The Aguas Teidas mine, hereinafter referred to as the ATE mine, is a copper and polymetallic (zinc, lead) underground mine located in the south of Spain, and uses primary exhaust ventilation. The physical limitations of the network due to the location of the Aguas Teidas mine, the limitations of electric power availability from the grid and the constant increase in the price of electricity were some of the reasons that accelerated the search for energy efficiency solutions in primary and auxiliary ventilation. Several energy saving strategies were examined. These ranged from controlling the fans by the worker in the stope, to having a remote manual control from the control room. At the same time, automatic control of the surface primary fans is being done during the shift changes, and work is being done on the implementation of a ventilation on-demand system according to work modes manually from the control room. Other energy efficiency opportunities that have been adopted include the replacement of underground secondary ventilation duct by an alternative that has a lower friction factor, using vent duct fittings with lower shock losses and lower leakage at couplings, as well as the replacement of a twin surface horizontal primary fan with a combined motor rating of 1,4 MW by a single vertical axial with a motor rating of 0,71 MW. Matsa, an energetic islandThe Aguas Teidas mine is located near the town of Almonaster la Real, in the province of Huelva, Spain. It is a mine of massive hydrothermal sulphides, with the presence of Cu, Zn and Pb. The mine produces 2 Mt per year of polymetallic ore and copper. Along with the ATE mine, MATSA has two other nearby mines, Sotiel and Magdalena, in operation. The three mines together produce 4.4 Mt of ore per year. The final product is a copper concentrate and a polymetallic concentrate. The method of mining is sublevel stoping, with some orebodies using drift and fill. The ore is transferred by diesel LHD to ore passes and then both ore and waste is trucked to surface via dedicated haulage ramps. The mine has five intakes: VR1 shaft, haulage ramp, service ramp and shafts VR8 and VRC1. There are three primary exhausts: VR2 of 3,1 m, VR3 of 4,5 m and VR7 of 4,1 m, allowing semi-independent primary ventilation districts for the various production zones. The primary fans of the mine extract up to 600 m3/s, through the following surface exhaust fans: VR3: two (twin) horizontal fans in parallel of 0,7 MW each (total 1,4 MW); VR2 fan: single horizontal fan of 710 kW; VR7 fans: two (twin) horizontal fans in parallel of 500 kW each (total 1,0 MW). All the fans are equipped with VFD and with control panels of different protection parameters, all connected and controlled by the SCADA. The VR3 will be replaced by vertical fans at the end of 2019, to reduce the installed and absorbed power. CITATION:de Miguel Fuentevilla, J and Castro Prez, R, 2019. Implementation of energy efficiency and ventilation on demand at the Aguas Teidas mine, in Proceedings Australian Mine Ventilation Conference 2019, pp 91106 (The Australasian Institute of Mining and Metallurgy: Melbourne).