The Dutch fresh produce industry has built up Europe’s most efficient and cleanest energy systems in an area known as Westland in South Holland, with a multitude of vegetables making their way over to the UK. With rising fuel prices and pressure from environmental issues, the industry has been striving to produce the most energy-efficient greenhouse systems for some time, but now the process has been accelerated by government intervention.
In June last year, the Dutch government issued a new policy document, entitled the Clean and Efficient Programme: New Energy for Climate Policy. The targets of the new policy are to reduce greenhouse gas emissions by 30 per cent compared to 1990’s levels; see a rate of energy efficiency improvement of two per cent a year; and to push the share of renewable energy to 20 per cent by 2020.
The Greenery, which groups 1,150 growers in the Netherlands under one banner, has long known that environmental sustainability would play an important role in the future of the fresh produce industry and actively supports and encourages its growers’ many energy-efficient schemes.
“Quality, food safety and energy sustainability are very important themes today,” says The Greenery’s quality and environment director, Arie van der Linden. “And we have moved through some dramatic changes. Some 10 years ago, it was the industry’s view that the customer received what the grower wanted to produce in the way it wanted to produce it, but now we are thinking about the bigger picture.
“To quote [US businessman and author] Peter Drucker: ‘Quality is not what the supplier puts in. It is what the customer gets out of the produce and is willing to pay for’.”
The Greenery believes that investment is needed to sustain the way crops are grown in the Netherlands and is prepared to lead the way. In addition to the research and investment going into energy-efficient systems, it is working with companies such as BASF and Bayer CropScience to reduce chemical use and promote integrated pest management (IPM), so that the Dutch industry can be less dependent on pesticides in the future.
“The national programme for 2020 has made energy efficiency the top priority now and, from that year, all new greenhouse developments will have to be energy neutral and economically viable,” continues Van der Linden. “It has given a good deal of projects within The Greenery a welcome push, as well as involving the Wageningen University on research into using solar energy, closed greenhouses, combined heat and gas and biofuels, to mention a few.”
The growers’ co-operative has also been working on producing energy-efficient plants, which would use less energy, water and heat to grow than conventional varieties. The Greenery hopes to have the first energy-efficient variety, which also produces a high yield and good eating quality, available by 2010.
Van den Bosch, Ridderkerk
Tomato specialist Van den Bosch was the first grower to trial geothermal energy and now runs a 14-hectare greenhouse site using the new technology. Geothermal energy involves drilling two - in this case 1,700m - pipes into the ground until they travel beyond a layer of sand to water. Cold water that has been used in the greenhouse is sent down one pipe and is heated by a layer of sand warmed by the earth’s core temperature. Water that has been heated to 65°C underground is then pumped up the other pipe and used to heat the greenhouse, which removes the need for burning gas.
In addition to this eco-friendly technology, the family company is pumping CO2 emissions from a nearby petrochemical plant into the greenhouse, which enhances tomato production.
One of just four beef tomato growers left in the Netherlands, the company accounts for 35 per cent of all the beef tomatoes grown in the country and sends the majority of its product to UK supermarkets.
“The principle of geothermal energy is simple and is a great alternative to using gasoline,” co-owner Petra van den Bosch explains. “With rising energy prices, there has been lots of research done by growers to make their systems more efficient; some have managed to create systems that produce electricity that they can sell at the same time as growing food and we thought, what if we use the warmth from the ground?
“In 2005, my brother Rik - who is also a co-owner of the business - started the first geothermal trial in the Netherlands in the hope that he could eliminate the need for gas in the process entirely.
“The problem in the Netherlands is that the less energy we use in the greenhouses, the more expensive per unit the gas is. It is better to use none at all if you can for this kind of investment.”
Van den Bosch opened the Netherlands’ first geothermal greenhouse in 2007. The company does not use gas to heat its product from April to November, while production during the winter months requires substantially less gas input than a conventional system.
“We used to use 10m3 of natural gas at this location before the geothermal system was introduced,” says Petra van den Bosch. “But now it is only 1m3 in the winter time and we are thinking about how we can save that last 1m3 too. We have also changed from being a CO2 producer to being a CO2 consumer.”
This partly government-funded €5.5million (£5.1m) project has put Van den Bosch on the map in the Netherlands. Rik van den Bosch now gives seminars to other growers on the advantages of geothermal energy.
And the company is putting its money where its mouth is by converting a second site so it can also use geothermal energy. Drilling began four weeks ago and the new system will serve a 6ha greenhouse in the area.
