Eco-Friendly Marine Energy Lubricant Helps Protect Fish and Increase Energy Generation

A team led by Oak Ridge National Laboratory (ORNL) is developing additives to be combined with environmentally acceptable lubricants (EALs) that can be used in tidal turbines to improve device performance. The team's results to date suggest great potential for the new lubricant to improve the energy-generating capabilities of tidal turbines while also decreasing risks to the environment in the event the liquid spills or discharges. 

Currently, lubricants used in tidal turbines are the same as those used in wind turbines because the design of the motors and gearboxes in both turbines is similar. However, the environments in which these two turbines operate are extremely different, which can change how the lubricant performs in practice. 

A lubricant is composed of a base oil and multiple functional additives. While the U.S. Environmental Protection Agency (EPA) has approved several groups of base oils as environmentally acceptable, there is a lack of eco-friendly, anti-wear additives. (Standards for EALs help support the design and development of lubricants to minimize the risk of adverse consequences to the aquatic environment compared to conventional mineral lubricants.) To address these issues, the multi-lab team is working with Solvay, Dow Chemical, Biosynthetic Technologies, and Driven Racing Oil to develop a new group of lubricant additives that possess significantly higher effectiveness in wear protection of the gearbox and lower aquatic toxicity compared with traditional options.

The additives the ORNL-led team developed are high performing, low cost, easily scalable for larger production quantities, and compatible with the EPA-approved base oils. The team added the newly developed additives to an already approved environmentally acceptable base oil, resulting in a lubricant that demonstrated 50% friction and wear reductions compared to a commercial gear oil. 

The team also tested the potential environmental impact of the new lubricant. They found that it is less toxic than traditional options used on tidal turbines and meets the EPA's not toxic and readily biodegradable standards. 

In January 2024, the team began focusing on additional issues that may impact tidal turbines, such as how seawater, if it enters the gearbox, could impact the new lubricant’s performance and toxicity for marine life. The team will also begin looking into lubricants that can be used on devices that are scheduled for multiyear deployments. 

This project is a "Sapling" funded through the Water Power Technologies Office's Seedling and Sapling program designed to support innovative concepts and new ideas at the U.S. Department of Energy's national laboratories.