Greenhouse on the road to be energy producer

The greenhouse sector currently has extremely high energy overheads, so finding ways of reducing energy consumption is of great economic and climatic interest. In the longer term the aim is for greenhouses to actually produce energy themselves.
“By altering the climate control system at Hjortebjerg Nursery to a dynamic climate in which optimum use is made of natural light, we can reduce the whole nursery’s energy consumption by around 20 percent. In specific terms, the concept is to accept slightly higher temperature and humidity variations, so the idea is relatively easy to implement once you have developed the model,” explains Project Manager Anker Kuehn of AgroTech, which is involved in developing the new greenhouse concept.
The next step in the project has already been taken, with energy depots established underground in which surplus energy from the summer can be stored and reused during the cold months.
A greenhouse functions like an efficient solar collector, and on an annual basis receives twice as much solar energy as is used for a whole year’s heating. On an annual basis the energy consumption for heating the glasshouse area is an average of approx. 400 kWh per m², while annual insulation is approx. 1020 kWh pr m².
“For eight months of the year the energy input is higher than energy consumption. By collecting and storing the summer’s surplus heat and using it in the heating season, the greenhouse can become self-sufficient on energy – and even supply the nursery’s six other greenhouses. For a large part of the year heating requirements are limited to night-time,” explains Anker Kuehn.