Sunshine and seawater. That’s all a new, futuristic-looking greenhouse needs to produce 15,000 tonnes of tomatoes per year in the South Australian desert.
It’s the first agricultural system of its kind in the world and uses no soil, pesticides, fossil fuels or groundwater. As the demand for fresh water and energy continues to rise, this might be the face of farming in the future.
An international team of scientists have spent the last six years fine-tuning the design – first with a pilot greenhouse built in 2010; then with a commercial-scale facility that began construction in 2014 and was officially launched today.
Seawater is piped 5.5 kilometres from the Spencer Gulf to Sundrop Farm – the 20-hectare site in the arid Port Augusta region. A solar-powered desalination plant removes the salt, creating enough fresh water to irrigate 180,000 tomato plants inside the greenhouse.
Scorching summer temperatures and dry conditions make the region unsuitable for conventional farming, but the greenhouse is lined with seawater-soaked cardboard to keep the plants cool enough to stay healthy. In winter, solar heating keeps the greenhouse warm.
There is no need for pesticides as seawater cleans and sterilises the air, and plants grow in coconut husks instead of soil.
The farm’s solar power is generated by 23,000 mirrors that reflect sunlight towards a 127-metre high receiver tower. On a sunny day, up to 39 megawatts of energy can be produced – enough to power the desalination plant and supply the greenhouse’s electricity needs.
Sundrop is now planning to launch similar sustainable greenhouses in Portugal and the US, and another in Australia. Other companies are also testing pilot seawater greenhouses in desert areas of Oman, Qatar and the United Arab Emirates.
“These closed production systems are very clever,” says Robert Park at the University of Sydney, Australia. “I believe that systems using renewable energy sources will become better and better and increase in the future, contributing even more of some of our foods.