Apples to Apples comparison is only needed when comparing which set of energy sources?

Apples to Apples comparison is only needed when comparing which set of energy sources?

• A. Electricity, oil and natural gas
• B. Oil, natural gas and steam
• C. Electricity and water
• D. Natural gas and coal

Answer: (A)

When you compare different energy sources, you must put them into a common energy unit so you’re evaluating energy on the same basis. Electricity, oil, and natural gas are three common energy carriers, but they’re measured in different units: electricity in kilowatt-hours, oil in gallons or barrels, and natural gas in cubic feet or therms. To compare total energy content, cost, or efficiency fairly, you convert all of them to a single unit such as BTU or gigajoules. That need to convert to a common basis is why apples-to-apples comparisons are used for electricity, oil, and natural gas. The other options mix forms that aren’t all primary energy carriers in the same way (steam is a heat-transfer medium, water isn’t an energy source in this context), so the standard apples-to-apples approach isn’t as clearly required there.

When you compare different energy sources, you must put them into a common energy unit so you’re evaluating energy on the same basis. Electricity, oil, and natural gas are three common energy carriers, but they’re measured in different units: electricity in kilowatt-hours, oil in gallons or barrels, and natural gas in cubic feet or therms. To compare total energy content, cost, or efficiency fairly, you convert all of them to a single unit such as BTU or gigajoules. That need to convert to a common basis is why apples-to-apples comparisons are used for electricity, oil, and natural gas.

The other options mix forms that aren’t all primary energy carriers in the same way (steam is a heat-transfer medium, water isn’t an energy source in this context), so the standard apples-to-apples approach isn’t as clearly required there.