Related by context. Frequent words. (Click for all words.) 60 saline aquifers 58 Coal seam 57 hydrocarbon reservoirs 56 coal seams 55 Coal gasification 55 corrosive fluids 54 brackish groundwater 54 superheated steam 54 combustible gases 54 unlined pits 54 sequester carbon dioxide 54 potent greenhouse gas 53 slushy crystalline form 53 hydro carbons 53 combustion gases 53 Calcium carbonate 53 coal seam 53 rank coals 53 Coalbed methane 53 acid leaching 53 mineral ores 53 bentonite clay 52 Tiny particles 52 Contaminated soil 52 bitumen extraction 52 methane 52 Sulphuric acid 52 Sulfuric acid 52 evaporation ponds 52 oilsand 52 superheat 52 Nitrogen oxides 52 compacted clay 51 Sulphur dioxide 51 radioactive byproducts 51 flue gases 51 methane CH4 51 superheating 51 gases 51 Powder River Basin PRB 51 scatter radioactive 51 deplete oxygen 51 coal 51 Radioactive waste 51 CO2 sequestration 51 Carbon sequestration 51 Reverse osmosis 51 geologic sequestration 51 cyclohexane 51 radioactively contaminated 51 sulfide minerals 51 biomass combustion 51 coalbed methane wells 51 iron sulfide 51 kerogen 50 noxious gases 50 coal petroleum coke 50 sludges 50 temperature inversions 50 diatomite 50 abrasive blasting 50 sub bituminous coal 50 opencast mines 50 Rinse thoroughly 50 lateritic 50 absorbs carbon dioxide 50 flammable gases 50 insitu 50 recharge groundwater 50 oxidizers 50 Methane 50 molten rocks 50 convection currents 50 calcium oxide 49 frac sand 49 basalt rock 49 oxidiser 49 Vast quantities 49 Burning fossil fuels 49 unconventional reservoirs 49 Highly radioactive 49 Horizontal drilling 49 methane hydrate 49 Donkin coal 49 mercury sulfur dioxide 49 magnetite ore 49 fumaroles 49 hazardous liquids 49 phosphine 49 dewater 49 Toxic fumes 49 hydrothermal fluids 49 inert gases 49 methane gas 49 methane hydrates 49 bauxite ore 49 methane nitrous oxide 49 pollute waterways 49 CO -2 49 decomposing garbage 49 Seafloor