. >> reporter: frustrating to coal state senator mike enzee who says the environmental issues are overblown, and the coal underappreciated. >> we're the saudi arabia of coal, and we're not putting any money into researching it. >> reporter: the coal companies are frustrated, too. their best hope for real growth, mining this coal and shipping it overseas. scott cohn, "nightly business report," decker, montana. >>> if you want to read more about coal's comeback and the industry's changes economics, go to our web site, nbr.com. >>> still ahead, can retailers successfully turn cabin fever into spring fever? and what's at stake if they do? >>> the messaging app tango has good reason to dance. china's ali baba group is making a big bet on tango. it's investing more than $200 million into the california-based mobile messaging service. tango not only allows its 200 million users to text each other but they can share music, photos and other content on their mobile devices. >>> air b and b could be worth a bundle will. the online home rental service is in advance talks with private equity firms inclu