Because that sort of thing requires such a huge base of basic research, proof of concept, and commercialization that it's hard to imagine such a huge conspiracy could remain quiet. On top of that, companies want some assurance that when all is said and done, they'll be able to sell the stuff. That means they need to get some assurances from those who would control the distribution system that it will actually happen.

If big oil really has all these solutions hidden away, how come independent researchers don't at least have an inkling of the same technologies?