Energy in the Western Regions

The primary energy resources in the contiguous Western states come from renewable sources, such as solar, wind, and hydroelectric power. California is the exception to this rule, with 54% of its energy production stemming from fossil fuels, and 15% from nuclear power.

Alaska’s energy production relies solely on fossil fuels, and Hawai’i’s solely on renewables.

Fossil Fuels

Fossil fuels—oil, natural gas, and coal—are made of the preserved organic remains of ancient organisms. Petroleum typically forms from the remains of aquatic life, primarily one-celled photosynthetic organisms, which can accumulate in sediments. Coal forms primarily from the accumulation of land plants. In either case, organic matter is only preserved when the rate of accumulation is higher than the rate the rate of decay. This happens most often when the oxygen supply is sufficiently low enough that oxygen- loving bacteria cannot thrive, greatly slowing breakdown of organic matter. In this way, the organic matter can be incorporated into the buried sediment. The organics are compacted and heated with the rest of the rock, eventually transforming into fossil fuels.

The history of surface environments, evolution of life, and geologic processes beneath the surface have all influenced where fossil fuel deposits formed and accumulated. The largest oil and gas reserves were at one time nutrient-rich seas with abundant surface phytoplankton and organic- rich bottom sediments; the largest coal beds were swampy environments where fallen forest trees and leaves were buried in stagnant muds.