Investigating Alternative Power Generation Strategies For Local Municipalities That Are Tied To The National Grid

Abstract

The demand for electricity keeps on increasing every year, and this puts pressure on municipalities that are supplying electricity to their communities. Once the demand for electricity goes up, municipalities consume a lot of electricity from national energy suppliers, putting a lot of pressure on the National Grid. Furthermore, some municipalities are struggling to pay off debt owed to national energy suppliers, such as Eskom, due to low revenue collection from electricity, because of non-paying customers, faulty meters and electricity theft. Under this condition, local municipalities may have to consider alternative power generation strategies to continue functioning to a limited degree. The challenge exists in identifying viable alternative power generation strategies for local municipalities to reduce pressure on the National Grid during the months of high energy demand and to provide limited power to their communities when disconnected from the National Grid, due to load-shedding. The first objective of this research was to conduct an energy audit of two towns in the Free State Province of South Africa, which is Koffiefontein and Petrusburg and correlate it to their electrical bill. Secondly, it was to identify various alternative power generation strategies, based on the energy audit and weather data for the two towns. Thirdly, it was to apply the HOMER simulation tool to evaluate the viability of the proposed strategies and then recommend the most appropriate strategy for the two identified towns. The payback period for the alternative power generation systems was also determined. The results of the audit indicated that Koffiefontein consists of a total of 2 038 houses, with 1 246 in the township and 792 in town. This town also has 113 businesses, with 36 in the township and 77 in town. Electricity sale statistics from the municipality indicated that Koffiefontein houses consume more electricity than businesses, with June 2016 having the highest electricity consumption of 1 135 572.98 kWh. For Petrusburg, the audit was conducted in town only, as the township is being supplied directly by Eskom. Petrusburg consists of 606 houses and 63 businesses in town. Businesses in Petrusburg town consume more electricity than houses, with August 2016 having the highest electricity consumption of 1 002 048 kWh. After conducting an energy audit, the HOMER program was used to simulate the output of the two identified potential strategies, which is solar and wind. HOMER indicated that solar energy is the best renewable energy strategy to supplement the current energy source of both Koffiefontein and Petrusburg town, due to it being cost effective and having high yearly energy production. The cost of energy for the battery-based solar PV system, suggested for Koffiefontein houses is R 6.10 /kWh, while the cost of energy for the battery-based wind turbine system is R 776.490 /kWh. For Petrusburg town, the cost of energy for the battery-based solar PV system suggested for Petrusburg businesses is R 4.04 /kWh, while the cost of energy for the battery-based wind turbine system is R 840.4 /kWh. The results revealed that the utilization of a battery-based solar PV system may lead to a payback period of 11.5 years and 7.6 years, for Koffiefontein and Petrusburg respectively. Municipalities should consider doing an energy audit at least every two years to make sure that they are aware of any energy loses, due to tampered meters and faulty meters so that it can be addressed before it affects revenue collection of the municipality. Towns in the Western Free State should consider installing battery-based solar PV systems for businesses and houses so that they can have access to electricity during load-shedding and reduce the pressure placed on the National Grid during high energy demanding hours. The battery-based wind turbine system is more expensive than the battery-based solar PV system and has a longer payback period. Furthermore, wind speed data collected at Fauresmith indicates that a battery-based wind turbine system would suffer poor performance, due to the low annual wind speed.