Greenhouse growers who depend on grid power should know their place in their utility’s emergency load-shedding order and prepare a written curtailment plan before an outage occurs, according to guidance from Energy Bridge Advisors energy analyst Ian Knisely. Utilities maintain emergency plans for cutting power when supply cannot meet demand, the article says. Those plans can shut off power systematically, often with only minutes of warning. Hospitals and other critical facilities are protected where possible, but most other customers, including greenhouses, remain at risk.
Knisely notes that California is unusual in printing a customer’s rotating outage group or block directly on the utility bill. That number tells a grower where the site stands in line if the grid runs short. Even where the information is not printed, every grower has a place in that line because grid operators nationwide must keep emergency load-cutting plans under federal reliability standards such as NERC’s EOP-011. Rolling outages have hit several regions in recent years during heat waves and winter storms, the article says, leaving greenhouse fans, pumps, irrigation, heat and controls vulnerable at the worst possible time.
The article distinguishes an outage from a planned 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. Knisely describes a curtailment plan as a written playbook for hours when the grid is stressed, built around four steps.
Four steps to a usable plan
- Inventory loads. List major equipment and roughly how much power each draws: supplemental lighting, fans, evaporative cooling, heating, pumps, dehumidification, controls and any cold storage.
- Sort loads by priority. Some can be dropped for a few hours without harm, some can be reduced by dimming lights, staggering fans or adjusting a setpoint a few degrees, and some must stay on, including controls, alarms and whatever keeps the most sensitive crop alive. The sorting depends on the crop and its stage and can change through the season.
- Use forecasts as a trigger. Outage orders may arrive with 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.
- Assign roles and automate where possible. Decide who receives the alert, who makes the decision and who carries it out. If the environmental controller can run the sequence automatically, program it and test it. The article warns that a plan relying on one person to answer a phone on a Saturday afternoon is not a real plan.
After those steps, the article says, a grower should know how many kilowatts can be given up, for how long and at what cost to the crop. That number is what the grid is willing to pay for, it says. Utilities and grid operators will pay customers who agree in advance to cut load before ordering outages, because a megawatt that disappears on request is cheaper than one bought at emergency prices. That market is demand response, which exists in most of the country, largely so the outage plan never has to be used.
The closing advice is for growers to ask their utility where their site falls in its plan and then start making their own. The recommendations are framed as preparation for grid stress, not as a claim that a curtailment plan will eliminate crop loss or create revenue.