The refrigeration machine for the ice maker operates outside of peak tariff periods, when the availability of electricity is more reliable and electricity is cheaper and particularly at night when the outside temperature is lower and the refrigeration machines operate more efficiently.  Ice is formed on the outside of submerged coils in an existing surface water dam and stored until required.  In peak tariff periods, all the refrigeration machines (providing some 40 MWR of cooling) can be turned off and cooling is then provided by melting ice in the dam.  Overall, in a 24-hour cycle, the ice thermal storage system uses less power than a conventional water cooling system and the system operates outside of Eskom peak tariff periods.

This turnkey project, awarded to BBE in 2008, included engineering design, procurement, construction, management and commissioning.  It is the second installation of its kind for AngloGold Ashanti — the first being an 800 ton ice mass thermal storage system at Mponeng Mine near Carletonville.  The Moab Khotsong installation is a third generation design where the ice is formed directly on refrigerant carrying coils.

Ice thermal storage schemes are in response to the critical need for power and energy management in the arena of mine ventilation, refrigeration and cooling systems and have become an integral part of BBE's expertise and competency.  BBE is a registered ESCO (Energy Services Company) with Eskom, acknowledging BBE’s technical expertise and competency in the field of energy saving and load-shift management for mine cooling and ventilation systems.

Being an ESCO, BBE is able to initiate these projects in conjunction with an enthusiastic mine who then provide a letter of intent with which BBE can then apply to Eskom for funding through the DSM (demand side management) programme.  BBE guarantee the performance of the system, while the mine contracts to operate the system as required.