a novel tidal and wave - power collection apparatus is disclosed which is adapted to produce hydrogen and / or oxygen gas . the apparatus is particularly well suited for oceanic installations . in the preferred embodiment , a matrix of gas producing units is easily assembled at sea , each being bridged and reinforced by catwalks extending therebetween which form trilateral gas producing modules having such units at each of the corners thereof . each gas producing unit comprises a central tubular pilaster embedded in the ocean floor around which is disposed a toroidal float which moves up and down with the waves and tide and which acts to drive a dc generator while rising and falling . the output of the generator is utilized to electrolytically produce hydrogen and / or oxygen gas , which is compressed for storage in the float &# 39 ; s chamber . the apparatus is efficient , economical and capable of capturing and storing large quantities of gas . in an alternative embodiment , the dc generator drives a high pressure pump which forces sea water through the microporous membrane of a reverse osmosis unit , thereby converting the sea water into potable water .