Related by context. Frequent words. (Click for all words.) 80 economically viable 79 feasible 66 commercially viable 64 viable 55 prohibitive 52 economical 51 doable 51 environmentally sound 48 workable 46 impractical 46 profitable 46 advantageous 45 environmentally sustainable 45 cheaper 45 self sustaining 44 acceptable 44 expensive 43 sustainable 43 environmentally responsible 43 usable 43 desirable 43 feasibility 43 amenable 43 necessary 43 preferable 43 achievable 43 suitable 42 affordable 42 attractive 42 relatively inexpensive 42 inexpensive 41 economically 41 environmentally friendly 41 efficient 41 brainer 41 readily available 41 beneficial 41 worthwhile 40 alternative 40 viability 40 alternatives 40 attainable 40 feasibility study 39 enforceable 38 recoverable 38 unaffordable 38 environmentally sensitive 38 profitably 38 impossible 38 retrofitting 37 effective 37 obsolete 37 sufficient 37 fiscally responsible 37 reasonable 37 logical 37 unusable 36 appropriate 36 costly 36 subsidize 36 unprofitable 36 cellulosic ethanol 36 prudent 36 silver bullet 36 commercially 36 accessible 36 warranted 36 equitable 36 grandfathered 36 untenable 36 underutilized 36 virtually impossible 36 biodiesel 36 retrofit 35 advisable 35 palatable 35 greenfield 35 marketable 35 moot 35 mutually beneficial 35 scalable 35 foreseeable future 35 centrally located 35 sustainably 35 feasibility studies 35 biomass 35 option 35 exist 35 uninhabitable 34 accretive 34 undeveloped 34 cost 34 ideal 34 operationally 34 unsustainable 34 alternative fuels 34 compatible 34 problematic 34 unworkable 34 adequate 34 mutually exclusive