The report on the Elkas II project from Wageningen UR Greenhouse Horticulture showed that it is possible to use a greenhouse to produce electricity in a climate neutral greenhouse. The greenhouse has internal transparent blinds with a near infrared reflective (NIR) filter. On sunny days, the horizontally mounted blinds reflect only the NIR radiation to a photovoltaic collector in the greenhouse. When outside temperatures drop, the blinds can be closed to keep the heat in.
The system generates eight kilowatt hours per square metre and a heat supply of 200 mega Joules per square metre annually. However, technical problems still limit the system’s efficiency. As a result, the project is not currently feasible in the Netherlands’ growing environment.
“The main reason for this is the relatively low efficiency for harvesting the solar energy and the amount of [photosynthetically active radiation] which is blocked by the system,” a report on the project read. “The concept is not expected to be feasible in the (near) future because conventional [photo voltaic] is getting cheaper in relation to concentrated [photo voltaic]. This applies particularly in Northern Europe where the performance of concentrated CPV is about 30 per cent in relation of conventional PV.”
The Dutch horticulture industry accounts for approximately 10 per cent of the country’s total natural gas consumption. The sector is aiming to make the cultivation of new greenhouses economically viable by 2020.