Geothermal systems use which medium for heat exchange?

Geothermal systems use which medium for heat exchange?

• A. Water
• B. Air
• C. The earth
• D. Sand

Answer: (C)

Geothermal systems exchange heat with the earth itself. They use buried loops that move a working fluid to tap heat from the surrounding ground, which stays at a relatively steady temperature below the surface. This stable ground temperature allows efficient heat transfer year-round—pulling heat from the earth in winter and rejecting heat into it in summer. Water or air aren’t the primary media for this typical setup (they’re used in other types of systems), and sand isn’t a separate medium here—the earth—the soil and rock around the loops—is the heat exchange reservoir.

Geothermal systems exchange heat with the earth itself. They use buried loops that move a working fluid to tap heat from the surrounding ground, which stays at a relatively steady temperature below the surface. This stable ground temperature allows efficient heat transfer year-round—pulling heat from the earth in winter and rejecting heat into it in summer. Water or air aren’t the primary media for this typical setup (they’re used in other types of systems), and sand isn’t a separate medium here—the earth—the soil and rock around the loops—is the heat exchange reservoir.