Reducing My Family's Carbon Footprint: Our Car - EV vs PHEV: Assessing the Carbon Cost

November 21, 2024 • be the difference • car • carbon footprint • climate change • climate crisis • climate emergency • easy eco swaps • eco • eco ideas • eco inspiration • ecofriendly • environmentally hopeful • family • make a change • travel

As you know, we are in the process of working out what the best car is for our family, and for the planet. We need to make sure that the car works for how we use it, but also helps our family reduce our carbon footprint so that we can help contribute to tackling climate change.

We currently have a hybrid car, but our lease is coming to an end at the end of the year and we want to make the most environmentally friendly decision as to what to get next, especially as ideally we want to keep this car for as long as possible (ten or more years…?) The main decision to make is: full electric car (EV) or plug-in hybrid (PHEV)?

Our current car usage

We are a very low mileage family. We have done about 7,500 miles in the two years since we moved back to the UK, and 2,500 of that has been on longer trips, 5,000 on local journeys, making us seem like perfect candidates for being able to use an electric solution to help reduce our carbon emissions to fight climate change.

We live in Twickenham, in (greater) London, so we have a lot of narrow roads with cars parked on both sides and small spaces in which to park. So we’re ideally looking for a car that is smaller than our current car, to make the majority of the driving we do easier and less stressful.

In addition to this, some of our family lives about 200 miles away in Yorkshire, so we’d really like to be able to get there ideally in one charge or better still no charge if possible. That said, what we are finding is that the longer the range of the battery, the larger the car… makes sense right? So that’s a tension we need to work out.

So back to reducing my family’s carbon footprint, let’s look at the carbon costs of Electric (EV) versus Plug-In Hybrid (PHEV) Cars

The carbon cost of manufacturing a car

When looking into this, I found two (slightly different) answers as to what the carbon output is for manufacturing a car. One showed these amounts:

Standard petrol / diesol CO2e in production = 5.6 tonnes
PHEV CO2e in production = 6.7 tonnes
EV CO2e in production = 8.8 tonnes

EV = 2.1 tonnes more in production compared to PHEV, and 3.2 tonnes more compared to a standard fuel car[1]

However, a recent study of car emissions in China estimates emissions for cars with internal combustion engines during manufacturing 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), 2.5 tonnes difference. (They don’t provide a figure for PHEVs.)

As well as comparing different types of cars, these reports are from different years and also looking at different countries. This matters because the fuel mix of the country in which the car is manufactured determines a great deal to the carbon cost of that car production.

For example, looking at cars made in Germany vs China.

German electricity by source in 2017[2]

Brown Coal: 134 TWh (24.5%)
Hard Coal: 81.7 TWh (14.9%)
Wind: 103.6 TWh (18.9%)
Nuclear: 72.2 TWh (13.2%)
Natural Gas: 49.1 TWh (9.0%)
Biomass: 47.4 TWh (8.7%)
Solar: 38.4 TWh (7.0%)
Hydro: 20.5 TWh (3.7%)

Generating capacity by source in China as of 2017[3]

Coal (incl. coal gangue): 981,300 MW (55.2%)
Natural gas: 75,697 MW (4.3%)
Other thermal: 33,069 MW (1.9%)
Nuclear: 35,817 MW (2.0%)
Hydro (conventional): 314,894 MW (17.7%)
Pumped storage hydro: 28,693 MW (1.6%)
Wind: 163,252 MW (9.2%)
Solar: 129,415 MW (7.3%)
Biomass: 14,880 MW (0.8%)

Let’s go with 2.5 tonnes more of carbon produced during manufacturing for us looking at an EV over a PHEV.

We would need to make that cost back (and more) during our usage to make it carbon-cost-effective for us to get a pure electric car.

So let’s look at our usage.

The carbon cost of our family using a car

As I said at the beginning of the blog, we drive about 5,000 miles locally and 2,500 long distance.

This means that most if not all of our 5,000 local miles should be covered by the 20-25 mile battery charge on a PHEV. However, after that distance, we would have to be using the petrol engine.

This is how that long distance mileage, which would mainly use the petrol engine, was made up in the past two years:

Return journeys

Disneyland - 660 miles
Yorkshire * 2 - 800 miles
Wales * 2 - 536 miles
Kent - 186
Swindon - 150
The Midlands – 230

TOTAL = 2,562 miles

HOWEVER….. as my hubby pointed out, the first few miles of those 16 journeys would have been covered by the battery in a PHEV.

Pessimistically, using only 15 miles on electric per journey, we can still take off 240 miles from those above journeys.

