The gold-mining industry is a significant user of energy, and is vulnerable to variations in energy supply and cost. Given the national power utility Eskom’s difficulties in meeting energy demand, security of constant supply is, by no means, certain. Eskom’s reliance on fossil fuel-based energy exposes its clients to impending carbon tax.
As a Group, Sibanye is committed to:
- developing and maintaining effective monitoring, reporting and management strategies for sound energy use;
- researching new and more efficient ways of energy use;
- designing, developing and implementing strategies that seek to reduce the energy consumption of the operations and, thereby, reduce the carbon footprint of the Group, pursue any potential opportunities and utilise energy-efficient technologies where this is feasible;
- complying with applicable legal and other requirements to which the organisation subscribes; and
- encouraging business partners and suppliers to adopt similar principles.
Sibanye understands that employees and business partners play a crucial role in achieving these objectives and, as a result, seeks to increase awareness of energy-related issues; providing an enabling environment to achieve energy savings, deploy energy-saving innovations, and ensure that energy-management considerations are included in decision-making processes.
Sibanye has undertaken numerous energy-saving, load-clipping and load-shifting projects over the years. The latter is aimed at reducing demand at times of peak consumer demand in projects undertaken with pump scheduling, compressed air and water control valves, as well as geyser load switches – often funded by Eskom Integrated Demand Management.
Although Sibanye has reduced energy consumption, a significant portion of this reduction has been as a result of downscaling operations and reduced production over the years.
Sibanye achieved a saving of 33.4MW in 2013 compared to 2012 due to various saving initiatives and projects.
Major contributors to the saving include:
- replacement of 45kW inline axial flow fans with high-efficiency fans;
- optimisation of air networks at Kloof 1 shaft;
- water and air-leak fixing at Driefontein;
- methane-to-electrical generation at Beatrix. (See case study: Methane value released at Beatrix).
However, there was also a 6.9MW increase due to new load that came on line during 2013. New load is due to additional waste milling at Beatrix; starting up of refrigeration plants due to operational requirements; additional houses built for employees; and failure of the hydro-generating plant.
The energy profiles for Driefontein and Kloof are fairly similar where water provision (39%) and the provision of compressed air (18%) consume more than half of the energy used. At Beatrix, water provision (23%) and ventilation (24%) consume almost half of all the energy used.
|Electricity purchased (Rm)||1,85||2,09||2,23|
|Diesel – Energy (TJ)||205.25||198.82||229.40|
|Direct energy consumption (TJ)||706||680||722|
|Indirect energy consumption (TJ)||14,653||13,806||13,586|
|Total energy used (TJ)||15,359||14,486||14,308|
|Composite In-line fans (DSM*)||0.49|
|Hybrid battery chargers||0.48|
|4 shaft change-house heat pumps (DSM*)||0.31|
|South methane-to-electrical generation||0.78|
|Stopped two fridge machines at Beatrix West Shaft||0.97|
|Pumping and mining load reduction||0.75|
|Three-chamber pipe system project at 5 shaft (DSM*)||1.21|
|Driefontein composite in-line fans (DSM*)||1.98|
|Heat pumps (DSM*)||0.09|
|Air and water consumption savings||7.60|
|5 shaft turbine||0.62|
|Kloof 1 shaft optimisation of air networks (DSM*)||0.93|
|Composite in-line fans (DSM*)||2.51|
|Kloof 7 shaft optimisation of air networks (DSM*)||1.03|
|Three-chamber pipe system project at 4 shaft (DSM*)||0.57|
|4 shaft reroute and reduction of surface overland pumping||0.46|
|Stop 3 shaft 37 level bulk air cooler (BAC)** (30l/s)||1.00|
- * Undertaken in line with Eskom’s Demand Side Management (DSM) programme.
- ** If the BAC stops, water consumption stops and pumping costs are thus reduced.
Key ongoing saving initiatives include:
- At Driefontein, the air and water leaks performance project started in 2013. Funded by Eskom, an approved group is paid to fix air and water leaks throughout the operations. The benefits include an improvement in the efficiency of air and water use.
- At Driefontein and Kloof, the three-chamber pipe system uses a static service water pressure head down the shaft to pump clear settled water out of a mine; eliminating the use of main dewatering pumps on some underground levels.
- The Beatrix methane project.
Emergency generators are available for use in the event of energy-supply disruption. It is understood that Eskom may, from time to time, experience challenges in meeting energy demands nationally. To assist Sibanye in managing energy supply during national emergencies, a Load Curtailment Procedure has been drafted.
Sibanye seeks to make use of alternative energy sources where feasible in order to offset fossil-fuel generated Eskom energy. The Beatrix methane project and the concentrated solar power (CSP) plant at Driefontein are examples.
Case study: Methane value released at Beatrix
Sibanye’s Beatrix Operation in the Free State has begun generating power from methane gas. Methane is released underground during mining. This project will reduce the safety and health risks associated with the gas, and contribute positively to sustainable development.
