Director-producers Gayatri Roshan and Emmanuel Vaughan-Lee structure their environmental documentary as a triptych of profiles in courage: In India, one water conservationist labors alone to clean up the lethally polluted Ganges River Basin; in Canada, one young Athabasca Chipewyan mother campaigns against the toxic exploitation of a 50,000-square-mile splotch of heavy crude oil; in Australia; one outsider inventor develops a nature-inspired contraption which he contends can “reduce the world’s energy bill by at least half” (or, for starters, simply freshen the air above Los Angeles and Beijing). Some peculiar personalities emerge, as do obstacles including disenchanted colleagues, quasi-unhelpful supporters (as in the San Francisco fundraiser schmooze-fest where Robert Kennedy Jr. comes off like a useless blob of self-satisfaction), skeptical investors, and angry protesters. But the filmmakers very clearly have their eco-crusaders’ backs. Why these three in particular, and together, isn’t exactly clear, although the film does tease out some elegant overlaps between their perspectives. If now and then Elemental resembles little more than a flattering medley of expository TED Talks, at least Roshan and Vaughan-Lee get across the basic idea that hope has to start somewhere, and so does the cleaning up of our already-much-too-filthy world.