Strong stuff: Delft company gives waste a second life

Techtalk in the 'Delft op Zondag' of week 19 2025

Did you know there's a company in Delft that makes road signs out of reeds? And facades out of toilet paper? It may sound crazy, but it happens at NPSP. In the Kabelfabriek they make sustainable materials from natural fibers and waste. 

From mushrooms to train noses

Without knowing it, you've probably come across their work. For example, NPSP made the red ANWB mushrooms that can be found throughout the Netherlands. And also the noses of the well-known NS koploper trains. These products have one thing in common: they are made of composite. A plastic that is light, strong and resistant to weather and wind. NPSP makes a sustainable version from natural materials such as hemp and flax. Heartily bio-based! 

Sustainable alternative to steel and concrete

The applications are numerous. For example, NPSP has already made benches, bridges, facades and traffic signs from bio-composite. The material is a sustainable substitute for steel and concrete, but also for ordinary composites. “This is because it takes a lot of energy and scarce raw materials to make such materials,” explains Willem Böttger, Director of Innovation at NPSP. “Bio-composite is light, strong ánd better for the environment.”

Second life 

A road sign from NPSP, for example, consists of three ingredients, says Willem. Reed, lime and resin. “In Dutch nature reserves, reeds are mowed every year, but the reeds are often burned afterwards. We give this type of residual stream a second life. The lime is a residual product from water companies, which extract lime from our drinking water.” The ingredients are mixed and compressed into a strong sheet, then milled into the right shape. 

Delft research

From onion peels to blue-green algae, NPSP is constantly looking for new ingredients. For this, the company works closely with TU Delft. “For our resin, for example, we still use part petroleum. But at The Green Village we are now testing traffic signs with a completely bio-based resin, sourced from the sugar industry,” explains Willem. “Actually, we are like chefs: we are always looking at which residual streams we can use to arrive at the best recipe.”

An inside look at NPSP     

Pinch of roof tile, dash of blue-green algae 

This search for new ingredients leads to surprising combinations. For the district water board De Stichtse Rijnlanden, NPSP made facade panels with recycled toilet paper. And even the dyes are natural or circular. For example, NPSP adds blue algae to make blue panels - and ground roof tiles for a red tint.

Grow

Their latest product? For ProRail, NPSP developed nature-inclusive facade panels, with holes for birds, insects and bats. This summer, the first panels will be tested on a transformer house in The Hague. Willem sees that more and more construction companies and architects are enthusiastic. “In the coming years, we especially want to grow. Technically, an awful lot is possible. We hope that bio-based building will increasingly become the norm.”

Willem Böttger and Mark Lepelaar of NPSP with one of their bio-composites

Photography: Erwin Dijkgraaf