Thermoplastic Resin Offers Recyclable Alternative for Tidal Turbines

Tidal turbines are an emerging technology in the renewable energy industry, capitalizing on their capacity to harness kinetic energy from tides and ocean currents. However, when wind turbines reach the end of their utility, the blades are not recyclable, causing negative environmental effects.

 

Tidal turbine. Image used courtesy of Wikimedia Commons by G. Mannaerts

 

An innovation by researchers at the National Renewable Energy Laboratory (NREL) could change that. They’ve developed a novel thermoplastic resin that enables recycling and reduces the carbon footprint of tidal turbines.
 

Thermoplastic Resin for Tidal Turbines

Tidal turbines are an emerging technology in the renewable energy industry, capitalizing on their capacity to harness kinetic energy from tides and ocean currents. This grants them a global reach and more predictable energy generation than alternative renewable technologies.

NREL researchers have introduced a novel thermoplastic resin to reduce the embodied carbon of traditional tidal turbines, which was deployed in Verdant Power's TriFrame tidal turbines. 

Verdant Power’s TriFrame system consists of a triangular frame mount supporting three five-meter tidal turbines strategically arranged at project sites to optimize energy generation based on water velocity, hydrodynamics, and accessibility.

 

Verdant Power’s TriFrame tidal turbine. The back turbine (right) is made from NREL’s thermoplastic resin. Image used courtesy of MDPI 

 

Previously, all three turbines on the TriFrame were made from conventional epoxy blades. However, for a trial deployment in 2021, one of the turbines was replaced with one made with thermoplastic resin. 

The NREL team points out that the problem with traditional epoxy is that it is not easily reused after its first application. Turbines made with epoxy are virtually useless at the end of their life cycle, necessitating new materials to construct replacements.

The thermoplastic resin can be recycled at the end of its lifecycle and has proven more durable in the aquatic environment. In 2021, the adapted TriFrame, using the innovative material, underwent a six-month trial and set a record within the U.S. marine energy industry. It generated approximately 312 megawatt-hours of energy during the trial period, marking the second-highest output of any marine energy project and providing sufficient electricity to power around a thousand households.

 

Next Steps With Thermoplastic Durability

Following the successful trial, the NREL team brought the thermoplastic blades back to their Colorado lab to assess the material’s durability after prolonged exposure to water. The thermoplastic exhibited promising performance under various stress tests, which is a positive sign for the future of tidal turbines, offering more sustainable and recyclable blade options.

However, it’s worth noting that this material may not be suitable for all energy applications due to concerns about long-term deformity. Post-deployment tests aim to provide insights into how thermoplastics perform, which could help determine their suitability for various renewable energy technologies. 

In the meantime, the NREL is also investigating alternative resin solutions, such as plant-based recyclable epoxy, competitive with petroleum-based products. 

Ultimately, the NREL team wants to ensure that materials used to manufacture renewable technologies are not derived from fossil fuels and are recyclable.

 

Tidal Power and Sustainability

The energy sector has made great strides in increasing the proportion of low-carbon energy sources, emphasizing renewables while reducing the reliance on fossil fuels, as part of a comprehensive initiative to decarbonize energy generation.

Unfortunately, as well-intentioned as these decarbonization efforts may be, there are still negative environmental effects from the materials used to build new renewable technologies. While the use of renewable technologies does not generate operational carbon ‒ emissions associated with the daily operations and activities of a system ‒ between resource extraction, production, and supply chain, these technologies still have a significant amount of embodied carbon ‒ emissions associated with manufacturing, transportation, and construction of a system.

The innovation of recyclable materials can be a step forward in sustainability.