Elimination of carbon dioxide from transport must be real not artefact
The United Kingdom has enacted a law for net-zero carbon dioxide (CO2) emissions across the economy from 2050, and other countries will likely follow. This has spawned a policy of targeting zero emissions from transportation, which is often spoken about interchangeably with the idea of replacing the vehicle fleet with battery electric vehicles (BEVs). A further benefit of this change is claimed to be improvement in air quality, due to the absence of a tailpipe, and the resulting health benefits. But is this apparent panacea as simple as it sounds?
Slowing climate change is now widely regarded to be of such importance that all ideas need to be robustly tested not just for the glamour of their ambition, but whether they can deliver. Admitting the existence of risk, a mix of approaches may be more robust than gambling all on red. Unintended consequences must also be considered for fear of achieving the goal but at an unacceptable price. As The Economist said in August 2020, “…Mr Xi is shifting to a sharp focus on supply-chain choke-points where China is either vulnerable to foreign coercion or where it can exert influence abroad. That means building up self-sufficiency in key technologies, including semiconductors and batteries.” The reality is that there is already, and will continue to be, a widely predicted global supply constraint on batteries for the rest of this decade if take-up of BEVs is as healthy as it needs to be to fulfil zero carbon transportation.
For transport, then, the right policy could be expressed as delivering zero carbon dioxide (including other gases with equivalent greenhouse gas effects) emissions with no worsening in other pollutants and no vexatious secondary effects. At least, any trade-offs should be understood scientifically and communicated politically. This newsletter will consider what would be necessary and sufficient to achieve this, and the implications.
So, let us set out Emissions Analytics’ Eight Principles of Decarbonisation – the material things that need to be delivered to achieve the stated policy:
Principles 1 and 2 are a significant enough challenge in themselves, but progress is being made in that direction by many countries. There remains a significant issue in the intermittency of many renewable energy sources, especially where there is no nuclear baseload. This newsletter will not go into these further, but unless they are achieved, the advantages of BEVs will be seriously compromised, whatever else is achieved in respect of the other principles.
Principle 3 arises from carbon being a global problem: the total matters, not the source. Reducing upstream CO2 emissions is a very serious challenge given the lack of control that governments can apply to foreign mining and manufacturing operations. It is also material, due to the higher CO2 emissions currently from BEV compared to ICE manufacture, like-for-like. Efforts are being made by manufacturers, including recent reports from BMW and others, to assert some control and transparency, but it remains a significant challenge. Even the transportation of vehicles by sea would need to be completely decarbonised to achieve this, which may conceivably be achieved with alternative fuels such as ammonia produced with zero carbon electricity.
Principle 4 is a growing challenge, with the need to recycle various rare earth metals from drive motors and batteries, or give them a second life before eventual recycling. This is a business opportunity that is already attracting entrants, yet achieving this with zero-carbon energy remains a stretching goal.
Principle 5, means that other emissions that have a global warming effect – often expressed in CO2-equivalence – should be included in analysis, to ensure one climate-charge-relevant emission is not swapped for another, through singular focus on CO2. This could include, for example, methane emissions from gas vehicles or nitrous oxide (N2O) from certain after-treatment systems.
Principle 6 is an important but complex one. This could mean that vehicles should not ‘crowd out’ the use of batteries from existing non-transportation uses. For example, where batteries may be used as static power sources or for powering handheld tools, if demand from transportation made battery prices too high, these uses may switch back to combustion engines. It could also mean that old ICEs that are replaced with BEVs in developed countries are exported to expand fleets in developing countries as their values fall.
Recalling the Dieselgate crisis, where nitrogen oxide (NOx) emissions were found to be insufficiently regulated in a way that led to damagingly high emissions in the real world, there is a big risk from the non-exhaust emissions from BEVs, especially in regard to tyre wear. Due to the weight of batteries, BEV vehicles are significantly heavier that like-for-like ICE vehicles. As a result, for the same grade of tyre and driving patterns, non-exhaust emissions from wear on those tyres will be higher for the BEV. The regenerative braking for BEVs may lead to lower brake wear emissions compared to ICEs, but this is unlikely to counterbalance the increased tyre wear emissions. Therefore, the risk is that the CO2 reduction from BEVs is traded for a degradation in air quality and other microplastic pollution.
Through our work on measuring pollution inside the vehicle cabin, we have observed that hybrid vehicles often have worse interior particle concentrations, which may lead to worse exposures and health effects for occupants. The hypothesis is that, due to the energy requirements, filtration is minimised as these vehicles are sold for their fuel efficiency. Therefore, CO2 may be traded off against human health in this additional dimension.
While carbon credits, Principle 7, may act as a positive incentive mechanism for carbon reduction, inherent in the system is their trading effectively permits the continued use of combustion engines by the purchasers. Therefore, while they may be expedient in the short run, they must be phased out permanently.
