The efficiency gains of electrification can reduce energy demand by up to 40%, says data scientist and science communicator Hannah Ritchie, citing a journal paper that examines the shift from heat-producing fossil fuels to work-producing renewables.
“When we electrify our energy systems, a magical thing happens: large inefficiencies vanish,” Ritchie writes in a post for her Sustainability By Numbers site. “In a decarbonized world, our final energy demand is much lower than it is today.”
It will be about 40% lower, found Oxford University professor Nick Eyre in a 2021 study—From using heat to using work: reconceptualising the zero carbon energy transition. In fact, Ritchie writes, since “electrification is efficiency,” as the International Energy Agency says, “let’s rebuild our energy systems to take advantage of that.”
Eyre’s abstract stresses that the energy transition will be more than just a shift away from carbonaceous fuels: it is more usefully thought of as including “a systemic shift from heat-producing to work-producing energy sources.”
The most rapidly expanding renewables are solar photovoltaics and wind, which produce electricity directly instead of first producing heat to generate electricity, so energy demand drops significantly. This enables very large improvements in “the conversion efficiency of final energy,” Eyre writes, especially through the use of electricity and hydrogen for heating and transportation.
With this logic at the crux of his “thought experiment,” Eyre plots global energy demand today compared to a post-energy-transition system, where suitable sectors are electrified and hydrogen fuels the rest. Electricity demand does increase, from 110 to 189 exajoules, but total energy demand drops from 416 to 247 exajoules.
“This is a fairly simplistic model of the global energy transition, but I think it’s a valuable one,” Ritchie says. And in reality, Eyre’s model may underestimate the total demand reduction, since it doesn’t assume any other efficiency gains besides electrification and a shift to hydrogen. (For instance, home retrofits for better insulation.)
And though it is a comparison of current energy, not future energy growth, “this shouldn’t really affect the ratio between the two scenarios—only the final numbers.”
By Eyre’s model, electrification boosts energy efficiency in transportation, with electric vehicles delivering substantial demand reductions because they are four times as efficient as fossil fuel-burning cars that convert only 20% of energy into motion. Projected energy demand for cars and vans is thus only around one-quarter of what it was in 2021.
Electrifying buildings also achieves “massive efficiency gains.” In temperate climates, the biggest energy use in buildings is space heating, so replacing current heating sources with 90% heat pumps and 10% hydrogen can cut demand from 43.8 to 12.4 exajoules per year.
The savings will be less dramatic for high-temperature industrial processes, but electrification will still reduce demand to a degree.
Ritchie points out that there may be further gains than Eyre’s model indicates, since it focuses on final energy without factoring efficiencies in primary energy—where heat is wasted when electricity is produced 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, Ritchie notes. “If we were to move away from coal and gas for electricity, the energy savings would be even larger.”
Other researchers grappling with the “lens” through which we view the energy transition say the very concept of primary energy is “outdated.” This past summer, in the paper Beyond Primary Energy [pdf], researchers noted that the energy transition is “fundamentally the transformation of an energy system based largely on the combustion of fossil fuels to a system more dependent on electricity produced by non-combustion methods.”
Primary energy is an important metric in a fossil-fuel based system, but does not accurately represent the emerging new system, they write. “It uses as a reference precisely what we are trying to move away from.”
The term “useful energy” gives a much more accurate view of the energy transition, they add. “Given that two-thirds of the current primary energy is lost at waste, the use of this indicator gives the false impression that the current system needs to be matched one to one, which is incorrect.”