Efficient energy the backbone of Prominent tomato grower cooperative
EIGHT energy managers monitor Prominent’s 52 greenhouse sites, writes SARAH HUDSON.
WHEN Jacco Besuijen gives a PowerPoint presentation, you’d be hard-pressed to know he’s a manager at one of the Netherlands largest tomato growers.
Instead he could be mistaken for an energy provider.
“Our greenhouses have three key needs: heat, electricity and CO2, in addition to water,” he explained to the Weekly Times, on an exclusive tour last month.
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“To power this we need half a megawatt of installed power per hectare, across our 418ha of greenhouses, which is overseen by eight energy managers in one location who monitor all 52 greenhouse sites around the Netherlands.
“In the early days we used oil boilers, then gas, followed by cogeneration but now because the Netherlands imports a lot of gas from Russia and because of the need to stop using fossil fuels we are looking to use geothermal heat.
“Over the past two years, three of our growers have invested 25 million Euros to go to a depth of 2200m to a temperature of 82C in order to tap into geothermal heat.”
JACCO BESUIJEN
WESTLAND, THE NETHERLANDS
MANAGER of Groeneweg II — the flagship company of the Prominent co-operative of 32 tomato growers
HAS 418ha of greenhouses spread across 52 sites
HARVESTS 40 weeks a year
BIGGEST market in Germany followed by the UK
Yes, this is tomato farming but on a scale most Australian farmers wouldn’t recognise.
Jacco is a manager at Groeneweg II, the flagship company of the Prominent co-operative group of 32 tomato growers, based across 52 locations in the Netherlands.
Prominent growers farm a total of 418ha in a long list of truss varieties, yielding 20kg per square metre at the lower end for such varieties as kiss, and up to 100kg/sqm for their most popular variety, the self-named Prominent large tomato.
Prominent harvests 40 weeks of the year, planting seedlings about half a metre in height in the darkest months of November - sourced from their nursery and pollinated by bumble bees (although planting in greenhouses with artificial light starts any time of the year). Tomatoes are then grown vertically up ropes and, because of rapid growth, are looped horizontally to allow for further growth.
“Then when it’s too long from the root to the head of the plant we pull it out and replant, which means we’re only about eight weeks out of production,” Jacco said.
EUROPEAN FLAVOUR
TOMATOES are then transported around western Europe - up to 60 per cent to Germany alone, about 25 per cent to the UK and just 5 per cent to Holland itself.
The Weekly Times visited Jacco at the Groeneweg II greenhouse research facility, which also has commercial production, located at Westland on the west coast of the Netherlands, considered the world’s horticultural cluster with 670 greenhouse companies.
All up members of Prominent (founded in 1994) have invested in three nurseries, two packaging and two distribution centres, managed by Groeneweg II.
“Traditionally farmers began farming grapes more than a century ago in Westland because it was close to the sea - the sandy soil was good for grapes and the climate was mild,” Jacco said.
“Also it was between The Hague and Rotterdam and these days close to the port, rail and airfreight.”
Jacco said truss tomato growing had advanced considerably since farmers first began using rock-wool substrate in hydroponic glass greenhouse production about three decades ago.
“Advances were quick. Tables moved above ground to make labour more efficient and greenhouses became higher to lower humidity and allow better temperature control, which helped air flow and therefore disease prevention.”
Jacco added that up until two years ago their greenhouses had largely been pest and disease free, but for reasons as yet unknown they have had an influx of tuta absoluta moth, in addition to white fly and a tomato mite, which they are battling with the introduction of biological controls.
“Only when we don’t have control through beneficial insects do we use chemicals, which we are reluctant to do because in doing that you disturb the total biological balance. As much as possible, we try the biological way.”
WATER WISE
JACCO said advances in water efficiency meant they used 4-10 litres per square metre via drip irrigation, largely captured from rainfall on the roof and re-used through a combined computerised fertigation system that constantly measured nutrient requirements.
“When captured water runs low we are able to top up by pumping groundwater, filtered through reverse osmosis to desalinate it. We never use consumer water.”
But undoubtedly the greatest advances in Prominent’s truss tomato greenhouses has been in electricity production.
In contrast to Australia, which has abundant light, dark winters in the Netherlands means light and CO2 for photosynthesis are critical.
“These are our two limits in winter. Outside CO2 levels are 300-400 parts per million, but inside a greenhouse we reach up to 1000 parts per million of CO2,” Jacco said, pointing to transparent plastic tubes that run under elevated tomatoes like long sausages to provide CO2 to plants.
“In winter increasingly we use artificial light in addition to natural light using sodium high pressure gas-filled lamps, which produces the whole spectrum of light.”
Tomato greenhouses also require humidity, cooling, and heating, with a daytime temperature between 20-25C and night time of 18C. Alongside CO2 plastic tubes under the elevated hydroponic tables, there is a metal grill system to provide heating to plants.
For these reasons power production is critical.
“There’s a big discussion in the Netherlands at the moment about energy sourcing so we’re currently looking at other ways to power the greenhouses than gas.”
POWER POINT
JACCO said geothermal was not a solution for every company, because it required “layers of sand and clay so you can pump up the hot water and then inject water back at 40C into the same layer to keep the temperatures and pressures right”.
“For this reason the Netherlands is also starting to work on a master plan for a heat grid using residual heat from industrial processes in Rotterdam, from such sources as hydrogen, which is wasted by industry but interesting for us,” he said.
Jacco’s is one of 100 companies taking part in the Netherland’s new World Horti Centre project in Westland, opened in March as a world-first joint partnership between government, researchers, universities and private business, combining the Dutch greenhouse horticultural sector under a single roof.
He said the World Horti Centre was an example of how greenhouse knowledge and technology was now globally available.
“For us there are no secrets any more. The technology is now available to build world’s best greenhouses anywhere in the world, whether Australia or the Netherlands.
“For us the secret to growing high yielding tomatoes is controlling and optimising the climate. That’s where the grower knowledge is.”
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