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Department of Engineering, ICT and Technologies for Energy and Transport Patent Title Thermoionic solar converter. Ref. CNR 10268 Assignee(s): CNR CNR Institute: INSEAN Main Inventor: Massimo Adriani Countries: IT, EP, US Priority date: 25/02/2011 Abstract The present invention refers to a device for the generation of electricity from concentration solar source and the cogeneration of hot water at low temperature. It can be used in systems for single user or production plants in linear arrays. This device ­ essentially a vacuum tube ­ is designed to operate at the highest temperature tolerated by conductive refractory materials and allows to exploit the full thermal gradient of a top thermodynamic cycle to the lowest available temperature to the cooling system. This allows to obtain particularly high electrical conversion efficiency ­ estimated in the order of 45% ­ and a recovery of cogeneration in the order of 15%; furthermore, it allows obtaining an estimated efficiency of 60%, occupying an area which represents a half of the current plant (for the same amount of produced electric power). Background The current thermionic converters exhibit very low efficiency owing to heat losses due to the very high operating temperatures. This device solves this problem by using measures to limit thermal losses, both internal and external. This allows to increase the operating temperatures and the Δt to the maximum levels tolerated by refractory materials and hence the efficiency. Technology The system is composed of linear modules comprising a mirror (plane parabolic) that concentrates the solar radiation on a cathode placed at the center of a vacuum tube suspended at the ends, with internal shields placed on the walls, and anodes cooled by internal piping. It’s assumed a conversion module of 1 kW of power with 1 m of length, opening mirrors of about 2.5 m, with a concentration ratio in the order of 100­200. Advantages and Applications Installing 6 Modules 1 kW it’s possible to achieve a production plant for individual home users with a footprint of 15 square meters instead of 42 square meters needed to the current commercial photovoltaic, and a cogeneration thermal power of 1.5 kW to 80°; obviously, it’s possible to realize manufacturing plants by installing several rows of connected modules. Development stage The inventions doesn’t have a prototipe yet. 61