Energy use must satisfy a set of conditions to be considered “sustainable”: it must not exhaust natural resources, it must not emit too much CO2 or other pollutants and, most importantly, it must form part of a virtuous “cycle” at every stage. Take, for example, electric and hydrogen cars, which are set to play a key role in the future of mobility.
A common mistake is to judge a vehicle’s environmental performance when it is in use, without considering what happens “before” (how it was made and where its fuelFuel is any solid, liquid or gaseous substance or material that can be combined with an oxidant... comes from) or “after” (whether it can be recycled).
All-electric vehicles are powered by an electric motor – as opposed to an internal combustion engine – and by a battery that is much bigger than the one used in a traditional car. This battery stores electricityForm of energy resulting from the movement of charged particles (electrons) through a conductor... supplied by the public powerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output... grid.
Here are a few phases in the “life cycle” of an electric car.
Engine and cabin production – This requires metals (iron, copper, etc.) and petroleum-based plastics, without which the car would be much heavier and would therefore consume more energy. But the process is virtually the same as for a traditional car.
Battery production – The battery in a Renault Zoé supermini weighs 326 kilograms. In the larger Tesla Model S sedan, which has a range in excess of 500 kilometers, the battery weighs a colossal 600 kilograms. The most widely used technology today is the lithium-ion battery, which is made from lithium (mined in Latin America), cobalt, nickel (found in Africa) and other metals that have now become strategic. All of these minerals have to be extracted and processed into usable materials. Note that “rare earths” (cerium, lanthanum, neodymium, etc.), of which China has major reserves, are used less and less in electric cars, except in small motors to power the air conditioning or to open and close the windows and doors.
Vehicle use – An electric car is only “clean” if the electricity of the country in which it is used is generated without emitting large quantities of greenhouse gases. France uses 70% nuclear power, which produces very little carbon. The situation is very different in Germany, where coalCoal is ranked by its degree of transformation or maturity, increasing in carbon content from... and natural gas make up a very large share of the power generation mix. Electrical power transmission is not a problem in industrialized countries, because their networks are highly developed. The same cannot be said of developing regions, notably Africa, where electrification remains low.
One major point on the side of “sustainabilitySustainability indicates a state that is sustainable or reasonably manageable over the long term. ” is the absence of exhaust fumes (although there is still brake dust).
Vehicle end-of-life – The end of a vehicle’s useful life offers the very interesting possibility of reusing the batteries for stationary applications, for example in buildings or to store surplus electricity generated by a wind turbine. When a car battery has lost 20% of its capacity, it is no longer suitable for the demanding performance requirements of a vehicle. But it can still handle regular charging and discharging for stationary uses. This “second life” can last several years.
Based on a lifespan of roughly ten years, it is estimated that an electric car emits an average of two to three times less greenhouse gas (ghg) Gas with physical properties that cause the Earth's atmosphere to warm up. There are a number of naturally occurring greenhouse gases... than a gasoline or dieselDiesel is the name of an internal combustion engine that works by compression-ignition... vehicle1. But the figures vary widely depending on the country, vehicle usage practices (proportion of high-powered cars, car-sharing, city driving, etc.) and government mobility policies.
HydrogenThe simplest and lightest atom, the most abundant element in the universe. cars also run on an electric motor. But instead of recharging from the public grid, they produce their own electricity from a hydrogen fuel cell. They have a battery too (but much smaller than those found in all-electric vehicles), and a tank that contains high-pressure hydrogen gas.
Compared with an all-electric car, there are two key issues to consider when assessing the life cycle of a hydrogen car:
- Is the hydrogen used “clean”? Today, 95% of hydrogen is derived from preservation (hydrocarbons)The final phase in petroleum system formation, after a deposit has accumulated... (oil, natural gas and coal). Ideally, it would be produced using renewable electricity (wind, solar) via electrolysis. While this is technically possible, it would require the creation of a new electrolyzer industry.
- How is the hydrogen transported to the car? Although the power grid extends to every corner of most developed countries, and natural gas is widely distributed too, there is no such network for hydrogen.
According to a report by the French Environment and Energy Management Agency (ADEME), producing hydrogen from fossil fuels results in a carbon footprintThe carbon footprint (also known as greenhouse gas inventory) of a good or service measures the impact human activities have on the environment ... nine times greater than for “green” hydrogen2. And when transporting green hydrogen to a fueling station, CO2See Carbon Dioxid emissions increase threefold every 100 kilometers.
1 Report by the European Climate Foundation, the Nicolas Hulot Foundation, ADEME and various industry bodies – See summary (in French)
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