China’s offhand bombshell about potentially consigning petrol-fuelled cars to the scrapheap has met, predictably, with a round of cheers and jeers.
This is about one of the latter, which concerns the chart below (graph: Steam Engines).
With coal dominating China’s electricity generation, a common refrain about electric vehicles (EVs) is: What’s the point? A car fed by a wire stretching back to a coalmine doesn’t seem like much of an improvement over a petrol pump.
It’s a legitimate point. But it risks obscuring a different, more fundamental point.
The question here is whether or not an EV truly results in less greenhouse-gas emissions than a traditional one with an internal combustion engine. This doesn’t just encompass how the vehicles use their energy, but also where that energy comes from and how the vehicles get built in the first place — what are sometimes called “life-cycle” emissions.
The math around emissions of carbon dioxide (CO2) from burning fuels and generating power is established. Meanwhile, some studies have also attempted to put numbers around the squishier concepts of emissions from building cars and batteries and producing and transporting fuels.
Different vehicles have different carbon footprints due to size, materials and so forth. For my purposes, I am going to use an assumption of 9.7 tonnes of carbon for a mid-sized vehicle, as per the study released by the Union of Concerned Scientists in 2015.
Building a battery (I’m only considering full- battery EVs here, not hybrids) adds further emissions for the EV. There are relatively few commercial-scale studies on this issue, with the ones I’ve seen offering estimates implying ranges of between roughly 150lb/kWh to 330lb/kWh of capacity. Taking the mid-point of that for a 60kWh battery — similar to what you might find in a Chevy Bolt or maybe a Tesla Model 3 — equates to 7.3 tonnes of emissions.
Now the fuel, starting with petrol:
Emissions from producing oil, refining it and distributing the fuel varies widely; Canadian oil sands, for example, require more energy to produce than many conventional fields. I’ve used the results of a model developed by the Argonne National Laboratory, which estimates about 5.2lb of emissions per gallon by the time it gets to the pump. Burning the stuff releases another 20lb.
Assuming a theoretical Chinese vehicle gets 35mpg — a slight improvement on the figure for 2015 — this adds up to just over 0.7lb per mile.
With the electric car, “fuel” emissions depend on the mix of power sources. The Intergovernmental Panel on Climate Change provides estimates of these before any fuel is burned. Using those, along with standard emissions for fossil-fuel combustion and assuming 6% of the power gets lost as it is transmitted over the grid, results in these estimates per kWh for the major power sources (graph: Measuring Footprints):
Let’s assume the EV gets 3.5 miles (5.6km) per kWh. This is 240 miles of range divided by 60kWh, subtracting half a mile as a conservative factor to take account of sub-optimal driving conditions and possible degradation of the battery over time. Use China’s coal-heavy power mix and you get emissions of just over half a pound per mile.
Now, assume both vehicles get driven 10,500 miles per year and last 12 years. Here’s how much carbon they emit overall (graph: Overtaken):
So, it takes about seven years to offset the emissions from making the battery, even with all that coal factored in. Granted, an 11% drop in cumulative emissions still may not seem worth the effort; a couple of alterations to the assumptions and you might end up with no savings at all.
But this brings us to the real story here: Choice.
The vehicle with the internal combustion engine can be tweaked in terms of miles per gallon. But chemistry dictates that burning petrol will always, more or less, send 20lb of CO2 into the atmosphere. It’s a closed system.
The battery vehicle, in contrast, is an open platform. Its menu of energy options can change dramatically according to the types of generation in your region, whether you’re using centralised or distributed power sources, and even the time of day you charge up. Critically, all those inputs can, and will, change over time.
To see how this affects things, the chart below shows my estimate of life-cycle emissions for the two vehicles described above, but also for Chinese vehicles using the International Energy Agency’s projected mix of power there in 2030. For this, I’ve also boosted the efficiency of the vehicles by almost 30%, so the one using petrol gets about 45mpg, while the EV gets about 4.5 miles per kWh. I’ve done the same for US vehicles travelling 13,000 miles per year, and starting at 31mpg for the petrol vehicle now, using the country’s current and projected power mix (graph: The Power to Change):
There are valid arguments against EVs, be it their high cost or concerns around charging infrastructure, range anxiety or whatever. Yet, it should also be acknowledged that all those concerns have diminished in importance over time and may well continue to do so. Certainly, much of the incumbent auto industry — not to mention some petro-states — seems to be thinking that way.
When it comes to carbon emissions, though, the argument that EVs are as bad or worse than those burning petrol is already hard to square with today’s numbers — and that will get harder over time. It ignores the inherent potential for change and choice that an electric drive-train opens up versus burning petrol. Oil bulls dismissing this should take note that governments look ever less likely to do the same. — Bloomberg
- Liam Denning is a Bloomberg Gadfly columnist covering energy, mining and commodities. This column does not necessarily reflect the opinion of Bloomberg LP and its owners.