Ian Knisely, an energy analyst at Energy Bridge Advisors, writes that most greenhouses do not have a plan for the moment when a utility orders a rolling outage. Growers who rely on electricity for ventilation, irrigation, heating and environmental controls may have a place in their local grid's emergency shutdown order, whether or not they know it.
Federal reliability standards, specifically NERC's EOP-011, require grid operators across the United States to keep emergency plans for cutting load, according to the article. California stands out because it prints a customer's rotating outage group or block directly on the utility bill. That number indicates where a site stands in line if the grid runs short, but every grower has a place in that line even when it is not printed.
When an emergency plan is implemented, power is systematically shut off, often with only minutes of warning. Hospitals and other critical facilities are protected where possible, but other customers, including greenhouses, are at risk. Heat waves and winter storms have caused rolling outages in several regions in recent years, the article notes. For a greenhouse, losing power can stop fans, pumps, irrigation, heat and controls at the worst possible time.
Outage versus curtailment
The article draws a distinction between an outage and a curtailment: control. In an outage, everything stops at once. In a planned curtailment, the grower decides in advance which loads to drop, by how much and which must remain on to protect the crop. That written playbook, the article says, usually comes down to four steps.
Four planning steps
The first step is to list major equipment and estimate its power draw, including supplemental lighting, fans, evaporative cooling, heating, pumps, dehumidification, controls and cold storage.
The second is to sort each load. Some equipment can be shut down entirely for a few hours without harming the crop. Some can be reduced through dimmed lights, staggered fans or a setpoint adjustment of a few degrees. Controls, alarms and whatever keeps the most sensitive crop alive must stay on. The ranking depends on the crop and its growth stage, so it can change through the season.
The third is to use warning signals as triggers. An outage order may arrive with only minutes of notice, but heat waves and cold snaps are forecast days ahead, and grid operators usually issue public alerts before an emergency. In summer, growers with a plan 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.
The fourth is to assign roles: who receives the alert, who makes the decision and who carries it out. If an environmental controller can run the sequence automatically, the article advises programming and testing it. A plan that depends on one person answering a phone at 4 p.m. on a Saturday is not a plan.
Demand response and the value of flexibility
Once those steps are complete, a grower should know how many kilowatts can be given up, for how long and at what cost to the crop. That figure is what the grid is willing to pay for, according to the article.
Before ordering outages, utilities and grid operators will pay customers that 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, the article says.
The practical advice is to ask the utility where a site falls in its emergency plan, then start building a greenhouse-specific plan. The article frames the choice plainly: utilities plan for the day in detail, but most greenhouses do not.