Various policy driven scenarios show electric vehicles (EVs) gaining market share over the next few decades but the question is by how much. According to Adam Whitmore, independent energy advisor, there are reasons to assume that annual sales of EVs will account for 7-22% of the vehicle stock by 2030. By 2050 they will account for a majority of light vehicles on the road.
I recently argued that BP’s projections showing almost no take-up of plug-in vehicles by 2035 was unrealistic in view of several convergent trends. There is increasing pressure to reduce CO2 emissions, there is large and growing concern about urban air quality, and electric vehicles are likely to prove attractive to consumers in many respects. In line with these drivers, sales are growing very quickly and many new models are coming on line, while battery technology is improving rapidly, with costs falling sharply and energy density rising.
However while these factors suggest that electric vehicles will gain substantial market share it does not say how much how soon. So how fast might the market for plug-in vehicles grow if policy drivers are strong and matched by favourable economics? Here I consider how quickly electric vehicles could gain market share on that sort of optimistic view.
Market share gains for new technologies
The transition to electric vehicles is in its early stages, so extrapolating historical trends offers only limited guidance. Similarly, highly detailed modelling may not offer robust insights, because too many assumptions are required. Instead it seems appropriate to look at some broad indicators.
A good starting point is to look at adoption other new technologies. The chart below shows the rates of penetration of new technologies in the USA over the 20th and early 21stcenturies. It shows variants on a characteristic s-curve shape, with most technologies reaching eventual penetrations of 80-100%. The typical time to reach about 80% penetration following the first 1% or so of deployment (about where plug-in vehicles are now) is around 20-30 years, although some modern highly scalable technologies have become nearly ubiquitous faster than this, and other technologies have taken as long as fifty years or so to reach high penetration.
For example, cars themselves experienced rapid growth between around 1910 and 1930, reaching 60% of households, before experiencing hiatus and decline during the Great Depression and Second World War, before growing steadily again through the to the second half of the 20th Century.
However these timings are for the USA, and, even in an increasingly homogenous world, global adoption may take a little longer.
The chart mainly shows technologies that fulfil a new function, rather than those that replace existing technologies, as plug-in vehicles do. However replacement technologies can also gain market share quickly. Digital cameras replaced film almost completely over a period of around 15-20 years, and DVDs replaced VHS in less than 10 years. In these cases the new technology brought clear advantages. For plug-in vehicles a combination of some advantages plus regulatory drivers could play a similar role.
Modelling the transition
EVs are rather different from many of these cases in that there is a large existing capital stock which is expensive to replace – a new car is much more costly than a new camera. This limits the rate of change of the stock. I have therefore applied the sorts of timescales shown above to a rough and ready model representing the potential rate at which new vehicles could gain market share, rather than changes to the stock. The model uses a standard s-curve (logistic function). Changes in the stock are then calculated considering stock turnover.
I have developed three scenarios representing respectively strong policy drivers, more moderate policy drivers, and a delayed transition representing either weaker policy or greater practical or economic obstacles. The strong policy case fits better with the historic data, but this may not be a reliable marker as the history is so short and there are a number of particular circumstances at work.
I have assumed plug-in vehicles will eventually account for 80%-90% of the market for light vehicles, with markets for internal combustion vehicles likely to remain where consumers seek low capital costs or they need long range with poor infrastructure. There will doubtless also be small niches for car enthusiasts seeking experience of the internal combustion engine, just as there are for taking photographs on film. However these are likely to play only a small role.
The rate at which the stock of vehicles is replaced depends on how long vehicles last. I have assumed this to be 15 years, although there is obviously a distribution around this. If this were to lengthen further it would slow the change in the stock, or could be shortened by incentives to scrap older vehicles. The life of new electric vehicles is unproven (although battery guarantees of typically around 8 years are available), but in any case I have assumed buyers replace their battery packs, or replace their EVs with other EVs rather than returning to internal combustion engines.
Growth of the vehicle fleet leads to a faster proportional changeover of the stock, assuming plug-in vehicles gain the same share of the larger market, because current sales are a greater proportion of the historic stock. I’ve here assumed a 2.5% p.a. global growth rate for car sales.
