What's the difference between a blimp and 365 used condoms? One is a good year, the other is a great year! /rimshot!
BTW, heavy-lift balloons have been in development all over the 1st World for a long while, funding always goes south, as there is not enough lift to do jobs that can't otherwise be done, and not enough jobs of that kind to justify further development costs.
The other 'new' idea that resurfaces every now and again is the high-altitude tethered windmill; weighs 20 tons, and the only idea keeping it aloft would be the same technology as we use to fly kites. Yeah, that should work.
Combining these ideas -- heavy-lift balloons and tethered high-altitude windmills -- might work out... ;')
Iceberg towing is another perpetual idea: The Many Failures and Few Successes of Zany Iceberg Towing Schemes
Every few years for the past couple centuries, even before the large-scale cultivation of marijuana, this idea occurs to someone: What if we towed an iceberg from the poles, where there are no people, to some dry, populous place and then melted it into freshwater?