Why going electric wins on emissions

We often hear from people who aren’t sure if switching to an electric alternative is the right move. One of the most common questions we get asked is ‘will switching to an electric machine actually reduce my carbon footprint if creating the new machine or materials produces emissions?’

It’s a fair question, and we completely agree it’s important to think about the full life cycle of the products we buy and use. Electric alternatives, including vehicles, often produce more emissions than fossil fuel equivalents during manufacturing. But, over the lifetime of the machine, they create much less carbon pollution because they don't burn any fuel.

In our latest Watt Now, we explain how this all works in a few sections:

• Embedded or embodied emissions
• Made better
• The long and the short of it
• Pumped up

Let's break it down.

TLDR? Check out our infographic here.

Embedded or embodied emissions

These are the greenhouse gas emissions associated with the production of machines and materials. It is important to consider these emissions when comparing electric and fossil fuel machines, as it enables a fuller understanding of the carbon emissions created by our household choices.

Electric alternatives can have higher embedded emissions than their fossil fuel counterparts due to the extraction and processing of metals such as lithium for use in batteries and steel in cars. 

Unlike internal combustion engine vehicles that burn fossil fuels to move, there are no ‘tailpipe emissions’ when driving an EV, but there are emissions resulting from manufacturing the vehicle and battery. Over their lifetime electric vehicles and appliances produce far less pollution than their fossil fuel equivalents. 

As our Electric Homes report showed, personal vehicles contribute the majority of a household’s emissions because they consume the most energy (around 60% for the average home). So, if someone in your home wants to switch their old petrol car for an EV, how will that affect their emissions? And how does that compare to a new petrol car?

‍Made better

A number of studies have estimated the emissions associated with manufacturing a vehicle. Work done by research and consulting firm Circular Energy Storage reviewed the range of estimates available and found that, on average, manufacturing an electric car battery creates 60-110 kg CO2-eq per kWh of battery capacity. This includes the emissions associated with mining, transporting and processing of the metals in the battery, and the battery’s assembly. The range reflects the level of renewable electricity in the grid where the battery is made. Where renewables make up a higher proportion of the electricity supply, the embodied emissions are lower.

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For example, a Tesla Model Y, the most popular EV in New Zealand of 2024, which has a 60kWh battery manufactured at a solar-powered Tesla Gigafactory, emits about 3.6 tonnes CO2-eq during its production. In contrast, a BYD Atto 3, the third most popular EV in New Zealand, which also has a 60kWh battery and is manufactured in China, emits around 6 tonnes CO2-eq. That’s the equivalent of nine and 15 return flights from Auckland to Queenstown, respectively.

Carbon Brief, which also reviewed a range of studies, estimated that manufacture of the rest of the vehicle produces about 5.7 tonnes CO2-eq on average. Based on this, we estimate the following embodied emissions for three popular vehicles in New Zealand.

Thanks to New Zealand’s highly renewable grid and the relatively small amount of fossil fuels burned to create electricity, charging these electric vehicles will only emit 0.13 tonnes CO2-eq per year if driven the national average of 11,000km. 

The long and the short of it

When you add that up, it might sound like a lot of emissions. But it’s nothing in comparison to a petrol car. 

A Toyota Rav4, one of the most popular cars in New Zealand, has a fuel efficiency of 7.5L per 100km on average. If the car is driven 11,000km each year it produces about 2.3 tonnes CO2-eq per year.

This means that a new electric car pays off the ‘carbon debt’ accrued from the manufacturing process in as little as 2-3 years compared to buying a new petrol car. If you remove the manufacturing emissions, you can pay off the carbon debt of an older petrol car in around five years. As you continue to drive the Rav4 over the next few years, you rack up more carbon emissions. And, as we have discussed in previous explainers, burning imported fossil fuels is more expensive, inefficient and bad for our health.

These numbers show clearly that buying a new electric car is better for the environment than keeping an existing petrol car. Many older cars are less fuel efficient, so their carbon emissions will be even higher if they continue to drive it, rather than upgrade to an electric vehicle. 

Recent work from the European Federation for Transport and Environment has also estimated that two tonnes CO2e could be avoided in the production of EVs through circular supply chains or via recycling. This would bring the emissions payback time forward another year.

A similar rule applies when it comes to the upfront cost of these electric machines (and also solar panels). They are more expensive to buy than fossil fuel equivalents, but because they are so much more efficient they cost much less to run and that leads to significant long-term savings. 

• It's not all about carbon, of course. For more on why renewable energy and the circular economy should be a match made in heaven, read our explainer Closing the Loop.

Pumped up

Machines to heat our homes and water also have a significant amount of embodied emissions. A study in the UK found that a heat pump unit has, on average, around 1.5 tonnes CO2-eq of embedded emissions. That’s the equivalent of about four return flights from Auckland to Queenstown.

For this analysis, we have assumed the same for a heat pump water heating unit. We were not able to find a study of embodied emissions of these machines in New Zealand, so note that these estimates may be slightly different.

Our Electric Homes report estimated that gas space and water heating combined produces an average of about 1.3 tonnes CO2-eq per year, while heat pump alternatives create just 0.1 tonnes. This means that new heat pumps for space and water heating have a lower emissions footprint than existing gas alternatives (i.e. they pay off their carbon debt) after about 2.5 years.

Even for solar panels and batteries, which only lead to relatively small emissions savings thanks to New Zealand’s highly renewable grid, the emissions reductions over their lifetime well outweigh the emissions caused by ongoing use of fossil fuel alternatives (keep an eye out for our next explainer on how solar panels can help New Zealand provide the additional electricity we’ll need as we electrify our homes, businesses and vehicles). 

It pays to electrify

The view held by some that replacing a fossil fuel machine with a new electric alternative will lead to higher overall emissions is a myth. Even though new electric machines produce some emissions in the mining of their materials and their manufacture, the operational emissions savings quickly pay back this carbon debt - and the cost savings quickly add up, too.

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