Written by Chadwick Dearing Oliver, Fatma Arf Oliver, and James Sun*
* James Sun, Yale College student ’21, Yale University.
Figure 1. Photovoltaic panels on roof are used to charge “Plug-in Battery Electric Vehicle” and provide other energy needs for the house. (Photos courtesy of Elisabeth Kennedy and Emma Kennedy.)
Trends in Electric Vehicles
Electric vehicles will soon enable people everywhere to avoid fossil use and CO2 (carbon dioxide) emissions in transportation. They can become a “leapfrog technology” by bypassing the infrastructure needs and vulnerabilities of electric grids and fossil fuel deliveries.
Figure 2. Evolution of electric vehicles globally during the pat decade; abbreviations are underlined. (Appendix 1, bottom of paper, describes vehicle types in detail.)
Electric vehicles are undergoing an evolution (Figure 2) from “hybrid electric vehicles” (HEV’s) to “plug-in battery swap electric vehicles” (PBSEV’s), with “plug-in hybrid electric vehicles” (PHEV’s) being an intermediate step.
The number of vehicles that run partly or fully on an electric motor has been increasing with dramatic technological changes in Asia, North America, and Europe (1). Hybrid electric vehicles (HEV’s) first developed, where an in-vehicle internal combustion motor recharged them. Then the additional ability to recharged them by plugging into a home or public charger followed (PHEV’s). At the same time, vehicles run fully on batteries and recharged from plug-ins developed (PBEV’s). Now quick battery swapping stations for fully battery powered vehicles are developing (BSEV’s). The full environmental potential of electric vehicles can be achieved when they have both battery swapping and home recharging (with off-grid electricity, Figure 1) capabilities (PBSEV’s).
The number of electric vehicles has been increasing dramatically in Asia, North America, and Europe.
Both battery electric vehicles (PBEV’s and PBSEV’s) and battery technologies are rapidly improving and becoming less expensive (2). They are becoming competitive with hybrid electric (HEV’s) and internal combustion vehicles in both cost of refueling and distance travelled between refueling; and, they are taking markets from both HEV’s and traditional non-electric (internal combustion) vehicles (1, 3, 4). Battery electric vehicles could easily replace all fossil fuel-based vehicles by 2060.
What Is Needed for Electric Vehicles To Be Environmentally and Socially Beneficial?
In addition to the current technical progress, three additional goals need to be achieved for battery electric vehicles to realize their full environmental and social potential:
I. Electric vehicle batteries need to be recharged with renewable energy: Batteries recharged with electricity generated from fossil fuel saves little, if any, fossil fuel and CO2 (carbon dioxide) emissions compared to internal combustion engines (5, 6) because the greater efficiency of motors in electric vehicles is offset by the inefficiency of converting fossil fuel to electricity (7, 8). Electricity generated from natural gas saves more CO2 than coal, but much less than renewable energy.
Batteries recharged with electricity generated from fossil fuel saves little fossil fuel and CO2 compared to internal combustion engines.
Battery electric vehicles (PBEV’s, BSEV’s, and PBSEV’s) and plug-in hybrid electric vehicles (PHEV’s) recharged from a grid are subject to the grid’s mixture of renewable and fossil fuel energy sources (9). Off-grid sources of renewable energy such as home photovoltaic panels and solar or wind farms dedicated to recharging batteries could increase renewable energy and free grid energy for other uses.
II. Electric vehicles should not be forced to wait for a recharged battery. Most PBEV owners currently recharge their batteries in “plug-in” stations at home or in public places. Home recharging can take hours and “recharging stations” can take 20 minutes or more without a waiting line, although faster chargers might be designed (10).
Battery swap stations can allow electric vehicles to be recharged quickly.
The alternative to “plug-in recharging stations” for battery electric vehicles is “battery swap stations” (a.k.a. “battery exchange stations”) where a driver has a nearly empty battery removed and replaced with a recharged one (11, 12). Technologies exist that can change the batteries in two minutes or less; however, actual times with inexperienced crews at the few existing battery swap stations were similar to the time needed to refuel an internal combustion engine vehicle (13), which is still shorter than the time needed for battery recharging at plug-in stations. Networks of battery swap stations already exists in parts of China (14).
Battery electric vehicles with combined plug-in and battery swap capabilities (PBSEV’s) will allow people to recharge their batteries slowly with home renewable energy (Figure 1) or swap empty batteries with full ones. Combined plug-in hybrid vehicles (PHEV’s) are already available and show the technological promise.
