From June 2013, the world´s largest collector field could be in Chile. The planned solar collector area amounts to 39,300 m², which would cover more than 80% of the heat used to refine copper at the world´s largest copper mine. The company that is going to set up the turnkey plant is Danish solar thermal system supplier and collector manufacturer Sunmark A/S.
The Gaby mine is located 100 km south of the town of Calama in Chile´s high central desert. The region in the far north of the country has the perfect climate and geography to make use of solar energy. The yearly irradiation can reach up to 2,200 kWh/m². It hardly ever rains and the sky is clear nearly all year round. Average temperatures are 20°C during the day and around 0°C at night. Given these perfect conditions, Sunmark estimates that the plant is going to produce 50,000 MWh per year (1,250 kWh/m²), even with delivering high temperatures of up to 95°C. In combination with a 3,300 m² storage tank, the solar plant is said to cover approximately 83% of the required energy. An oil boiler would cover the remaining 17%. What makes solar even more attractive is the fact that the solar installation could save 250 truckloads of fuel per year, or 8,300 m³ of oil annually.
After inviting international tenders, the contract with Codelco, the Chilean state-owned mining company, was finally awarded to Sunmark. As in all Sunmark plants, the Danish company will use the 14 m² collector produced at its Vietnam factory. The collectors come with aluminium tubes, a copper absorber and a highly selective blue coating.
The solar heat is needed during the last step of copper production, the electrolytic refining of the copper in an acid bath. This bath has to be kept at a temperature of 48°C at all times.
The design for the hydraulics of the large collector field has not been finalised yet. But, as can already be seen on the drawing above, Codelco has its own special design idea: The field is going to look like the company´s logo. Located a few hundred metres away from the factory buildings, the collectors would not be affected by the dust and acid from the refining process. Construction is planned to start in October; the solar panels should be delivered in April 2013.
The plant is said to be completed by June 2013. Unless another large-scale project is going to be announced, the installation will then be the world´s largest solar thermal plant, outrunning the 36,000 m² plant in Riyadh, Saudi Arabia (finished at the end of 2011), and the district heating plants in the Danish towns of Marstal (currently 18,300 m² of a total of 36,300 m² planned) and Dronninglund (35,000 m² planned), including all planned extensions. The largest announced size for a collector field so far has come from Denmark, too: Braedstrup District Heating in Denmark aims at a collector area of 50,000 m² (so far 18,600 m²) – but no schedule has been set yet.
Codelco is a state-owned copper mining company, which was founded in 1955 and is the largest copper mining company of the world. The company itself quotes data from 2007, when it produced 1.66 million tonnes of copper, or 11% of the world’s total production. According to the news agency Reuters, Codelco’s production in the first half of 2012 was 767,000 tonnes due to sinking ore contents in the rock, but planned production for 2012 is 1.708 million tonnes of copper.
Sunmark is one of a few turnkey providers of large-scale solar thermal plants. The company´s references include a 12,581 m² solar plant close to Lillestrøm, Norway, the Marstal district heating plant in Denmark (see above) and three solar plants (7,270 m² in total) for process heat at Heineken breweries.
This text was written by Eva Augsten, a German freelance journalist specialised in renewable energies (firstname.lastname@example.org).