Electricity + Control 2019

ENGINEERING THE FUTURE

ings 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, running costs are considerably reduced.” Klein Karoo tannery Klein Karoo International (KKI) has installed a 600 m 2 solar collector system to deliver process heat at the tannery. With the primary aim of reducing costs and increasing its competitiveness in the global market, KKI was also motivated by the strategic intention to move its production to a more sustainable base. Stellenbosch University’s CRSES had ap- proached a number of tanneries to look at the viability of using solar energy for process heat ap- plications. KKI was prepared to take the risk and committed to contributing to the study. Doran Schoeman of E3 Energy, the company that handled the installation, explained: “The pro- cess heat infrastructure uses an oil burner and not electrical heating. The fuel used is LO10 paraffin oil, at an indicated rate of 11.8 kWh per litre. The feasibility study looked at using solar energy in place of the local fuel and indicated a 60% solar fraction. The savings, based on measurements from the plant over the period of eight months from installation, amount to about R265 000, or 24 150 litres of oil. “The feasibility study indicated a payback period on the plant of six and a half years, based on a solar fraction of 60%. The financial model used includes maintenance, finance costs and all system related expenses.” He added that, “Strategically, the approach was to implement a first phase using solar thermal en- ergy and to monitor actual results to estimated savings. This analysis is still in progress and further commitment will be based on the results achieved.” Dr Karen Surridge, Centre Manager, Renewa- ble Energy Centre of Research & Development at SANEDI said, “SANEDI is delighted to be associ- ated with such landmark developments that put the SOLTRAIN projects firmly on the renewables table. The successful conference we have just held with SOLTRAIN regional partners indicates the relevance of this programme for the SADC re- newable energy strategy and the development of successful systems across six countries.”

The plant room of the district heating project at Wits Junction.

The 600 m 2 solar collector system installed at KKI supplies process heat to the tannery.

Wally Weber of BlackDot Energy explained: “A combined system uses the advantages of each technology: solar has a very low running cost, while CHP (combined heat and power) provides continuous base load coverage. The combination covers thermal and essential electrical loads. “For the more than 1 100 students, average con- sumption amounts to 94 000 litres of hot water per day. Peak demand is in the morning, averaging 30% of daily consumption, with a maximum demand of 28 200 litres in an hour.The system supplies the en- tire hot water demand, including kitchens, laundry, cleaning and other domestic uses. Each student has his/her own kitchen and there are some cen- tralised service rooms for cleaning staff. Fana Sibanyoni, Chief Operating Officer atWits, highlighted that, as well as the cost savings, one of the major benefits of the new system is that students’ complaints of not having hot water have reduced significantly to almost nil. Weber added that the redundancy design guarantees supply, even during maintenance periods. He noted further: “Estimated cost savings are R40 million over the next 20 years and already the university has seen substantial electricity sav-

For more information, visit www.sanedi.org.za or https://soltrain.org

38 Electricity + Control

JUNE 2019