Green' energy is hot in Dutch greenhouses. Some of the world's most innovative energy solutions are being developed in the Netherlands for its energy-intensive greenhouse farming industry. Dutch companies are re-using heat that is created by other sources, such as an IT data centre and a fertilizer factory, in greenhouse cultivation. In turn, greenhouses are being used as solar panels to harvest and supply surplus energy to schools and retirement homes. This cross-sector innovation is a growing trend.

Take the Dutch energy project, 'Warm CO2'. It has turned Terneuzen, in the south of the Netherlands, into the most sustainable horticulture-under-glass area in the country. WarmCO2 recently inaugurated its innovative heating network which derives residual heat and CO2 from the Yara artificial fertilizer plant and distributes it through its own 5 km pipeline to nearby greenhouses. The system produces up to 84MW of residual heat and 70,000 tonnes of pure CO2 per year. Greenhouse farmers traditionally use a gas-fired furnace to produce both CO2 and heat for the entire growing season. By taking advantage of the WarmCO2 system, farmers can reduce their use of fossil fuels by 90 percent. That is a drastic reduction in their carbon footprint.

Similar reductions are being made by greenhouse farmers in the northern Dutch town of Wieringermeer only here the energy source is an IT data centre. Dutch company, Parthenon, has come up with the world's first 'green' IT solution. It has built its new data centre right in the middle of a vast greenhouse farming area. The heat from the data centre, which in conventional buildings disappears through the roof, is being channelled to the greenhouses to grow peppers and tomatoes. This will save up to 800 tons of carbon emissions per year.

The revolutionary centre is being designed and built by Parthenon Data Centres together with Royal Haskoning, a Dutch engineering consulting firm. The project is already gaining international acclaim. Parthenon's Managing Director Pieter Duijves says the world's IT giants have expressed serious interest in the unique Dutch design. "We now realise it could become a Dutch export item," he says.

"The cooperation between a greenhouse complex and a data centre is a splendid example of cross-sector innovation," stated the Dutch Minister of Agriculture, Nature and Food Quality, GerdaVerburg.

The new data centre measures 10,000 square metres and has an average power capacity of 5 kilowatts per square metre. The available energy is optimised across the data centre and the surrounding greenhouses through the exchange of heat, cold and electricity. This results in lower energy costs across the board.

A similar but also unique approach is being taken by a tomato grower in Venlo, in the south of the Netherlands. JoepRaemakers is actually harvesting surplus heat from his greenhouses and using it to heat a nearby home for the elderly, a school for disabled children and a public swimming pool. The savings in energy costs that these new partners enjoy, are subsequently channelled into their core tasks, such as providing care for their clients.

The Greenport Glasshouse is one of the first projects to combine technical, environmental and social sustainability in greenhouse production. In traditional growing systems, heat from solar radiation or from a gas-driven source could only be used momentarily in the greenhouse. New technical solutions make it possible to store heat for longer periods of time in aquifers located deep under the ground. This allows growers to use summer heat in winter conditions. The excess of solar heat from the greenhouse is used to cool the greenhouse in the summer, and surplus heat can be offered to external parties. This effectively gives growers an additional profession: that of heat supplier. No longer will they only harvest fruit and vegetables in their greenhouses, but also heat.

Pioneer Raemakers explains: "I want to grow tasty tomatos, decrease the use of fossil fuel, reduce the carbon footprint and integrate my company in the local society." Many of Raemakers peers in the greenhouse industry have already expressed interest in the sustainable system. The Dutch SynErgy network is pooling knowledge and resources to support the growing trend.

• www.warmco.nl (Dutch language only)