# Joules, BTUs, Quads—Let’s Call the Whole Thing Off

## How to replace a cubic mile of oil

Illustration: Bryan Christie Design

The fact that energy sources and uses are stated in so many different kinds of terms is increasingly seen as not merely an annoyance but as a serious impediment to public understanding of critical choices. In an effort to get matters onto a more intuitive, citizen-friendly basis, a number of experts have hit on the convenient fact that the world at present consumes about 1 cubic mile of oil (CMO) per year. Among these experts are Ed Kinderman and Hewitt Crane at SRI International, in Menlo Park, Calif., who are preparing a book for Oxford University Press that will be built around the idea of normalizing all energy units to 1 CMO (4.17 cubic kilometers).

One dramatic way of portraying their results is to ask how many alternative energy sources—say coal-fired plants or solar panels—it would take to produce the equivalent of one CMO.

Amplifying on the rationale for CMO, Ripudaman Malhotra—an SRI chemist and a colleague of Kinderman and Crane—puts it like this: “When talking about energy and its different sources, we run into two main problems that impede meaningful discussion. If you ask the question—How much energy does the world use in a ­second?—you get answers that combine many different units: 150 tons of coal, 37 000 gallons of oil, 3.2 million cubic feet of gas, and so on.”

“The second problem,” Malhotra says, “is that these units themselves represent fairly small amounts of energy, and one needs modifiers such as millions, billions, and trillions in front of them. It is difficult to keep these numbers straight, and there are examples in the press when million was used when the intent was to use a billion.”

“Remember also that billion means 1012 in the UK and not 109 as per the U.S. usage,” Malhotra adds.

Some results of the exercise are displayed here. Prepare for your mind to be wonderfully sobered. To obtain in one year the amount of energy contained in one cubic mile of oil, each year for 50 years we would need to have produced the numbers of dams, nuclear power plants, coal plants, windmills, or solar panels shown here.

Assumptions: The Three Gorges Dam is rated at its full design capacity of 18 gigawatts. A nuclear power plant is postulated to be the equivalent of a 1.1-GW unit at the Diablo Canyon plant in California. A coal plant is one rated at 500 megawatts. A wind turbine is one with a 100-meter blade span, and rated at 1.65 MW. A solar panel is a 2.1-kilowatt system made for home roofs. In comparing ­categories, bear in mind that the average amount of time that power is produced varies among them, so that total energy obtained is not a simple function of power rating.Illustration: Bryan Christie Design

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