Combined Cycle

A combined cycle is a power-generation arrangement that captures the hot exhaust of a gas (combustion) turbine and uses it to raise steam for a second, steam-turbine generating stage. By harvesting energy that a single turbine would otherwise dump to atmosphere, the configuration lifts electrical efficiency from the 33-43% range of a turbine alone to roughly 55-61% at full load. For every megawatt produced, a combined-cycle plant burns about a third less fuel than a simple-cycle unit, which directly lowers the cost per kilowatt-hour and the carbon intensity of that power.

How the two stages work together

The first stage is a Brayton-cycle gas turbine. Its exhaust, still several hundred degrees Celsius, passes through a heat recovery steam generator (HRSG) that boils water into high-pressure steam. That steam drives a Rankine-cycle steam turbine, the second stage. Two generators are turned from one fuel feed, which is why combined-cycle gas turbines (CCGTs) dominate efficient grid-scale natural-gas generation.

Relevance to mining heat economics

Bitcoin miners rarely run combined-cycle plants themselves, but the concept matters when evaluating behind-the-meter or stranded-gas deals. A simple-cycle peaker or a flare-gas genset wastes most of its fuel energy as heat, whereas combined-cycle hardware is reserved for baseload. Understanding the gap helps operators judge whether a power offer reflects efficient generation or cheap, otherwise-curtailed energy that mining can monetize. The same waste-heat logic that drives combined cycles also underpins heat-reuse strategies inside a Hashcenter.

Compare this with the lower-efficiency, fast-dispatch sibling at Simple Cycle, and see how recovered exhaust energy is captured in Waste Heat Recovery.