In underground mines, it has been recognized that there is a requirement for an independent battery charging system other than the AC power source that can be used in case of emergency since the radios located through the underground mines can’t stay charged for sufficient periods to insure the safety of trapped mineworkers.
Since it was a necessity to always have air distributed throughout the mine in order to supply oxygen and remove unwanted gases, it was suggested to use this air (wasted energy) to charge the batteries using small wind turbines that can be installed in the path of moving air that is forced into the underground mine.
It was necessary to determine the feasibility of the idea of using small wind turbines that are placed in the airflow path to charge batteries especially since the airflow will not be much variant. It was found that it was feasible and a numerical model was developed utilizing Blade Element Momentum theory to produce optimal battery charging system to aid in case of emergency mine communications.
The power requirements to charge the batteries were 4 Watts and several rotor configurations have been found to produce the amount of power required. However, due to safety issues and structural concerns in an underground mine, the required wind turbine should be designed and shielded to protect mine workers. It was possible to provide the structural protection with the use of a diffuser shroud which also helped in increasing the power output of the wind turbine system.
Results from the model and the physical parameters needed to efficiently design a wind turbine system for underground mines was addressed by this thesis and has been published in this book: Feasibility and optimum design study of a low speed wind turbine rotor system for underground communication power.