General News

Clean Development Mechanism sees carbon emission reductions - 1 February 2008

The United Nations Framework Convention on Climate Change secretariat says that over 860 Clean Development Mechanism (CDM) projects have been registered globally. The CDM is expected to generate over 2,6-billion credit emission reductions, each equivalent to one ton of carbon dioxide (CO2) by 2012, through programmes in developing countries to reduce CO2 and poisonous gas emissions and improve energy efficiency.

Mining company Gold Fields’ methodology proposes capturing and destroying naturally venting methane by flaring the gas to generate electricity and cold water, using waste heat.

Developments that allow methane to be burnt as fuel to generate power, and use waste heat to produce cold water in absorption chillers, have been identified as the second phase of this project, Gold Fields manager for group corporate affairs and corporate communication Reidwaan Wookay tells Mining Weekly.

Gold Fields’ South African operations aim to achieve the 15% target of the Energy Efficiency Accord by 2015, and have set internal targets of 4% a year in energy saving. Each mine is developing an energy efficiency strategy.

As part of the South African Energy Efficiency Accord, Gold Fields is also addressing energy consumption in pumping, compressors, and ventilation. Findings show that pumping, compressors, and ventilation collectively make up more than 60% of the electrical energy used in a deep gold mine, and are the primary focus of energy saving projects.

Pumping is addressed through the installation of continuous pump efficiency monitors, which will schedule pump maintenance based on pump efficiency. These systems are currently being installed and commissioned, and results from the first pumpstation at Driefontein indicate that a 5% saving in electricity used for pumping will be achieved.

Three chamber pipe feed systems (CPFSs) are also being installed at Kloof and Driefontein, as pilot systems, to reduce the energy used to pump water out of the mine by using the potential energy of the service water. These three pilot systems are being installed as part of an Eskom demand-side manage- ment (DSM) project, where the first three CPFSs will be commissioned before the end of this year, and the remaining two by mid-2009.

The compressors are enhanced with a more efficient operation through the installation of advanced compressor control systems to manage the compressor stations.

The ventilation is managed by the implementation of real-time systems, which model and monitor air flows and pressures, and then reduce air flow in off-shift times. Two systems are currently being installed, and, when commissioned by mid-2008, will save more than one-million kWh a month.

In total, Gold Fields has put in place 32 DSM projects in conjunction with Eskom, that shift electricity use from peak periods to nonpeak periods. Ten of these projects have been completed and have shifted over 50 MW from the peak period, achieving savings of over R5-million in the first half of this financial year. Eighteen more such projects are in construction, and commissioning will continue until the end of 2009.

Another project involves replacing diesel-powered locomotives with battery-powered locomotives, and training for drivers for the new locomotives is under way. The first locomotives will be deployed in the first quarter of this year.

Investigations into the use of passive solar heating technology for industrial and residential use show a potential to save an average of 5 MW by the installation of 10 000 solar water heaters at a cost of R200-million. The financial viability of this project will be re-evaluated once an Eskom subsidy for this project is in place early this year.

Read the remainder of this article by Desislava Tzoneva on Mining Weekly