In the world's largest blackout, some 600 million Indians lost power Tuesday. It is the second major failure of the country's power grid this week. Exactly what caused these monumental power outages is still under investigation, but the blackouts are raising new questions about India's rising energy needs. In this series, GlobalPost looks at the nearly 150 dams planned for the state of Arunachal Pradesh. Together, the dams would fill India's energy gap. But they will also devastate dozens of indigenous tribal peoples, wipe out thousands of acres of breathtaking forest and destroy some of the world's best whitewater.