Closed-Loop Coolant Without Consumption

A sealed coolant loop moves heat without losing water; rejecting that heat to air rather than evaporating it is what keeps consumption near zero.

Sealed means unconsumed

In a closed loop, coolant circulates permanently between the heat source and a heat exchanger. It carries heat from one place to another but is not itself lost. The only losses are small leaks and maintenance draining. This is fundamentally different from an evaporative loop, where consuming water is the cooling mechanism itself.

The critical choice: reject to air, not vapor

A closed loop can reject its heat two ways: to an evaporative tower (consuming water) or to a dry air-cooled exchanger (consuming none). MetroVolt uses dry rejection because its heat loads are small enough that the efficiency penalty is minor. This combination, closed loop plus dry rejection, is what delivers near-zero water consumption.

Why steam plants cannot do this at scale

• A steam plant's rejected heat is enormous, so dry rejection costs it dearly in efficiency
• The burner's residual heat is small, so dry rejection costs it little
• Scale, not principle, is why one can go dry-cooled and the other struggles to

The result

The coolant inside the burner's loops is used indefinitely, not consumed. The heat leaves as warmed air. No basin water is evaporated to make the plant run. This is the concrete mechanism behind the water story's headline: firm power with almost no water.