ecoSUP – the pleasure of paddling on a 100 percent bio-based board

From wind turbine to stand-up paddle board

Palm trees, pristine beaches, a crystal clear ocean: Christoph Pöhler is enjoying his vacation on the Fiji islands thousands of miles away. Yet civilization soon catches up with the engineer on his stand-up paddle board (SUP): His suddenly finds himself paddling between flip flops, washing-detergent bottles and parts of a surfboard. Yet this piece of sports equipment, on which he was hoping to relax, is also made of plastic, hardly likely to be recycled in this far flung corner of the world. Pöhler doesn't want to be part of the problem for very much longer: And so the idea for the ecoSUP was born. His vision: a SUP consisting of nothing but renewable raw materials. The PhD student found the perfect setting for his idea at the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI. Fraunhofer WKI has a unique method for producing wood foams. The researchers there also experiment with components made from natural fibers and specialize in process engineering, natural-fiber composite plastics and surface technologies for wood preservation and emission control. And of course, recycling processes are another area of research at the Fraunhofer Institute in Braunschweig. Having received initial funding for the exploratory phase from the Federal Ministry of Education and Research (BMBF), Pöhler now plans to move his project to the next level through a crowdfunding campaign on the Startnext platform. We talked to the impassioned scientist, water sports enthusiast and savior of the world about the particular challenges he faces and what's next on the agenda for ecoSUP.

Plastic garbage on the beach
© C. Pöhler
Plastic garbage on the beach of the Fiji Islands. On the beach of this remote group of islands, the problem is particularly acute.
The first drafts for the ecoSUP
© Fraunhofer WKI
The first drafts for the ecoSUP are already available. When designing the board, the Fraunhofer WKI doctoral student will pay particular attention to ensuring that existing production units can continue to be used.

Please, Tell us more about your idea of a 100 percent bio-based stand-up paddle board?

Its structure is similar to that of a conventional surfboard. Normally, a polystyrene core, which we know as styrofoam, is reinforced with fiberglass and sealed with an epoxy resin. The approach is cost-effective and manufacturing processes are optimized for these materials. The product properties deliver high rigidity and stability. The ecoSUP project, though, is about developing plant-based alternatives to these materials, which are not exactly environmentally friendly.

One of our objectives, beyond that, is to simplify the process so that any existing production equipment can still be used with our renewable materials. If the level of investment is too high to start with, it will be difficult to get the idea of this process across. Of course, it's always tempting to develop a product that could turn out to be a hit. But we should never lose sight of the economic viability. That's why we are concentrating on developing materials and methods that can be used in established processes.

Is there a problem building a paddle board from wood?

There are a number of criteria. The board has to be transportable, we have to balance rigidity and weight. Wood gives us plenty of rigidity, but at the expense of weight. Our indigenous types of wood have a high density (Mostly spruce or beech in Germany). So to achieve the necessary buoyancy, the board would be extremely large and this would make it too heavy. You could make the floating body hollow and use wood just on the outside, but you would soon be at the limit of economic viability. This kind of construction is highly labor intensive, and in my view, large scale production would be barely viable. In other words, the end product would simply be too expensive for most customers.

What are the main obstacles?

We definitely consider the development of the biopolymer to be one of the biggest challenges. We are of course trying to unite various objectives or product properties. The bio-based material we are looking for has to be durable in a number of respects. It will be exposed to UV radiation, a range of different temperatures and saltwater - always a critical aspect for polymers. If we use natural fibers, we are also limited in terms of process temperatures. That's why our focus is on thermosetting polymers, as these compounds do not have to be melted for reshaping. AND, ideally, the material is readily recyclable or biologically degradable at the end of its life cycle. So we have very little choice when it comes to the resin. Working with chemists from Fraunhofer WKI, we are looking to develop a proprietary 100 percent bio-based and durable biopolymer with itaconic acid. This acid consists of tiny molecules and can be obtained relatively cheaply and in large quantities from agricultural by-products.

Kampagnenvideo ecoSUP

View into the interior of a wind turbine rotor blade.
© Fraunhofer WKI
View into the interior of a wind turbine rotor blade. These propellers are hollow and consist of small balsa wood cubes bonded with glass fibers and resins. After about 20 years of operation, a large part of these rotors must be recycled. Until now, this has hardly been possible.
 the used and valuable balsa wood from the fiber composite of the rotors
© Fraunhofer WKI
In several steps, the WKI experts are able to separate the used and valuable balsa wood from the fiber composite of the rotors. What remains are small cubes that are not suitable for further processing in this form.
These cubes are further processed into a kind of wood wool or wood glue.
© Fraunhofer WKI
These cubes are further processed into a kind of wood wool or wood glue.

So this bio-resin will be used to create the board's hull?

There's a core and a hull. The mineral oil-based epoxy resin currently in use does offer good protection, but cannot withstand strong forces, so it's reinforced with fiberglass. We want to reinforce the outer skin of the ecoSUP with flax fibers. Natural fibers include flax fibers with the highest mechanical strength and elasticity. Another advantage is that these fibers are produced in Europe. So they don't have to be transported over long distances, and the carbon footprint is smaller. Although glass fibers are around two or three times as strong as flax fibers, the flax fiber is about half as dense - a huge bonus in lightweight constructions. So we can use around twice the amount of flax to compensate for the low stability.

Which materials make up the bulk of the board?

