Three methods are proposed for coupling a conventional co-generation system with a refrigerator operating partly by compression, using cheap electricity at off-peak hours, and partly by absorption using waste heat or even excess heat produced in summer. The system uses a binary mixture (i.e. ammonia + sodium thiocyanate) with reservoirs for storing the separated components. This constitutes an exergy storage system, for accommodating the fluctuations of shaft work, heat and cold demands.