Petra van den Bosch maintains that geothermal energy is not a quick-fix solution and that the company is thinking strictly in the long term. “We are in a favourable position as the largest of only four beef tomato growers in the Netherlands,” she says. “This process has been essential to make our future business sustainable.
“At the moment, it is not really much more efficient cost-wise because it was a massive investment, but we do not want to use gas at all and now have a long-term solution. We now have stability and a very green product.”
Prominent, Gravenzande
Grower association Prominent has built a greenhouse called Prominent Groeneweg II according to the closed greenhouse principle, which not only reduces the need for fossil fuels by 20 per cent and lowers the emission of greenhouse gases, but uses leftover energy to heat nearby homes.
Construction of the greenhouse started in 2006 and in October of that year, the first batch of on-the-vine tomatoes started to grow. The new 9.3ha greenhouse also uses growth lights and 3.4ha of it is under a semi-closed system.
With a closed greenhouse system, the greenhouse windows are shut during the summer and the extra heat that would traditionally escape is harvested in ground aquifers, to be used in the winter. Cold water from another aquifer is used in the summer to cool down the greenhouse.
Prominent discovered that the system could store enough energy to supply surrounding houses and therefore generate further income, as well as power the greenhouse in the winter.
Heat-power coupling installations are used in conjunction with the growth lights and this technology generates power and helps provide the electricity needs of the location. “The advantages of using a closed greenhouse are numerous,” says Prominent Groeneweg II’s Joost van der Voort. “As well as saving energy and lowering emissions, it vastly improves the crop’s yields. And once the housing development nearby completes in two to three years’ time, we will become an energy provider.
“The system has become more and more efficient every year and it is very new -there are only five companies using this in the Netherlands -and we are constantly on a learning curve.
“Last year, we used 22 per cent fewer fossil fuels, so that is the big plus,” he continues. “The open greenhouse is heated by pipes, which transfer heat between them and produce electricity at the same time. In the semi-closed greenhouse, there is still a bit of an opening to let heat out at the top, as the cooling process is expensive. We always have two-thirds of the greenhouses closed, as at the moment there is too much heat. There is a cool/heat exchange unit within the greenhouse and with this system we have seen a 10 per cent increase in CO2, which has meant a 50 per cent increase in production.”
Similarly to Van den Bosch, Van der Voort explains that although the technology is working, the level of investment is too high to see any profit. But as production becomes more efficient because of the system and when the housing development is finished, Prominent will start to reap the rewards.
“We do not waste any energy and so any natural gas we use is 89 per cent effective,” he says. “Five years ago, our system used boilers that needed a lot of energy just to heat the greenhouse, but this system has made them obsolete. Now we use a limited amount of gas but manage to heat the greenhouses, produce electricity for the lights and the running of the whole site.”
Koppert Cress, Monster
Cress and edible flower producer Koppert Cress has been trialling a light-emitting diode (LED) system for the last two and a half years in an attempt to make its crops grow more efficiently, while using less energy.
It has been found that LED, which is a semi-conducting material that produces only a certain colour or spectrum of light, leads to an 80 per cent reduction in costs because its intensity can be varied according to weather conditions. When the weather is sunny, a sensor allows the lights to be dimmed, but when it is cloudy the light intensity increases.
This provides an environment-friendly solution to traditional high-power fluorescent grow lights, which shine white light and waste energy, as a good deal of the light provided does not affect the crop’s growth.
In addition, there is a connection between the light LEDs produce and photosynthesis of plants. Plants use the blue and red parts of the visible light more efficiently than other parts, so by using only red and blue LEDs the plants grow more efficiently.
The installation of LED is three times as expensive as fluorescent lighting, but offers an 80 per cent electricity pay-back time of less than three years.
LED technology has not yet reached its full potential and Koppert Cress is keen to take it to the next level. “At Christmas time, our greenhouses are at full capacity and we send up to 30,000 boxes of products to the UK a week, so we need to utilise the space we have and grow our crops more efficiently,” says Edwin Koning, the company’s production manager. “We finished building our 17,400sqm greenhouse in Monster in 2006 and there is space to expand, so we are trialling new technologies in the hope of using them in the future.
“We are looking to use a layered system with LED as the lights are close to the plants and maybe eight layers of planting systems can be stacked on top of each other to increase capacity.
“Traditional fluorescent lights practically boil vegetables, but with LEDs we can control the temperature. We have tested a lot of systems over the years and we are waiting for our end results for LED. We really need to get out of using old-fashioned lights.
“We want to roll the LED system out to all of our crops eventually, but we need to develop the system first,” he adds.
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