So…. minus 240 miles on electric in a PHEV = 2,322 miles = 3,715 kilometres * 251g of CO2 per km[4] = 932 kg CO2 over two years.

Let’s call it 1 tonne to account for extra medium distance trips I haven’t remembered or if we run out of charge. One tonne in two years, 1/2 tonne per year.

Usage conclusion: That means for the type of mileage we do (7,500 over two years), it would take our family 5 years to realise the carbon-benefit of having an electric car.

The carbon cost of using an electric car in general

The carbon footprint of powering and using an EV once it’s made depends on the carbon mix of the country in which you’re using the car. Luckily for us the UK is making good progress towards carbon-neutral energy production.

National Grid says that in the past decade, coal generation will have plunged from 30% to 3%.[5]

And for our family in particular, our electricity is Ovo and we are on their 100% renewables tariff, so as long as we’re charging at home the majority of the time, we should not be emitting any / much CO2.

And, as UK power sources continue to switch speedily away from coal power and towards renewables and zero-carbon sources[6], so that will continue to decrease the carbon footprint, though for now, there will be a carbon impact if we charge away from our home, which we will on long journeys.

The carbon cost of recycling a car

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.

Recycling conclusion: For us this would add another 1.5 years of us needing to own an EV to make it a better carbon choice for us, making the total 6.5 years.

The overall carbon cost of an electric car

This short video from the Union of Concerned Scientists has a good explanation about the carbon costs of Electric cars and is a good place to start coming to a conclusion about the overall carbon costs.

In the end, it comes down to the balancing of two factors:

the carbon cost of making and recycling each type of car (electric does have a higher carbon cost)
the carbon cost of running and using the car

Both of these rely to an extent on the electricity source of the country in which 1) it is made and 2) it is used.

Looking at this graph below it shows the different impact of the same car being used in different countries. It has a much lower impact in Norway than it does in Germany.

Lifecycle greenhouse gas emissions for conventional and electric vehicles (by country) in grammes CO2-equivalent per kilometre, assuming 150,000 kilometres driven over the vehicle lifetime.

Adapted from Figure 1 in Hall and Lutsey 2018. Details of the calculations are in the methods section at the end of the article. The error bars show a range of values for emissions from battery manufacture. Chart by Carbon Brief using Highcharts.

So what’s our family's decision???

Battery life is one final factor we need to consider in our decision making as to what we get. We would like to own our car for as long as possible. Before we moved to the US, we owned our car for seven years, and only sold it because we were moving. We’d like to aim for that or longer. But will the battery last?

The life of EV batteries is a topic of debate. Some manufacturers give a warranty for seven to eight years, or some up to 100,000 miles.

But according to one article, if the battery is properly cared for, an EV’s battery pack should last for well in excess of 100,000 miles before its range becomes restricted. Consumer Reports estimates the average EV battery pack’s lifespan to be at around 200,000 miles, which is nearly 17 years of use if driven 12,000 miles per year. And we do under half that.

In addition, apparently, Tesla says it’s working on technology that would enable its electric car batteries to last for as many as one million miles!![7]

So…. based on the fact that we would only have to own an electric car for 6.5 years to make it more carbon-cost-effective than a PHEV, and the battery should last for 10 or more years, maybe that’s the way we should look?

It certainly feels to me that going pure electric is the right choice longer term as petrol fuel is never going to have the opportunity to be carbon free. That said, if if for the first 6.5 years we’ve essentially put more carbon into the world, maybe we should go for a PHEV for now, keep it for 6.5 years and then put it into the second-hand market and look to buy an electric car then…?

I’m still not 100% sure at all.....!! ;-)

But at least I feel a lot more informed and that we will be making our decision based on a better understanding of the carbon impact of owning and using a car.

We have test-driven the BMW i3 (EV) and the Mini Countryman (PHEV), and have the Kia Niro (EV) (and maybe Renault Zoe (EV)) lined up.

And then we need to look back at our size specifications, the cost and also what we like the best.

As ever, with love from our family to yours,

Elena x

Elena Cimelli Signature

*****

RESOURCES:

FOOTNOTES:

[1]	Estimated lifecycle emissions (tonnes CO2e)	Proportion of emissions in production	Estimated emissions in production (tonnes CO2e)
Standard gasoline vehicle	24	23%	5.6
Hybrid vehicle	21	31%	6.5
Plug-in hybrid vehicle	19	35%	6.7
Battery-electric vehicle	19	46%	8.8
Based upon a 2015 vehicle in use for 150k KM using 10% ethanol blend and 500g/kWh grid electricity.