Over the past month, I’ve seen a familiar argument making the rounds again: biofuels, in this case, sustainable aviation fuel (SAF), simply cannot scale to meet global aviation demand, therefore electrification must be the answer, or at least the more realistic path forward. The media has picked up the story and run with it as well.
On its face, this argument looks data-driven and sensible. Aviation uses a lot of energy. SAF makes up only a tiny share of that today. The math does not seem to work. Right? This framing keeps resurfacing for a reason, and it is not because the data are wrong per se. It is because something important is missing from the comparison. The system itself.
Most of these comparisons rely on a narrow slice of reality. They take today’s SAF production, compare it to today’s aviation fuel demand, and conclude that the gap is too large to bridge. The arithmetic is correct. The conclusion is not.
The first problem is that this kind of comparison quietly assumes today’s production levels represent something close to a physical limit. They do not. They reflect policy choices and design, investment decisions, infrastructure availability, and risk tolerance. Biofuel and SAF production did not grow slowly because it could not grow faster. It grew slowly largely because policy designs were flawed, incentives were uneven, capital was cautious and markets were uncertain. Treating the current state as a ceiling rather than a snapshot leads to the same predictable conclusions.
At the same time, it treats electricity as if it were infinitely scalable. The electricity side of the ledger is often reduced to generation capacity alone. If we can build enough wind and solar, the thinking goes, the rest will follow. That assumption deserves a lot more scrutiny than it gets.
Electricity is not just energy production. It is an interconnected system that has to be built, permitted, supplied and balanced in real time. Every additional unit of electricity requires upstream materials, manufacturing capacity, grid infrastructure and regulatory approvals that can take years. None of those pieces are trivial, and many of them are already very strained.
Start with materials. Electrification at scale requires enormous quantities of copper, aluminum, lithium, nickel, cobalt and rare earth elements, as shown in the chart below.
The International Energy Agency (IEA) estimates that a clean energy transition could quadruple mineral demand by 2040, with demand for some materials growing even faster. These materials do not appear on demand. They require mining, processing and refining, often concentrated in a small number of countries. Supply chains for critical minerals are already tight, and permitting new mines routinely takes a decade or more.
Then there is the grid itself. In the U.S., the interconnection queue for new generation projects has become one of the most serious bottlenecks in the energy system. As of 2023, thousands of gigawatts of proposed generation and storage projects were waiting in line to connect to the grid, often facing delays measured in years (up to 7 in some cases!) rather than months. Similar challenges exist in Europe and elsewhere.
Even when generation is available, electricity still has to move. Transmission expansion has lagged demand for decades. New high-voltage lines face siting challenges, local opposition and complex regulatory processes. Transformers and substations are not interchangeable commodities. They are custom-built, long-lead items and global shortages have pushed delivery timelines out by several years in some cases.
All of this matters because electrification pathways are often presented as if they avoid the constraints that plague liquid fuels. In reality, they simply face a different set of constraints, many of which are less visible but no less difficult. This is where the comparison with biofuels breaks down.
Liquid fuels benefit from energy density, storage and existing logistics. They can be produced in one place and used in another. They can be stockpiled. They do not require real-time balancing between supply and demand in the way that electricity does. Aviation in particular depends on these attributes. That is not a political preference. It is a physical reality.
None of this means biofuels are easy. They are not. Feedstock availability, land use, lifecycle emissions, and cost all matter. Some SAF pathways perform better than others on these kinds of metrics.
The point is not that SAF is the single answer. It’s that dismissing fuel-based pathways based on a static snapshot misunderstands how energy systems actually operate and evolve. When the system is left out of the comparison, the result is not any real insight, but an oversimplified view of what can realistically be built, supplied and integrated over time.
And that’s not a good outcome for anyone.
