A GREENHOUSE project utilising seawater to grow produce near Port Augusta could potentially be mimicked in the Upper Gulf St Vincent, according to Regional Planning Directions consultant, Henri Mueller.
Mr Mueller, who previously worked at the District Council of Mallala, assisted as an independent consultant with Port Augusta council’s Community Planner in the assessment process of the recently approved project.
Sundrop Farms lodged the application to construct eight greenhouses, built in four five-hectare modules, providing a growing area of 20 hectares.
The greenhouses are supported by state of the art technology and infrastructure for solar thermal energy generation, plus related facilities within the boundaries of a 380 hectare pastoral property located down the road from its existing 0.2 hectare pilot operation.
The Sundrop Farms greenhouse project harnesses the sun’s energy to desalinate seawater to produce freshwater for irrigation, produce electricity to power the greenhouse and provide the energy to heat and cool the greenhouse.
It is a complex process to explain but here goes: a field of mirrors reflect the sun’s light onto a solar thermal tower, which absorbs heat.
The tower contains a boiler to generate steam, which is condensed into hot water to heat a large hot water storage tank (storing up to 22,000 cubic metres of hot water) situated adjacent to the tower.
The solar thermal infrastructure will heat a closed loop system of hot water that heats another closed loop-transferring heat to the greenhouses in winter by circulating through the internal pipework.
Some of the stored heat will also be used to distil seawater in two multiple effect distillation units (MED’s) that distil seawater into fresh water to satisfy the operational needs of the project.
The steam also drives a turbine within the tower, generating electricity for the project and to run the evaporative cooling fans in summer.
Mr Mueller said there may be potential to host a similar system near the Upper Gulf St Vincent.
“Provided that there are sufficient sun access days to generate the solar thermal energy to run such a complex, then distillation of seawater for use in irrigating horticulture, could be feasible, particularly in the vicinity of Middle Beach north west of Two Wells,” he said.
“The existing channels at Middle Beach previously used for drawing seawater for the salt fields could be used to draw water for distillation and for the outfall of brine.
“However, the channels at Middle beach may need dredging to ensure that the tidal velocities of the water are sufficient for the dispersal of the brine at the outfall, while minimising any negative effects on the environment.”
Environmental impacts from returning saline water to the sea were limited.
“The salinity level of the brine associated with desalination by distillation is not as high as from reverse osmosis and would be closer to ambient levels within the Salt Creek estuary,” Mr Mueller explained.
“Other effects of the development would need to be considered including solar glare during daytime and appropriate landscaping and environmental controls.
“The effects of such a development would also need to be balanced against the benefits including job creation and spinoffs for business in the area.”