The Hydrocurrent system has been developed by Calnetix in conjunction with Mitsubishi Heavy Industries Marine Machinery and Engine (MHI-MME) and is claimed to offer short payback times. “It pays for itself in a very short time by reducing the load on the ship’s bunker-fueled generators,” said Vatche Artinian, Calnetix chairman and CEO. “This can translate into fuel savings of up to 200 tons per year.”

The system uses organic Rankine cycle (ORC) heat recovery technology with Calnetix’s patented Thermapower and Carefree integrated power module to convert thermal energy into mechanical power. Calnetix claims its system is unique in that it can pull usable heat from a source with temperatures as low as 80°C where other heat recovery systems require much higher temperatures. It is said to not affect engine performance, and to leave sufficient heat in the jacket water for fresh water makers.

Calnetix says its Hydrocurrent ORC module is a closed-cycle evaporator-condenser phase-change loop, using an organic fluid that has a very low boiling point. The fluid is pumped through an evaporator that pulls heat from the engine’s jacket water. The superheated vapour is expanded across the Carefree module, producing electric power, which is connected to the ship’s grid. The warm vapour then flows into a seawater-cooled condenser where it turns back into liquid form. The integrated power module consists of a high-speed turbine expander and high-efficiency permanent-magnet generator in a single hermetically sealed housing. The friction-free magnetic bearings are said to require no lubrication or maintenance.

The system has a small footprint and can be retrofitted in existing ships without major modifications to the engines. It is designed specifically for the shipboard environment, to operate automatically and to require low maintenance. It is designed and built to ClassNK and Lloyd’s Register guidelines.

Calnetix says it will be adapting the Hydrocurrent technology for exhaust and engine scavenge air heat recovery.

“The core technologies comprising the Hydrocurrent and Thermapower ORC modules have been used for heat recovery in various applications in the US, Canada, Europe, the Middle East and Asia since 2009 under Calnetix and our distributors and licensees, including GE and Daiichi Jitsugyo,” said Mr Artinian.