I attended a power generation trade show a few years back in Baltimore where a similar product was being pitched. They proposed building a processing plant near the power plant and would grow, harvest and process region appropriate plants to turn into "coal". They had small sample cups there and I went by the booth about 5 times to get a sample cup!
I brought it home and put my small sample on the grates to see if it burned a different color or smoked. I didn't see any difference, but my 5 samples added up to less than a coffee cup so it was probably overwhelmed by the volume of anthracite already burning there.