The world contains abundant energy resources. The challenge is extracting and utilizing these resources affordably, in an environmentally responsible way, and in a dense enough form to be useful to humans. The link between energy, the environment, and the economy is unavoidable and involves the geosciences at its core.

Carbon-based fuels such as wood, hay, and coal powered human society for millennia. Then, in the early twentieth century, petroleum in various refined forms came into use for lighting, heating, and early combustion engines. Today, fossil fuels—coal, petroleum products, and natural gas—represent an important 85% of the global energy mix, but they are not without challenges. Coal's greatest challenges are environmental: the impact of surface mining; water contamination; discharge of airborne pollutants including sulfur, nitrogen, and mercury; and the emission of CO₂. The emerging technologies of carbon capture and sequestration may offer the prospect (such as coal-fired of solving one of coal's problems; large, stationary sources of CO₂ power plants) are the most efficient targets for carbon capture. However, capturing CO₂ is expensive. Oil and, to a much lesser degree, natural gas also produce CO₂ and other emissions when combusted. Oil and natural gas require drilling, entailing the associated environmental impacts of oil-field operations; yet there remain considerable global oil and natural gas resources. The current frontiers for conventional oil and natural gas production include ultra-deep water, the Arctic, sediments deposited beneath major salt formations, and other extreme operational environments. As existing and new conventional oil and natural gas reserves decline, unconventional reservoirs—shale gas, coal bed natural gas, tight gas, shale oil, oil shale, oil sands, and perhaps eventually natural gas hydrates—will represent a growing part of the fossil-fuel mix.

Nuclear energy—today fission, and tomorrow, perhaps, fusion—is very dense, has no emissions, is highly efficient, and is very affordable on a kilowatt-hour basis. Adoption of nuclear energy is limited by the high initial cost of building a power plant, public perception, issues of waste handling, the fear of proliferation, and the very real need to make reactors safe from natural and human-caused disasters.

“Renewable” forms of energy—those that are generated by “renewable” motion such as wind and moving water; or “renewable” sources of heat such as geothermal and solar; or those that are grown such as biofuels—will increase as a proportion of the energy mix. These sources are currently limited in growth rate by their lower energy density and, for some, their intermittency. Intermittency—the wind does not always blow and the sun does not always shine—must be addressed by significant improvements in energy storage technologies: in chemical batteries; as pumped water or compressed air; as heat stored in molten salt, buildings, and other forms; as kinetic energy in flywheels; as electrons in advanced capacitors; or by various other technologies. But these energy storage technologies need to be made efficient, affordable, and scalable before they will be deployed broadly.

Because the transition from a fossil-energy present to an alternate-energy future involves the interplay between energy, environment, economy, and policy, almost without exception all forms of energy involve the geosciences. Coal mining requires geologic understanding. Large-scale geologic carbon sequestration, which might someday make coal more environmentally friendly, will rely on a whole new discipline involving advanced subsurface characterization and monitoring. The subsurface understanding and technology required for conventional and unconventional oil and gas exploration and extraction are substantial. From the scale of nanopores to tectonic plates, the use of advanced seismic imaging, ever more-quantified field and laboratory experimentation, airborne remote sensing, and much more is required to unlock the fossil-fuel resources that remain trapped in the Earth.

Nuclear energy relies on sources of uranium, plutonium, thorium, and many other mined products. And eventually, geologic repositories will be required to store the waste products of nuclear power generation.

In terms of renewable energy, production of biofuels involves soil science, hydrogeology, fertilizers, weather, and climate. Harnessing geothermal energy involves the ability to characterize the subsurface geothermal resource. Generating power from tides and waves involves oceanography and analysis of coastal change. Utilizing wind depends on weather pattern studies and geomorphology for the siting of turbines, as well as the mining of copper, carbon, and other materials. Producing solar energy involves the geosciences, with the need for silicon, gallium, cadmium, copper, and other materials. As large-scale energy-storage solutions become necessary, input from the geosciences will range from characterizing the subsurface for compressed-air storage to mining rare-earth elements for chemical batteries.

The involvement of geosciences in energy does not stop with subsurface understanding or the construction of a power plant. “Above-ground” environmental and policy challenges covering the full lifecycle of any form of energy are as great as the “below-ground” technical challenges. Environmental geologists, biologists, energy economists, and policymakers must come together to develop sensible policies and regulatory rules that make it possible for industry, government, academe, and nongovernmental organizations (NGOs) to work together to deliver balanced solutions.