Large-scale South African solar water-heating projects save money and the environment

May 16th, 2019, Published in Articles: Energize

Industry uses more energy in the form of heat than as electricity, giving South African companies the perfect opportunity to exploit the country’s abundant solar and wind resources to produce power and heat for the re-industrialisation of the country.

Speaking at the launch of two of Southern African Solar Thermal Training and Demonstration Initiative’s (Soltrain’s) solar water heater projects recently, Dr Johann Brieger, the Austrian Ambassador said South Africa has demonstrated its commitment to the UN Climate Change Initiative repeatedly with its large rollout of domestic solar water heaters and is now doing so as it introduces large-scale district solar-power hot water systems.

Dr Johann Brieger

The ambassador was referring to two Soltrain projects, a district heating plant for the University of the Witwatersrand’s (Wits’) student residences and a solar process heat plant for the Klein Karoo International (KKI) tannery. These projects will not just save money but will, by reducing demand on the national electricity system, assist in reducing the amount of carbon emitted into the atmosphere.

Soltrain is managed by the Centre for Renewable and Sustainable Energy Studies at Stellenbosch University, and the South African National Energy Development Institute (SANEDI), in partnership with Austria’s AEE-Institute for Sustainable Technologies (AEE INTEC).

Wits Junction

The Wits Junction district heating project combines solar, co-generation and gas heating technologies, servicing 14 student residence buildings with hot water from one centralised hot water plant room. The installation includes 600 m2 solar heating plant with 10 m2 Austrian-made collectors.

There are 1103 students in the 14 buildings, with an average consumption of 94 000 l of hot water per day. Peak demand is in the morning, averaging 30% of daily consumption, with a maximum demand of 28 200 l in an hour. The system supplies the entire hot water demand, including kitchens, laundry, cleaning and other domestic uses. Each student has their own kitchen and there are some centralised service rooms for cleaning staff.

The solar hot water system on the roof of the Wits Junction student residence.

Since the system was commissioned, the complaints of not having hot water have reduced dramatically. The estimated costs savings are R40-million over the next 20 years and already the university has seen substantial electricity savings over the trial period of eight months. As the electricity cost from the co-generator is equal to municipal cost, the thermal energy is free and the centralised plant requires a lot less maintenance intervention, hence lower costs.

Klein Karoo tannery 

The KKI tannery section has installed a 600 m2 solar collector system to reduce costs and increase competitiveness, since fuel costs are highly volatile, and to move its production to a more renewable base.

The solar hot water system installation at KKI Tannery’s factory.

Stellenbosch University approached various tanneries for process heat application viabilities and the KKI tannery was both willing and had the budget to contribute to the study. The tannery’s process heat infrastructure is an oil burner and the feasibility study design determined that solar would displace the local fuel as a primary energy source, indicated as 60% solar fraction. Stellenbosch University predicted a payback of 6,5 years, based on a financial model analysis from the feasibility study, which includes maintenance, finance costs and all system related expenses.

New academic programmes

The Department of Higher Education’s director general, Gwebinkundla Qonde commended Wits University for taking the initiative of installing solar-power water heaters on the roofs of its student residences, saying that academic institutions should ensure that their curricula includes, and even focuses on, the use of natural sources of energy. The increase of incidents of wild fires, floods, droughts, tornadoes, cyclones, and other destructive weather patterns in South Africa and elsewhere show that new techniques need to be developed to combat the changes in the weather. Fana Sibanyoni, Wits’ chief operating officer, said Wits will continue to work on reducing its carbon footprint and that new academic programmes will be introduced to assist students to improve the efficiency of renewable energy-based technologies for the good of Wits, South Africa and beyond.

Additional dedicated funding promised

In his speech, the Austrian Development Agency’s Dr Martin Ledolter, said that Soltrain’s installations are unique in that they are designed to suit specific applications and needs. One should expect a “domino” effect, he said, as more and more people see the real benefits of heating water by means of solar energy instead of, or in combination with, electric power. These benefits are more than just financial, he added, saying that industrial companies will also benefit from being able to contribute to the slowing of atmospheric temperature rise by moving away from electrically-heated water to solar-heated water for their process heat needs. He promised a further €2,5-million support for Soltrain’s projects.

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