Engineers aboard a floating power station on Lake Kivu could only watch nervously as a volcano in the distance erupted violently, sending tremors rumbling through the water beneath them. However, it was not the lava shooting from Mount Nyiragongo in May last year that spooked them, but the enormous concentrations of potentially explosive gases within Kivu, one of Africa’s great Rift lakes lying between Rwanda and the Democratic Republic of the Congo (DR Congo). Flanked by rolling green hills tumbling into glassy waters, Kivu is not quite the picture of tranquility it seems, said Francois Dar...