Anxiety about electric cars misplaced, says study
Simon Evans15.08.2016 | 4:01pm
At least 98% of the cars used daily on US roads could be replaced by electric cars on a single charge, according to new research.
The study, published in Nature Energy, show fears over electric car batteries running out, known as range anxiety, could be misplaced for all but the longest days of driving. Similarly, data from the UK government shows that more than 99% of car journeys are shorter than 100 miles.
Carbon Brief runs through the study’s findings and what it means for electric car adoption.
The new research compares the distribution of daily miles driven in different parts of the US with the range of existing electric cars. Information on distances comes from the US National Household Travel Survey.
The paper modifies published electric vehicle range data to take account of two ways drivers can significantly increase a car’s energy use, thereby decreasing the miles that can be covered on a single charge.
First, it matches journey data with hourly temperature records to account for air conditioning needs in warmer areas. Second, it includes driving behaviour using second-by-second GPS tracking.
The researchers compare their driving model to the battery capacity of a 2013 Nissan Leaf, an electric car with a battery capacity of 24 kilowatt hours (kWh) and a published range of 70-80 miles. For longer battery life, Nissan recommends a maximum 80% discharge, or 19kWh.
This energy is enough to drive the distance covered during 87% of daily travel in the US data, the paper says. More recent Leaf models already have a larger 30kWh battery.
Similarly, the 2017 Volkswagen e-Golf will have a 39kWh battery, compared to 24kWh for the current model. The 2017 Chevy Bolt will have a 60kWh battery, similar to that rumoured for the Tesla Model 3, and a 90kWh Tesla Model S is now on the market.
These larger battery sizes will push the share of cars on the road that could be replaced with an electric model on a single charge from 87% to around 98% for the 60kWh Bolt and, perhaps, 99% for the 90kWh Tesla.
The paper highlights the fact that long-distance journeys account for a small share of driving days, but a sizeable minority of miles driven, fuel use and emissions. These journeys will be the hardest to shift, along with their emissions, even as battery capacities increase.
The 87% of US daily travel that could be driven in a 2013 Nissan Leaf only accounts for 60% of fuel use, with the longest journeys needing a disproportionate share. Similarly, newer electric cars could meet 98% of days’ driving needs, but would only displace 80% of car fuel demand.
All the same, a shift to electric cars would be good news for transport CO2 targets, the paper suggests. Cars with the capacity of a 2013 Nissan Leaf drawing power, with current US electric grid emissions, could still cut US transport CO2 in 2025 by 29% below 2005 levels, it says.
Jessika Trancik, associate professor of energy studies at Massachusetts Institute of Technology, tells Carbon Brief that transport CO2 could fall 45% below 2005 levels with higher-capacity electric vehicles and around 60% if CO2 intensity of the electric grid falls 45% by 2025.
The paper’s findings raise some intriguing questions. If existing electric car models can, on a single charge, already cover the distance driven on the vast majority of days in the US, then why is range anxiety still seen as a primary barrier to adoption? Or is range anxiety a myth?
Range anxiety is still a real barrier, Trancik says, because consumers find it hard to predict how likely they are to exceed a car’s range and “Nobody wants to get stranded along the side of the road.” She tells Carbon Brief:
“Drivers needs have to be met on all days, even that small number of very-high-energy days.”
In a news and views article published with today’s research, Willett Kempton at the University of Delaware echoes this view:
“The problem may be that when a car purchase is made, the customer wants to be able to make all of their trips [ever], not just 90%.”
He tells Carbon Brief that range anxiety remains “perhaps the most important barrier” to electric car uptake. The need to drive long distances on rare occasions – for instance, for a holiday – may be enough to put customers off electric vehicles that would serve all their everyday driving needs.
Kempton and Trancik both suggest shared long-distance cars could be part of the solution – for instance, through a commercial car-sharing scheme.
Still, range should not be a barrier for a significant minority of drivers, Kempton says. Some 25% of US drivers never travelled more than 150 miles in a day across a whole year, he says, citing his own research from 2011.
Though these drivers ought to offer plenty of scope to build a market for electric cars, none of the major car companies are targeting them, Kempton says.
There are now more than a million electric cars on the road worldwide, yet they still account for a tiny share of sales in the US and the UK. All this points to other factors slowing wider adoption.
A prime contender is the upfront cost, even if lifetime ownership of an electric car is cheaper overall because of lower fuel bills.
Despite rapid falls in battery prices and government grants in countries including the UK, an all-electric Volkswagen e-Golf remains more expensive than its combustion engine equivalent. While a Nissan Leaf costs less up front, the battery must be leased on top.
Electric cars are expected to be cheapest across the board within a decade, according to analysis from Bloomberg New Energy Finance, which said 35% of new cars would be electric by 2040. Bloomberg news said this could cut oil demand and so cause the next oil price crash.
Other analysts range from sceptical (underlying demand growth will outweigh oil displaced by electric cars) through to pessimistic (electric vehicles will do well to reach 10% of sales by 2050).
The rate of uptake of electric cars has major implications for oil demand and CO2 emissions. Transport emissions in many industrialised countries are holding steady or increasing, even as other parts of the economy decarbonise.
In the UK, National Grid scenarios now see up to a quarter of cars on the road being electric by 2035, while the Committee on Climate Change says electric cars will need to make up 60% of new sales in 2030 if the UK is to stay on track with its climate goals.
This new research shows current electric cars can cover most daily needs on a single charge. Newer models will be able to meet the vast majority of needs and could have a “huge effect” in terms of unlocking the electric car market, Willett tells Carbon Brief.
Needell, Z. A. et al. (2016) Potential for widespread electrification of personal vehicle travel in the United States, Nature Energy, doi:10.1038/nenergy.2016.112 Kempton, W. (2016) Driving range, Nature Energy, doi:10.1038/nenergy.2016.131
Anxiety about electric cars misplaced, says study
Vast majority of daily US car journeys can be covered by electric cars on a single charge