Cubic mile of oil

The cubic mile of oil (CMO) is a unit of energy. It was created by Hew Crane of SRI International to aid in public understanding of global-scale energy consumption and resources.

Significant sources of energy include oil, coal, natural gas, nuclear, hydroelectric, and biomass (primarily the burning of wood). Other energy sources include geothermal, wind, photovoltaic, and solar thermal. The various energy units commonly used to measure these sources (e.g., joules, BTUs, kilowatt hours, therms) are only somewhat familiar to the general public, and their relationships can be confusing. These common energy units are sized for everyday activities (a joule is the energy required to lift a small apple one metre vertically). For regional, national, and global scales, larger energy units, such as the exajoule, the billion barrels of oil equivalent (BBOE) and the quad are used. Derived by multiplying the small common units by large powers of ten these larger units pose additional conceptual difficulties for many citizens.

Crane intended the cubic mile of oil to provide a visualizable scale for comparing the contributions of these diverse energy components as a percentage of total worldwide, energy use.

The global economy consumes approximately 30 billion barrels of oil (1.26 trillion U.S. gallons or 4.75 trillion litres) each year. Numbers of this magnitude are difficult to conceive by most people. The volume occupied by one trillion U.S. gallons is about one cubic mile. Crane felt that a cubic mile would be an easier concept for the general public than a trillion gallons.

Definition and energy equivalents
The CMO is the energy released by burning a cubic mile of oil. Conversions to other units may be calculated based on the barrel of oil equivalent (BOE), an approximation of the energy released by burning one 42-US-gallon barrel of crude oil. Since one BOE is about $5.8 BTU$ and one cubic mile is about $2.62 barrels$:




 * 1 CMO
 * colspan=2|≈ $63360^{3}/42 × 231$
 * width=20pt|
 * = 160 exajoules
 * colspan=2|≈ $2.622 bbl$
 * colspan=2|
 * = 44.54 petawatt-hours
 * colspan=2|≈ $1.6 joules$
 * colspan=2|
 * = 152 quads
 * colspan=2|
 * ≈ 150 trillion (1012) cubic feet of natural gas
 * colspan=2|≈ $4.454 kilowatt-hours$
 * }
 * colspan=2|≈ $1.52 BTU$
 * colspan=2|
 * = 152 quads
 * colspan=2|
 * ≈ 150 trillion (1012) cubic feet of natural gas
 * colspan=2|≈ $2.62 BOE$
 * }
 * ≈ 150 trillion (1012) cubic feet of natural gas
 * colspan=2|≈ ⇭⇭⇭
 * }
 * colspan=2|≈ ⇭⇭⇭
 * }

Annual energy consumption by source
The world consumes approximately 3 CMO annually from all sources. The table shows the small contribution from alternative energies in 2006.

Global energy reserves
Proved oil reserves are those that can be extracted with reasonable certainty under existing conditions using existing technology. Global proved oil reserves are estimated at approximately 1300 Goilbbl. This corresponds to roughly 43 cubic miles, or 43 CMO. At the current rate of use, this would last about 40 years. Technological advances, new discoveries, and political changes will likely lead to additional proved oil reserves in the future. Concurrently, the International Energy Agency predicted in its 2005 World Energy Outlook that the annual consumption will increase by 50% by 2030. Coal and natural gas currently provide 1.42 CMO of energy per year. Global reserves of these fossil resources are as follows:
 * Natural gas reserves total 42 CMOs (69 years at current consumption)
 * Coal reserves total 121 CMOs (150 years at current consumption)
 * Additionally, there are large, albeit uncertain, amounts of tar sands, shale gas, and other unconventional fossil sources

Replacement of oil by alternative sources
While oil has many other important uses (lubrication, plastics, roadways, roofing) this section considers only its use as an energy source.

The CMO is a powerful means of understanding the difficulty of replacing oil energy by other sources. SRI International chemist Ripudaman Malhotra, working with Crane and colleague Ed Kinderman, used it to describe the looming energy crisis in sobering terms. Malhotra illustrates the problem of producing one CMO energy that we currently derive from oil each year from five different alternative sources. Installing capacity to produce 1 CMO per year requires long and significant development.

Allowing fifty years to develop the requisite capacity, 1 CMO of energy per year could be produced by any one of these developments: The energy produced is the power rating of the source multiplied by the duration it is operational. These comparisons take into account the variability of available power (solar panels work only during the day, turbines work only when the wind blows). Also, whereas 1 kWh is equivalent to 3412 BTU of primary energy, in practice it takes closer to 10,000 BTU to produce 1 kWh of electricity from coal and other fossil sources. Thus, when considering sources such as wind and solar which directly produce electricity, the required installed capacity was calculated by using 1 kWh as equivalent to 10,000 BTU.
 * 4 Three Gorges Dams, developed each year for 50 years, or
 * 52 nuclear power plants, developed each year for 50 years, or
 * 104 coal-fired power plants, developed each year for 50 years, or
 * 32,850 wind turbines, developed each year for 50 years, or
 * 91,250,000 rooftop solar photovoltaic panels developed each year for 50 years

The environmental, social, and financial costs of such development projects are immense:
 * The Three Gorges Dam is the world's largest, flooding 632 km2, displacing 1.25 million people, and costing roughly US$30 billion.
 * A conventional nuclear power plant produces hazardous radioactive waste, raises fears of radiation or nuclear proliferation, requires 10 years to construct for a 40-year lifetime, occupies about 4 km2, and may cost upwards of US$5 billion.
 * A 500 MW coal-fired power plant may contribute to acid rain, global warming, and air pollution, occupies about 2 km2, may obtain its fuel via controversial methods such as mountaintop removal, and costs about US$650 million.
 * A large wind turbine requires a location with an abundance of steady wind, may be visually obtrusive, can interfere with aviation, needs about 0.16 km2 to avoid interfering with adjacent turbines, and costs about US$2 million.
 * A 2.1 kW rooftop solar array requires technical skills for installation, needs a sunny location, presents few aesthetic or environmental problems, covers about 14 m2, but costs around US$15,000.

For comparison, US$3.2 trillion is the approximate gross domestic product of Germany, China, or the United Kingdom. The total land area of New Zealand is approximately 270000 km2.

At a 2008 market price of US$120 per barrel (US$750/m3), the cost of one CMO was about US$3 trillion.