The gas burners used for heating water for students living at the University of Witwatersrand’s Barnato Hall residence were generating enormous costs for the university owing to old and inefficient equipment, which was ultimately affecting service delivery.
The university, which previously had piped natural gas infrastructure available from Egoli Gas, evaluated the situation and strategically decided to reapply for a piped natural gas supply to generate an embedded baseload of 160 kWh with a natural gas generator solution.
By installing heat exchangers to harvest waste heat from the gas engine block and exhaust, a significant amount of waste heat is captured and re-used to heat water in the residence.
By generating baseload energy with a natural gas engine, every 1 kWh of electric energy produces 1.6 kWh of thermal energy. A hybrid solution, combining gas with a 30% solar application, yields a constant flow of hot water to about 2 500 students at no additional cost. The boiler room delivers between 70 000 ℓ/d to 80 000 ℓ/d of hot ablution water to Barnato Hall.
The waste heat is retained through a groundbreaking 40 000 ℓ, low pressure
storage unit. It consists of a high temperature liner with heat maintained at 80° C. Low pressure vessels assist with corrosion prevention and are low maintenance. This solution carries a 25- to 30-year life span.
The investment of less than R10-million now offers a saving of R119-million over the next 20 years, while the old redundant water plant serves as a backup hot water generator.
The annual operational costs are kept low through a service-level agreement on the natural gas generator.
A joint venture between Egoli Gas and engineering consultants Black Dot Energy and GA Solutions was key to changing the energy environment and backup systems at Wits.
The support from local suppliers, along with their international partners, played a vital role in the project’s success while delivering quality returns.
Wits has already confirmed a successful feasibility study to implement additional piped natural gas technology for other residences.
The generation of hot water and HVAC services onsite enhances the financial model, creating a competitive solution for tenants and levies, and alleviates concerns in an unstable economic climate.