Related by context. Frequent words. (Click for all words.) 60 fossil fuels 57 nonrenewable resources 56 fossil fuel 51 artificial photosynthesis 51 polluting fossil fuels 50 biomass feedstock 50 Cellulosic ethanol 50 alternative fuels 50 CO -2 50 biofuel feedstocks 49 biofuel crops 49 distiller grain 49 biodegradable plastics 49 Synthetic biology 49 heat trapping carbon emissions 48 greenhouse gasses 48 nitrogen fertilizers 48 biofuels 48 renewable 48 carbon dioxide emissions 48 emit CO2 48 sequester carbon dioxide 48 artificial fertilizers 48 greenhouse gases 48 crop residues 48 renewable feedstocks 48 bioenergy crops 47 environmentally friendly 47 biofuel 47 conventional internal combustion 47 cellulose ethanol 47 Fossil fuels 47 renewable energy 47 synthetic fertilizers 47 emitting greenhouse gases 47 nonpolluting 47 renewable fuels 47 biofuel feedstock 46 decarbonising 46 Drip irrigation 46 energy 46 efficient lightbulbs 46 environmentally benign 46 biomass 46 bio fuels 46 rice husk 46 rice husks 46 heat trapping gasses 46 sequester carbon 46 stover 46 carbon emissions 46 agricultural residues 46 nonrenewable 46 liquid fuels 45 cellulosic feedstocks 45 switchgrass 45 greenhouse gas emissions 45 chemical fertilizers 45 compact fluorescent bulbs 45 recyclable plastics 45 VRB ESS 45 alternative energies 45 carbon dioxide CO2 emissions 45 Renewable fuels 45 cleaner fuels 45 recycle plastic bags 45 compact fluorescents 45 toxic solvents 45 CO2 emissions 45 spintronic 45 purity silicon 45 agrofuels 45 Carbon sequestration 45 carbon emission reductions 45 cellulosic materials 45 carbon dioxide 45 sugar cane ethanol 44 biodiesel feedstock 44 corn ethanol 44 woody biomass 44 petcoke 44 decarbonisation 44 CO ² 44 reduce carbon emissions 44 cleaner burning 44 disposable plastic bags 44 NF3 44 greenhouse emissions 44 bioplastic 44 recycled plastics 44 decarbonise 44 wood chips 44 heat trapping carbon dioxide 44 petrochemical feedstock 44 tropical hardwoods 44 Rechargeable batteries 44 nanogenerator 44 environmentally sound 44 carbon footprint 44 biodegradable packaging 44 pellet stoves