The best innovations are those from which the economy, consumers and the environment benefit. The hydroculture greenhouse in Oftringen in the canton of Aargau has clearly set itself this objective and the resource efficiency network Reffnet has created the basis for making it possible.
Yvonne von Hunnius, 11.03.2016
“From May, 8,000 heads of lettuce will be harvested here every day,” says Patrick Forster. The greenhouse in which the owner of Trachsel Fruchtimporte AG stands is still empty. It’s a cold morning in Oftringen, barely above zero. The greenhouse seems enormous – at a total area of 1.6 hectares it could accommodate two football fields. Building workers are getting everything ready for the first lettuce seedlings, which must not be allowed to freeze on any account. Forster points to pipes under the glass roof and explains: “Warm water will soon flow through them so that the lettuce plants will thrive, both summer and winter alike.” A solution of water and nutrients also runs almost one metre above the ground in kilometre-long channels, which form a kind of conveyor belt for the lettuce plants. In six to eight weeks, the seedlings flourish to become mature lettuce trios and oak leaf lettuces. They are then ready to be sent to the branches of the Migros Aare retail cooperative. The lettuce trios, which are sold with roots in a pot, can even continue to grow when they reach their final destination with the customer.
A first for Switzerland yields added-value
The hydroponics cultivation method is already widely practised throughout the world. Due to its efficiency, many observers see it as a solution to the problem of feeding a global population that will soon exceed nine billion people. The first greenhouse in Switzerland that is designed to operate entirely using this method is currently being developed in Oftringen. Its main sales partner, the retail cooperative Migros Aare, aims to maintain the added-value from lettuce production in the region all year round, and in this way largely dispense with imports as a source of supply. However, customers will have to get used to the idea that these lettuce products were never planted in the ground. According to Migros Aare’s media spokesperson Andrea Bauer, the sceptics will be won over by the taste. She reports that the managers have tested hydro lettuces produced abroad: “The lettuce has an excellent taste as it is not exposed to any weather impacts – for example long periods of rain– and the plants enjoy consistent growth conditions that are tailored to their needs,” says Bauer.
A hydro lettuce factory saves on space, nutrients and time. But does it not consume a lot of energy and ultimately generate considerable environmental impacts? If that were the case, vegetable grower Forster would not have pursued this project. This was also a clear understanding with Migros Aare. Studies recently confirmed that this hydro lettuce is substantially superior to open-air lettuce in relation to all of the relevant environmental factors (see Fact box 2).
Quest for the greatest environmental gain
Studies carried out in the context of the resource efficiency network Reffnet compared the water, energy and materials requirement of hydro lettuce production in summer and winter with that of open-grown lettuce and standard greenhouse lettuce from Switzerland and Italy. The studies were carried out by a team of climate protection experts from the NGO myclimate led by Daniel Kammerer.
The Reffnet network, which is funded by the federal authorities, has been helping Swiss companies to improve their efficiency since 2014. The aim is to enable companies to save on materials, energy and costs with the help of the network’s consultancy services. For example, the result of the hydro lettuce studies showed that dispensing with heating oil brings major environmental advantages. Patrick Forster says: “Once we had the results of the study in our hands, we looked for a building site that would enable us to use environmentally friendly energy sources.” A plot right next to the Oftringen waste incineration plant (WIP) was found. The greenhouse can use waste heat from the plant which is not hot enough to be used in the normal heating network. In addition to water with a temperature of 83 degrees, the WIP also produces water with a temperature of 53 degrees – which is perfect for the greenhouse. Once it has provided heat for the greenhouse, it is channelled back into the WIP’s water cycle.
Fewer resources – higher yields
Reffnet projects constantly produce surprising results. Kammerer reports: “Who would have believed that a hydro lettuce from wintry Switzerland would be so superior in terms of its environmental impacts?” The reason for this lies first and foremost in the efficient production process which generates greater yields from the same resources in a smaller space. As a result, the volume of irrigation water is more than halved compared to that required for open-air cultivation. The nutrient solution flows in a loop and is produced almost entirely from harvested rainwater. From Kammerer’s perspective, the CO2 question is crucial, that is the fact that the greenhouse is not heated using oil: “Just 80 to 100 grams of CO2 are emitted from the production of a head of hydro lettuce. That is the volume emitted by an efficient modern car per kilometre. In contrast, up to 1.32 kilograms or 16 times more CO2 is generated by the production of a head of lettuce from a conventional greenhouse. To stay with the car example, we are comparing a highly efficient vehicle that produces over three times fewer emissions than a real gas guzzler.”
There is parameter that reflects the overall effect of resource efficiency: eco-points (EP) summarize the main factors involved here. At 116 EP, the total impact of a head of summer lettuce produced using hydroculture is 47 percent lower than that of open-air lettuce. However, according to Kammerer, the results cannot be transferred directly to tomatoes or other products. “The correlations are complex and we have to start over from scratch every time and study everything in detail,” he says.
A partner for resource budgeting
The Reffnet network has undertaken to help companies to save on 74 billion eco-points annually from 2016. Its consultants’ knowledge of resources is as wide-ranging as the Swiss corporate landscape itself (see Fact box 1). Daniel Kammerer, the chairperson of Reffnet, explains: “For this reason, 25 experts from the most wide-ranging areas and institutions work with Reffnet.” Newly accredited experts are constantly being added to the network. They have a lot to do: Reffnet estimates suggest that the resource efficiency of Swiss companies could be improved by around 25 percent within a period of ten years. This represents an enormous potential which is important, not only in times of a strong Swiss franc.
Last modification 18.04.2016
