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Desert farming with next era solar

Farming in the desert might seem a bit optimistic. An Australian greenhouse uses concentrated solar power to produce energy and become independent of fresh water supplies. The result is 17,000 tons of tomatoes a year.

ENERGY-WATER-FOOD NEXUS

Relying on nature’s abundance of sunlight and desalinated seawater to produce high value crops in arid areas, Australia’s Sundrop Farms operates the first greenhouse of its kind. The project takes concentrated solar power to the next level.

Growing fresh fruit and vegetables in the desert may seem like a Sisyphean project. Yet that is exactly what Sundrop Farms does in South Australia, using primarily sunshine and seawater to fill eight trucks with tomatoes every day, or about 17,000 tons a year for consumers across the country.

Approaching Sundrop’s farm outside Port Augusta, a three hour drive south of Adelaide, the arid outback is dominated by the facility’s 127 metre tall, sky-piercing solar tower. Get closer and the 23,000 mirrors placed at its base come into view, each of them collecting the sun’s rays and reflecting them to the tip of the tower.

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According to Denmark’s technical university, large scale production of food, such as lamb and fruit in New Zealand, often appears to be less energy intensive than smaller scale production of the same products by countries already importing them

The heat warms up a pipe that contains a sealed-in supply of oil, which in turn brings the water pumped up from the nearby Spencer Gulf to 160°C and desalinates it. The water is then used to irrigate tomato plants growing on the 20 hectare greenhouse area during the seasons. Periodically, it is also used to run a steam turbine for electricity generation.

The integrated energy system, designed and delivered by Denmark’s Aalborg CSP, a concentrated solar power specialist, is the first agricultural set-up of its kind. Contrary to conventional greenhouses, it uses no pesticides, fossil fuels, groundwater or soil, while avoiding the emissions of up to 16,000 tons of CO2 annually.

“If you can farm successfully here, you can farm almost anywhere in the world,” Sundrop Farm boss Philipp Saumweber recently stated as the company seeks to launch similar projects in Portugal and the US. Other companies thinking along the same lines as Sundrop are testing pilot seawater greenhouses in desert areas in the Middle East.

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WATER GUZZLER

Agriculture today consumes 70% of the earth’s available fresh water. With the world’s water demand for all uses projected to increase by more than 50% globally between 2000 and 2050, projects like Sundrop Farms may well be the face of the farming future, experts predict.

“It’s a very interesting configuration because it’s an extremely high-tech and potentially cost-effective way of making food,” says Keith Lovegrove of IT Power Group, an energy consultancy. He adds that the business of integrated energy systems is gaining a foothold as an industry in its own right.

A recent report from the Technical University of Denmark (DTU), the International Energy Report, supports his view. It concludes that energy, water, and food need to be considered together in the so-called energy-water-food nexus if the world is to respond successfully to the resource challenges posed by climate change and population growth.

The Sundrop Farms initiative and projects like it depend on a high degree of predictability of production output and a stable resource-efficient water and energy supply. They have promising prospects to make a huge difference in drought stricken agricultural areas around the world, says DTU’s Martin Drews, one of the report authors.

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Somewhere in the region of 30-50% of all food produced is wasted, along with the energy used to produce, supply and dispose of the
discarded feedstuff

COST LIMITATIONS

Sundrop Farms, however, clearly has its limitations in terms of what can be grown, says professor Robert Park of Sydney University. “Many staple foods that are crucial to food security are grown over very large areas that could not be achieved in a greenhouse system, for example wheat, rice, maize and so on,” he says. Other critics argue that desalination really only make sense in places that are water-stressed.

While Sundrop Farms does not use any fresh water, the solar driven project still relies on main grid power for 10-15% of its power needs, especially during winter. On site, there is storage for about ten days for water, heating, cooling and electricity.

According to Drews, it is no surprise that Sundrop Farms, with a total project cost of around $200 million, was established in Australia, which also has a strong infrastructure and a financially sound customer base.

“If a project is to be economically viable, there has to be a strong market as well as an adequate distribution chain in place, which would currently disqualify many of the obvious production places in the developing countries,” he says.

The economics of Sundrop Farms are hard to ascertain, with the company declining to provide information on its cost of energy. Lovegrove, however, insists that integrated energy systems can be made to have a good return on investment once the full costs of energy provision are taken into consideration. “Every sustainable approach is linked to the world’s approach to greenhouse gas emissions and how much we value its cost versus the price on oil and other fossil fuels,” he says. •

TEXT Sofie Buch Hoyer /PHOTO Sundrop Farms