- Oct 31, 2023

100% adoption of BEVs for passenger vehicles only yields a 4% drop in GHG emissions

Why greening the grid on a global scale must come before mass adoption of BEVs

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In the pursuit of electrification, understanding the true benefits of our actions is crucial. We need to know if we are having the desired impact and moving the needle meaningfully in the right direction in terms of emission reductions. Electric vehicle (EV) sales have been steadily increasing. 14% of all new cars sold were electric in 2022, with solid growth over 9% in 2021 and less than 5% in 2020

according to the International Energy Agency [1]. Many automotive manufacturers have pledged to phase out internal combustion engine (ICE) vehicles by 2035, committing to building battery electric vehicles (BEVs) to reduce greenhouse gas (GHG) emissions. However, a closer examination of the potential impact is necessary.

This article explores the quantitative aspects of de-carbonizing road

transportation and sheds light on the critical factors, with a particular focus on the power grid. If we electrified all passenger vehicles around the globe by tomorrow, what would the impact be? How much would our emissions be reduced? In this article we will look at the estimated emissions reductions we can expect if all passenger vehicles globally became BEVs. Although this is unlikely to happen

overnight, it is important to understand the potential impact of our activities. Does this direction help us achieve our emissions reduction goals?

Although transportation as a whole accounts for approximately 15% of GHG emissions, this includes aviation, shipping, and cargo transport on roads [2,] These modes of transportation are much further away from being electrified and so the analysis here will focus on passenger vehicles as we are already seeing a substantial shift from ICEs to BEVs in recent years. We will also look at what the highest priority needs to be in order to achieve substantial reductions in global emissions. It all starts with how we generate electricity in the first place – the power grid.

Do Electric Vehicles Have Emissions?

To assess the lifetime emissions of an electric vehicle, several factors must be considered, including vehicle manufacturing, battery manufacturing, maintenance, and operation. Each of these stages involves processes that emit GHGs. For instance, mining minerals and manufacturing processes can contribute to emissions as they rely heavily on fossil fuel-based energy and power generation. Battery manufacturing for BEVs can also cause the emissions of a substantial amount of fossil fuels during mineral extraction and production. Operation of the vehicle also has emissions since the power used to charge the vehicle is often fossil fuel based.

Estimating BEV Operation Emissions:

In a recent Lark Scientific article [3] our analysis has revealed that one of the most significant factors affecting the lifetime emissions of BEVs is the GHG emissions of the power grid. This is of course not surprising. Regions with a high reliance on fossil fuels for electricity generation will have diminished benefits from adopting BEVs, whereas areas with cleaner grids exhibit clear advantages in terms of GHG emissions reduction. In areas where the grid relies heavily on fossil fuels, the operational emissions dominate over all others. Although BEV manufacturing emits more GHGs than an ICE, If BEVs are charged from a green grid, those manufacturing emissions can be saved in a short time of 1 to 2 years of driving. If however the grid uses fossil fuels, the lifetime GHG reduction becomes much less compelling.

In this analysis we are only looking at the emissions differences during operation. The increased emissions to build a BEV over an ICE will clearly reduce the benefit for BEVs, but will not be considered in this article. This analysis also assumes that the power grid emissions will stay the same per kW generated despite the increased power demand as BEVs are adopted. We will also examine the impact of renewables coming online in the near future relative to the increased demand for electricity later in this article.

Global Grid Emissions:

The global average electricity production relies on fossil fuels for much of its energy mix. The emissions factors for several countries are shown in the graph below [4]. To put these numbers into context, in China, with grid emissions of 0.56 kg CO2e/kWh, an average BEV would emit about 0.11 kg CO2e/km. For comparison, the average ICE globally emits roughly 0.20 kg CO2e/km. It is important to note that the countries with the highest vehicle use such as China, the US, Germany and Russia all have significant grid emissions.

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Figure 1. GHG emissions from power generation in kg CO2 equivalent per kWh of electricity.

BEV emissions:

According to the International Energy Agency (IEA), the global average ICE emits

202 g CO2 e/km and the global average BEV emissions are 83 g CO2 e/km [5]. Using these global averages, emissions of BEVs are then approximately 59% lower than the ICE emissions based on current global grid emissions as estimated by the IEA. We can then estimate the overall impact of BEV adoption on global GHG emissions.

