A disclosure program regarding shale natural gas development in Europe will give policymakers confidence about their resource potential, an executive said. Exxon Mobil Chief Executive Officer Rex Tillerson made a case for more transparency regarding hydraulic fracturing fluid in Europe. \"Natural gas from shale holds tremendous promise in many places in Europe due to its lower carbon intensity and suitability for power generation but we want policymakers and the public to be confident that it can be produced safely and responsibly,\" he said at an energy meeting in Houston. Exxon Mobil has a deal with Ukraine\'s state-run energy company Naftogaz and another tender is scheduled by April. The U.S. Energy Information Administration estimates Ukraine has as much as 42 trillion cubic feet of shale natural gas. Some European countries rich in shale natural gas deposits placed a moratorium on extraction because of concerns about the environmental impact of hydraulic fracturing fluid. \"Exxon Mobil believes that a comprehensive disclosure program allows citizens and communities to consider this technology with a strong factual foundation,\" said Tillerson. \"We believe that will lead to open discussion about environmental protection and risk management, and the potential benefits of shale development in Europe.\"