Your Utility Has an Outage Plan, but Does Your Greenhouse Have One?

Look closely at a California utility bill, and you’ll find a number most growers skip past: your rotating outage group or block. It tells you where you stand in line if the grid runs short. 

Every grower has a place in that line, whether or not it’s printed on the bill. Federal reliability standards (NERC’s EOP-011) require grid operators nationwide to keep emergency plans for cutting load. Yet, California is unusual in that it prints this information directly on the utility bill. 

Utilities across the country maintain emergency plans for cutting power when supply can’t meet demand. When the plan is implemented, power is systematically shut off, often with only minutes of warning. Critical facilities like hospitals are protected where possible. However, almost everyone else, including your greenhouse, is at risk. 

Rolling outages have hit several regions in recent years during both heat waves and winter storms. For a greenhouse, that means fans, pumps, irrigation, heat, and controls going dark at the worst possible time. 

Utilities plan for that day in detail, but most greenhouses don’t. The difference between an outage and a curtailment is control. In an outage, everything stops at once. In a planned curtailment, the grower decides in advance which loads drop, by how much, and which stay on to protect the crop. 

What a Curtailment Plan Looks Like

A curtailment plan is a written playbook for the hours when the grid is stressed. Most come down to four steps.

1. Know Your Loads

List the major equipment and roughly how much power each piece draws: supplemental lighting, fans, evaporative cooling, heating, pumps, dehumidification, controls, and any cold storage.

2. Sort Them Into Three Groups

Some loads can drop entirely for a few hours with no harm to the crop. Some can be reduced, like dimming lights, staggering fans, or adjusting a setpoint a few degrees. Some must stay on no matter what, like controls, alarms, and whatever keeps your most sensitive crop alive. The sorting depends on what you grow and its stage, so it can change through the season.

3. Act on the Forecast, Not the Order

The outage order may come with minutes of notice, but heat waves and cold snaps are forecast days ahead, and grid operators usually issue public alerts before an emergency. Growers with a plan treat those signals as the trigger. In summer, they pre-cool in the morning, irrigate early, and close shade curtains before the afternoon peak. In winter, they heat ahead of the cold peak, close thermal curtains early, and make sure backup heat is fueled and tested. Either way, the crop goes into the hard hours with some margin.

4. Assign the Call

Decide who receives the alert, who makes the decision, and who carries it out. If your environmental controller can run the sequence automatically, program it and test it. A plan that depends on one person answering a phone at 4 p.m. on a Saturday is not a plan. 

Once those steps are done, you should know how many kilowatts you can give up, for how long, and at what cost to the crop. That number is what the grid is willing to pay for. 

Before ordering outages, utilities and grid operators will pay customers who agree in advance to cut load, because a megawatt that disappears on request is cheaper than one bought at emergency prices. That market is demand response. It exists in most of the country, largely so the outage plan never has to be used. 

So, make sure to ask your utility where your site falls in its plan, and then start making your own.