At Fraunhofer WKI, we have a patented method for producing foams from timber or wood debris, and these foams don't require any adhesives! For the ecoSUP, we're using balsa wood. It's much lighter than indigenous wood types and grows very quickly. The key growing areas, though, are in Ecuador and Papua New Guinea. The raw material would travel half way around the world before we were able to use it. Hence our decision to use the balsa wood that's recovered from the rotor blades of decommissioned wind turbines.

Balsa wood from wind turbine rotors is embedded in the form of small cuboids – barely bigger than a matchbox – in a fiber composite, sometimes measuring several centimeters. If we split this apart again in a hammer mill or reactor, we get tiny pieces of wood. These parts are further processed in various refiners. We can use our patented technology to make these parts first into a kind of goo, and then into a lightweight, yet solid wood foam.

Is this wood foam, which goes on to form the board's core, a unique selling point of the ecoSUP?

In other projects, we are of course exploring the use of this basic raw material in various applications such as insulation or terrace decking. The aim of our project, though, was to license this material to achieve the broadest possible market reach and make the greatest possible impact.

So how many rotor blades can be recycled per year?

In 2020, a total of 6000 wind turbines will be decommissioned. The first great impetus for wind power came around 20 years ago. The turbines are now being decommissioned because EEC funding has dried up and it's no longer viable for operators to keep them running. Sometimes, the parts are sent abroad, but all too often, they are dismantled and have to be disposed of somehow or other. A great deal of them are currently "thermally" processed, but this goes against the law on life cycle management. Some manufacturers pulverize the rotor blades and supply them to the cement industry as additives and fuel. The composition of glass fibers is suitable as an additive and as a substitute for cement. The rest, including the wood, are burned.

To reinforce the outer shell, the scientist is replacing the glass fibers with renewable flax fibers.
© Fraunhofer WKI
To reinforce the outer shell, the scientist is replacing the glass fibers with renewable flax fibers.
Christoph Pöhler wants to go one step further and use bio-resins or paints for these fibers for his project.
© Fraunhofer WKI/Natalie Vellguth
Flax untreated and flax in polyamide (left) as well as flax with coating and the corresponding test specimen (right). Researchers at the WKI are working on natural fiber-reinforced plastics (NFK), which are coated with a special coating for this purpose. In the future, such NFRPs are to be used in various areas of application, for example in vehicle interiors. However, Christoph Pöhler wants to go one step further and use bio-resins or paints for these fibers for his project.

Every rotor blade yields up to 6 cubic centimeters of wood. And we can use the foaming process to obtain a much greater volume. The balsa-wood foam weighs less than 100 kilogram per cubic meter, in the basic raw material, it's around 300 kilograms per cubic meter. We want to reduce the density even further so that in the end, the weight matches that of a conventional board. The first step, then, does not solve the whole problem, but we are highlighting a form of recycling. We are preventing such an exceptional material as balsa wood having to be burned.

And we also want to tap into other applications using this material. The stand-up paddle board is our first flagship project. The material can, of course, be used in other areas as well. Our goal, however, is quite clear. We want to use the material in water first in order to ultimately develop other possible fields of application. It could be used to make office partitions, for instance.

That might sound fantastic, but how will such a sustainable product be received?

There's the example of a manufacturer who wanted to bring a bamboo paddle for a SUP onto the market. A wonderful idea in terms of material choice. Nonetheless, this paddle was ultimately removed from the market. Customers were not convinced. But just because a product is made of a biomaterial doesn't necessarily mean it won't last. Instead, we are now once again seeing the sale of carbon paddles, which are very difficult to recycle and dispose of. There are no real recycling concepts for this material. These are the experiences we want to learn from. It would be a shame if we're not able to convince users. I believe there's a lot of work to be done. Perhaps it would help if our product came with guarantees.

So what's next?

We received funding from the Federal Ministry of Education and Research for the so-called exploratory phase. Our application for the feasibility phase is still in progress. The Fraunhofer headquarters and Fraunhofer IMW encouraged me to set up the crowdfunding project. Fraunhofer IMW is currently examining new forms of finance in a scientific project. However, my prime motivation for the crowdfunding campaign was to reach as many people as possible and raise awareness of the problem among the wider public.

What kind of support are you getting from Fraunhofer WKI?

I can spend at least some of my time at work on the project, and also use parts of the institute's infrastructure. My department head is fully behind the project and the campaign and I have the support of many of my colleagues. Besides all that, I draw on the expertise from the various departments at Fraunhofer WKI, from our chemists for example. They are investigating ways of impregnating wood without using toxicological substances. So I get insights into a number of areas. What I don't get through the institute, though, is any kind of funding for short-time advanced research.

Do you have any thoughts about continuing the project once the development phase is complete?

It would be incredible to transfer the concept to a spin-off. I have already been in contact with Fraunhofer Venture and AHEAD. But right now, we are still focused on developing the product. That said, a spin-off would definitely be an aim.

Were the areas you mentioned of interest to you while you were studying?

Yes, in fact I was involved with flax fibers and alternatives to conventional concrete, so-called geopolymers, while I was doing my master's degree. For different applications though. My bachelor's degree was in industrial engineering, with structural engineering as a special subject and my master's in civil engineering. My doctoral thesis on the long-term bonding of fiber-reinforced plastics and wood is focused on usage in civil engineering. One aspect of the thesis, for example, is that timber construction is being promoted for higher building classes. Beyond the height of detached houses, wood reaches its structural limits because the dimensions become too large. One option is to combine it with other construction materials. Carbon fibers, for instance, are the obvious choice for increasing strength and rigidity. In terms of their sustainability, however, such alternatives have to be critically regarded.

Mr Pöhler, thank you for talking to us.