Plant for the production of thermal energy from biomass fed to the plant in the form of pellets with humidity no higher than 35%, comprising: - a drying chamber for the pellets; - a combustion chamber fed from above with the dried pellets and provided with at least two combustion shelves or braziers (72,74), one above the other, having opposite inclination and adapted to receive the pellets in cascade, the braziers (72, 74) being provided with uniformly distributed through holes having dimensions that prevent the pellets from passing directly through them, means also being provided adapted to vibrate the braziers (72, 74) so as to facilitate cascading of the pellets from one brazier to the other until they drop, as ashes, into an ash collecting compartment; - means for collecting part of the fumes produced in the combustion chamber and sending them to the drying chamber for drying the pellets which pass through the latter; - a heat exchanger for recovering thermal energy from the fumes produced in the combustion chamber and en route to the chimney; characterised in that: - the drying chamber has a cylindrical casing with substantially horizontal axis, an opening being provided in the area of one of the two bases of said casing to feed the pellets to be dried to the chamber, the cylindrical casing being motorised so that it can rotate about its own axis, coaxial helical means being fixed to the inner wall of said casing for mixing-feeding the pellets, the cylindrical casing being also provided with an outlet for the pellets in the area of its other base; - a metering device is provided for feeding the combustion chamber, said device being in turn fed with the pellets coming from the drying chamber; - in the upper part of the combustion chamber means are provided for receiving the pellets fed by the metering device and retaining them for a sufficient time to cause the formation of syngas following heating of said pellets caused by the combustion which takes place in the combustion chamber, and means for collecting the syngas formed; - means (85, 86) are provided for collecting the fumes and the exhalations present in the drying chamber and conveying them to a mixer where they are mixed with an appropriate quantity of air; - means are provided for feeding the mixture obtained in the mixer to the combustion chamber in the area of the braziers (72, 74) so that the process of pyrolysis with oxygen in excess occurs; - means are provided for feeding to the combustion chamber, in the area of the braziers (72, 74), the syngas collected by the syngas collection means. - a drying chamber for the pellets; - a combustion chamber fed from above with the dried pellets and provided with at least two combustion shelves or braziers (72,74), one above the other, having opposite inclination and adapted to receive the pellets in cascade, the braziers (72, 74) being provided with uniformly distributed through holes having dimensions that prevent the pellets from passing directly through them, means also being provided adapted to vibrate the braziers (72, 74) so as to facilitate cascading of the pellets from one brazier to the other until they drop, as ashes, into an ash collecting compartment; - means for collecting part of the fumes produced in the combustion chamber and sending them to the drying chamber for drying the pellets which pass through the latter; - a heat exchanger for recovering thermal energy from the fumes produced in the combustion chamber and en route to the chimney; - the drying chamber has a cylindrical casing with substantially horizontal axis, an opening being provided in the area of one of the two bases of said casing to feed the pellets to be dried to the chamber, the cylindrical casing being motorised so that it can rotate about its own axis, coaxial helical means being fixed to the inner wall of said casing for mixing-feeding the pellets, the cylindrical casing being also provided with an outlet for the pellets in the area of its other base; - a metering device is provided for feeding the combustion chamber, said device being in turn fed with the pellets coming from the drying chamber; - in the upper part of the combustion chamber means are provided for receiving the pellets fed by the metering device and retaining them for a sufficient time to cause the formation of syngas following heating of said pellets caused by the combustion which takes place in the combustion chamber, and means for collecting the syngas formed; - means (85, 86) are provided for collecting the fumes and the exhalations present in the drying chamber and conveying them to a mixer where they are mixed with an appropriate quantity of air; - means are provided for feeding the mixture obtained in the mixer to the combustion chamber in the area of the braziers (72, 74) so that the process of pyrolysis with oxygen in excess occurs; - means are provided for feeding to the combustion chamber, in the area of the braziers (72, 74), the syngas collected by the syngas collection means.