Tribocorrosion performance of cellulose bio-base hydraulics fluids and their application in wave energy converters. 

Offshore wave energy converters (WECs) rely on different mechanical sub-systems such as hydraulic cylinders, joints, hinges, cables, gears and bearings to convert and transmit the kinematic energy transported by the waves and tides into mechanical usable energy. In order to comply with the increasing environmental regulations, and protect the mechanical moving components exposed to the marine environment from excessive wear, and primarily to transmit the power through the hydraulic circuit bio-based lubricants have been proposed as a green alternative to replace conventional hydraulic-fluids and mineral oil.

The development of cellulose base lubricants has received an increasing attention by the scientific community during the last decade due to the abundance, biodegradability, and renewability exhibited by forest resources. Environmentally acceptable hydraulic lubricants (EAHL) that can be biodegraded in case of leakage are essential to guarantee a reliable and sustainable operation of wave-energy-converters.  The functional groups available in the structure of cellulose compounds, and the possibility of functionalization, provide the opportunity of increasing the load carrying capacity, and wear resistance exhibited by water-base lubricants in polymer-metal contacts. The aim of this project is to investigate the impact of water soluble cellulose compounds on the tribological properties of aqueous-based lubricants under boundary and elasto-hydrodynamic operating conditions, that are encountered in hydraulic wave energy converters. The performance of different EAHL fluids will be evaluated, establishing a relationship between fluid rheological, and chemical structure, and their wear-friction performance.