Clean energy
Why solar and wind became cheap so fast, why electric machines waste far less energy, and where the hard parts of the switch still are.
THE PRICE COLLAPSE
Solar and wind got cheap, fast
According to the IPCC, between 2010 and 2019 the cost of electricity from solar fell by about 85%, from wind by about 55%, and the cost of lithium-ion batteries by about 85%. In many places, new solar and wind are now among the cheapest ways to make electricity at all.
Sunny countries, Iran among them, have some of the best solar resources on Earth: lots of strong sunshine and plenty of open land.
Check yourself
Leila sits on a town council in a sunny region. A colleague wants to rule out solar because a study from 2012 found it too expensive. What should Leila suggest?
- Accept the study, because energy technology costs rarely change much in a decade
- Skip solar, because panels stop working in hot weather
- Redo the numbers with current prices
- Wait a few more years until solar becomes completely free
Show the answer
Redo the numbers with current prices
Right. Solar costs fell by around 85% in the 2010s alone, so a 2012 comparison is badly out of date.
TWO MOVES
Clean the grid, then plug everything in
The main plan in most climate scenarios has two parts. First, make electricity clean with solar, wind, hydro and other low-carbon sources. Second, electrify the things that now burn fuel directly: cars and buses, home heating, and some industry. Each step makes the other more valuable.
An electric bus on a coal-heavy grid is a modest gain. The same bus on a grid that's mostly solar and wind is a big one, and it improves every year the grid gets cleaner.
Petrol car: 7 litres per 100 km
Energy in 1 litre of petrol ≈ 9 kWh
7 × 9 = energy burned per 100 km
Electric car: about 15–20 kWh per 100 kmPetrol car ≈ 63 kWh per 100 km
Electric ≈ 15–20 kWh per 100 km
→ the electric car uses roughly a third to a quarter of the energyMost of a petrol engine's energy leaves as heat through the radiator and exhaust. Electric motors turn most of their energy into motion.
Check yourself
Omid says: 'An electric car charged from a grid that still burns gas has no climate benefit at all, because the emissions just move to the power plant.'
Show the answer
False
False. The emissions do move to the power plant, but an electric car needs far less energy per kilometre, so in most countries its lifetime emissions are already lower. The gap widens as the grid adds more clean power.
HEAT PUMPS
Moving heat instead of making it
A gas heater burns fuel to make heat. A heat pump uses electricity to move heat from outside air or ground into your home, like a fridge working in reverse. Because moving heat is easier than making it, a typical heat pump delivers around 3 units of heat or more for each unit of electricity. It works less well in very cold weather.
A split air conditioner is already a heat pump running one way. Many models can also run in reverse to heat a room in winter.
EFFICIENCY
The cleanest energy is the energy you don't need
Using less energy for the same comfort is often the cheapest climate action of all. Insulating roofs and walls and sealing gaps cuts heating and cooling needs. LED bulbs use roughly 75–80% less electricity than old incandescent bulbs. An efficient fridge or air conditioner can use a fraction of what an old one does.
A well-insulated flat stays cooler on a summer afternoon, so its air conditioner runs less, which also takes pressure off the grid at peak hours.
Check yourself
Which of the three moves is each one?
- Building a wind farm to replace an old oil-fired plant
- Replacing a gas heater with a heat pump
- Insulating the roof of a school
- Putting solar panels on factory roofs
- Switching a city's diesel buses to electric ones
- Swapping old bulbs for LEDs
Show the answer
Clean the supply: Building a wind farm to replace an old oil-fired plant, Putting solar panels on factory roofs
Electrify: Replacing a gas heater with a heat pump, Switching a city's diesel buses to electric ones
Use less: Insulating the roof of a school, Swapping old bulbs for LEDs
The hard parts that remain
- Sun and wind vary. Grids need batteries and other storage, stronger links between regions, and demand that can shift to sunny or windy hours.
- Some industry needs very high heat or uses carbon in the chemistry itself, as in steel and cement.
- Long-distance flying and shipping need dense fuels; batteries are still too heavy for long routes.
- Building grids, mines and factories fast enough, and fairly, is a big job in its own right.
Check yourself
Sina works at an energy ministry and is asked which of these is hardest to run on batteries with today's technology. What should he answer?
- City buses on fixed daily routes
- Heating homes through the winter
- Long-haul passenger flights
- Cooking meals in family kitchens
Show the answer
Long-haul passenger flights
Right. Batteries hold far less energy per kilogram than jet fuel, which matters most when a plane has to lift its own fuel for thousands of kilometres.
Lesson recap
- Solar costs fell about 85% and wind about 55% in the 2010s; batteries fell about 85% too.
- The core plan: clean the grid, electrify what burns fuel directly, and use less energy for the same comfort.
- Electric motors and heat pumps waste far less energy than engines and burners, so electrifying helps even before the grid is fully clean.
- Storage, heavy industry and long-distance flying and shipping remain the hard parts.