Financial services firm Standard Bank began oper- ating South Africa’s second trigeneration plant at its new green 65 000 m2 corporate head office, in Rosebank, Johan- nesburg, last month and will produce more than eight-million kilowatt hours a year.

The country’s first trigenera- tion plant is located at telecom- munications group MTN’s Fair- land offices, in Johannesburg.

Standand Bank head of project management and real estate man- agement Rob

Gravette says Standard Bank will save about R7.8-million in electricity costs at the current equivalent rate of R1/kWh. The trigeneration plant will also save the company about 3 400 t/y on carbon emissions.

Contractors for the installa- tion of the Rosebank plant were appointed in June 2011. Cons- truction of the building is expected to be completed in May, after which the first of about 5 000 client-facing staff will occupy the premises in a phased-in relocation process.

Standard Bank’s 200 000 m2 head office, which houses 15 500 employees, will remain in the Johannesburg central business district.

Trigeneration is the simultaneous production of electrical energy, heating and cooling from a single energy source, such as natural gas, and is also referred to as combined cooling, heating and power generation.

Standard Bank’s gas-powered plant will supplement State-owned power utility Eskom as a baseload application and will supply the building with energy for baseload power, lighting, heating and cooling.

“The gas-powered trigeneration plant in the building uses innovative tech- nology to meet our energy needs. It is a reliable option that provides a method of balancing our energy requirements against the need to reduce our carbon footprint,” says Gravette.

The plant comprises an alternator, a gas engine, heat exchangers, absorption chillers, cooling towers and pumps.

It will reduce the building’s overall power demand requirements by about 30%, produce less greenhouse gases and reduce the overall strain on the electricity infrastructure in the area around the building.

Gravette explains that the alter- nator, which is turned by the gas engine, produces 1 000 kW of electrical power. This generated power reduces the building’s baseload demand, which is esti- mated at 5 000 kW, by about 20%.

The absorption chillers use a chemical reaction of absorption with lithium bromide refrigerant to convert hot water into cold water and this process produces 850 kW of cooling.

The cold water is used to precool the building’s air-conditioning return water, which reduces the amount of energy required from the power network to cool the water to a required set point.