Renewable energy sources provided 17% of U.S. electricity generation in 2017. Most of this was in the form of hydro and wind power.

The U.S. Energy Information Administration (EIA) estimates that, in 2015, around 12% of world marketed (bought and sold) energy consumption came from renewable sources (biomass, geothermal, hydropower, solar, and wind).^[1] EIA projections suggest that this will increase to 17% by 2040.

Frac sand is a type of sand with small, uniform particles. It is injected into the rock formation along with the water used to fracture the rock in the process known as hydraulic fracturing ("fracking"). The sand is used to prop open the fractures that are created. Because the particles are uniform, fluids like water, oil, and gas are able to flow through the spaces between the particles.

U.S. Geological Survey FAQs:

"To date, roughly 700 million metric tons of copper have been produced around the world. This would fit into a cube measuring about 430 meters on a side.

Water flowing through active or abandoned mine sites can become polluted by the material being mined^[1]. By far the most common mine drainage problem is that of acid mine drainage (AMD). Sulfuric acid is produced when water interacts with sulfur-bearing materials in the presence of oxygen and common bacteria^[1].

U.S. Geological Survey FAQs:

"To maintain our standard of living, each person in the United States requires over 38,449 pounds of minerals each year:

U.S. Geological Survey news release, "Critical Minerals of the United States":

U.S. Geological Survey news release "Going Critical"

From the U.S. Geological Survey news release "Going Critical":

"Although currently no U.S. Government-wide definition exists, broadly speaking, if a vital sector of the economy requires a mineral in order to function, that mineral would likely be deemed “critical".

Energy Information Administration's "Energy Explained" series:

"Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles and is easily broken into thin, parallel layers. Black shale contains organic material that can generate oil and natural gas and trap the generated oil and natural gas within its pores.