The Results:

What does this mean for overall global emissions? According to the IPCC, (2023)[2], 15% (8.7 GtCO2 e) of global emissions in 2019 were from transport as a whole. Passenger vehicles are estimated to be roughly 45% of global transportation emissions [6]. This includes cars, buses, taxis and motorcycles. Based on these numbers, passenger vehicles are estimated to generate 6.8% of global GHG emissions. A 59% reduction in passenger vehicle emissions equates to roughly a 4% reduction in global GHG emissions based on operation of BEVs alone.

Translated, this means that if 100% of passenger vehicles were to be converted to BEVs overnight, that would reduce global emissions by about 4% per year.

What other emissions will be caused by expanded adoption of BEVs?

There are other emissions however that need to be considered in the transition to BEVs including expanded power generation, vehicle manufacturing and the hardware and electrical upgrades that will need to happen in homes and charging stations to support the charging of BEVs.

Electrical generation around the world will need to expand to support the additional electricity needed to charge BEVs. Global power demand in 2022 was approx. 26,000 TWh [7]. Global demand is expected to roughly double by 2050 as electrification of transport and the adoption of electricity for home heating will continue to drive demand according to the IEA [8].

But where will the power come from?

An important question to ask is: "Where will the additional power come from?" Grids everywhere will need to expand to accommodate the charging of millions of electric vehicles. While grids are getting cleaner over time in general, an increase in demand over the next 5-10 years will mean that the supply must come from somewhere. If the demand increases faster than we can supply renewable power, there is a real possibility that fossil fuel consumption will increase to supply the growing BEV adoption. To increase fossil fuel power generation so that we can convert to BEV vehicles would be extremely wasteful and counterproductive.

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Looking at the estimates on how much more power will be needed globally, we can see that the current increase in electricity generation average is 938 TWh per year [9]. The IEA has also estimated the amount of renewable power that is planned to be installed up to 2027. The total renewables production in 2022 was 8567 TWh and the forecast for 2027 is 12469 TWh. This is 780TWh added per year, with some estimates showing faster implementation of renewables [10,11,12]

The bottom line is that the demand for electricity is increasing slightly faster than the forecasted rate of renewables coming online over the next 5 years. Something will need to make up the gap in energy production which will most likely be the increased output of existing coal and natural gas generation. Inevitably more fossil fuels will be burned to generate the needed power, reducing the benefit of the transition to BEVs.

Estimating the emissions from building the new electricity generation capacity is beyond the scope of this article. In any case, the construction and implementation for double the power generation capacity globally will certainly result in added GHG emissions.

The impact of 100% adoption of passenger BEVs on global GHG emissions will then in all likelihood be significantly less than 4% per year.

Should we stop developing BEVs?

Although the improvements in GHG emissions may seem underwhelming, its important to begin on the path towards greater electrification. The transition will take decades. We cannot wait for the perfect solution, or the perfect grid to be developed so that we can begin implementing solutions. We must however temper our expectations and be realistic about the real benefit of the changes.

Our goal in this article is not to discourage the development of BEVs. Our goal is to simply state what the expected benefits would be if we succeed in converting all passenger vehicles to BEVs. Policy makers in Canada and around the World need to be aware of the importance of greening the grid as a higher priority than implementation of BEVs if we are serious about reducing our GHG emissions. A greener grid will have far reaching benefits over many sectors beyond just passenger vehicles, and likely needs to be the highest priority globally. A green grid allows a multitude of other benefits including electric home heating and greener manufacturing. Roughly 15 GT of global emissions are from power and heat generation [13]. This is over 25% of global emissions. Tackling the grid emissions is an absolute requirement if any of the effort being spent on implementing BEVs is to have a meaningful impact on emissions.

Conclusion:

While the transition to electric vehicles is a positive step towards reducing GHG emissions, it is essential to consider the whole lifecycle impact, including the environmental impact of power generation. The actual reduction in emissions depends heavily on the energy mix of the grid. Therefore, increasing efforts to transition to cleaner sources of electricity will significantly amplify the benefits of widespread vehicle electrification in our drive to combat climate change.

Contributors

Researchers

Chukwudi Amadi, Ph.D.

Mauro Aiello, Ph.D.

Authors

Mauro Aiello, Ph.D.

Axel Doerwald

Lark Scientific Financial Support