Holistic analysis of the effect on electricity cost in South Africa’s platinum mines when varying shift schedules according to time-of-use tariffs

Abstract

In the past the cost of electricity was not a significant concern and was not common practice for mining companies to consider peak time-of-use (TOU) tariffs for their shift schedules. It has become more prevalent, as TOU tariffs continue increasing, to consider energy saving important. A study was carried out to analyse the mining operation of a South African deep-level platinum mine in respect of integrated load management, shift changes and TOU schedules. This was achieved by thoroughly analysing energy consumers, mine operational schedules and their interconnectedness. A specific mining system was analysed as a case study and a maximum savings scenario was determined, using the methodology formulated. The maximum savings scenario schedule change resulted in a 1.3% cost reduction. System improvements had an additional potential reduction effect of 8.4%, which was primarily the result of a reduction in compressors’ power consumption. The implications of the proposed schedule adjustments necessitated a realistic scenario. The realistic scenario had an effective financial reduction of 0.7%. The realistic schedule change, however, opened the door for large system operational improvements, which could increase the reduction potential by 7.6%. The study methods described illustrate the potential implications of integrated load management and operational schedule optimisation on the power demand and cost savings in the mining industry, specifically focusing on deep-level platinum mines.

Investigating the Link Between Compressed Air Wastage and Ventilation Shortfalls in Deep-Level Mines

“…In addition, increasing electricity tariffs are placing further strain on the South African deep-level mining industry, resulting in a need to reduce energy consumption to contain electricity costs [2] [3]. Deep underground mines are highly energy-intensive [4] [5], and electricity is a very large expenditure item of a typical platinum mine, second only to mining operational costs [6]. Figure 1 showcases the typical electricity cost distribution of a deep-level platinum mine.…”

A cost-benefit analysis of implementing a 54 MW solar PV plant in a South African platinum mining company: A case study

“…The South African platinum mining industry relies heavily on a consistent and cost-effective supply of electricity to optimise production (Ryan, 2014;Shaw et al, 2019;Mahony et al, 2018). The primary supplier of electricity currently in South Africa is the national utility Eskom, with the state-owned enterprise supplying 95% of the country's electricity (Van der Zee, 2014; Van der Merwe et al, 2020).…”

“…This type of energy source for electricity generation is non-renewable and contributes to environmental degradation, thereby constraining environmental sustainability (Nathaniel et al, 2021). Coal is also becoming scarcer and, in turn, costlier to produce, which is evident in the exponential increases in Eskom's electricity costs (Shaw et al, 2019;Votteler et al, 2016;Van der Zee, 2014). Furthermore, there is uncertainty around the reliable and consistent electricity supply provided by the utility.…”