III. Battery electric vehicles need to be able to bypass the electric grid, thus reducing vulnerability to hacking and giving access to developing regions without waiting for a grid, mass transit, or a fossil fuel delivery infrastructure. Electric vehicle battery sizes currently range from 25 to 80 kWh, with a few larger and smaller. Driving distances between charges are about 160 to 480 km (100-300 mile), respectively—5-6.5 km/kWh (3-4 mile/kWh), depending on the weather (7). In 2015 a 50-kWh battery weighed 190 kg (418 lbs) with a charge range of 320 km (200 miles) (15)—about the range of 26.5 liters (7 gal’s) of gasoline, that weighs 19 kg (42 lbs). Even as batteries become lighter, they will be much heavier than fossil fuels and so local recharging and transport of batteries will be important.
Off-grid wind turbines or fields (or rooftops) of photovoltaic panels close to swapping stations can recharge batteries renewably. Photovoltaic panels can produce between 500 and 1200 kW per hectare, depending on panel quality and geography, with deserts producing more energy than cloudy climates (16); consequently, one hectare of high quality photovoltaic panels can recharge about ninety 80-kWh batteries per 6-hour day. Costs of photovoltaic energy are declining (17, 18).
Off-grid wind turbines or photovoltaic panels near swapping stations can recharge batteries renewably.
An Achievable Scale of Change
People in the United States drive about 5.2 trillion km (3.2 trillion miles) per year (19). If all such driving were in battery swap electric vehicles (BSEV’s) with eighty kWh batteries that propelled their vehicles 480 km (300 miles) between charges, a total of 10.7 billion recharges per year would occur. To recharge these batteries with efficient photovoltaic panels would require 328 thousand ha’s (810 thousand acres) of efficient PV panels—which is only 0.2% of the 2012 USA cropland (20). Photovoltaic energy to recharge batteries that replace all 90 quads of fossil fuel energy used globally for transportation each year would require only 0.07% of the world’s land area--0.6% of the cropland area (8).
Photovoltaic panels to recharge enough batteries to replace all fossil fuel transportation energy would need only 0.07% of the world’s land area—0.6% of the cropland area.
Complete, global conversion to battery electric vehicles recharged with renewable electricity will result in 18% reduction of global fossil fuel use and CO2 emissions with no loss in ability to travel in one’s own vehicle—and possibly a reduction in irrigation and agriculture chemical use, as discussed below.
Steps to Achieve the Goals
Several, discrete steps could help reach the goals described above:
i. Similar to automobile tires and electric light bulbs, standardized electric vehicle batteries could be used in all battery electric vehicles for easy swapping. Standardized battery placements could be instituted on vehicles for easy battery replacing similar to standardized gas tank spouts. And, standardized robots could be designed for exchanging batteries at swap stations. Each battery could contain updated information on its condition, charge, and when/where it was last charged.
ii. It may be appropriate for vehicle manufacturers, battery manufacturers, recharging facilities, and swap stations to be separate businesses.
iii. Battery swap stations could first be located at gasoline filling stations, especially those that could host nearby areas of photovoltaics or wind turbines for recharging batteries.
iv. Bioethanol would primarily be needed for jet fuel as battery electric vehicles replace internal combustion engines and hybrid electric vehicles. This bioethanol could be provided by nonedible wood and agriculture waste (8). To offset farmers’ loss of bioethanol revenues from crops, farmers previously growing bioethanol crops could be given priority of shifting appropriate land to photovoltaic fields. In the USA, 3.4 million ha (8.3 million acres) that grow corn ethanol could be replaced for energy with one tenth the area of photovoltaics and produce the same amount of energy (8). Unless needed for food, the remaining nine tenths currently growing food crops for ethanol could be reallocated for biodiversity easements that provide habitats and save fertilizer, pesticides, and irrigation water.
Complete conversion of battery electric vehicles recharged with renewable electricity will save 18% of the global fossil fuel use and CO2 emissions.
