The Water Cycle And Fuel

Drawing deuterium from water does not consume water in any meaningful sense; the separated water returns to the hydrological cycle.

Extraction is not consumption

Separating deuterium takes in water, removes a minute fraction of its hydrogen atoms as the heavy isotope, and returns the rest. The water itself is not destroyed. Because deuterium is such a small fraction of the hydrogen present, the volume of water involved is tiny relative to any natural flow, and it rejoins the environment.

A negligible draw on freshwater

The hydrological cycle moves an immense quantity of water continuously. The amount touched to extract a plant's deuterium is negligible within that flow, and much of the fuel supply can draw on seawater rather than freshwater. The fuel supply does not compete meaningfully with drinking water or agriculture.

• Water is returned after deuterium is separated
• Only a minute fraction of hydrogen is removed
• Seawater can be the source, sparing freshwater
• The draw is negligible within the hydrological cycle

Distinct from plant cooling

This page concerns water as a fuel source. The separate question of how little water a plant uses for cooling — very little, because direct energy conversion avoids a steam cycle — is covered in the water and resources pages. See the ocean reservoir and a sustainable fuel cycle.

Borrowing water, not consuming it

Extracting deuterium borrows water briefly and returns nearly all of it, removing only a minute fraction of hydrogen atoms. Set against the immense flows of the hydrological cycle, the draw is imperceptible, and drawing on seawater spares freshwater entirely. The fuel supply therefore does not trade energy for water stress, a distinction that matters as water becomes a more contested resource.