LOAD shedding, unreliable power supply and increasing electricity costs are realities that businesses in South Africa must contend with. This was a key factor in the decision by an international manufacturer to consider own power generation using natural gas.
It chose Energas Technologies, a supplier of equipment to the oil and gas industries in sub-Saharan Africa, to deliver the complete turnkey project.
It entails the supply and installation of a new gas reticulation pipeline; gas engines (gensets); a new gas-fired steam boiler; a waste-heat boiler which will use exhaust heat from the engines to produce steam; interconnecting piping; a new gas engine building and associated electrical infrastructure.
Energas Product Manager, Laetitia Jansen van Vuuren said the pipeline will take gas from a new high-pressure customer metering station to the gas generator sets and steam boilers. The R Schmitt Enertec (RSE) G500 gensets will be installed in a new building that Energas will supply.
The exhaust heat from the engines will be used in a waste heat boiler. This free steam will result in a substantial annual saving in the gas bill. Projections show that a substantial saving can be realised, compared with importing electricity from the grid in the first year of operation.
The accumulated saving over 10 years, based on inflation and price assumptions, is substantially more than the project value.
“With the equipment offered, the supplier and Energas can monitor the operation of the engines. Various engine parameters can be monitored to ensure the most efficient operation. Very few plant operation and maintenance staff are required to oversee the gensets and steam plant,” said Jansen van Vuuren.
“We are convinced that the solutions offered will reduce the overall energy cost to the customer, meet environmental requirements and ensure efficient operation. Our team is capable of executing the project successfully, and we are set to complete the project in December this year.”
Talking points
She highlighted two key talking points with this project. Firstly, heat recovery from engine exhaust gas makes it a very interesting project. Usually, the heat is discharged into the atmosphere. However, the efficiency is significantly increased if the exhaust gas can be used.
“The client operated a coal fired boiler, but it will now be replaced with a waste heat steam boiler. When more steam is required than what could be recovered, the additional steam will be supplied with gas as fuel source.
“The waste heat boiler is a combination boiler; it works by recovering energy from the exhaust heat and also has a gas burner. When the waste heat boiler is being serviced or the engines are not working, there is a standby gas boiler to ensure continuous supply of steam to the plant,” she said.
Secondly, having four smaller engines (4x 500 kW) instead of a single large engine (1x 2 MW) allows continuous power supply to the plant. When one engine is serviced, the other three can still operate. Or if the plant’s usage is low, one or two engines can switch off while the other operates at a higher and more efficient load.
Jansen van Vuuren urged businesses to consider the natural gas energy route because of the documented benefits.
“We believe several industries should consider own power generation with natural gas. It will reduce their energy costs and also make them more independent from the grid, especially when combined with heat recovery. They can save millions of rands over a few years and ensure that their production is not affected during load shedding.”
