Thorium is a natural impurity found in coal. It has been estimated, in fact, that the thorium in coal would, if used as fuel for LFTRs, generate eleven times the energy that you would get from just burning the coal. And right now, all that thorium is simply wasted in the coal ash, or worse, goes up the smokestack and becomes an environmental pollutant!
Also, due to the higher temperature LFTRs run at, they can directly supply heat to drive the Fischer-Tropsch process to convert the coal that we'll no longer need to burn for electricity into synthetic petroleum. This would allow the U.S. to completely supply all its petroleum needs (especially for transportation fuel) from coal for at least 100 years, and eliminate the need for foreign oil. This, in turn, would allow the defense budget to be cut in at least half, as much of that expenditure is to protect our access to foreign oil. And it also reduces carbon emissions, since, while we're still burning the coal (after it's been transformed into synthetic petroleum), we're not burning the oil it replaced!
None of this requires new technology; we were running LFTRs at Oak Ridge in the 1960's (and they proved their safety by literally cutting power to the reactor systems and going home for the weekend!), and Germany was using Fischer-Tropsch back in World War II. All it requires is some engineering refinements...and, of course, the political will to do it. The latter, sadly, is lacking.