Background
Featured Tom van de Kooij

Sustainable
Greenhouses

Background

The R&D Center and the greenhouse complex in Metslawier were thoroughly renovated in 2010. Before this time, heating took place with gas-fired boilers. Plastic tunnels were in place, under which the mini-tubers grew. The climate was not controlled in any way. Tom van de Kooij, Manager Operations, felt that things had to be done differently. He sought out a solution for the next 30 years. It had to be solid. Away from fossil fuel usage. Without stove, without gas. Time for a thorough revamp.

The current greenhouse complex is beautiful and many sustainable options have been incorporated within. Right now, Aquifer Thermal Energy Storage takes care of the cooling needs in summer and heating needs in winter. Solar heat is stored in the ground. This is pumped out of the ground for heating during winter months, and vice versa.

Proper fine-tuning and finding a balance for the right climate proved to be a challenge the first year and a half. The balance has now been achieved. The climate control aspect has exceeded our expectations, says Tom. This will be expanded in winter 2014 / 2015 to include the laboratory, for which we will be able to use extra heat from the Aquifer Thermal Energy Storage (ATES).

The greenhouse complex was also made more sustainable on other fronts. We use a closed greenhouse principle. This implies that the doors and windows are closed. This means fewer pesticides are needed, because bugs and fungi don’t get in. However, some sort of crop protection is always needed, explains Tom. However, we are able to restrict this to a minimum, and we naturally opt for organic cultivation where possible.

No matter what we do, we always use rainwater instead of tap water. The water consumption in the greenhouse is based entirely on (grey) rainwater. This water is stored in a large lagoon. The water is sterilised shortly before being used, by means of a high-pressure UV process, amongst other things. Half of our cultivation currently involves water-culture methods (instead of potting soil). The plant roots are suspended in streaming water.  The plants stay in place, and you then pick the potatoes. This makes a substantial difference in terms of costs. Fewer plants are needed, because the production per plant equals about 10 to 15 x more. We also save significantly in terms of (tap) water.

In the meantime, the greenhouses are able to function almost entirely without gas. The ATES minimised this. We can always switch to gas in the event of emergencies. When the boilers need replacement in the future, Tom wants to consider using residual heat from the ATES for office space. Electricity, on the other hand, is still being used. Tom’s ambition is to make this more sustainable in the future as well. He believes that it must be feasible to generate energy in-house or collectively, because sun, wind and water are abundant in the high north. If we then proceed to join forces locally, the community of Metslawier will also benefit from this. This way everyone gains wisdom, says Tom.

close this window