Op-ed views and opinions expressed are solely those of the author.

Though touted as next-generation energy sources, solar and wind technologies have been shoe-horned into electricity grids only through government fiat and subsidies. Their failure to be adopted freely by investors and consumers lies in the pathetic energy density of solar panels and wind turbines. Energy density is defined as the amount of energy stored in a given unit of mass or volume — a metric that is critical in determining the viability of energy sources. It is typically measured in joules per kilogram (J/kg) for mass, or joules per cubic meter (J/m³) for volume. Often, the expression is in millions of joules, or megajoules (MJ).

Wood, which was widely used before the introduction of coal, has an energy density of just 16 MJ/kg. Society’s ready adoption of fossil fuels stems from their significantly higher concentrations of energy: Coal is approximately 24 MJ/kg; oil, 45 MJ/kg; and natural gas, 55 MJ/kg. In an entirely different league, nuclear fuel, depending on the type, has an energy density of about 4 million MJ/kg and will certainly be used extensively as society progresses throughout the 21st century and into the next.

The lithium-ion battery is considered important to compensating for the appallingly poor reliability of wind and solar. However, most commercial-scale batteries have an energy density of less than 1 MJ/kg, orders of magnitude less than wood.

Hydrogen, a supposedly futuristic fuel, has just a third of wood’s energy density.

As one would expect, solar and wind fall short in comparisons of power density, which is a measure of how much energy is produced. In terms of land use, solar and wind put out 5-20 and 2-3 watts per square meter of land area where a natural gas power plant generates 1,000 watts.

The superior potency of fossil fuels enabled a quantum leap in human productivity, fundamentally altering the trajectory of civilization. This characteristic allowed for the creation of compact, portable, and highly efficient energy systems powering everything from small engines to massive manufacturing complexes. Industrial processes requiring intense heat or large amounts of power in a short time could be accommodated.

Transportation, manufacturing, agriculture — virtually every aspect of modern life — were transformed. Cities grew larger and more complex, global trade expanded exponentially, and technological innovation accelerated at an unprecedented pace. Ultimately, the ability to generate large amounts of electricity on demand, coupled with the development of extensive distribution networks, brought power to billions of people, dramatically improving living standards across the globe.

Fossil fuels have been particularly crucial for energy-intensive industries such as steel and cement production. These sectors require not only large amounts of heat but also specific chemical properties that fossil fuels provide. 

Energy and power density don’t tell the whole story. Relative abundance and ease of extraction and processing are important factors that make fossil fuels preferable to other sources. 

Another is the capacity factor of a power plant, or the ratio of its actual output to its potential output if it were to operate continuously at full nameplate capacity. Coal-fired plants approach 50% capacity factor, and natural gas combined-cycle plants exceed 55%. Nuclear plants achieve an astounding 93% average capacity factor.

However, the capacity factors for wind and solar are less than 35% and 25%, respectively, due to their dependence on weather conditions and the amount of sunlight. This means wind and solar are not able to be turned on anytime their energy is needed. Nor are they able to adjust output quickly to changes in demand.  In other words, they produce energy when resources are available rather than when they are needed. 

Fossil fuels are vital, not just for enabling developing countries to scale up rapidly, but also for rich nations that need to sustain economic growth and continue to provide energy at an affordable price to industries and homes. Even Tesla’s Elon Musk uses an oil-derived fuel — rocket-grade kerosene — for the SpaceX Falcon rocket.

Calls to abandon coal, oil and natural gas would have society regress by hundreds of years when it is human nature to move forward — even upward toward other worlds. It simply is not in our DNA to yield to such nonsense.

Vijay Jayaraj is a Research Associate at the CO2 Coalition, Arlington, Virginia. He holds a master’s degree in environmental sciences from the University of East Anglia, U.K.

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Vijay Jayaraj

Vijay Jayaraj is a research associate at the CO2 Coalition, Arlington, Va., and holds a master's degree in environmental sciences from the University of East Anglia, U.K.He resides in Bengaluru, India.

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