Solar thermal plant approved for Port Augusta greenhouse

Plans for what will be Australia’s largest solar tower power and water distillation plant has been approved for construction at commercial greenhouse business in South Australia, which already uses solar power and seawater to grow vegetables.

The proposal by Sundrop Farms to build eight more greenhouses, totalling 20 hectares, which will use 36MWth of solar-thermal energy to heat the greenhouses and desalinate water from Spencer Gulf, was this week approved by the Port Augusta council, subject to conditions.

The plans approved include the construction of a 100 metre high solar power tower topped by a 15 metre high solar receiver, and a ‘solar field’ of around 11,000 stands, each holding three heliostat mirrors.

The plans also include the construction of two Multiple Effect Distillation (MED) plants, several seawater pipelines, a pipe for brine dispersal into the gulf, and a visitor centre to help promote tourism interest in the venture.

According to council notes, the solar tower will contain 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 by circulating through the internal pipework. After being circulated through the greenhouses the water is returned to the hot water storage tank for reheating.

Some of the stored heat will also be used to distil seawater in the two (MED units to distil seawater into fresh water for the plants in the greenhouses.

According to the council submission, around 3,000 megalitres of seawater a year will be drawn from Alinta’s Northern 2 intake channel, to produce over 335 ML of freshwater for use in the greenhouses and for other purposes on the site.

Most of the solar thermal generated steam will be used for the greenhouses and the desalination, but the steam will also be used to spin a turbine that powers a generator, producing up to 1.5MW of electricity to run the site. A connection to the mains power supply will provide backup power.

A diesel driven backup boiler will also be installed, to supplement the hot water if the solar thermal power supply is disrupted.

According to Sundrop, work on the expansion is expected to begin this year. Last year, the Clean Energy Finance Corporation said it would help finance the facility, which could cost up to $100 million.

The project is expected to employ more than 200 people and will produce over 15,000 tonnes of tomatoes a year for metropolitan markets across Australia. The company hopes it will be the fore-runner of many more projects in Australia and other desert regions, particularly in the Middle East and north Africa.