Although only 1MW of the 82MW of electricity consumed by the operation is generated at this stage, Dirk van Greuning, Environmental Engineering Manager for Sibanye, is hopeful. “We will be able to generate even more electricity when the operational efficiency of the generators has improved and the secondary methane sealing project has been completed to increase the flow of methane gas,” he says.
Beatrix has entered into a power rental contract with Aggreko Energy Rental SA Proprietary Limited to generate 2MW of electricity, using two power-generation units, from methane gas extracted from its underground mining operations by Q4 2014. The methane power-generation units were commissioned in April 2013 with each unit currently generating just more than 500kW.
Mitigating the methane risk
Methane gas is a colourless and odourless gas, which cannot be detected without specialised electronic equipment. Unlocked during mining operations and transported by air from sources deep underground, it is extremely dangerous as it is highly explosive and can displace oxygen; leading to possible suffocation.
The Beatrix Operation has developed a methane-management system to control this risk. The mine standard requires a minimum of two flammable-gas detection instruments per stope panel while there must be at least one instrument per development end when work takes place.
At Beatrix mining units 1 and 2, there is a telemetry system with strategically placed flammable gas and velocity sensors, critical fans and carbon-monoxide sensors. Environmental conditions are monitored in the central control room at Beatrix Mining Unit 1, located at No 3 shaft, on a 24-hour basis. Clear call-out procedures are followed in the event of an emergency.
Where elevated concentrations of flammable gas are constantly present in the general atmosphere, a location is declared hazardous based on the results of risk assessments. Hazardous locations require special operating conditions to be followed, such as explosion-protected apparatus, telemetry monitoring, strict adherence to mine standards and awareness training for all employees. Hazardous location meetings are held on a monthly basis, involving all related disciplines.
To ensure proper supervision at all working places, the mine has developed a Work Place Management (WPM) system – documents containing special instructions, hazard identification, risk assessments, DMR recommendations, a flammable-gas register and handing-over notes are stored in the mine overseers’ offices. The WPM system is also used during the induction of new employees or for people moved from one mining section to another.
In addition to the normal flammable-gas induction training, the mine has regular safety awareness sessions, such as safety flashes, special awareness drives, including the annual methane month in May and the monthly Methane Emergency Preparedness Safety Health (MESH) days when specific methane safety-related topics are discussed.
Capturing and using methane
At a cost of R54 million, the Beatrix methane capture and destruction project (the Beatrix Project) officially began on 28 July 2006 when the mine entered into an agreement with carbon and climate-change advisory firm, Promethium Carbon Proprietary Limited, for project administration and approvals. The system was designed and built to extract and flare, on surface, 400l/s of methane gas from identified sealed-off working areas at the Beatrix South section. The flare was commissioned on 21 May 2011, extracting an initial 50l/s of methane gas. At present, 211l/s of methane gas is extracted from underground and flared.
As methane is also a potent GHG, which contributes to global warming and climate change at a rate 21 times higher than CO2, the Beatrix Project was registered under the CDM of the Kyoto Protocol to the UNFCCC in 2011 to earn CERs or carbon credits. Since then, Sibanye has begun the issuance process to earn 36,010 CERs (from 1 July 2011 to 31 March 2012). The issuance request will be reviewed by the Executive Board of the UNFCCC in Q1 2014. The CERs are expected in Q2 2014.
The project generated 28,000 CERs in Q3 2013. This is an improvement from the previous quarter when only 13,311 CERs were generated due to power problems affecting one of the borehole flares. The monetary value is 92.25% of the spot price currently at 0.40 per CER or R6.12 per CER. Sibanye is the first gold-mining Group in the world to trade in CERs.
The project was also registered under the Voluntary Carbon Standard for the reduction of GHGs on 13 March 2013 and 9,643 voluntary carbon units (VCUs) were issued on 5 September 2013. The VCUs were held in Sibanye’s Markit Registry account and transferred to the VCU buyer’s account (Nedbank) on 7 November 2013. The income generated from the 9,643 VCUs amounted to R323,084.
The Markit Registry allows account holders to manage all their global carbon, water and biodiversity credits in a centralised, financial markets-based registry system. It manages environmental portfolios, and provides support for existing and emerging environmental programmes and markets.
The volume of methane destroyed since commissioning of the Beatrix Project to November 2013, including the main flare as well as the borehole flares, is 19,430,919m³. A total of 151,739 equivalent tons of CO2 was destroyed between July 2011 and the end of November 2013, considering that the global-warming impact of methane gas is 21 times higher than CO2.
Although the project has not yet reached its full capacity of 400l/s, it contributes to foreign-reserve earnings for South Africa via the carbon-credit sales revenue.
It has also had a positive impact on the environment in that it contributed to clean power generation, reducing reliance on coal-based electricity and harmful GHGs.
In addition, the project created jobs during the construction and operation phases, and facilitated skills development, and it made the working environment at the Beatrix Operation safer.