the primary focus of their marketing. They’re well aware that the science, engineering and design underpinning the machine is more than enough to woo a crowd for their phenomenal electric robot supercars. Other companies, like Porsche, use clean energy as a selling point for their vehicles.
Outside of this, though, we’re going to have to learn to engage with the magic behind our domestic power outlets in a very different way - understanding the ebb and flow of generation and demand, and the increasing utility of battery storage. Many of the cheapest and most widely accepted renewable energy technologies are subject to resources that change over time - namely, wind and sunlight. My bet: through the EV revolution, we’ll blend information, technology and environmental protection in very novel, very cool ways.
Raw calculations and data (including some extra charts) in this piece are in this spreadsheet. Ketan Joshi is a research and communications expert in the renewable energy industry. He blogs on energy and technology here, and tweets here.