Key Points
- Curtailment means a mining site powers down during demand spikes to avoid extreme prices or, in markets like Texas, get paid through demand response programs.
- It is a revenue strategy and a grid service, not a malfunction.
- Hosting questions about curtailment tend to turn on four points: whether an event matched grid conditions, how it counts against uptime, where the revenue goes, and how machines came back online.
- Curtailment events leave records that can be compared against grid data.
What Curtailment Is
A bitcoin mining site is one of the only industrial loads that can shut off in seconds without damage and restart just as fast. Grid operators value that flexibility. When electricity demand spikes, a mining site can power down and either avoid extreme prices or, in markets like Texas, get paid for the power it releases through demand response programs. In a bad heat wave, an hour of not mining can be worth more than a day of mining. Disputes over curtailment and demand-response revenue appear in both hosting and power contract cases.
So curtailment is not a malfunction. It is a revenue strategy and a grid service. Modern firmware can drop a whole facility’s load in moments in a controlled way rather than a hard cut. Fast power down is one of the features of third party firmware.
Why It Raises Questions in Hosting
Here is the tension. When a hosted site curtails, the host’s power position earns money or avoids cost, while the customer’s machines sit dark and earn nothing from mining. A customer may see downtime, and a host may see a normal operating decision. How that time is treated depends on what the agreement says and what the records show. Agreements vary widely, and some say nothing at all about curtailment.
- Did the event match grid conditions? Grid events are documented through prices, dispatch instructions, and program calls. Downtime attributed to curtailment can be compared against grid data for the same hours.
- How does it count against uptime? If curtailment hours are excluded from uptime, a 95 percent uptime figure can translate into much less hashing time. Some agreements cap excluded curtailment hours or set a price for them, and others do not address the point.
- Where does the revenue go? Demand response payments and power sales depend on the load a site releases. Parties have disputed whether that revenue belongs to the host’s power position or the customer’s load. Rhodium claimed its host owed it $7 to $10 million of this kind of revenue at the Rockdale facility. Some agreements share curtailment revenue, and others are silent.
- How did machines come back online? Mass restarts can create their own problems: breakers tripping under inrush current (see mining electrical basics), machines hanging and needing manual recovery, and hours of reduced hashrate after the event ends. Event logs typically show the ramp down and the ramp back.
What Records Typically Exist
Many sites record each curtailment event with a start time, end time, reason, program or price trigger, machines affected, revenue or savings, and restoration time. Some hosts notify customers in advance for planned programs, and others report afterward. Some monthly reports separate curtailment hours from fault hours, and pool data gives an outside view of when hashrate dropped and when it returned.
These records, along with public grid data such as ERCOT prices and program announcements, make it possible to compare what happened on site with what happened on the grid.
The short version
Curtailment is a legitimate and often profitable grid service, and how it is counted in a hosting relationship depends on the agreement language and the records.
Curtailment and uptime are two of the recurring terms covered in Mining Hosting Agreements: Terms That Recur in Disputes. Comparing downtime logs with grid records and pool data is a regular part of my work as a crypto hosting expert witness.
Common Questions
What is curtailment in bitcoin mining?
Curtailment is when a mining site powers down during electricity demand spikes, either to avoid extreme prices or, in markets like Texas, to get paid for the power it releases through demand response programs. Mining sites can shut off in seconds without damage and restart just as fast.
Does curtailment count against hosting uptime?
It depends on the agreement. If curtailment hours are excluded from uptime, a 95 percent uptime figure can translate into much less hashing time. Some agreements cap excluded curtailment hours or set a price for them, and others do not address the point.
Who gets curtailment revenue at a hosting site?
It depends on the agreement. Parties have disputed whether that revenue belongs to the host’s power position or to the customer’s load. Some agreements share it, and others are silent.
How can downtime be compared with curtailment events?
Grid events are documented by prices, dispatch instructions, or program calls. Downtime attributed to curtailment can be compared against that grid data and against pool data, and host event logs typically show the ramp down and the ramp back.
Sources: ERCOT on its voluntary curtailment program for large flexible loads
This article is general commentary on how bitcoin mining sites and hosting arrangements commonly work, based on industry practice and public information. It is not legal advice. Nothing here states an opinion on any standard of care or on any party’s conduct.
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