methane leakage is also a problem directly associated with hydraulic fracturing, as an environmental defense fund (edf) report in the us highlights, where the leakage rate in pennsylvania during extensive testing and analysis was found to be approximately 10%, or over five times the reported figures. this leakage rate is considered representative of the hydraulic fracturing industry in the us generally. the edf have recently announced a satellite mission to further locate and measure methane emissions.