Curtailment

Curtailment is the deliberate reduction of electricity use or generation to keep a grid balanced. Supply and demand on an electrical grid must match instant to instant; when they do not, something gets curtailed.

It cuts both directions, and Bitcoin mining touches both:

• Generation curtailment. When a wind or solar farm produces more power than the grid can use or transmit, the surplus is curtailed - the turbines are feathered, the panels clipped, and the energy is simply wasted. This happens constantly on renewable-heavy grids with limited transmission or storage. It is the canonical example of stranded energy: electricity with no buyer.
• Load curtailment. A flexible consumer reduces its draw on command so the grid can serve higher-priority demand. This is the demand-response side.

Why mining fits both ends

A miner is a buyer of last resort for curtailed generation - it will run on the surplus electrons a wind farm would otherwise waste, because those are the cheapest electrons available. And it is a first candidate for load curtailment - it can shut down in seconds when the grid needs that capacity back, because unlike a factory it loses only forgone mining revenue, not work in progress.

That two-sided flexibility is why mining keeps appearing in grid-balancing arguments. The same property - indifference to when the power flows - lets a miner soak up power nobody wants and give back power everybody suddenly needs.

See the Bitcoin and Energy rabbit hole for how this plays out on real grids, and the honest limits of the argument.