Techno-Economic Analysis of Sustainable Energy Systems for Meeting the Energy Demand of a Greenhouse in South Australia
Jeremy Rudston BSc Eng
Project submitted in partial fulfilment of the requirements for the degree of MSc (Energy and Resources), UCL School of Energy and Resources, Australia
Torrens Medal Winner - UCL 2011
To address the supply constraints of energy and water in the agricultural sector, Sundrop Farms (with the support of the South Australian government) have developed a seawater greenhouse system that taps into the abundant renewable resources of seawater and sunlight to produce freshwater, and generate heat and electricity. The aim of this dissertation is to conduct a techno-economic analysis of the sustainable energy supply of heat and electricity required for controlling the climate inside the greenhouse. Two well-recognized freeware packages are used in the analysis; RETScreen for the thermal energy analysis and HOMER for the electrical energy analysis. Given the semi-arid conditions experienced at the location and its sunny weather for much of the year, the main focus of this work is on solar energy (both solar thermal and photo-voltaic). Due to the high thermal energy demand being out of phase with the higher levels of solar radiation, seasonal thermal energy storage is also considered. It is concluded that at current system costs and conventional energy prices, energy from sustainable resources remains expensive. A sensitivity analysis is performed on the internal rate of return to realize the prices and system costs needed for higher solar fractions to be economically viable. Despite sustainable energy solutions not being cost competitive with conventional fuel-source energy at this time, the gap has certainly narrowed over the past two decades. As further price increases for emission-intensive forms of energy can be expected in the near future, while the cost of PV and solar thermal collectors decrease exponentially, it is a matter of time before sustainable solutions will be financially, as well as ethically, more attractive. In turn, the future of greenhouse agriculture may be brighter as the security of energy and water for the sector is guaranteed.