NOVELTY - The biomass combustion chamber (10) comprises combustion chamber walls (18) with a refractory wall component, an input apparatus for continually feeding a biomass (B) into the combustion chamber, and an ignition source to ignite the biomass in the combustion chamber. Each refractory wall component has a surface exposed to heat (H) generated within the combustion chamber by the combustion of biomass. A thermal protective layer (14) consisting of a thermal enhancing high emissivity coating is disposed on a part of the exposed refractory surface on the combustion chamber wall.    USE - The chamber is useful for the combustion of biomass for the generation of electricity.    ADVANTAGE - The biomass combustion chamber has improved thermal and combustion efficiency, can able to control the air emissions and global warming, and provides improved fuel utilization and increased thermal output.    DETAILED DESCRIPTION - The biomass combustion chamber (10) comprises combustion chamber walls (18) with a refractory wall component, an input apparatus for continually feeding a biomass (B) into the combustion chamber, and an ignition source to ignite the biomass in the combustion chamber. Each refractory wall component has a surface exposed to heat (H) generated within the combustion chamber by the combustion of biomass. A thermal protective layer (14) consisting of a thermal enhancing high emissivity coating is disposed on a part of the exposed refractory surface on the combustion chamber wall. The thermal protective layer contains 10-30% of colloidal silica and/or colloidal alumina, 50-79% of silicon dioxide powder, 23-79% of a filler, 2-20% of emissivity agents, 1.5-5% of a stabilizer, 0.25% of a surfactant, and a colorant. The wall of the combustion chamber has refractory bricks (20) or boards forming the internal surface of the combustion chamber. The thermal protective layer is disposed upon an exposed surface of the refractory bricks or boards. A refractory wall of the combustion chamber is composed of a composite refractory material. INDEPENDENT CLAIMS are included for:    (1) a refractory wall component; and    (2) a method of forming a thermal protective layer on a refractory surface in a biomass combustion chamber.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic top view of a generic biomass combustion chamber.    Chamber (10)    Thermal protective layer (14)    Castable refractory (16)    Chamber wall (18)    Refractory bricks (20)    Exposed refractory panels. (22)