Both money and environmentalism are green, so Wal-Mart's promising to go green (environmentally friendly) and an effort to make more green (money). This could be a silver lining to all the evils of the wal-monster. A great read from the SF Gate:
Like any giant company suddenly "embracing" the green initiative (hi, GM and Ford), Wal-Mart's rationale for all of this, of course, has absolutely zero to do with any sort of deep concern for the planet (though it does make for good PR), nothing at all to do with humanitarian beliefs or honest emotion or spiritual reverence, and has absolutely everything to do with the corporation's rabid manifesto: cost cutting and profit.
The reason...that Wal-Mart will double the fuel efficiency of its huge truck fleet within a decade? Not to save the air but to save $300 million in fuel costs per year. The reason it aims to increase store efficiency and reduce greenhouse gases by 20 percent across all stores worldwide? To save money in heating and electrical bills and also to help lessen the impact of global warming, which is indirectly causing more violent weather, which in turn endangers production and delivery and Wal-Mart's ability to, well, sell more junk. Ah, capitalism.
Seems Wal-Mart has realized one vital maxim that so many fundamentalist right-wing capitalist GOPers have so far failed to grasp: The apocalypse is just really bad for business.