Composite materials are today important constituents in many applications which contribute to a sustainable development as they allow efficient production of low weight products which have very good properties, which can be tailored according to the end-user needs and requirements. Glass fibre and carbon fibre are the main reinforcements which are combined with either thermoset or thermoplastic polymer resins. 

The production technology for composites has developed from using manual hand and spray-lay up processing to highly advanced techniques such as resin infusion, filament winding and resin transfer moulding. Although composites are sustainable due to their low weight, excellent durability and low energy consuming production, there are some challenges to consider. Firstly, the recycling of end-of-life composites is not yet established, which is partly due to their rather small consumption volumes, but as more and more composite products are reaching their end-of-life, recycling options must be created. Secondly composites are made from fossil, non-renewable materials, which is seen as a challenge in some end-use sectors. 

Natural fibres made from lignocellulosic plants and trees are an option to increase the amount of renewability in composites. Annual plant fibres such as flax, hemp, jute and sisal can easily be converted to textile fabrics which can be used as a reinforcement in a composite. The man-made cellulose fibres, mainly made from wood are also an option, and viscose yarns and fabrics can be suitable reinforcement in some composite applications. The use of natural fibre composites has also been demonstrated in many applications, and their properties have been investigated in detail. Natural fibre reinforcements are also available today for commercial use, and many suppliers provide natural fibre reinforcements of different type and characteristics. 

To replace non-renewable resins is more challenging, and there are no fully renewable thermoset resins on the market. Thermoset resins with a partly renewable content are available, such as epoxy and unsaturated polyester resins, but their use has not yet reached larger market share. Renewable thermoplastic resins are available, such as poly lactic acid, but the properties do not meet the requirements for more demanding structural applications. 

Natural fibre composites are still a developing type of composite material, which must find their best applications, where their properties can be best utilised.