The invention pertains to an agricultural unit (100) comprising: a tank system (110) adapted to provide a combined aquatic environment for raising aquatic animals in aquaculture and cultivating plants in hydroponic culture, whereby excretions of said aquatic animals are released directly into said aquatic environment so as to produce nutrients for said plants； and an electrochemical device (130)； wherein said electrochemical device (130) is operable in an electrolysis mode to produce hydrogen and oxygen while consurning electrical energy provided by a source of electrical energy； wherein said electrochemical device is further operable in a fuel cell mode to produce electrical energy and heat by oxidizing said produced hydrogen； and wherein said electrochemical device is operatively coupled to said tank system so as to transfer at least part of said produced heat and said produced oxygen to said aquatic environment. The invention also pertains to use of such a unit.
