Are we far from a world where everybody drives an EV?

Electric vehicles on the rise

The increasing focus on renewable energy sources and low carbon technologies is triggering a substantial shift in the automotive industry, promoting a switch from Internal Combustion Engine Vehicles (ICEVs) to Electric Vehicles (EVs). Governments worldwide have implemented policies aiming to massify the electrification of public and private transport, boosted by subsidies and tax regulations targeted to equal the cost of EVs and ICEVs. In consequence, the uptake of EVs has been rapidly increasing.

Currently, Norway is leading in terms of market share, closely followed by Japan, the United States, and China[1]. The UK aims to keep up too. As part of an unprecedented plan to reduce greenhouse gas emissions by 25%, the British government has committed to stop selling new petrol and diesel cars by 2040 – a government policy deemed to be one of the strongest ones[2]. In line with this, public and private institutions have set up their calculations regarding the rise of EVS in the next three decades. There is a lack of consensus on global numbers, though they all show pronounced increases. The relevant estimates for the uptake of EVs are summarised Table 1.

  Table          SEQ Table \* ARABIC       1          . Forecasts at a glance. Taken from  [3]

Table 1. Forecasts at a glance. Taken from [3]

Amidst the hype, some experts show scepticism about the feasibility of such rapid EV growth. During the event "Reinforcing the grid for the roll-out of Electric Vehicles" held in London earlier this year, a strong debate formed around the question "would it be possible at all to live in a world where everyone drives an EV?" The conservative side suggested no; the more futuristic and ambitious believed yes. Nevertheless, from a purely realistic point of view, full electrification of transport would only be achievable through a robust and thorough plan to reinforce the electricity grid in its critical stages: generation, transmission and distribution.

Amidst the hype, some experts show scepticism about the feasibility of such rapid EV growth. During the event "Reinforcing the grid for the roll-out of Electric Vehicles" held in London earlier this year, a strong debate formed around the question "would it be possible at all to live in a world where everyone drives an EV?" The conservative side suggested no; the more futuristic and ambitious believed yes. Nevertheless, from a purely realistic point of view, full electrification of transport would only be achievable through a robust and thorough plan to reinforce the electricity grid in its critical stages: generation, transmission and distribution.

Impacts on the Electricity System

Distribution networks

Without compensatory actions, the growth in EVs usage will have significant impacts on distribution networks. The electricity system will face a drastic surge in consumption every time a large number of EVs recharge their batteries simultaneously. Distribution transformers supplying residential areas can be easily overloaded during peak hours of electricity demand, when people return from work and start doing conventional end-of-the-day tasks, like cooking, washing, ironing, and others on top of charging their EVs in the garage at the same time.

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While this may seem like a bearable increase for an individual or a household, the collective effect is enormous. For example, if every home in an average UK neighbourhood[6] charge an EV from the grid using a regular EV charger, the overall load demand would increase by 50% [for details see the text box]. This would mean that the operation of the distribution transformer supplying the neighbourhood could go up to 140% of its rated power during peak demand time. To modulate the impacts of this, increase appropriate adequation of the existing grid and consumer engagement would be required.

However, EV adoption does not have to reach 100% to cause issues within the infrastructure. To exemplify the point, researchers from the University of Cardiff have carried out a study, looking at the simulated impacts of EVs in a residential distribution network in Britain[7]. The study investigated three loading scenarios, where 12.5%, 33%, and 71% of the residences used an EV. It has determined that the distribution transformer was overloaded in all three of these scenarios. Moreover, a probabilistic analysis determined that the overloaded distribution transformer showed abnormal operation with 95% probability, in all EV uptake scenarios.

This study simulated a generic three-phase low voltage network, nonetheless, other analyses found that distribution networks’ tolerance for EVs can vary between 10% and 40% of residential EV adoption, depending on network characteristics and consumer behaviour[8]. It is clear that above those numbers imbalances, transformer overloading, and other issues arise.

Generation and grid capacity

Road transportation accounted for 30% of the UK’s annual energy consumption in 2016[9]. This has mainly been supplied for by the petrol industry, providing 80% of passenger kilometres in 2016 in Great Britain[10]. A full switch to EVs would mean that almost all of transportation’s energy requirements would shift from petrol stations to burden the same electricity network that is already at its limits supplying current domestic and industrial needs.

The impact of EV growth on the entire grid has been extensively analysed by National Grid in its Future Energy Scenarios (FES) report 2017, assessing scenarios of different degrees of EV adoption. All proposed scenarios consider EV growth but with varying degree (Figure 1), and accordingly, the peak demand is expected to proportionally increase (Figure 2).

  Figure 1. The Growth of EVs. [5]

Figure 1. The Growth of EVs.[5]

Scenario "Two Degrees" predicts the highest proportion of EVs. In order to keep the 2050 carbon reduction targets, this scenario estimates 2045 as the year where all vehicle registered in the UK must be Pure Electric Vehicle (PEVs). Scenario "Steady State" is the counterpart, it assumes the lowest uptake of EVs with of PEVs and PHEVs amounting to only 30% of all vehicles by 2050. In scenarios "Slow Progression" and "Consumer Power", PEVs sales finally overtake PHEV before 2040.

