NOVELTY - Plant (100) for producing gas from biomass comprises gasifier (8) is of the open-core downdraft type, and apparatus (10) for cleaning the gas produced by the gasifier and comprises: inlet line (12) suitable for conveying the flow of gas to be cleaned exiting the gasifier and/or dedusting unit (14); evaporative cooler (16) suitable for treating the incoming flow of gas from the line; condensing wet electrostatic precipitator (26) suitable for treating the flow of gas exiting the cooler; and outlet line (36) suitable for conveying the flow of cleaned gas to external utilization unit (38).    USE - For the production of gas from biomass (claimed).    ADVANTAGE - The present plant provides gas cleaning apparatus which has small overall dimensions, which is of economic construction and which is capable of producing a gas with a sufficient degree of filtration so that it is used in modern sophisticated internal-combustion engines.    DETAILED DESCRIPTION - Plant (100) for the production of gas from biomass, comprises gasifier (8), and apparatus (10) for cleaning the gas produced by the gasifier, where the gasifier is of the open-core downdraft type and where the apparatus comprises: an inlet line (12) suitable for conveying the flow of gas to be cleaned exiting the gasifier and/or dedusting unit (14); an evaporative cooler (16) suitable for treating the incoming flow of gas from the line, the evaporative cooler comprising: units (18) for spraying aqueous mixture (MA) into the flow of gas, a basin (20) suitable for keeping in the evaporative cooler a reserve of mixture (MA) in the condensed state, and a first bleed pipe (22) suitable for removing from the bottom of the basin the condensed pollutants and conveying them to the gasifier; a condensing wet electrostatic precipitator (26) suitable for treating the flow of gas exiting the evaporative cooler, the precipitator comprising: units (28) for cooling the walls (29) in contact with the gas, a tank (30) suitable for collecting the contaminated mixture (MA) condensed during cooling of the gas, a recirculation pipe (31) suitable for removing from the tank excess mixture (MA) and conveying it to the evaporative cooler, a second bleed pipe (32) suitable for removing the condensed pollutants from the bottom of the tank and conveying them to the gasifier, and a discharge pipe (34) suitable for removing the excess mixture (MA) from the tank (34) and conveying it to the outside; and an outlet line (36) suitable for conveying the flow of cleaned gas to an external utilization unit (38). An INDEPENDENT CLAIM is included for treating the gas produced by gasifier involving, in steady state: preparing apparatus comprising inlet line, evaporative cooler, condensing wet electrostatic precipitator and outlet line; conveying the flow of gas to be cleaned coming from the gasifier into the evaporative cooler; spraying aqueous mixture into the flow of gas so as to achieve elimination of some of the dust suspended in the gas and evaporation of at least some of the sprayed aqueous mixture and provide first cooling step for the gas by the absorption of latent heat of evaporation in the aqueous mixture; keeping in the evaporative cooler a reserve of mixture in the condensed state; removing from the bottom of the reserve of condensed aqueous mixture the condensed pollutants and conveying them to the gasifier; conveying the flow of gas from the evaporative cooler into the condensing wet electrostatic precipitator; cooling the walls of the condensing wet electrostatic precipitator in contact with the gas so as to achieve a second cooling step for the gas by heat removal; applying electrostatic field to the flow of gas so as to remove from the flow of gas at least some of the suspended pollutants; collecting the aqueous mixture which has condensed during the second cooling step of the gas in the condensing wet electrostatic precipitator and which contains the pollutants removed from the flow of gas; removing the aqueous mixture condensed in the condensing wet electrostatic precipitator and conveying it to the evaporative cooler; removing from the aqueous mixture the pollutants condensed in the condensing wet electrostatic precipitator and conveying them to the gasifier; removing any excess aqueous mixture in the condensing wet electrostatic precipitator and conveying it to the outside; and conveying the flow of cleaned gas to external utilization unit.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of a plant for the production of energy from biomass, comprising the gas cleaning apparatus.    Gasifier (8)    Apparatus (10)    Inlet line (12)    Evaporative cooler (16)    Basin (20)    First bleed pipe (22)    Condensing wet electrostatic precipitator (26)    Tank (30)    Recirculation pipe (31)    Second bleed pipe (32)    Discharge pipe (34)    Outlet line (36)    External utilization unit (38)    Plant (100)