In Australia, the deployment of large commercial solar thermal plants is picking up speed. This year, Monash University had a solar field of 0.5 MW put into operation and aims to expand it to 1 MW. The solar heat that is fed into the district heating system of the large campus area in Clayton, a suburb of Melbourne, is said to meet the entire heat demand in summer. The field consists of vacuum tube collectors by Australian manufacturer Greenland Systems (see photo) and was designed and installed by the LCI engineering consultancy from Melbourne. Currently, Danish Aalborg CSP is in dialogue with Perth-based Agrimin about the supply of solar process heat to a planned sulphate of potash (SOP) mine and processing factory in the state of Western Australia.

Photo: Greenland

The district heating system at Monash Campus runs at 150 °C and 12 bars and is supplied by two 8 MW central gas boilers. LCI chose the highly efficient Greenland Orange Series because it can provide hot water at up to 200 °C. In contrast to concentrating systems, the Greenland collector can make use of diffused solar irradiation, meaning it performs well even in Melbourne’s often cloudy weather. 

The prototype of the heat pipe collector series was examined at the now-closed German Test Centre Saarbrücken in 2012. The unit has a single-glass vacuum tube with a diameter of 100 mm and a length of 1,975 mm and a Tinox-coated absorber fin, which is dry-connected to the manifold. The Greenland collector’s specific yield based on Solar Keymark calculations was somewhere between the Aqua Plasma collector by German manufacturer Ritter and the Thermomax one by Irish producer Kingspan (see the table below). For more details on the yield calculations for Solar Keymark, please see this news article.

Specific annual yield of Aqua Plasma and Thermomax according to the certificates available online in the Solar Keymark database. ScenoCalc was used to determine the Greenland collector’s annual yield based on a test report from the now-closed German Test Centre Saarbrücken.

“The great thermal performance of our GLX 100 solar collector is the result of several incremental improvements, all the time remaining fully mindful of the economic implementation,” explained Marko Pintar, Founder and Managing Director of Greenland Systems. The company’s technical designers have reduced emissions at the backside of the absorber fin and optimised the number of tubes in a collector frame. “We are now aiming at solar cooling installations with double-stage sorption chillers. They need entry temperatures of around 150 °C, which our collectors can deliver,” said Pintar. These systems can then be used for heating in winter, something that will again improve efficiency. 

Greenland, which was founded as an industrial electronics supplier, runs an assembling production line for vacuum tube collectors in China and purchases key components from OEM manufacturers. Since the first-ever solar thermal installation in 2004, this segment has grown steadily, dominating the company’s turnover today. According to Pintar, the two drivers of commercial solar heat in Australia are the relatively high energy prices and the small-scale technology certificates (STCs, former RECs), for which larger solar heat plants are eligible as well. 

Process heat for potash mine

A March 2017 news piece at abc.net.au reported that Agrimin had announced an ambitious target, namely to employ solar thermal to meet 70 % of the hot water demand for a planned potash production factory in Western Australia: “Potash is used as a fertiliser and the company will start construction on a plant to process its raw product into an export-ready fertiliser in 2019.” Aalborg CSP, the Danish turnkey supplier of the solar tower with 52,000 m² of mirror area at the Sundrop tomato farm in the desert of South Australia, has confirmed that joint development work are underway. “In March 2017, we signed an exclusivity agreement with Agrimin to investigate the potential of using solar heat for the company’s Mackay Sulphate of Potash Project in Western Australia,” said Jes Donneborg, Executive Vice President at Aalborg CSP. “So far, a scoping study has been completed and as part of this study, we are working closely with Agrimin to investigate the best individual solar thermal solution for their energy needs before the final contract is closed.” Agrimin is planning to extract SOP from the surface of Lake Mackay, a large dry salt lake, by pumping ground water into evaporation ponds to harvest the crystallised potash salts. A clip at agrimin.com.au/mackay-project explains the process.