Chrysanthemum growers Leeuwis originally planned to install hybrid lighting throughout their entire operation, but due to the energy crisis, half of the greenhouse was equipped with full LED lighting while the other half remained empty. Six months later, the growers are more than satisfied with their choice. "The transition went smoothly, and with current prices, we have more profit."
"It was either full LED or leave the greenhouse empty," explains chrysanthemum grower Yorick Leeuwis from Tuil, near Zaltbommel, describing last summer's business dilemma. Gas prices were skyrocketing, and the market for cut chrysanthemums was uncertain. Thus, the initial plan to switch the entire greenhouse to hybrid lighting was scrapped. "We opted for full LED in one half of the greenhouse."
In mid-November last year, the 1,000-watt LED lamps from MechaTronix were installed. The choice for this manufacturer was partly due to the greater variety in the light spectrum offered. "Besides a basic spectrum of red, blue, green, and white, separately controllable and dimmable far-red is also integrated into the lamp," says Patrick Casteleyn, sales director at the lamp manufacturer. He notes that all active chrysanthemum growers currently use full LED or at least hybrid lighting. "Otherwise, the financial risk is too great."
Compensation for Radiant Heat
Far-red light is used by the chrysanthemum growers at the end of a lighting day. "When the lamps go off, we continue with far-red for another twenty minutes. It's comparable to twilight and the last rays of the sun that reach the small vegetation in the forest, triggering a growth spurt," explains Yorick Leeuwis, who runs the company with his father Marcel.
The growers combine chrysanthemum cultivation with fruit farming on 65 hectares. "We are originally fruit growers, but after our harvest was twice damaged by hail, we looked for alternatives. Since the nearby chrysanthemum growers were doing well, we chose that path," continues the entrepreneur, who was young at the time and, like his father, had no background in greenhouse horticulture. "We went from an uncontrolled climate to a fully controlled greenhouse environment."
Seamless Transition
The current 7.6-hectare greenhouse dates back to 2009 and is still the second-longest chrysanthemum greenhouse in the Netherlands, measuring 500 meters in length. This length, which was also dictated by the shape of the plot, brings significant labor efficiency. "For example, the supply of plant material has a completely separate entrance, so the two activities do not interfere with each other," says Lewis Jr. The greenhouse is divided into 93 sections, which come into production sequentially.
Twenty years after starting, the Gelderlanders have clearly mastered the cultivation process. The grower describes how the introduction of LED lamps went smoothly without any decline in production or quality. "We are looking for the right balance between light, heat, and a few other factors. We compensate for the lack of radiant heat partly with far-red light and additionally with heat from the CHP."
Unprecedented Price Formation
This winter, only one of the two CHP units is being used for cultivation. By leaving half of the greenhouse empty, the growers aimed to mitigate the risks of high gas prices. “If electricity prices are favorable, the second CHP can run to supply power to the grid, utilizing the extra heat in cultivation,” says the 37-year-old grower, who also purchased a second-hand generator to prepare for potential blackouts.
Despite lower but still high energy prices, the cultivation is not unprofitable. “Selling prices are currently at an unprecedented level. We are making more profit with half the area than we normally do with the entire greenhouse.” He attributes this to the production losses experienced by other Dutch growers. “In the first weeks of January, at the lowest point, there was 54 percent less supply than last year.” Less supply means better prices. The company has not yet felt the effects of declining consumer spending, which is often discussed. “Most of our produce is exported.”
Additional Cost Benefits
The LEDs have increased the light level from 130 to 200 µmol/m².s. This allowed for higher plant density. Whereas the company now plants 60 plants per m², depending on the species, this was 47-50 during the SON-T period. Leeuwis adds that LED lamps with dimming functionality provide better light distribution in the high greenhouse compared to simply switching SON-T on or off. This promotes the uniformity of the crops and reduces stress on the crops. When fully switching from SON-T to LED, the total power requirement in the greenhouse decreases from 6 MW to 4 MW. This results in substantial savings on electricity costs, while production remains at or even exceeds the previous level. The grower states: "The windows stay closed longer, so no heat is lost. Additionally, as the plants evaporate less, less water and nutrients are needed."
The switch also results in savings in the area of chemicals. Leeuwis: "Previously, we chemically inhibited the plants. With the LED lamps, we can control this with far-red light, reducing the need for chemical agents, and possibly eliminating it in the long term."
Dimming Function and Battery
Another very important feature of the LED lamps is the dimming function. The fact that the grower frequently uses this option is evident from the lamps changing brightness every few minutes. “We dim the lights depending on the electricity price,” says Leeuwis, who has set three levels on his computer for this purpose. “I set the levels based on the expected sales price, and we can also dim according to solar radiation when the sun starts shining again.”
The grower acknowledges that he cannot dim indefinitely, as the plants have a minimum energy requirement. To better manage this in the future, he has ordered a battery with a storage capacity of 340 KW. The battery costs 400,000 euros and is intended to buffer the peaks and troughs in the power grid. Thus, the CHP unit can charge the battery when prices on the grid are negative, and the battery can power the LEDs when prices peak.
His experience with the new lamps strengthens the grower’s belief that full LED is the future. However, he is not certain if he will place another order soon. “There are still too many uncertain factors in the energy market. We will evaluate the situation throughout the year and decide in due course whether to grow the other half with full LED or perhaps skip a winter.”
Until this decision is made, he continues to grow with the seasons on the rest of the farm. The first planting there will occur in week 9. From that time onwards, the lights will hardly need to be on.
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