by Joseph Powell

Since coal powered the Industrial Revolution (circa 1850), humans have relied on burning fossil fuels to meet energy demands, releasing ancient carbon into the atmosphere as carbon dioxide (CO₂) (Figure 1). The progression of energy sources—from coal to oil and then to natural gas—was driven by the need for lower-cost, more efficient fuels to meet the evolving demands of transportation, power generation, and other applications. Key to their success was their high energy density and widespread availability, far surpassing the energy potential of traditional biomass that sustained humans for 2 to 6 million years (Figure 2).

Fossil fuels have transformed human life. Before the Industrial Revolution, most people lived in subsistence economies, spending their days growing or harvesting food, gathering wood or other biomass for fuel, and using basic tools to make clothing and build shelter. Today, thanks to advanced machinery powered by high-energy-density fossil fuels, less than 1% of the population in developed countries is needed to produce food for all. Modern energy systems allow us to heat and cool our homes, travel the world, and access information remotely—made possible by materials, plastics, and technologies derived from fossil hydrocarbons.

However, this dependence on fossil fuels comes with a significant cost: the environmental impact of carbon dioxide emissions from combustion. Addressing this challenge requires reimagining our energy systems to either capture carbon dioxide emissions or transition to alternative, non-fossil energy sources. This is the grand challenge of today’s energy transition.

Around the globe, individuals and institutions are working to create a sustainable energy future for all.

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Figure 1: Historical Global Energy Consumption 

The Industrial Revolution was launched in 1850 by the addition of coal as a high-energy-density source of energy, after 2 to 6 million years of human reliance on biomass as the primary energy source. Currently, 80% of global energy still relies on high-energy-density fossil fuels, which can be readily transported and stored. Recent progress has been made in transitioning to renewable but variable energy sources such as wind and solar.

Source: Adapted from OurWorldInData.org/energy, with original data from Vaclav Smil (2010) and BP Statistical Review of World Energy

• V. Smil, Energy Transitions: History, Requirements, Prospects, Praeger, Santa Barbara, Calif., 2010.

Figure 2: Energy Density of Fuels and Energy Vectors (MJ/kg, MJ/Liter)

Including weight of tank for on-board vehicle storage.  
Sources: Afdc.energy.gov; EIA.gov;  Energy.gov/EERE.  

Note: First-generation ethanol and biodiesel have high energy density but compete with food supplies and are limited in availability. Advanced biofuels derived from non-food biomass crops are more abundant but incur high production costs and can only sustainably supply approximately 20% of future global energy demand.