Why DEC Removes the Steam Cycle

The steam cycle is the reason thermal plants are large, hot, and thirsty; direct conversion lets the burner skip it entirely.

What the steam cycle costs you

A Rankine steam cycle is a beautiful, mature, and unavoidable compromise for a heat source. You raise water to high-pressure steam, expand it through turbine stages, then condense it back to water — and condensation is where the water goes, either evaporated in cooling towers or drawn from and returned to a river. The cycle also fixes a large fraction of the plant's mass and footprint: boiler, turbine hall, condenser, feedwater train, and cooling infrastructure.

The Carnot ceiling

A heat engine's efficiency is capped by the Carnot limit, one minus the ratio of cold to hot absolute temperatures. Practical steam plants live well below that ceiling. To push efficiency up you must raise the hot-side temperature, which stresses materials. DEC is not a heat engine at all: it converts ordered kinetic energy of charged particles, so it is not bound by Carnot and can, in principle, reach higher fractions of the source energy.

What is left to cool

DEC is not perfectly lossless, and the burner still produces some neutrons — the D-3He primary is aneutronic, but D-D side reactions give a neutron fraction near 5.44%. That neutron energy, plus the small collector and radiation heat loads, is deposited thermally and must be removed. The point is one of proportion: a thermal plant must reject the majority of its input as low-grade heat, while a DEC burner rejects only a minority, so its cooling duty and water demand are far smaller.

The result is a generator that can be sited where the electricity is used, rather than where the water is. That is the whole premise of MetroVolt.