Liquid metal magnetohydrodynamic power conversion (LMMHD PC) systems have been recently proposed for electrical power generation for various heat sources. These systems are based on extension of the Faraday law of induction to liquid metal. They contain high density liquid metal and a suitable thermodynamic fluid. A unique solar and waste heat coupled demonstration plant has been designed for generation of hydrogen. A steady-state two-fluid model, consisting of a one-dimensional continuity equation for each phase, combined momentum equation, vapour momentum equation and appropriate drag force for multibubble, churn-turbulent and slug flow along with the virtual mass force and related transport and thermodynamic relations, have been used to determine various two-phase parameters in the riser. Electrodynamic equations have been solved for the MHD generator. End losses due to recirculating currents at the entrance and exit of the generator have been taken into account. Single fluid equations in the rest of the loop have been solved. Liquid metal lead and lead bismuth have been chosen as the electrodynamic fluid and steam as the thermodynamic fluid. Extensive optimization of various parameters, like geometry, fluid flow rates, electrical parameters etc., have been performed to design the LMMHD PC system. The optimized system consists of two loops of LMMHD-Loop 1 operating with lead at 350 degrees C and loop 2 operating with lead-bismuth (25% of bismuth) at 215 degrees C. Steam at 430 degrees C enters loop 1 after receiving thermal energy of 2.5 MW from the regenerator, solar tower and incinerator waste heat. Net electrical power of 230 kW is generated by the system. The net efficiency of conversion from thermal to electrical is 9.2 % with a voltage of 3.4 V and current of 84 kA.