Tata Power, which is hoping to commission its 4,000-mw ultra mega power plant (UMPP) in Mundra early next year, has been dealt a blow by the Indonesian government, which has called for a sharp increase in the price of coal exported out of the country. At current prices of $110 per tonne of coal, the increased cost could set the company back by about $100 million when all five units are up and running.