Dec 7 (Reuters) - The U.S Federal Permitting Improvement Steering Council on Thursday approved the construction of a $1.5 billion offshore wind farm off the coast of Rhode Island. The project, Revolution Wind, is run by Danish company Orsted ORSTED.CO and U.S.-based Eversource ES.N, and would bring a total of 704 megawatts (MW) clean energy to Connecticut and Rhode Island. Yet soaring costs from rising inflation, high interest rates, and delays in supply chains cast doubts on plans to bring 30 gigawatts (GW) of offshore wind power online by 2030.