Energy saving potential in the New Zealand agricultural sector with emphasis on the vegetable greenhouse industry : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Natural Resource Management at Massey University

Abstract

In the last decade, the energy demand of New Zealand's horticultural and agricultural sub sectors has increased as a result of land use conversion, intensity of production, the use of irrigation and an increase in energy intensive horticulture, such as greenhouse vegetable production. This has highlighted the sector's reliance on fossil fuels leaving it susceptible to future shortages, higher prices and the forthcoming carbon charge. As part of a contract with the Energy Efficiency Conservation Authority, which aimed to compile, estimate and analyse information from a wide variety of sources on energy end uses and patterns of energy consumption within the agricultural sub-sectors, available literature on energy demand by fuel type and the various uses to which energy is put in the New Zealand primary production sub-sectors was collated in matrices. Through the compilation of these matrices it was evident that limited energy related research was available relating to the greenhouse sub sector. The New Zealand greenhouse industry is a relatively energy intensive sub-sector of the primary production industry and relies heavily on the use of fossil fuels. The impending carbon charge may result in a cost which growers may be unable to pass on due to competition on the domestic and export markets from non-Kyoto countries. It follows that reducing energy consumption and consequently avoiding the emissions charge would be a means of increased viability for the industry. This part of the research was funded and conducted in conjunction with the New Zealand Vegetable and Potato Grower's Federation Inc. A walk-through energy audit was designed and conducted with 22 greenhouse vegetable growers. This provided an in-depth case study perspective in terms of what technologies and practices are currently used by the New Zealand's protected cropping industry. The findings from the energy audit show that location and the heating system type are significant factors in determining energy use. The main areas identified where potential energy saving could be made were minimising heat loss, through the cladding, the heat distribution system and the flue, and improving heating efficiency, through improved heater maintenance. An energy saving model was designed using Microsoft Excel for the purpose of encouraging the user to think about potential energy savings that could be made within their individual greenhouse operation, and also the potential cost of the carbon charge on to their business. Recommendations from the model were based on best practice and use of energy saving technologies identified through the energy audits, review of current literature and consultation with manufacturers.