Principle 8 is simple: to achieve zero carbon, the whole ICE and hybrid fleet on the road must be replaced. It is likely that the last few percent of vehicles will be hard to shift due to stubborn owners, and therefore the incentives needed may be high. In conjunction with Principle 6, old ICE vehicles should be responsibly recycled, not exported to developing economies, to avoid the scandals associated with the scrappage scheme following the financial crash of 2008, when dirty diesels were ‘scrapped’ at the expense of taxpayers only to be found to have been exported to Eastern Europe and beyond.
Last year, we published this newsletter which showed that hybrids were the best way to reduce CO2 in a world of limited battery capacity. Full hybrids deliver around 30% CO2 reduction compared to the nearest equivalent ICE, compared to the 100% tailpipe reduction of BEVs; but 14 times more hybrids can be built for the same battery capacity, meaning hybrids could actually deliver four times more CO2 reduction than BEVs while the battery constraint remains.
While limited battery capacity remains true for now, let us project forward to a hypothetical world of unconstrained and cost-competitive battery supply. In addition, we also make the critical assumption that all electricity will be zero carbon (Principles 1 and 2). We assume that complete grid decarbonisation will be achieved. We also assume that manufacturing CO2 emissions (Principle 3) remains the same as currently, but also that there is no improvement in ICE efficiency. Further, we are putting no negative value on the utility limitation of the reduced range of BEVs compared to ICEs, which may well persist even when batteries are plentiful in supply and cost competitive due to the weight they add to the vehicle.
To assess these effects, Emissions Analytics has created its own model of the CO2 effects of electrification. Three scenarios were modelled: complete switched to BEVs and full hybrids compared to the ICE baseline.
The manufacture emissions of ICEs, full hybrids (FHEVs; for clarity these exclude mild hybrids and plug-in hybrids, but sit between them in terms of battery size, and rely only on on-board gasoline or diesel for energy) and BEVs are 5.8, 6.2 and 11.4 tonnes per unit1. In use, the average CO2 emissions are 111, 78 and 0 g/km. Assumed annual usage of all three are 16,000km over a lifetime of 200,000km. On the switch-to-BEV strategy, the new car sales mix is assumed to be 100% BEV by 2040, and the whole fleet by early 2050s.
Crucially, as CO2 is cumulative in the atmosphere – it lasts between 300 and 1,000 years once emitted – we must consider cumulative emissions in our analysis. This is the basis of the Paris agreement and countries’ carbon budgets.
On this BEV scenario, cumulative total CO2 emissions emitted are higher for over a decade due to the front-loaded emissions in the manufacture of the BEVs. From 2034, the cumulative CO2 is lower than the benchmark ICE strategy as the benefits of zero in-use emissions begin to outweigh the higher embedded emissions from manufacturing and batteries. By 2070, cumulative emissions are 811m tonnes lower from BEVs. However, this is only 47% down on the ICE strategy; in 2050 it is only 23% down. So, unless you can eliminate manufacture emissions, we are not even close to zero emissions – even ignoring Principles 5 to 8.
If you double average battery size, and therefore double the CO2 in their manufacture, to compensate for the bounded utility of BEVs and bring range more in line with ICEs, then the reduction by 2070 is just 11%, and it is 1% worse still in 2050.
Revisiting the potential for hybrids set out last year, the BEV strategy can also be compared in this model to a FHEV strategy of switching the whole vehicle fleet to FHEVs by the earlier 2050s, and it yields dramatic results.
The BEV strategy is still superior, but the total CO2 reduction by 2050 is just 11% and by 2070 it is 26%. Good, but far from zero. Less good is if you double average battery size, when cumulative CO2 emissions are 5% worse from BEVs than FHEVs.
These results stem from the higher manufacturing emissions of BEVs, which are true not just in the initial switch to BEVs but on subsequent future vehicle replacement, together with the lower in-use CO2 from hybrids. This will only change if Principle 3 is delivered – hence its vital importance. The cynic may think that net vehicle importing countries may be quite content to ‘off-shore’ rather than genuinely reduce the emissions.
Although the legal position is that net zero must be achieved by 2050, from the point of view of climate change, what happens in the next twenty years is just as important. Carbon dioxide has no discount rate. Every gram of CO2 that is reduced now makes the challenge post-2050 easier. Therefore, inaction today on the promise of a miracle solution tomorrow is not a robust policy.
Unless a more robust policy is developed, delivering real and measurable CO2 reduction soon, it is likely around 2035 that BEVgate will break, where much of the promised reduction will have proved illusory and air quality may be worse. As it took 15 years from the introduction of explicit NOx reduction under the ill-fated Euro regulations until Dieselgate, it may be 15 years from now that the folly of dogma rather than facts becomes clear. And our carbon budgets will by then be spent.
Footnotes:
- Derived from https://www.volkswagen-newsroom.com/en/press-releases/electric-vehicles-with-lowest-co2-emissions-4886; in-use emissions for FHEVs applies 30% efficiency estimated by Emissions Analytics