Fossil Fuels

VII

World Fossil Fuel Supply

Because the global economy is powered by fossil fuels, it is critical to know how long world reserves will last. However, estimating the world’s remaining fossil fuel reserves requires extensive information, including comprehensive geological maps of the world’s sedimentary basins, models of energy production systems, and data showing world energy consumption patterns and trends.

A

Reserves and Resources

When estimating the world’s fossil fuel supply, experts distinguish between reserves and resources. Reserves are fossil fuel deposits that have already been discovered and are immediately available. Resources are fossil fuel deposits that geologists believe are located in certain sedimentary basins, but have not yet been discovered. Because geologists base fossil fuel resource estimates on the location, extent, and formation of deposits recovered in geologically similar basins, resource estimates are less certain than reserve estimates. Both reserve and resource estimates are revised as data about new and existing deposits become available.

Fossil fuel reserves can be further divided into proved reserves and inferred reserves. Proved reserves are deposits that have been measured, sampled, and evaluated for production quality. Inferred reserves have been discovered but have not been measured or evaluated.

The definition of fossil fuel resources can be narrowed to technically recoverable resources. This definition does not consider whether a deposit can be extracted economically, but only whether the fossil fuel can be recovered using existing technology. By definition, the world fossil fuel supply increases as technological advances are made allowing previously unrecoverable resources to be extracted and processed.

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B

World Energy Data

Worldwide deposits of fossil fuels are finite. Some experts use data on world energy deposits to estimate how many years world energy supplies will last at current and projected consumption rates.

At the beginning of the 21st century, the world reserves of petroleum were estimated to be roughly 1.3 trillion barrels. By 2003 worldwide consumption of petroleum totaled 29 billion barrels a year. The world’s natural gas reserves were estimated to be roughly 170 trillion cubic meters (6,000 trillion cubic feet). Worldwide consumption of natural gas by 2003 totaled 2.7 trillion cubic meters (96 trillion cubic feet) a year. At the beginning of the 21st century the world coal reserves were estimated to be roughly 1 trillion metric tons, and by 2003 worldwide consumption of coal totaled 5 billion metric tons a year. Total worldwide energy consumption is expected to grow at about 2.2 percent per year until 2015.

Theoretical models can be developed to estimate how many years the world fossil fuel supply will last. However, these models are complicated by technological advances in the energy production industry, unexpected discoveries of new fossil fuel deposits, and political, social, and economic factors that influence energy production and consumption.

Because fossil fuels are being consumed at much faster rates than they are produced in the earth’s crust, humankind will eventually deplete these nonrenewable resources. While it is unclear how far in the future this will happen, there is evidence that some regions are becoming depleted in certain types of fossil fuels. For example, production of crude petroleum in the United States peaked in 1970. Today the United States imports significantly higher proportions of its petroleum needs.

C

Alternative Energy Sources

The prospect of reducing the world’s dependence on fossil fuels is problematic. Alternative energy industries, such as nuclear energy, hydroelectric energy, solar energy, wind energy, and geothermal energy exist, but these energy sources currently only account for a combined 14 percent of energy consumed worldwide. To date, alternative energy sources have been hindered by technological and environmental difficulties. For instance, although the uranium that fuels nuclear power is abundant, the risk of nuclear accidents and the difficulty associated with safe disposal of radioactive waste have led to the decline of the nuclear power industry (see Chernobyl’). Conversely, solar and wind power seem environmentally safe, but they are unreliable as steady sources of energy. As global energy consumption grows each year, development of certain alternative energy sources becomes increasingly important.

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