Energy
Although The Netherlands is known for it’s agricultural expertise, it is also common knowledge that Holland does not have as much warm sunny weather as some of her Mediterranean counterparts.
Another form of green energy
Consequently, Dutch organic greenhouse growers like Ruud van Schie are looking for innovative, environmentally friendly ways of heating their greenhouses without using fossil fuels. These guys are clearly sticking their necks out and investing millions to achieve this goal.
Ruud van Schie is the first Dutch organic horticulturist, recognising the potential of geothermal energy for greenhouses. He applied for a subsidy from the Dutch government for a project that will start in 2010.
The principle works as follows: To heat a greenhouse, the warm water (55-60 degrees Celsius) needs to come from a certain layer in the ground. Using a heat exchanger, the water is pumped back into the ground.
To use the warmth of the earth, two pipes (each with a length of 1.5 km) and around 2 km apart from each other need to be drilled through the earth’s crust. Through the first pipe the warm water is pumped up from the sand layer. Once on the surface, the water releases it’s warmth and the colder water (30 degrees Celsius) is pumped back into the same sand layer using an “injection pipe”. Due to the fact that the water is pumped back into the original layer, the pressure remains the same. TNO (Dutch Research Organisation) expects the pipes to have a life expectancy of more than 30 years and more.
Another example is Cogeneration in the Greenhouse. Cogeneration consists of transforming fuel into mechanical energy, electric energy and thermal energy. Through this double transformation, yields close to 100% can be obtained from the energy contained in the fuel. The exhaust gasses of gas-fuelled cogeneration modules contain C02. Once treated, these gasses can be mixed with the air in a greenhouse and act on the plants which assimilate carbon dioxide, converting it into carbohydrates. A further advantage is that as a result the productivity increases by around 35%. Due to its great energy utilisation rate and contribution to photosynthesis, cogeneration reaches its maximum level of effectiveness when applied to greenhouses.
