A supertorrefaction system comprising a plurality of pools (70, 72, 74, 76, 78, 80) and a conveyor system that transports the biomass through the plurality of pools (70, 72, 74, 76, 78, 80), characterised in that: the plurality of pools (70, 72, 74, 76, 78, 80) include at least one supertorrefying pool (78, 80) containing molten salt as a liquid heat transfer agent, that is in direct contact with the biomass and that converts the biomass into biocoal, and at least one water pool (70, 72) containing salty water in direct contact with the biocoal; and the conveyor system being arranged in at least two rows in each of the plurality of pools (70, 72, 74, 76, 78, 80), wherein the conveyor system is configured to transport the biomass through the plurality of pools (70, 72, 74, 76, 78, 80) along a first row and in a first direction while transporting the biocoal through the same plurality of pools (70, 72, 74, 76, 78, 80) along a second row and in a second direction opposite to the first direction such that the biomass is preheated in the at least one water pool (70, 72) before conveyed to the at least one supertorrefying pool (78, 80) and such that the biocoal is cooled in the same at least one water pool (70, 72) that preheats the biomass after the biocoal leaves the at least one supertorrefying pool (78, 80). the plurality of pools (70, 72, 74, 76, 78, 80) include at least one supertorrefying pool (78, 80) containing molten salt as a liquid heat transfer agent, that is in direct contact with the biomass and that converts the biomass into biocoal, and at least one water pool (70, 72) containing salty water in direct contact with the biocoal; and the conveyor system being arranged in at least two rows in each of the plurality of pools (70, 72, 74, 76, 78, 80), wherein the conveyor system is configured to transport the biomass through the plurality of pools (70, 72, 74, 76, 78, 80) along a first row and in a first direction while transporting the biocoal through the same plurality of pools (70, 72, 74, 76, 78, 80) along a second row and in a second direction opposite to the first direction such that the biomass is preheated in the at least one water pool (70, 72) before conveyed to the at least one supertorrefying pool (78, 80) and such that the biocoal is cooled in the same at least one water pool (70, 72) that preheats the biomass after the biocoal leaves the at least one supertorrefying pool (78, 80). the conveyor system being arranged in at least two rows in each of the plurality of pools (70, 72, 74, 76, 78, 80), wherein the conveyor system is configured to transport the biomass through the plurality of pools (70, 72, 74, 76, 78, 80) along a first row and in a first direction while transporting the biocoal through the same plurality of pools (70, 72, 74, 76, 78, 80) along a second row and in a second direction opposite to the first direction such that the biomass is preheated in the at least one water pool (70, 72) before conveyed to the at least one supertorrefying pool (78, 80) and such that the biocoal is cooled in the same at least one water pool (70, 72) that preheats the biomass after the biocoal leaves the at least one supertorrefying pool (78, 80).