A greenhouse with daylight installation will be built at the Innovation and Demo Centre (IDC) in Bleiswijk. A greenhouse with such an installation can generate electric and thermal energy. In this greenhouse Wageningen UR Greenhouse Horticulture will be investigating improvement of the energy-efficiency of a daylight installation as well as the crop reaction of a number of pot plants. Bode Project- en Ingenieursbureau has designed the greenhouse which is to be built by Technokas.
Part of the daylight installation is a Fresnel lens placed in the greenhouse cover. This is a special lens which is thinner and lighter in weight than a normal lens and it has a small focal distance. This lens enables concentration of direct sunlight. Another part of the installation is the collector. The direct light is collected by this collector; a tube with solar cells then provides heat and electricity. The remaining diffuse light creates a greenhouse climate that is in particular suitable for pot plants.
A first prototype of a greenhouse with such an installation has been tested in Wageningen. This preliminary research showed that the principle works. An electricity production of 29 kWh per m2 was achieved. The horticultural sector is meanwhile showing great interest in this type of greenhouse with such an installation; growers as well as architects see perspectives in the technology.
Experimental greenhouse
A greenhouse with daylight installation of 500 m2 with a bay width of 4 metres is being built in Bleiswijk, at the IDC on the site of Wageningen UR Greenhouse Horticulture. The Fresnel lenses are placed between antireflection (AR) coated double glass. The greenhouse will have an asymmetrical cover with south-facing lenses. Direct sunlight will be caught by collector tubes that are partly fitted with PV cells.
The study will be running for 1.5 years and its objective is an increase in energy production and light transmission. The ambition is a greenhouse that annually at least produces 35 kWh of electricity per m2 and 240 kW heat per m2. The installation can then be written off in five years. One of the challenges is the development of serial production of the greenhouse with daylight installation. And the control algorithms need further optimisation. The crop reaction of six types of pot plants (from shadow-demanding to light-demanding) will be monitored during the study in the new greenhouse.
This research is financed by the Netherlands Ministry of LNV (Agriculture, Nature and Food Quality) and the Product Board for Horticulture in the context of the programme ‘Greenhouse as Source of Energy’.