Research by Wageningen UR Greenhouse Horticulture shows that the use of a thermo-electric generator (TEG), utilising residual heat for electricity production, is economically not interesting for horticulture in the Netherlands. Together with the energy consulting company KEMA Wageningen UR scientists conducted a so-called desk study, analysing existing research results, in which they investigated the possibilities for application of the TEG technology in greenhouse horticulture.
More efficient energy utilisation in greenhouse horticulture will require the best possible utilisation of all available heat. New techniques are therefore studied in the context of the programme Greenhouse as Energy Source. One of those techniques is the thermo-electric generator (TEG). This device is based on the principle that temperature differences between two materials result in an electric current. TEGs are currently, e.g., used for generating electricity at very remote places and in the space industry.
Heat loss
Energy loss in the form of residual heat occurs in different places in greenhouse horticulture. Utilisation of this heat is desirable to make the most efficient use of fossil fuels. The possibilities of TEG in combination with Heat Power Coupling, tube heating, heat buffers and lighting have been assessed in the desk study.
Technical possibilities for generating electricity with residual heat were identified for all situations. Practicability at the moment, however, is limited. The main bottleneck in case of tube heating and heat buffers is the fact that the temperature difference with the environment is not large; this means that electricity generation cannot be efficient. In combination with lighting, TEC is technically very complicated. At the moment only a combination with Heat Power Coupling seems to be feasible but the current costs of the systems are still very high, resulting in long cost recovery times. The researchers do not expect application of the TEG technology in horticulture before a considerable price decrease of TEGs per produced Watt.
The study has been carried out for the Product Board for Horticulture and the Dutch Ministry of Agriculture, in cooperation with KEMA and Gasterra.