Related by context. Frequent words. (Click for all words.) 89 fossil fuel 66 renewables 65 biofuels 65 alternative fuels 64 greenhouse gases 64 renewable energy 63 renewable 61 renewable fuels 60 carbon emissions 59 biomass 59 greenhouse gas emissions 59 carbon dioxide emissions 58 greenhouse emissions 58 biofuel 57 coal 57 energy 56 carbon dioxide 55 fuels 55 reduce carbon emissions 54 greenhouse gas 53 ethanol 53 CO2 53 feedstocks 52 CO2 emissions 52 natural gas 52 carbon 52 emissions 52 hydrogen 52 global warming 52 coal fired 51 tar sands 51 cellulosic ethanol 51 GHG emissions 51 feedstock 50 climate change 50 biodiesel 48 carbon capture 48 petroleum 48 electricity 48 diesel 48 reduce greenhouse gas 47 polluting 47 gasoline 47 bio diesel 47 diesel fuel 46 emission reduction 46 hydrogen fuel 46 Hydrogen 46 wood chips 45 reducing greenhouse gas 45 fuel 45 methane 44 hydrocarbons 44 environmentally sound 44 Emissions 44 oil 44 Ethanol 44 Global warming 44 gas 43 environmentally sustainable 43 arable land 43 gas guzzlers 43 zero emission 43 Clean Energy 43 pollution 43 rare earths 42 IEA 42 deforestation 42 carbon footprint 42 Energy Agency 42 Biofuels 42 environmentalism 42 environmental degradation 42 wind farms 42 fossil 42 geothermal 42 oil sands 41 greener 41 EVs 41 carbon neutral 41 environmental impacts 41 biogas 41 liquefied natural gas 41 pollutants 41 environmentally friendly 41 hydropower 41 combustion 41 incineration 41 Kyoto Protocol 41 Global Warming 41 shale gas 40 Climate Change 40 cellulose 40 emission 40 carbon credits 40 offshore drilling 40 solar 40 cleaner 40 pollute 40 LNG 40 dependence