The power unit of the India-based Tata Group conglomerate has said it will favor solar and wind projects over coal-fired plants in future global energy investments, citing the increasing difficulty of developing coal projects. In an interview with Bloomberg News, Tata Power Executive Director S. Padmanabhan said coal shortages in India have limited production at coal-fired plants and environmental hurdles have made it “impossible” to pursue coal plants in the U.S. and Europe with any long-term certainty. “Why would anyone want to invest at this stage in a coal project?” he said. “Investment has stopped.” Investment in renewable plants, he said, make more sense because the investment is smaller, plants are built faster, and costs are more uniform. The Tata Group, which accounts for nearly 5 percent of India’s gross domestic product, this week made its first bid for overseas wind and solar farms in South Africa.