Solar Panels Don't Smelt Steel: Why Fossil Fuels and Nuclear Endure

Understanding Energy Transitions: Why Fossil Fuels and Nuclear Endure

By Richard Martin | The Strategic Code

Energy debates often assume that a revolution is just around the corner. Advocates speak as though wind and solar will sweep away coal, oil, gas, and nuclear within a generation. Vaclav Smil’s long study of energy history shows a very different reality. Transitions unfold over decades and centuries, and they are constrained by the physical properties of fuels and technologies. My interpretation, influenced by Smil, is that fossil fuels and nuclear power did not become dominant by chance or politics. They became dominant because they are superior on three decisive measures: density, portability, and flexibility.

Coal, oil, gas, and uranium are extraordinarily dense sources of energy. A kilogram of coal contains about 24 megajoules (MJ), oil about 42 MJ, and natural gas about 55 MJ per kilogram. In practice, uranium used in reactors yields on the order of 500 gigajoules (GJ) per kilogram of fuel, tens of thousands of times more concentrated than fossil fuels. By contrast, a kilogram of dry wood contains only about 15 MJ, and the solar radiation striking one square metre of land averages about 200 watts under good conditions. This compactness translates directly into systemic efficiency. High-density fuels require less land, less material, and less sprawl to produce the same amount of energy.

They are also portable. Oil products such as gasoline, diesel, and kerosene carry around 35–36 MJ per litre, which can be stored in tanks, shipped in bulk carriers of over 2 million barrels (~300,000 tonnes), or piped across continents. Liquefied natural gas (LNG) holds 55 MJ per kilogram and can be cooled and shipped globally. These properties make hydrocarbons and uranium fungible commodities. Wind and solar, in contrast, are tied to the sites where the sun shines and the wind blows, and while electricity can be transmitted, high-voltage direct-current lines typically lose about 3% of power per 1,000 km, and large-scale storage remains costly.

Finally, hydrocarbons are remarkably flexible. They can be burned for heat, refined into liquid fuels, or transformed into plastics and fertilizers. Combustion can be ramped up or down to meet demand, which makes hydrocarbons dispatchable in a way that solar and wind are not. Most important, liquid fuels remain unrivalled for mobility. A 50-litre tank of gasoline holds roughly 1.8 gigajoules of energy, enough to move a car 600–700 km. A Boeing 787 consumes about 5.5 tonnes of kerosene on a 10,000 km flight, equivalent to roughly 230 GJ — the energy content of more than 60,000 kilowatt-hours of electricity. No battery technology comes close to that combination of density and portability.

These characteristics explain why fossil fuels and nuclear became the backbone of modern civilization. Their endurance is not the result of habit but of physical superiority.

The argument that we can simply replace them with renewables misses this deeper truth. Wind turbines typically achieve power densities of 1–2 watts per square metre, while solar photovoltaic farms deliver around 5–20 W/m² under optimal conditions. By comparison, fossil fuel power plants deliver thousands of W/m² and nuclear plants tens of thousands. Hydro and geothermal can be reliable but are limited to specific regions. Nuclear is dense and reliable but politically constrained and slow to build. Batteries and hydrogen are secondary carriers rather than primary sources, and they introduce efficiency losses. The result is that new sources add to the mix but rarely displace the incumbents.

Smil’s work highlights a set of general patterns. New sources tend to layer on top of existing ones. Global coal use, for example, reached about 8 billion tonnes in 2023 — higher in absolute terms than a century ago, even though oil, gas, nuclear, and renewables have since entered the system. Renewables are dispersed and variable, while fossil fuels and nuclear are concentrated and steady. Wind and solar cannot on their own provide baseload power, so they must be paired with dispatchable fuels or with large hydro where geography permits. Efficiency improvements, far from reducing overall consumption, often expand it by lowering costs and creating new applications. This is Jevons’s paradox at work, visible today in the rising demand of data centers, which consumed about 460 terawatt-hours in 2022 (roughly 2% of global electricity) and are projected to exceed 1,000 TWh by 2030 (close to 10%). Most important, electricity itself represents only about 20% of total final energy use worldwide. Transport, heavy industry, and resource extraction remain overwhelmingly fossil-fuelled and are very difficult to electrify.

The shape of the transition, then, is not one of clean replacement. Renewables will continue to grow, especially in electricity, but fossil fuels and nuclear will remain central because no other sources match their systemic advantages. Hydro and geothermal will remain anchors where nature allows. The global energy system will become more diverse, more dispersed, and more complex, but coal, hydrocarbons, and nuclear will continue to provide the foundation.

Smil’s central insight is that energy transitions are not revolutions but evolutions. They unfold over generations, shaped by density, portability, flexibility, and rising demand. Fossil fuels and nuclear endure because they are physically better.

If decarbonization is truly needed, the rational path lies not in attempting to eliminate hydrocarbons and uranium but in managing their consequences. That means extracting and storing carbon at scale and pursuing efficiencies throughout the energy chain, from generation and transmission to industry and end use. These approaches address emissions directly while preserving the compactness, versatility, and mobility of the fuels that built and sustain the modern world.

Until alternatives emerge that can rival the density, portability, and flexibility of fossil fuels and nuclear, they will remain the backbone of civilization. Wind and solar will continue to play supporting roles, but the real levers of decarbonization are carbon management and efficiency.

Summary Table of Key Metrics

References

• Smil, Vaclav. Energy and Civilization: A History. MIT Press, 2017.

• Smil, Vaclav. Power Density: A Key to Understanding Energy Sources and Uses. MIT Press, 2015.

• Smil, Vaclav. Energy Transitions: Global and National Perspectives. Praeger, 2017 (2nd ed.).

• Smil, Vaclav. Prime Movers of Globalization: The History and Impact of Diesel Engines and Gas Turbines. MIT Press, 2010.

About the Author

Richard Martin equips leaders to achieve strategic alignment through nested hierarchical action, harnessing initiative for maximal effectiveness with minimal friction.

www.thestrategiccode.com

© 2025 Richard Martin