Have we been duped by the primary energy fallacy?
Whenever I post something on renewable energy on social media it never takes long for negative comments to arrive in my feed. One type of comment I get frequently is from people who share a chart showing global primary energy demand over the last 200 years. They say “Look at the vast amount of fossil fuels we use. We will never be able to replace them with renewable energy, look how tiny their contribution is.” The suggestion is that we will need to replace all of that primary energy with renewable energy and that it would be impossible to do. Because of that we should just accept that we need fossil fuels forever.
I tend to differ. Here’s why:
Simply put, we don’t need to replace all of the energy inputs into the energy system as long as can deliver the same services more efficiently. The commentators showing primary consumption graphs have fallen for the primary energy fallacy, a term coined by Paul Martin. This fallacy arises when comparing energy sources based on their primary energy consumption, often overlooking fundamental differences in efficiency and utility.
What is the primary energy fallacy?
Primary energy refers to the total energy content of natural resources before any conversion processes, such as coal, oil, or renewable electricity. The fallacy occurs when people equate high primary energy inputs with energy services. Measuring energy systems purely on primary energy inflates the perceived contribution of fossil fuels while underestimating renewables’ efficiency and untapped efficiency potentials through electrification.
The Sankey diagramme below shows the UK energy system. All of the energy on the left hand side is paid for, as Rick Wheatley from consulting firm S7 points out. But consumers are only interested in the energy service they get (dark grey box in bottom right corner). What this Sankey diagram shows very nicely is the huge amount of waste heat produced by the current energy system (rejected energy in light grey box in top right corner).
Why do we waste more than 2/3 of the energy inputs you may ask? One reason is to do with the technologies we use: In conventional fossil fuel systems, significant amounts of primary energy are lost as waste heat during combustion. For example, a coal fired power station only converts 40% or so of the coal burned into electricity. By contrast, renewable systems like wind and solar produce electricity directly.
The second reason is that historically fossil fuels have been cheap whereas renewables have been more expensive, although that has fundamentally changed. Infrastructure developed that delivered the energy services people wanted without having to pay too much attention to the efficiency of the system. During energy crisis these inefficiencies come back and bite us, most evident during the recent spikes in fossil fuel prices experienced in 2022.
Comparing apples with apples
It is sometimes argued that also the solar and wind energy that is not captured by renewables should also be counted towards primary energy inputs. But that approach is not how energy statistics are typically produced. For electricity derived from non-combustible sources, the International Energy Agency (IEA), following the guidelines of the International Recommendations for Energy Statistics (IRES), employs the “physical content method.” This method ensures a consistent approach across all such energy sources. The primary energy equivalent is determined at the first point in the production chain where multiple energy uses are feasible.
In practice, this means that for sources like hydropower, wind, and solar, the primary energy is quantified as the amount of electricity produced at the generation stage. The kinetic energy of moving water or wind, while scientifically a form of energy, is not included in the “energy balance” statistics. Instead, only the electricity output is treated as an energy product in these calculations. This distinction aligns the statistical treatment of non-combustible energy sources with their practical energy contributions.
Also, to be consistent with the proposal of counting all the solar and wind energy not converted by renewable energy technologies one would need to apply the same approach to fossil fuels: only up to 6% of solar energy is converted into biomass which in turn is converted into fossil fuels.
Electrification and efficiency
On the energy demand side the primary energy fallacy fails to recognise the inefficiency of existing technologies and the potential for dramatic improvements. Electrification of energy uses currently served by combusting fossil fuels is often significantly more efficient offering the same energy service for less energy input. Take electric cars for example — they are about 3x more efficiency than internal combustion engine vehicles. Or heat pumps which can provide the same amount of heat by using electricity to harvest pre-existing ambient or waste heat but with 3–5x less energy input than a fossil fuel boiler.
Prof Nick Eyre at Oxford University has run a fascinating thought experiment: What if the world was to electrify industry, buildings and transport to the full potential? The results are presented in the graph below which Hannah Richie developed based on the research carried out by Prof Nick Eyre. What the analysis shows is that just by electrification alone the world would use 40% less final energy, a huge efficiency improvement.
So if the primary energy fallacy is so obviously misleading why are people falling for it and where does it come from?
The roots of the fallacy
Historically, primary energy metrics were developed in the context of fossil fuels, where the focus was on extraction, combustion, and thermal efficiency. As renewable energy technologies matured, this outdated approach persisted in energy accounting frameworks. In the European Union, the reliance on primary energy metrics has led to flawed renewable energy metrics and hindered electrification efforts in sectors like heating and transport as analysis by the Regulatory Assistance Project (RAP) has shown.
The primary energy fallacy also gets perpetuated because it suits those who are critical of the energy transition. For the uninformed, the argument that we cannot possibly replace the vast amount of fossil fuel we currently use with clean energy seems compelling at first glance. The good news is that we don’t have to.
Implications for energy policy
The primary energy fallacy has practical consequences. Policies designed to reduce primary energy consumption may inadvertently discourage investments in renewables or electrification technologies. Energy efficiency is a good example: Many energy efficiency policies have been based on primary energy savings targets and incentivised technologies that reduce primary energy consumption. But in the worst case scenario such policies can lock in marginally more efficiency fossil fuel infrastructure at a time when the world needs to speed up electrification and the direct use of renewable energy. That’s why Prof Nick Eyre and I have written a paper on how to reform energy efficiency policy to move away from this approach.
The way forward
The primary energy fallacy represents a critical hurdle in the energy transition, perpetuating outdated paradigms that favour fossil fuels. Addressing this fallacy requires a shift in both mindset and policy tools, ensuring that energy metrics reflect efficiency, sustainability, and carbon reduction. By embracing these changes, energy systems can align more effectively with the demands of a zero-carbon future.
In the future, we need to move away from primary energy-based assessments towards metrics that prioritise system efficiency and emissions reductions. By focusing on the carbon intensity of energy systems and the actual energy delivered to end-users, policymakers can better align their goals with the realities of a renewable-powered future.