The results of this analysis are shown in the chart. Annual sales of EVs reach 20-60% of the market by 2030, expected to be over 100 million vehicles p.a. by then. They by then account for around 7-22% of the vehicle stock, or around 100-330 million vehicles. By 2050 electric vehicles account for a majority of light vehicles on the roads in all the scenarios.
Global market share of plug-in light vehicles
So do these projections make sense, and what might stop them?
Cost competitiveness. Analysis by a variety of commentators show EVs becoming economically competitive in the early to mid-2020s, varying between geographies depending on factors such as driving patterns and petrol prices. This timing corresponds with the period when vehicles begin to gain market share much more rapidly in the above model, especially in the first two cases, which appears consistent.
China. A large proportion of vehicle sales in the coming years will be in developing countries, especially China. Concerns around urban air quality, development of the indigenous automotive industry, infrastructure development, and oil imports look likely to tend to favour EVs in China. Driving patterns based around lots of shorter distance urban driving are also compatible with EVs. For these reasons government policy in China strongly favours EVs. Again this seems consistent.
Growth rate. The compound annual growth rate for annual sales over the period to 2030 ranges from 25% to 33%, both well below current growth rates of around 60% p.a.
Scale-up. The need to produce tens of millions of additional EVs by 2030 is a formidable challenge. However the international car industry increased production by about 35 million units p.a. over the two decades between the 1990s and 2015, and added 20 million units p.a. in the last decade alone. Replacing models with electric equivalents at this scale does not seem like an insuperable barrier, at least in the lower two scenarios. However the challenges of achieving this for the stronger policy scenario are formidable, and policy drivers would need to be correspondingly strong to overcome these barriers.
Battery production would also need to be scaled up by orders of magnitude. There don’t appear to be any fundamental barriers to supply of the vast quantities of lithium that would be needed, but it may take time to develop the infrastructure.
The need to ramp up production of both new models and batteries may act to slow growth, at least for a while and especially in the strong policy case, but do not seem likely to act as a fundamental longer term constraint.
Grid constraints. EVs are likely to require reinforcement of grids, but again this does not look like a major barrier given the timescales involved.
These projections show much faster growth than analysis by Bloomberg New Energy Finance (BNEF), which suggests 35% market share by 2045. However the reasons that BNEF sees growth being so restricted are unclear, and there appear to be few examples where the penetration of a new technology has been so slow. It seems a more likely estimate for a share of the stock by that date, though even then looks to be towards the low end of the range.
Goldman Sachs estimates 22% of the market being EVs by 2025. This includes conventional hybrids, with the share of plug-in vehicles being only about a third of this, closer to the moderate case. However it would not seem to require a fundamental change to the market’s development for a greater share of hybrids to be plug-in, so Goldman’s analysis seems at least potentially consistent with the strong regulation case shown here.
Other scenarios show something close to the moderate case shown here. The IEA 450 scenario and Statoil’s reform scenario both show EV sales reaching around 30% of the market by 2030.
Outturn will doubtless differ from these projections. But they do highlight the extent to which policy might succeed in stimulating a major transition in car markets in the next two or three decades.
 All estimates here refer to pure electric vehicles and plug-in hybrids, which get much or all of their energy from externally generated electricity. Depending on driving patterns, a PHEV may typically get 70% of its energy from external electricity. I exclude conventional hybrids, which are essentially a variant of internal combustion engines with increased efficiency, in that they still get all their energy from petrol.
 Some have made the case that on pure resource cost grounds internal combustion engine vehicles will continue to predominate. See http://www.energypost.eu/can-battery-electrics-disrupt-internal-combustion-engine-part-1/ This is potentially true in the absence of any policy drivers due to emissions or other factors, but this seems unrealistic.
 For comparison, BP assume a doubling of the vehicle fleet by 2035, about a 3.5% p.a. growth rate (see there 2035 outlook).
 See Lost in transition, Carbon tracker p. 102 for plots of these projections
Adam Whitmore is an independent advisor on energy economics and climate change policy, with over 25 years’ experience of the energy sector. He was previously Chief Advisor, Energy and Climate Change Policy for one of the world’s 100 largest companies. He is a member of the supervisory board of the British Institute of Energy Economics, and also gives guest lectures at several leading universities. This article was first published on his website On Climate Change Policy.