Automobiles Motors Exhaust gas 145 Renewable energy sources 136 Officials and employees 128 Air quality management 114 Air Pollution 98 Air Pollution Measurement 88 Photovoltaic cells Research 77 Uranium ores 76 Personnel management 64 Photovoltaic power generation 63 Energy policy 60 Wind power 60 Coastal ecology 59 Nuclear power plants Licenses 55 Experimental automobiles Testing 52 Electric power distribution 49 Nuclear power plants Safety measures 49 Wind power Research 49 Architecture and energy conservation 47 Solar energy 47 Automobiles Fuel consumption 46 Air quality Standards 45 Hydrogen as fuel 45 Air Pollution Standards 42 Automobiles Motors Exhaust gas Analysis 42 Photovoltaic power systems 42 Automobiles Motors Exhaust gas Testing 41 Biomass energy 39 Interconnected electric utility systems 39 Electric power production 38 Wind turbines 38 Nuclear facilities Licenses 37 Energy consumption 36 Solar cells Research 35 Wind turbines Testing 35 Motor vehicles Pollution control devices Testing 34 Thin films 34 Automobiles Motors Exhaust gas Measurement 33 Automobiles Pollution control devices 33 Geology 33 Military education 32 Nuclear power plants Environmental aspects 32 Nuclear weapons Testing 32 Electric power systems 31 Volcanoes 31 Distributed generation of electric power 30 Motor vehicles Motors Exhaust gas Analysis 30 Wind power plants 30 Atomic bomb Testing 29 Decision making 29 Solar cells 29 Electric utilities 28 Motor vehicles Fuel consumption 28 Motor vehicles Motors Exhaust gas 28 Distributed resources (Electric utilities) 27 Radioactive waste disposal in the ground 27 Energy storage 26 Methanol as fuel Testing 26 Mississippi River 26 Photovoltaic power generation Finance 26 Water quality 26 Solar cells Design and construction 25 Climatic changes 24 Electric power transmission 24 Motor vehicles Motors Exhaust gas Testing 24 Reclamation of land 24 Electric vehicles 23 Motor vehicles Pollution control devices 23 Automobiles Fuel consumption Standards 22 Forest management 22 Reservoir sedimentation 22 Sedimentation and deposition 22 Solar power plants Location Planning 22 Architecture and energy conservation Research 21 Clean energy 21 Dynamometer 21 Nevada National Security Site (Nev.) 21 Air Pollution Mathematical models 20 Automobiles Inspection 20 Biomass 20 Earthquakes 20 Fuel cells 20 Methanol as fuel 20 Radioactive fallout 20 Stream measurements 20 Automobiles Fuel consumption Measurement 19 Automobiles Pollution control devices Testing 19 Biomass conversion 19 Brownfields 19 Buses, Electric 19 Greenhouse gas mitigation 19 Motor vehicle fleets 19 Outcome assessment (Medical care) 19 Water resources development 19 Archaeological surveying 18 Energy conservation 18 Flood control 18 Wind power Economic aspects 18 Automobiles Maintenance and repair 17 Biomass energy Research 17