Power optimization strategies for wireless sensor networks in coal mines

Coal continues to be mined in over 50 countries. Coal accounts for approximately 64% of India´s electricity. Spontaneous explosions in the coal mines are one of the most common accidents. The main cause for mine explosions is the presence of toxic methane gas in an environment with insufficient oxygen. Gas detection is crucial for explosion prediction. Currently gas monitoring in coal mines is not so reliable. This paper introduces the use of a wireless sensor network (WSN) with gas sensors to predict methane outbursts in coal mines. This research work has developed an Early Warning System (EWS) deployment in the complicated environment of mines as low cost and power efficient wireless sensor network nodes have been designed to substitute the traditional wired and fixed monitoring equipment. The system can thus reduce the impact of mining explosions by facilitating the timely evacuation the miners from the areas of highest risk by providing an early warning and alarm system. Special attention has been paid to the WSN power optimization design strategies that include: using low power components, only sending the minimum amount of data (with efficient data acquisition protocols and data aggregation protocols), appropriate configuration of nodes (with clustering protocols) and automatic timely variation of power consuming states (with state transitions of listening, sleeping and transmitting modes).