A greenhouse energy specialist is urging growers to prepare for rolling power outages with a written curtailment plan, arguing that the difference between a controlled load reduction and a crop-damaging shutdown is preparation.
Ian Knisely, an energy analyst at Energy Bridge Advisors, points growers to a detail that many overlook on California utility bills: the rotating outage group or block. That number indicates where a site stands in line if the grid runs short. Every grower has a place in that line, he writes, whether or not it appears on the bill.
Federal reliability standards, specifically NERC’s EOP-011, require grid operators nationwide to maintain emergency plans for cutting load, according to the article. California is unusual in printing outage-group information directly on utility bills. The underlying grid emergency planning exists nationwide, even where the customer-facing detail is less visible.
When those emergency plans are used, power is shut off systematically, often with only minutes of warning. Hospitals and other critical facilities are protected where possible; almost everyone else, including greenhouses, is at risk. Rolling outages have hit several regions in recent years during heat waves and winter storms, the article notes. For a greenhouse, that can mean fans, pumps, irrigation, heating and controls going dark at the worst possible time.
Knisely distinguishes an outage from a curtailment. 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. The goal is to enter the stressed hours with some margin rather than improvise after the grid operator acts.
Four steps to a workable plan
The article lays out a four-step playbook. First, list major equipment and estimate how much power each item draws. The inventory should cover supplemental lighting, fans, evaporative cooling, heating, pumps, dehumidification, controls and any cold storage.
Second, sort loads into three groups: equipment that can be shut off entirely for a few hours without harming the crop; equipment that can be reduced, such as dimmed lights, staggered fans or a setpoint adjusted by a few degrees; and must-run systems such as controls, alarms and whatever keeps the most sensitive crop alive. The sorting depends on crop and growth stage, so it can change through the season.
Third, use forecasts and public grid alerts 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 can pre-cool in the morning, irrigate early and close shade curtains before the afternoon peak. In winter, they can heat ahead of the cold peak, close thermal curtains early and confirm backup heat is fueled and tested.
Fourth, assign roles: who receives the alert, who makes the decision and who carries it out. If an environmental controller can run the sequence automatically, it should be programmed and tested. A plan that depends on one person answering a phone on a Saturday afternoon is not a plan, the article warns.
After those steps, a grower should know how many kilowatts can be given up, for how long, and at what cost to the crop. That calculation also matters beyond emergency shutdowns. Utilities and grid operators pay customers that agree in advance to cut load before ordering outages, because a megawatt that disappears on request is cheaper than one bought at emergency prices, according to the article. The market is known as demand response and exists in most of the country, largely so the outage plan never has to be used.
The practical next step, Knisely says, is to ask the utility where a site falls in its emergency plan and then build a greenhouse-specific plan. For growers, the exercise is less about predicting the next grid emergency than about deciding, in advance, which equipment can go dark and which cannot.