Energy density and human DNA will determine the energy future – Watts Up With That?

By Vijay Jayaraj

Despite being touted as next-generation energy sources, solar and wind technologies are only being introduced to the grid through government mandates and subsidies. The reason investors and consumers are reluctant to adopt them is because of the pitiful 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—an important metric in determining the viability of energy sources. It is usually measured in joules per kilogram (J/kg) for mass or joules per cubic meter (J/m³) for volume. Often, the expression is given in million joules or megajoules (MJ).

Wood, which was widely used before coal came along, has an energy density of just 16 MJ/kg. Society’s willingness to accept fossil fuels stems from their significantly higher energy densities: Coal has an energy density of about 24 MJ/kg; oil, 45 MJ/kg; and natural gas, 55 MJ/kg. In a completely different category, nuclear fuels, depending on the type, have an energy density of about 4 million MJ/kg and will undoubtedly be widely used as society progresses through the 21st century.^rank this century and into the next.

Lithium-ion batteries are seen as important to make up for the woefully unreliable nature of wind and solar. However, most commercial-scale batteries have energy densities below 1 MJ/kg, orders of magnitude smaller than wood.

Hydrogen, a fuel that is supposed to be the future, has only one-third the energy density of wood.

As one might expect, solar and wind fall short in terms of power density, which is a measure of the amount of energy produced. In terms of land use, solar and wind generate 5-20 and 2-3 watts per square meter of land, respectively, while a natural gas power plant generates 1,000 watts.

The superior efficiency of fossil fuels has enabled a quantum leap in human productivity that has fundamentally changed the trajectory of civilization. This characteristic allows for the creation of compact, portable, and highly efficient energy systems that power everything from small engines to large manufacturing complexes. Industrial processes that require high temperatures or large amounts of electricity in short periods of time can be accommodated.

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

Fossil fuels are especially important for energy-intensive industries such as steel and cement production. These industries not only need large amounts of heat, but also need the specific chemical properties that fossil fuels provide.

Energy density and capacity 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 factor is the power plant’s capacity factor, or the ratio of actual output to potential output if the plant operated continuously at rated capacity. Coal-fired power plants achieve capacity factors of 50 percent, and natural gas-fired combined-cycle plants exceed 55 percent. Nuclear power plants average a staggering 93 percent capacity factor.

However, capacity factors for wind and solar, which are 35% and 25% less respectively, due to their dependence on weather conditions and the amount of sunlight. This means that wind and solar cannot turn on whenever energy is needed. Nor can they adjust their output quickly to changes in demand. In other words, they generate energy when the resource is available, not when it is needed.

Fossil fuels are vital, not only to helping developing countries expand rapidly, but also to helping wealthy nations sustain economic growth and continue to provide affordable energy to industries and homes. Even Tesla’s Elon Musk uses oil-based fuel—rocket-grade kerosene—for his SpaceX Falcon rocket.

Calls to abandon coal, oil, and natural gas would set society back hundreds of years when human nature was to move forward—even upward to other worlds. Our DNA simply refuses to submit to such nonsense.

This commentary was first published at BizPac Review on July 16, 2024.

Vijay Jayaraj is a research associate at CO2 AllianceArlington, Virginia. He holds a master’s degree in environmental science from the University of East Anglia, UK and a postgraduate degree in energy management from Robert Gordon University, UK.