Electrification is efficiency: The world will need less energy after the transition
Electrification means that final energy demand falls, without changing the value that we get from energy services.
When we electrify our energy systems, a magical thing happens: large inefficiencies vanish. As the International Energy Agency puts it: “Electrification is efficiency”.
This is shown in the chart below. It plots global final energy demand today2 compared to a ‘post-transition’ energy system where suitable sectors are electrified, and the rest is fuelled by hydrogen.
Electricity demand does increase – from 110 to 189 EJ, but total energy demand drops from 416 to 247 exajoules (EJ).
This is a fairly simplistic model of the global energy transition, but I think it’s a valuable one. I worked through Nick’s numbers to see what’s going on and will take you through them below.
A few assumptions to start:
It doesn’t assume any efficiency gains other than electrification or a move to hydrogen. This is likely to underestimate the reduction in energy demand.
It’s a comparison of energy use today: it doesn’t account for energy growth as countries develop. This shouldn’t really affect the ratio between the two scenarios; only the final numbers.
All non-electrified sectors will be powered by hydrogen. I’m sure some would disagree and suggest that a few sub-sectors will eventually be electrified, or other alternatives – such as biofuels for aviation – should be used instead. This won’t change the overall conclusion, so feel free to imagine that some of these sub-sectors are powered by non-hydrogen alternatives.
Prospects for electrification vary across sectors
Cars are easy to electrify, high-temperature industrial processes aren’t.
The current and post-transition energy demand by sector is shown in the chart below. Energy demand for transport and buildings drop significantly – we can electrify a lot of road transport, and swap our gas boilers for electric heat pumps.
There are fewer opportunities for industry. Some industrial processes such as space heating can be electrified, but high-temperature industrial processes can’t.
We can also break this down by the mix of fuel and electricity in each sector.
You can see that pre-transition, fuels (burning fossil fuels directly) dominate. Electricity only accounts for one-quarter of the final energy demand.
In the post-transition system, electricity supplies three-quarters. The rest is assumed to be supplied by hydrogen, in sub-sectors that can’t be electrified at the moment.
I’ll now go through each of these sectors in more detail.
Electric vehicles are around four times as efficient as petrol. In a petrol car, only 20% of the energy is converted to motion. In electric cars, this is around 80% (with some variation dependent on regenerative braking). I wrote about this extensively in a previous article.
As you can see in the chart below, the post-transition energy demand for cars and vans is about one-quarter of the current demand.
For heavy-goods vehicles (HGVs), it’s assumed that around half of the distance travelled can be electrified. The other half comes from hydrogen fuel cell electric vehicles.
Buses are 80% electrified, with only long-distance buses powered by hydrogen.
Rail is fully electrified.
Short-haul aviation is electrified, but medium- and long-haul requires hydrogen. So, only one-third is electrified.
Only 10% of marine transport is electrified – this is short-distance trips, such as ferries.
Buildings are nearly completely electrified, and achieve massive efficiency gains.
The biggest user of energy in buildings in temperate climates is space heating. There are large efficiency gains from moving to electric heat pumps.
Nick Eyre suggests that 100% substitution is non-economic during large demand peaks in winter, so 90% are replaced with heat pumps, and 10% comes from hydrogen.
Water heating is entirely replaced by electric heat pumps.
Cooking is completely electrified. The big reduction in energy demand here is partly caused by a transition away from ‘traditional biomass’ in lower-income countries.
Lighting is already electrified, so there’s little change there.
Industrial energy is harder to tackle.
Some high-temperature processes are moved to hydrogen. Most efficiency gains happen from the steel industry: around 25% of the sector is powered by electric arc furnaces. It’s assumed that this increases to 50% (the current mix in OECD countries).
Low-temperature processes are reliant on steam. It’s assumed that fossil fuels are replaced with electric boilers, which are around 20% more efficient.
Drying and separation processes below 120℃ can be converted to heat pumps using existing technologies.
Space heating can also be transitioned to electric heat pumps.
Energy demand could fall even more through other efficiency measures
This simple thought experiment shows that electrifying our energy system as much as possible will lead to large reductions in final energy demand. Around 40%.
But this underestimates the potential energy savings for two reasons.
The first is that it is based on final, not primary energy. Primary energy also includes heat that is wasted in producing electricity in the first place: only around one-third of raw coal energy, and half of gas energy is converted to electricity. Eyre estimates that around 70% of primary energy is converted to final energy.3 If we were to move away from coal and gas for electricity, the energy savings would be even larger.
The second is that it assumes no other efficiency measures are taken. But we know that there are lots of options there – a number of which could improve human wellbeing, cut bills, and reduce energy demand at the same time. Improved insulation is a good example.
Combine some of these measures with electrification, and energy demand could fall a lot. This is a point that has been made many times before.
For a deep dive into different ways of measuring energy, and why electrification reduces demand, see the report “Beyond Primary Energy: The energy transition needs a new lens” by Kevin Pahud and colleagues.
“Electrification is efficiency”. Let’s rebuild our energy systems to take advantage of that.
Eyre, N. (2021). From using heat to using work: reconceptualising the zero carbon energy transition. Energy Efficiency, 14(7), 77.
Actually, it's based on global final energy demand in 2020.
An additional note on the difference between primary and final energy demand.
You might be wondering – like I was – where the electricity that's needed to produce hydrogen is included. Nick Eyre estimates that hydrogen production would need around 72 EJ of electricity.
This 72 EJ is not final energy demand: it's primary (or secondary) demand – I explain the difference here. This cannot be added to the final energy stack, because it would be double-counting the 52 EJ of hydrogen.
So, it is included in these balances, just further upstream.