(JP8503738-W)      A method of producing hydrogen using solar energy is disclosed, in which the solar radiation is converted into thermal energy and electrical energy; these are then used to electrolyse water to H2+O2.    In the method, the solar radiation is split into a shorter wavelength component, which is converted into electrical energy, and a longer wavelength component which is converted into thermal energy the thermal energy is used to convert water into steam at more than 700%; the electrical energy is then used to electrolyse the steam.    Pref. the thermal energy of the hot H2, O2 and exhaust steam leaving the electrolysis cell is recovered and used for preheating the water and the steam fed to the electrolysis cell. The recovery device is e.g. a heat exchanger.    Appts. (F16.1) for conducting the method is described and claimed, comprising a solar concentrator (3) which focuses solar radiation on an array or solar cells (5), which generate electricity, and on a thermal energy generator (7). The thermal energy and electricity are used in an electrolysis cell (9) to generate steam and electrolyse it to H2 and O2; the H2 is stored (11).    Pref. the H2 and O2 can be sepd. in or close to the electrolysis cell the longer and shorter-wavelength radiation is pref. separated using an appropriate mirror fitted with a spectrally-selective filter e.g. an edge or interference filter. Part of the radiation may be conducted to the thermal energy generator using e.g., an optical fibre or light guide.    Use of a selectively, reflecting mirror for separating solar radiation into longer and shorter wavelengths, is also claimed.    USE/ADVANTAGE -   For prodn. of H2 from solar energy, the H2 may be used as e.g. fuel gas. Has high efficiency of solar energy conversion (e.g. 22% in an example). has low operating cost/unit energy produced.    (EP927857-A2)      A method of producing hydrogen using solar energy is disclosed, in which the solar radiation is converted into thermal energy and electrical energy; these are then used to electrolyse water to H2+O2.    In the method, the solar radiation is split into a shorter wavelength component, which is converted into electrical energy, and a longer wavelength component which is converted into thermal energy the thermal energy is used to convert water into steam at more than 700%; the electrical energy is then used to electrolyse the steam.    Pref. the thermal energy of the hot H2, O2 and exhaust steam leaving the electrolysis cell is recovered and used for preheating the water and the steam fed to the electrolysis cell. The recovery device is e.g. a heat exchanger.    Appts. (F16.1) for conducting the method is described and claimed, comprising a solar concentrator (3) which focuses solar radiation on an array or solar cells (5), which generate electricity, and on a thermal energy generator (7). The thermal energy and electricity are used in an electrolysis cell (9) to generate steam and electrolyse it to H2 and O2; the H2 is stored (11).    Pref. the H2 and O2 can be sepd. in or close to the electrolysis cell the longer and shorter-wavelength radiation is pref. separated using an appropriate mirror fitted with a spectrally-selective filter e.g. an edge or interference filter. Part of the radiation may be conducted to the thermal energy generator using e.g., an optical fibre or light guide.    Use of a selectively, reflecting mirror for separating solar radiation into longer and shorter wavelengths, is also claimed.    USE/ADVANTAGE -   For prodn. of H2 from solar energy, the H2 may be used as e.g. fuel gas. Has high efficiency of solar energy conversion (e.g. 22% in an example). has low operating cost/unit energy produced.    (EP670915-B1)      A method of producing hydrogen using solar energy is disclosed, in which the solar radiation is converted into thermal energy and electrical energy; these are then used to electrolyse water to H2+O2.    In the method, the solar radiation is split into a shorter wavelength component, which is converted into electrical energy, and a longer wavelength component which is converted into thermal energy the thermal energy is used to convert water into steam at more than 700%; the electrical energy is then used to electrolyse the steam.    Pref. the thermal energy of the hot H2, O2 and exhaust steam leaving the electrolysis cell is recovered and used for preheating the water and the steam fed to the electrolysis cell. The recovery device is e.g. a heat exchanger.    Appts. (F16.1) for conducting the method is described and claimed, comprising a solar concentrator (3) which focuses solar radiation on an array or solar cells (5), which generate electricity, and on a thermal energy generator (7). The thermal energy and electricity are used in an electrolysis cell (9) to generate steam and electrolyse it to H2 and O2; the H2 is stored (11).    Pref. the H2 and O2 can be sepd. in or close to the electrolysis cell the longer and shorter-wavelength radiation is pref. separated using an appropriate mirror fitted with a spectrally-selective filter e.g. an edge or interference filter. Part of the radiation may be conducted to the thermal energy generator using e.g., an optical fibre or light guide.    Use of a selectively, reflecting mirror for separating solar radiation into longer and shorter wavelengths, is also claimed.    USE/ADVANTAGE -   For prodn. of H2 from solar energy, the H2 may be used as e.g. fuel gas. Has high efficiency of solar energy conversion (e.g. 22% in an example). has low operating cost/unit energy produced.    (US5973825-A)      A method of producing hydrogen using solar energy is disclosed, in which the solar radiation is converted into thermal energy and electrical energy; these are then used to electrolyse water to H2+O2.    In the method, the solar radiation is split into a shorter wavelength component, which is converted into electrical energy, and a longer wavelength component which is converted into thermal energy the thermal energy is used to convert water into steam at more than 700%; the electrical energy is then used to electrolyse the steam.    Pref. the thermal energy of the hot H2, O2 and exhaust steam leaving the electrolysis cell is recovered and used for preheating the water and the steam fed to the electrolysis cell. The recovery device is e.g. a heat exchanger.    Appts. (F16.1) for conducting the method is described and claimed, comprising a solar concentrator (3) which focuses solar radiation on an array or solar cells (5), which generate electricity, and on a thermal energy generator (7). The thermal energy and electricity are used in an electrolysis cell (9) to generate steam and electrolyse it to H2 and O2; the H2 is stored (11).    Pref. the H2 and O2 can be sepd. in or close to the electrolysis cell the longer and shorter-wavelength radiation is pref. separated using an appropriate mirror fitted with a spectrally-selective filter e.g. an edge or interference filter. Part of the radiation may be conducted to the thermal energy generator using e.g., an optical fibre or light guide.    Use of a selectively, reflecting mirror for separating solar radiation into longer and shorter wavelengths, is also claimed.    USE/ADVANTAGE -   For prodn. of H2 from solar energy, the H2 may be used as e.g. fuel gas. Has high efficiency of solar energy conversion (e.g. 22% in an example). has low operating cost/unit energy produced.