Energy recovery devices (ERDs) capture work that fluid systems would otherwise waste in discharge lines or expansion valves. This presentation offers a concise explanation of ERDs—their working concept and some of the key challenges they face. It focuses on two representative loops: reverse-osmosis desalination, where pressure exchangers and turbochargers reclaim energy from the high-pressure brine reject stream, and CO₂ refrigeration, where throttling valves normally waste the PV work available during expansion. We outline the operating principles behind each device, the hydraulic/thermodynamic losses they target, and the efficiency and cost gains they deliver in practice. The talk highlights shared design principles and key trade-offs, offering a framework for identifying where energy recovery makes the greatest impact across industrial fluid systems.