Harmony Gold Mining Company Ltd.
In South Africa, where electricity is still mostly coal generated, mining consumes approximately 15% of the electricity produced in the country, with gold mining alone responsible for almost half of this.
As the availability of gold ore is declining in South Africa  the exploration of mines is going deeper, pushing energy demand to an all-time high. So improving energy efficiency to reduce carbon emissions and operation costs is a pressing challenge for the sector.
Harmony Gold is a mining company that is aware of the urgent need to find alternative solutions that make both environmental and business sense. In its Kusasalethu mine, situated 75 km west of Johannesburg, for example, the company has attempted to do just that. Since 2009, Harmony has been investing in increasingly energy-efficient technologies to make operations at Kusasalethu more sustainable. For instance, it improved the efficiency of its air pumping systems, whose energy consumption, emissions and costs tend to increase with the depth of underground mining.
Cumulative investment in efficient technology has resulted in a significant reduction of carbon emissions right from the start. Between 2008 and 2012, 616,000 tonnes of CO2 were avoided at the mine. After investing approximately US$1.7 million in the new pumping systems, among other investments in energy efficient technology and maintenance, the mine saw its profits rise by 33% in just one year—also due to increased gold output and other contributing factors. 
As Harmony Gold is showing, investing in energy efficiency is both an environmental necessity and a financially progressive decision in the mining sector.