Related by context. Frequent words. (Click for all words.) 74 financially viable 74 viable 73 commercially viable 69 feasible 56 environmentally sound 55 sustainable 55 environmentally sustainable 54 profitable 53 economical 52 self sustaining 52 viability 51 workable 51 economically 47 alternative 47 environmentally responsible 46 prohibitive 46 affordable 46 attractive 45 desirable 44 profitably 44 environmentally friendly 43 achievable 43 acceptable 42 suitable 42 efficient 42 doable 42 useable 42 sustainably 42 unsustainable 41 greenfield 41 unaffordable 41 usable 41 cheaper 40 carbon neutral 40 equitable 40 unprofitable 40 advantageous 40 mutually beneficial 40 beneficial 39 silver bullet 39 commercially 39 biofuel 39 environmentally sensitive 39 impractical 39 preferable 39 feasibility 39 untenable 38 uncompetitive 38 undeveloped 38 feasibility study 38 attainable 38 readily available 38 foreseeable future 38 environmentally 38 accessible 38 alternatives 38 redeveloped 38 marketable 38 prosper 38 expensive 38 worthwhile 37 unworkable 37 cellulosic ethanol 37 renewable energy 37 necessary 37 reliable 37 renewable 37 subsidize 37 greener 37 easily accessible 37 recoverable 37 feedstock 37 thriving 36 financially 36 enforceable 36 mutually exclusive 36 biomass 36 prosperous 36 obsolete 36 inexpensive 36 amenable 36 fossil fuels 36 fossil fuel 36 sufficient 36 defensible 35 biodiesel 35 relatively inexpensive 35 biofuels 35 feasibility studies 35 fertile ground 35 mineral reserves 35 subsidizing 35 safe 35 alternative fuels 35 operationally 35 productive 35 ecologically 35 unattractive 35 adequate 34 self reliant 34 subsidy