If it is a viable source of energy a revolutionary product would have been introduced long ago.
You don't need the permission of "mainstream science" to build something that works. You just have to have a technology that works.
You don’t need ‘permission’ of mainstream science, but when the archive known as arXiv blocks any science papers on it, and when scientists are demoted who investigate it, and when your source of funding dries up if you pursue it, you more or less need their permission (unless you can build in your garage on your own dime).