A petrol engine turns about 25 in 100 of its fuel's energy into motion. The rest leaves as heat, out of the exhaust and the radiator. An electric motor turns about 90 in 100 into motion. That is why an electric car goes three to four times as far on the same energy.
Swap the engine for a motor→Swap the boiler for a heat pump→Make the electricity without burning→Nothing left to burn
Here is the plan most countries follow. First, swap things that burn a fuel for things that run on electricity: cars, heaters, some furnaces. Second, make the electricity from sources that do not burn. Do the first without the second and you have moved the smoke to the power station. Do both and the smoke is gone.
Every car electric
↓→
Charged from a coal plant
A country swaps every car for an electric one but still makes all its electricity from coal. What happens to the carbon dioxide from driving?
It disappears. Electric cars make none.
Not yet. The car makes none. The coal plant charging it makes about 800 grams for every unit it sends down the wire. The smoke has moved, not gone.
It moves from exhausts to the power station, and falls a little, because a motor wastes less than an engine.
Right. The car makes none; the coal plant charging it makes plenty. But a motor at 90 in 100 fed by a coal plant still uses less fuel per kilometre than an engine at 25, so the total comes down somewhat.
It doubles. Coal is worse than petrol.
Not yet. Coal is dirtier per unit of energy, but the motor wastes so much less that a coal-charged electric car comes out about even with petrol, or a little better. Doubling is not on the table.
Gas boiler0.9 units
Electric heat pump3.5 units
Units of heat for each unit of energy used.
The same trick works for heat. A gas boiler gives about 0.9 units of heat for each unit of gas it burns. A heat pump does not make heat. It moves heat from the outside air into the house, 3 to 4 units for each unit of electricity. Cold air still holds heat; the pump squeezes it out.
Move the control to change how clean the grid is that charges the car. The petrol car makes about 170 grams a kilometre; the electric car uses 0.18 units of electricity a kilometre.
Petrol car, per kilometre170 grams
Electric car, per kilometre, on this grid144 grams
A coal-heavy gridA coal-heavy grid: 800 grams of carbon dioxide for each unit of electricity. The electric car makes 144 grams a kilometre, just under the petrol car's 170.
Petrol car, per kilometre170 grams
Electric car, per kilometre, on this grid86 grams
The world averageThe world average: 480 grams of carbon dioxide for each unit of electricity. The electric car makes 86 grams a kilometre, well under the petrol car's 170.
Petrol car, per kilometre170 grams
Electric car, per kilometre, on this grid72 grams
A gas-heavy gridA gas-heavy grid: 400 grams of carbon dioxide for each unit of electricity. The electric car makes 72 grams a kilometre, well under the petrol car's 170.
Petrol car, per kilometre170 grams
Electric car, per kilometre, on this grid36 grams
Britain in 2023Britain in 2023: 200 grams of carbon dioxide for each unit of electricity. The electric car makes 36 grams a kilometre, well under the petrol car's 170.
Petrol car, per kilometre170 grams
Electric car, per kilometre, on this grid9 grams
FranceFrance: 50 grams of carbon dioxide for each unit of electricity. The electric car makes 9 grams a kilometre, well under the petrol car's 170.
On which of these grids does the electric car make less carbon dioxide than the petrol one?
On every one of them, though only just on the coal-heavy grid.
Right. Even on coal the motor's efficiency wins, narrowly: 144 grams against 170. Making the battery adds a lump at the start, paid back within one to two years of driving on an average grid. From then on the car gets cleaner every time the grid does.
Only in France.
Not yet. France's near-zero grid makes the gap enormous, 9 against 170. But the gap exists on every grid here, because a motor wastes so much less than an engine.
Only on grids cleaner than the world average.
Not yet. The coal-heavy grid gives 144 grams against petrol's 170. It is close, but the electric car is still under. Cleaner grids widen the gap; they do not create it.
Move the control.
Which of these can run on electricity today, and which still needs a fuel for now?
One card at a time. Tap the pile it belongs to.
Card 1 of 6
A family car
A home's heating
A long-haul plane
A cargo ship crossing the Pacific
A furnace melting scrap steel
Making steel from iron ore
A family car → Electricity today
Not yet. A car can run on electricity today. An electric motor and a battery do the job, and millions already do.
A home's heating → Electricity today
Not yet. Home heating can run on electricity today. A heat pump warms a house with no flame at all.
A long-haul plane → Still needs a fuel
Not yet. A long-haul plane still needs a fuel. A battery for a twelve-hour flight would weigh more than the plane.
A cargo ship crossing the Pacific → Still needs a fuel
Not yet. A ship crossing the Pacific still needs a fuel. Weeks at sea need more energy than any battery can carry.
A furnace melting scrap steel → Electricity today
Not yet. Melting scrap can run on electricity today. An electric arc furnace melts old steel with no coal.
Making steel from iron ore → Still needs a fuel
Not yet. Steel from ore still needs a fuel. Something has to pull the oxygen off the iron, and today that something is coal.
Has a motor or a heat pumpelectricity today
vsvs
Planes, ships, iron orestill a fuel
Planes, ships and iron ore are the next lesson.Right. Motors and heat pumps cover most of what happens on land. Planes and ships need something light that holds a lot of energy; a battery for a long flight would weigh more than the plane. Iron ore needs a chemical to pull the oxygen off it, and today that chemical is coal.
Electricity before20 units
Fuel for cars and heating, before50 units
The same cars and heating on electricity20 units
A country uses 100 units of energy, 20 of them as electricity. It moves cars and heating onto electricity. Because motors and heat pumps waste less, the 50 units those used become 20. How much electricity does it need now?
units
The old 20, plus what the cars and heating now need.
Right. Forty: double the electricity. And the country's total energy use fell from 100 to 70, because so much of a fuel's energy was leaving as waste heat. Electrifying uses more electricity and less energy.
Electricity's share of the energy people use, 202320%
In most plans for 205050%
So the grid has to roughly double in most plans, while every coal and gas station on it is replaced. Britain built its grid over a century. The plan asks for a second one in a few decades, plus wires to wind farms at sea and every home's charger. The panels are cheap. The wires and the pace are not.
Of the new cars sold in the world in 2023, about what share were electric or plug-in?
Pick one. Nothing is scored.
Norway93%
China38%
The world18%
United States10%
Share of new cars sold in 2023 that were electric or plug-in.
About 18 in 100.The world number hides two different worlds. China alone was about 60 in 100 of those sales, and more than a third of its own new cars. Norway was over 90. The United States was about 10. The shift is nearly complete in some places and barely started in others.
A city switched its buses to electric in 2015, when its grid was mostly gas. Every year since, the buses' carbon dioxide per kilometre has fallen, and nobody has touched the buses. Why?
Batteries improve as they age.
Not yet. Batteries lose a little capacity as they age; they do not get cleaner. The improvement is upstream, in what makes the electricity that fills them.
The grid got cleaner, and the buses run on the grid.
Right. A diesel bus is as dirty in its tenth year as in its first. An electric bus inherits every improvement made to the grid behind it, without anyone touching the bus.
Electric buses use less energy each year.
Not yet. A bus uses about the same energy per kilometre every year. What changed is how much carbon dioxide was made for each unit of that energy, and that is the grid's number, not the bus's.
Lesson complete
Turn a burning job into an electric job, and it gets cleaner every time the grid does.