References
1. Block, D., and J. Harrison. 2014. Electric vehicle sales and future projections. Electric Vehicle Transportation Center Report EVTC-RR-01-14. U.S. Department of Transportation. http://evtc.fsec.ucf.edu/reports/EVTC-RR-01-14.pdf
2. Nykvist, Bjorn, and Mans Nilsson. 2015. Rapidly falling costs of battery packs for electric vehicles. Nature Climate Change 5, 329-332. https://www.nature.com/articles/nclimate2564
3. Gao, Paul, Hans-Werner Kaas, Detlev Mohr, and Dominik Wee. 2016. Automotive revolution—perspective towards 2030: How the convergence of disruptive technology-driven trends could transform the auto industry. Advanced Industries, January 2016. McKinsey & Company, 20 pp. https://www.mckinsey.com/~/media/mckinsey/industries/high%20tech/our%20insights/disruptive%20trends%20that%20will%20transform%20the%20auto%20industry/auto%202030%20report%20jan%202016.ashx
4. IEA. 2017. “Tracking clean energy progress 2017” International Energy Agency. https://www.iea.org/publications/freepublications/publication/TrackingCleanEnergyProgress2017.pdf
5. Biello, David. 2016. Electric cars are not necessarily clean. Scientific American: Sustainability. https://www.scientificamerican.com/article/electric-cars-are-not-necessarily-clean/?redirect=1
6. Nordelof, Anders, Maarten Messagie, Anne-Marie Tillman, Maria Ljunggren Soderman, and Joeri Van Mierlo. 2014. Environmental impacts of hybrid, plug-in hybrid, and battery electric vehicles—what can we learn from life cycle assessment. International Journal of Life Cycle Assessment 19: 1866-1890. https://link.springer.com/content/pdf/10.1007%2Fs11367-014-0788-0.pdf
7. “All-Electric Vehicles” U.S. Dept. of Energy, Office of Energy Efficiency & Renewable Energy. https://fueleconomy.gov/feg/evtech.shtml
8. Oliver, C.D., and F.A.Oliver. 2018. Global Resources and the Environment. Cambridge University Press. https://www.cambridge.org/core/books/global-resources-and-the-environment/BC44D92549B080B75CBB4F1DDACD66
9. Mwasilu, F., John J. Jackson, Eun-Kyung Kim, Ton Duc Do, and Jin-Woo Jung. 2014. Electric vehicles and smart grid interaction: A review on vehicle to grid and renewable energy source integration. Renewable and Sustainable Energy Reviews 34: 501-516. https://www.sciencedirect.com/science/article/pii/S1364032114001920
10. Threewitt, Cherise. 2019. “Electric car charging goes super fast.” https://auto.howstuffworks.com/fuel-efficiency/vehicles/electric-car-charging-goes-super-fast.htm
11. Sarker, Mushfiqur R., Hrvojoe Pandzic, Miguel A. Ortega-Vazquez, et al. 2014. Optimal operation and services scheduling for an electric vehicle battery swapping station. IEEE Transactions on Power Systems 30 (2): 901-910. https://ieeexplore.ieee.org/abstract/document/6857439
12. Yang, Shengjie, Jiangang Yao, Tong Kang, and Xiangqian Zhu. 2013. Dynamic operation model of the battery swapping station for EV (electric vehicle) in electricity market. Journal of Energy 65. 544-549. https://www.sciencedirect.com/science/article/abs/pii/S0360544213009729
13. “Battery Swap.” 2015. https://teslaowner.wordpress.com/2015/07/01/battery-swap/
14. Zart, Nicolas. 2018. “Nio builds battery swap stations in China for its electric vehicles.” https://cleantechnica.com/2018/11/24/nio-builds-battery-swap-stations-in-china-for-its-electric-vehicles/
15. Tostengard, A. 2015. 50 kWh Bosch EV battery will soon weigh just 190 kilograms. The Green Optimist. https://www.greenoptimistic.com/bosch-electric-vehicle-battery-kg/#.XOK6H6R7nIU
16. “How to calculate the annual solar energy output of a photovoltaic system?” https://photovoltaic-software.com/principle-ressources/how-calculate-solar-energy-power-pv-systems
17. Pillai, Unni. 2015. Drivers of cost reduction in solar photovoltaics. Journal of Energy Economics 50, 286-293. https://www.sciencedirect.com/science/article/pii/S014098831500167X?via%3Dihub
18. Lewis, Nathan S. 2016. Research opportunities to advance solar energy utilization. Science 22. https://science.sciencemag.org/content/351/6271/aad1920
19. Schaper, D. 2017. Record number of miles driven in U.S. last year. National Public Radio. https://www.npr.org/sections/thetwo-way/2017/02/21/516512439/record-number-of-miles-driven-in-u-s-last-year
20. Bigelow, D., and A. Borchers. 2017. “Major uses of land in the United States, 2012.” USDA Economic Research Service. https://www.ers.usda.gov/publications/pub-details/?pubid=84879
Disclaimer
Reasonable efforts for accuracy are made for this blog; however, it does not have the rigorous scrutiny of a scientific paper. Constructive corrections are welcome on Chad’s LinkedIn website: https://www.linkedin.com/in/chadwick-dearing-oliver-36844570/detail/recent-activity/shares/
