There is another answer to our problem, but the US government and the UN have gone to the trouble to make sure we can't have it. What is it? Hemp. Hemp is one of the most nutritious plants on the planet. Hemp seed oil is high in omega 3 and omega 6 fatty acids, protein, fiber, etc. Hemp can also be turned into clean biofuels, fiber, hempcrete (R25 for a 12" wall), fashion, biodegradable plastics, paper and thousands of products. Growing hemp is good for the soil, does not need pesticides and requires less irrigation than most any crop. If this information is new to you, it shouldn't be. It has been written about many times before. It has been stated that it was probably the first agricultural endeavor of man. "I don't know if hemp will save the planet, but I know it is the only thing that can." Jack Herer, the Emperor of Hemp.
Hemp contains only .3% THC, so it can't get you high. Yet, our government managed to make it illegal world wide in order to protect petrochemical business, the timber (for paper) business and cotton business. If you don't know the story, read the Emperor Wears No Clothes, by Jack Herer. http://jackherer.com.
The article in the Guardian you posted is critical of Thorium reactors, but stops short of saying they won't work. This reminds me of the argument for cannabis medicine that keeps coming up by critics. "Cannabis hasn't been proven to cure cancer in large clinical trials." However, it has been proven to reduce tumors in mice more than once. The normal progression then is to study it in dogs, then humans. I'm sure that there would be no shortage of humans lining up to be tested when the alternative is to go the path of surgery, radiation and chemotherapy, neither of which is a sure thing albeit FDA approved. It is very convenient to say that cannabis has not been proven to cure cancer when the government itself stands in the way of the research that could prove things one way or the other.
So, I think the jury is still out on LFTR. If we spend some research dollars on it, get the bright minds to figure it out, who knows? And if we lift the ban on hemp world wide, perhaps there can be a future for those who come after us.