- Greenhouses have been used by gardeners for many hundreds of years.
- They provide an enclosed, controlled environment to grow fruits and vegetables.
- In the Netherlands, authorities want to make the sector more sustainable.
With its coastline buffeted by the chilly waters of the North Sea, it's perhaps counterintuitive to think of the Netherlands as a place that cultivates large amounts of tomatoes, peppers and cucumbers.
Thanks in large part to its widespread adoption of greenhouse technology, however, it does. The sight of these structures, with their glass and aluminum glinting in the sun, is a common one across the country.
"Greenhouses are just as Dutch as wooden shoes, as tulips," Marc Middeldorp, manager for design and engineering at Van Der Hoeven, a firm that specializes in horticultural developments, told CNBC's Sustainable Energy. "It's a cliché, but it's true," he added.
Greenhouses – which have been used by gardeners for many hundreds of years – provide an enclosed, controlled environment to grow things such as fruits and vegetables. The Royal Horticultural Society has also described them as being "invaluable for creating a protected growing environment for tender plants and seedlings."
Founded in 1953, Van Der Hoeven is involved in schemes that use greenhouse technology to produce fruits and vegetables. Referencing variables such as temperature, humidity and levels of pests and insects, Middeldorp explained that a greenhouse enabled users to "fully control the climate inside." Nevertheless, creating a system where conditions are just right can be quite an energy intensive process.
"There is a demand, definitely, for clients to build sustainable greenhouses with efficient use of energy and to reduce as much as possible the use of fresh water, electricity," he added. "And that's where our challenge lies at the moment."
This drive for sustainable greenhouses is an ambition shared by Dutch authorities. From this year, according to the government, all new greenhouses will have to be climate neutral.
This goal, it says, can be met through the use of everything from measures designed to save light, to solar power and what it describes as "geothermal applications."
One company that has developed sustainable tech for the greenhouse sector is Solho.
Headquartered in the Dutch city of Delft, the company's Solar Powered Horticultural Off-grid Unit, or SPRHOUT, combines solar power with thermal energy storage.
"It uses solar energy as an input to generate all the energy flows required to operate the greenhouse farm: heating, cooling and electricity," Adriano Desideri, Solho's CEO and co-founder, said.
Desideri explained solar panels were used to heat water. "We store it in our thermal storage which we call the TESMOD," he added.
"And then from here, we harvest this thermal energy: either for heating, or for cooling through a thermal chiller, or for electricity through a power unit."
"In this way, we end up with a system that uses only the sun to generate all the energy streams required to operate the greenhouse farms."
Olivier Dubois is senior natural resources officer at the Food and Agriculture Organization of the United Nations and co-ordinates its program on energy.
Speaking to CNBC, he described the "greenhouse model" as "part of a series of farming systems which try to optimize the use of land and produce the maximum… food on a small amount of land."
"Which is great, because it's part of the whole need to be very efficient in the way we use resources," he added.
"The problem is you need to also look at the other inputs and resources needed to produce the food. So, if you're in a place where you don't have a lot of water, you need to think twice before promoting that kind of model."
Dubois went on to cite vertical farming as a method of growing that sought to maximize the use of both land and water but cautioned that "sophisticated systems" could not "produce everything."
"In particular, they cannot produce staple crops like cereals, they cannot produce trees that produce fruits and they cannot produce oil crops," he noted. "So you need, also, the other systems, that use land, to complement these systems."