  Figure2. Peak demand from EVs. [5]

Figure2. Peak demand from EVs. [5]

While putting a significant burden on generation capacity, such intense demands would also have negative effects on the network operation. A drastic increase would introduce instability on the system level (e.g., in the form of voltage drops), which would further reduce the life of network components, drive down efficiency, and potentially cause serious damage to the equipment being powered. Ultimately, a network that is unable to handle the forecasted surges in demand will lead to spiralling electricity costs and degrading reliability of service.

It is unthinkable to stand the expanding uptake of EVs without extending public and private charging points. Ambitious projects, such as the POLAR network in the UK, and Shell and Ionity’s joint global venture build their business models on occupying the charging market by rolling out charging points rapidly. Their readiness to supply is nonetheless contingent upon the upgrade of the electric network because existing distribution transformers are not suitable to support their full use.

Not all green yet

EVs are generally regarded as a key technology towards a low carbon future – but how “green” are they? Although the vehicles do not generate the same emissions as fuel-powered engines, their potential emission reduction depends on the emissions from the generation of electricity within the grid. Currently electricity powering up charging points and electricity used in the manufacturing process of batteries is still likely to come from fossil fuels.

For instance, producing the electricity to fully charge a Tesla Model S in the UK generates 74g of carbon emissions per Km driven, numbers which can vary depending on the model[11]. However, such emissions are not to be underestimated. Similarly, emissions of driving an average EV can reach 0.96t per 10,000 miles when charged from UK mains electricity.

Additionally, a detailed analysis carried out by the Union of Concerned Scientists of the US determined that production of EVs results in higher emissions than the making gasoline or diesel cars, mainly due to the materials and fabrication of the ion-lithium batteries, roughly adding 1 ton of emissions to the total manufacturing emissions, approximately 15% greater than ICEVs[12]

More EVs alone will not solve the emission problems, a fully environmentally-friendly solution requires a systemic change and greater proportions of renewable electricity compensating for the drastically increasing electricity demand.  

While up to 40% of the generated electricity in the UK by 2030 is expected to come from these sources, increasing to 60% by 2050[5], there are limits to the integration of more renewable energy into the grid within the current architecture. Characteristics inherent to solar and wind power, such as intermittence and volatility will introduce distortion to the system. This ultimately leaves the grid concerningly inefficient and again: less stable. In order to be able to handle greater proportions of renewables with sustained stability, the grid architecture needs an upgrade in flexibility and resilience.

Charging smarter

Consumer engagement is believed to have potential in relieving some of the demand pressures posed by EVs. If drivers commit to charge their vehicles outside of peak demand times, the overall rise in demand would be distributed more evenly. Nonetheless, the efforts to promote a sustainable consumption behaviour may be insufficient: a number of statistics converge that only a small percentage of EV owners charge their units at off-peak time either at work or at public charging stations. The rest do it at home based on convenience[13].

Such behavioural factors can be somewhat controlled for by smart chargers, which essentially provide the automated version of the same solution. According to National Grid’s predictions, this could mean the difference of 5GW, instead of 18GW of increase in the peak demand in the Future Energy Scenario of the highest proportion of EVs. Although more expensive than regular chargers, this technology can assist a less dramatic transition. However, it still may be viewed inconvenient to use and does not address the massive overall increase in demand and the greater demand for renewable energy by itself.

A world where everybody drives an EV

Although the challenges standing in the way of large-scale EV adoption appear to be multi-faceted, they all crystallise in one area: the electricity grid. In the current architecture, all predicted transition paths project demand pressures and imbalances on an electricity system that is already at its stability limits.

On the other hand, enabling the grid to support the changes associated with EVs would make the greatest concerns facing wide-scale deployment disappear. In realising an overall switch to EVs, grid modernisation in both structural and functional levels will therefore be inevitable.

To support full electrification of transportation, electricity systems will have to develop characteristics today’s grids lack or must improve upon. They will have to have substantially greater capacity for the amount of electricity in the system. Flexibility, perhaps even antifragility will be key. This will enable handling big variations in supply and maintaining stability at high levels of intermittent renewable energy.

Ultimately, electricity systems functioning as robust distribution platforms could even allow trading of energy currently not possible, such as vehicle-to-grid energy transactions. A system where changes are not compensated for in a reactive manner but are catalysed by the very structure in place to support the transfer of energy will enable a world where everyone can drive an EV.

[1] International Energy Agency: Global EV Outlook 2017

[2] UK Committee of Climate Change, Renewable Energy Association: Jobs, infrastructure and vision of the growth of EVs in UK

[3] Bloomberg New Energy Finance

[4] Assessing the role of the plug-in car grant and plugged-in places scheme in electric vehicle take-up

[5] National Grid. Future Energy Scenarios (FES) report 2017

[6] A typical 500KVA distribution transformer, with roughly 7.5KW allocated for each household, would supply around 67 homes.

[7] Electric vehicles’ impact on British distribution networks - IET Electrical Systems in Transportation

[8] Impact of EV Charger Load on Distribution Network Capacity. Canadian Journal of Electrical and Computer Engineering.

[9] Energy Consumption in the UK – Department of Business, Energy & Industrial Strategy

[10] Department for Transport: Transport Statistics Great Britain 2017

[11] Drax; Do electric vehicles actually reduce carbon emissions?

[12] Union of Concerned Scientists: Cleaner Cars from Craddle to Grave

[13] insideevs.com