Introduction
Electric vehicles (EVs) are not new. The first crude electric vehicle was credited to Robert Anderson in Scotland sometime between 1832 to 1839. The first “real” vehicle is regarded as being produced by Andreas Flocken of Heinrich Lanz AG in Mannheim, in 1888. The Flocken Elektrowagenan had a 900 W electric motor, the power was transferred to the rear axle by means of leather belts. The wooden vehicle is said to have reached a top speed of 15 km/h. It had a rechargeable lead-acid battery. NOT MUCH CHANGED FOR OVER 100 YEARS!
Current Global State
There are about 1.6 billion vehicles worldwide - in 2024 there were 80 million electric or plug-in hybrid electric vehicles (internal combustion + electric) – about 5 % of all vehicles. 16 % of car sales in 2023 were electric. The total cars (not vehicles) in use over recent years had grown to 40 million worldwide inn 2023 with 22.5 million in China, which is showing the fastest growth. From 80 million EVs in 2024, this is expected to rise to 360 million in 2030.
What Has Enabled This?
The move to using green energy has motivated the move to EVs but what has enabled this? Old EVs used commutator DC motors with mechanical switchgear supplied from lead-acid batteries: Lead-acid batteries are heavy and low energy density; Commutator DC motors are not very efficient; and Hence old EVs were slow with a small range.
New EVs utilize modern technology developments:
Battery technologies have improved immensely in recent years, primarily in high-energy-density batteries utilizing lithium-ion; Drive trains utilize high-efficiency motors that often use high-energy sintered neodymium-iron-boron magnets; Motors are AC and require variable voltage and frequency. This is generated by high-power low-loss power-electronic inverters that can convert DC into AC and vice versa for regenerative braking. Power electronics (electronics that work as fast-acting switches) has been a key technology in EV development; and Hence modern EVs are fast, efficient, and have good range capabilities.
Vehicle Efficiencies
From American data: Internal combustion engine (ICE) cars can lose over 75% of energy and often over 80%; however, EVs lose about 31-35% energy BUT can recapture up 22 % through regenerative braking.
Overall Operating Energy Balance
Replacing ICE vehicles with EVs charged from the most inefficient carbon fuel-generated electricity still gives about 29 % energy saving. Using renewable energy will increase this saving!
Vehicle Energy Production Costs
EVs do use more energy (and hence produce more greenhouse gases) than ICE vehicles in production due to the energy required to produce high-energy lithium-ion batteries, but this is changing all the time as EV manufacturing improves. This energy only represents the energy equivalent of a few months of its on-road use. Over a lifecycle, EVs use less energy and produce less greenhouse gases than equivalent ICE vehicles. A study in 2019 found that the life cycle GHG emissions of an EV are about 41.0 t CO2eq in 2015, 18% lower than those of an Internal Combustion Engine Vehicle (ICEV). This value will decrease to only 34.1 t CO2eq in 2020 due to the reduction of GHG emission factor of electricity. [Qinyu Qiao, Fuquan Zhao, Zongwei Liu, Xin He, Han Hao, Life cycle greenhouse gas emissions of Electric Vehicles in China: Combining the vehicle cycle and fuel cycle, Energy, Vol 177, 2019, pp 222-233].
EV Technology Issues – Materials
Lithium-ion batteries use expensive lithium on other related rare-earth materials which are expensive and hazardous to mine and scarce. They are also difficult to recycle. The mining methods have been improved and better recycling methods developed.
Lithium batteries need very careful handling and control on their charging and discharging. Lithium fires are hot and very dangerous. (You can’t put these batteries in your checked luggage when flying; and China has a lot of electric scooters and they have banned the indoor charging of their batteries.)
High-efficiency neodymium magnet motors again use expensive rare-earth materials. At one point over 90 % of these magnets came from China although with new mines opening elsewhere, it is down to 70 %. Induction motors can be used which use just steel and copper. These are much cheaper though not as efficient. Tesla EVs often come with both types on one vehicle.
EV Technology Issues – Other
Power electronic inverters are expensive. Their cost has come down a lot but they run with DC rails up to maybe 600 V representing a hazard. Logistical issues: slow charging and few charging stations. Infrastructure needs to be developed to satisfy charging needs, not just home charging. Added power system load demands.
Future Developments – Batteries
- Higher energy and more efficient types of lithium batteries are being developed
- A safer option is sodium-ion batteries. They have only about half the energy density but:
- Do not use expensive rare earth materials, including the electrode which can be made from aluminium;
- They are currently about half the price;
- Easily recycled;
- Do not burn with intense fires;
- Can be transported fully discharged;
- Work in cold climates; and
- Require less protection.
Future Developments – Charging
- Development of charging facilities. These could include:
- More fast charging stations;
- Under-road charging for vehicles such as buses that charge while stationary;
- Battery swapping stations so that batteries are swapped out in a very few minutes and charged at the station. This is very relevant to high-use commercial and industrial vehicles. This could also lead to changes in EV ownership where vehicles are bought but batteries are rented;
- Mobile charging stations for peak periods such as national holiday periods; and
- Development of microgrids for charging stations with their own generation through, for instance, solar energy, and localized battery storage.
Future Developments – Power Electronics
- Inverters are very efficient but they are being developed further. Some developments include:
- Cheaper devices;
- Lower losses with higher power density – less cooling needed; and
- Alternative devices such as wide band gap devices that can switch faster and give higher voltage blocking capability:
- Early devices (1950s onwards): Germanium
- Current devices: Silicon
- Future devices: Silicon Carbide, Gallium Nitride.
