For about one and a half winters now, Kok Aardbeien has been appreciating the solar boiler installed right next to their strawberry greenhouse in Zwaagdijk-Oost, the Netherlands. Arjen and Esmeralde Kok achieved significant gas savings thanks to this investment. "Without that, I believe we could hardly make it through the gas crisis," they say.
To operate even more sustainably as relatively small growers, they have now set their sights on a small wind turbine. Since new tax regulations got announced, the couple realized how crucial was both to reach retirement but also to keep selling quality strawberries until then. Unfortunately, the local municipality hasn't chipped in to support their plans yet. 
Arjen and Esmeralda Kok grow strawberries in Zwaagdijk-Oost
Independent from the auction
On a grey mid-Febrary Wednesday afternoon, the first green strawberries are already hanging from the plants in one of their three newest greenhouses. It's comfortably warm, yet too dark. This means that getting to Easter with large volumes won't be possible. The first ripe kilos will be for direct sales.
Their departure from The Greenery as of January 1 is all about the size of the business, explains Esmeralda. As relatively small growers with 4000 square meters of glass and outdoor cultivation, they don't have the volumes required for growers within a cooperative that qualifies for European SIG&F subsidy. Other growers have encountered the same problem, they say.
In close consultation with The Greenery, the variety Fandango was chosen for the newest greenhouse.
Solar boiler yields gas savings
The limited company size appears to be a common thread in the enthusiastic entrepreneurial story that we hear during the tour of the company. We first enter the oldest of the three greenhouses, which is full of plants but still cold, through a curtain of bubble wrap for extra insulation in the greenhouse that was newly built in 2022. An additional 1,200 square meters was added. Too little for many greenhouse builders. Prins agreed, also because the story was too good. The oldest greenhouse was also one of Prins.
Looking up in the newest greenhouse, we see heating pipes hanging above. Not so common these days, Arjen knows, but quite handy in his situation. Thanks to the solar boiler, the grower can use low-grade heat. Then to cool it down again through colder sections, and because the farm lacks pipe rails, it's the best option.
In the winter of 2022/2023, thanks to the latest investments, about thirty percent was saved on gas. Fifty percent is possible, but although the system itself worked immediately, optimally integrating the solar boiler into the business operations was still a challenge. This has now been achieved after adjustments to the climate computer, among other things.
The choice of Kok Aardbeien for a solar boiler has since been followed by various companies, including a blacksmith and an ice cream maker who heats his toppings with boiler heat. Unfortunately for new interested parties, the ISDE subsidy that the growers from Zwaagdijk could receive has been significantly reduced in 2024.
Wind turbine for winter electricity
The growers are now busy with a project to improve the strawberry farm's sustainability. In addition to the solar boiler, solar panels, and a boiler for the much-needed CO2 – something people often forget, emphasizes Arjen – a small wind turbine would complete the picture. The wind turbine would also generate electricity in the winter.
Currently, thanks to the solar boiler, which fills the buffer, they have heat for about one to two days. Installing an additional buffer is possible, but unlike colleagues with a solar boiler, Kok Aardbeien cannot store heat in the ground. The challenge is that the boiler has to be turned on to supplement heating. Arjen: "However, with the new legislation from 2027, that will no longer be affordable."
Disadvantage of tax law
This winter, the growers didn't have a fixed-price gas contract. That turned out well; they can say now that the gas price has unexpectedly dropped, but with the new tax regulations, they realize that gas consumption must be reduced even further. Arjen: "We are in the most expensive tier. It would be fairer if everyone, big or small, paid the same." They expect to be able to secure gas again this spring.
With additional electricity from the wind turbine, electric supplemental heating would become possible. In this way, the growers could get through the season. They had the same hope when they installed the solar boiler, but it didn't quite succeed last spring. The variety Fandango performs well in a somewhat colder cultivation, but with also a more stable harvest, the volumes were not such that the supermarket customers could count on Kok strawberries early on.
Arjen knows colleagues who, for similar reasons as his business, have purchased a heat pump. However, the electricity bill in the winter was a shock, he knows.
The heating pipes hang above. Not so common these days, Arjen knows, but quite handy in his situation. This way, he can cool down the heat used from the solar boiler well.
Built a stand-alone business
In the Medemblik municipality, a pilot project focused on wind turbines at businesses has been announced. Fifteen businesses qualified for five pilot spots. Kok Aardbeien did not make the cut. Arjen and Esmeralda understand, but they suspect it's not in their favor that they are relatively small.
Yet, they are not giving up. On Thursday, February 29, the city council discussed the pilot. Arjen and Esmeralda explain the story they told us on that grey Wednesday afternoon in the greenhouse.
For more information:
Kok Aardbeien
Zwaagdijk 310
1682 NS, Zwaagdijk-Oost
info@kokaardbeien.nl
www.kokaardbeien.nl