Last edited 17 May 2019

Electric vehicles

Tesla 340.jpg
Tesla's Model X electric car has a 100kWh battery that provides a range of 351 miles.


[edit] Introduction

Electric vehicles (EVs) are typically cars, although they can be motorcycles, trains, buses, trams, trucks, aircraft, ships, submarines and other vehicle types. They may have one or more motors powered by electric batteries, as opposed to an internal combustion engine.

[edit] Benefits and drawbacks

Compared to petrol-driven varieties, electric vehicles tend to be quieter, cheaper to run and have no exhaust emissions, however the carbon footprint will depend on how the electricity driving the vehicle has been generated. Electricity derived from wind, tidal and solar has a better carbon footprint than that generated from fossil fuels.

Potential drawbacks of EVs include relatively high purchase costs, limited choice of models, battery life and replacement costs, and lower range compared to petrol-driven vehicles.

[edit] Charging methods

Batteries can be recharged either by off-vehicle electricity sources or integrated sources such as solar panels and fuel cells. Lithium-ion (Li-Ion) batteries are generally the predominant type used for EVs as they are longer lasting and have a higher energy- and power-density than most other battery types. Li-Ions have superceded the earlier and pricier nickel metal hydride batteries due to the latter’s tendency to lose charge in heat.

Cars recharged from external electricity sources are known as plug-in electric vehicles (PEVs), with the Nissan Leaf being the world’s top-selling model (2018). Cars that combine conventional fuel-powered engines with electric propulsion are known as hybrid electric vehicles (HEVs), a market dominated by Japan followed by the US and Europe.

In the UK, the 12 months to December 2018 saw a dramatic slowdown in sales of electric cars which is undermining government plans to cut roadside emissions. This is attributed to factors, including public scepticism over safety issues, a lack of charging points, few affordable models, cuts in green car incentives by the UK government and sluggish progress in EV roll-out.

[edit] Automated vehicles

EV technology lends itself more readily to automation than conventional technology and this has generated much interest in autonomous vehicles (AVs). There are varying levels of automation for road vehicles: fully autonomous, where the AV can complete journeys safely without a driver in normally-encountered traffic conditions, and highly automated, where the vehicle can operate in driverless mode but must have a driver on-board to take control if necessary.

AVs will potentially transform cities due to zero exhaust emissions, safer roads, fewer accidents, less congestion and smoother traffic flow, with extensive freeing-up of conventional parking space. It could also bring about changes in car ownership patterns and raise questions in terms of insurance. If an accident occurs with a fully autonomous vehicle, who is responsible? The vehicle provider, the manufacturer or the software developer?

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