Coal studded with rocks and mud is India's new energy headache

India’s power producers have a new problem now that a squeeze on coal supply has eased, they’re contending with declining quality of domestic fuel -- an issue that risks adding costs and wrecking equipment.

Electricity producers have complained to the country’s power ministry about increasing instances in recent months of impurities such as rocks and mud being found mixed with coal, according to government and company officials with knowledge of the issue.

Coal that’s laced with rubble or other material can damage power plant equipment such as conveyor belts, crushers and even boiler parts if not filtered out. That can cause supply