British company B&M Longworth is the developer of the DEECOM composite recycling process. According to news on September 6, 2023, a consortium (including multiple partners) organized by it has launched an EMPHASING project partially funded by Innovate UK (British Innovation Agency), aiming to investigate the real upgrade of fiberglass Recycling to provide truly viable materials with huge potential for secondary applications.

The consortium is particularly interested in non-biodegradable fiberglass used in wind turbine blades, as it can be argued that they have been neglected compared to the recycling of some known blade materials (wood, aluminum, carbon fibre). In addition, the cost of virgin fiberglass is relatively low, around €2 per kilogram. Therefore, the secondary use of this material is currently limited and there is no commercial case.

The aim of this UK project is to develop a material with better mechanical properties than virgin fiberglass but less expensive than carbon fiber, providing a viable, commercially acceptable material that can bridge the gap between fiberglass and carbon fiber.

Graphene selected as sizing agent for this project

Each wind turbine blade will be cut into commercially acceptable secondary use sizes and recycled through B&M Longworth’s globally developed and patented Pressure Decomposition process (also known as DEECOM). This process removes the resin using superheated steam, which undergoes a pressurization and depressurization cycle to strip the resin from the fibers. Unlike solvolysis or thermal decomposition, pressure decomposition does not interact with the fibers in any way, leaving the fibers in their original state. The resin can also be recycled during this process, but this is not the subject of this project and is being explored through separate R&D projects.

Crucially, stripping the resin from the fiber also removes its sizing, allowing the fiber to be upcycled and re-coated with sizing as needed.

In order to improve the mechanical properties of the fibers, graphene will be used as a sizing agent for the recycled fibers. This project will determine the effect of graphene sizing on the mechanical properties of fiberglass, as well as the cost equation for bringing this material to commercial use. The consortium believes that the mechanical properties of recycled glass fiber will be near the midpoint between fiberglass and carbon fiber, and the price point will be closer to that of virgin fiberglass.

Graphene was chosen as the sizing agent for this project due to its versatility and suitability for upgrading fiberglass. On its own, graphene is a very expensive material. However, the amount of graphene required is about 0.5% compared to the base material (fiberglass), thus making the cost of recycling fiberglass acceptable.

There are many methods to produce graphene, including chemical vapor deposition, flash Joule heating, laser-induced graphene, etc. Although the production method is not critical to this research project, the full suite of work required will include a life cycle analysis (LCA), so flash Joule heating is specifically considered for this project. "Flash graphene" is created by using electrical pulses to heat any element of carbon to 3,000°F. All non-carbon elements are "sublimated" out, leaving graphene as the only remaining material within the heating chamber. This process leaves the graphene in a non-stacked (turbine layer) state for easier dispersion.

In addition to determining the material properties of fiberglass sizing with graphene, a suspension component will be fabricated and tested against metal components to assess the suitability of the fiberglass for structural components.

The final element of the project is to understand the life cycle assessment of Scope 1 and Scope 2 (material production and manufacturing phases), as well as Scope 3 (weight reduction of vehicle components during the use phase). Scope 1 data will include the CO2 output of the pressure decomposition process to ensure full emissions are assessed.

The EMPHASING project is due to be completed in October 2024 and its members want to ensure a business case for using upcycled fiberglass is published.