Technology Overview

The construction sector consumes large quantities of raw materials, 42 billion tons of materials/year, and generates 25-30% of the total waste in the EU. A circular economy approach could help this sector reduce its environmental impact. The use of agricultural by-products, for the creation of eco-sustainable materials can address these issues. Currently, many building materials have been developed using by-products from rice, sugar, corncob, pineapple, peanuts, coffee, coconut, sunflowers, walnuts, and durian processing.

Orange is the most cultivated fruit in the world and accounts for about 50-60% of the total citrus production. An enormous amount of waste derived from this production; considering that 50% is made up of peels, the waste produced is about 3.4 million tons per year.

The technology presented, aims at reusing orange processing by-products for the fabrication of thermal and acoustical insulation material. The technology allows for the production of rigid, completely natural and self-bonded panels, without the addition of chemical additives. The good thermal properties of the material see a field of application in construction sector, as a thermal insulation panel of the external infill walls of buildings.

Technology Features, Specifications and Advantages

The process involves a series of steps to transform the orange waste into the building material:

• Shredding the waste into smaller size
• Evaporating of aqueous components whilst hot pressing the biomass.

Pressing the shredded biomass during the evaporation phase, ensures the compactness and consistency of the panel without the need to use binders, glues and / or adhesives. Furthermore, drying the material during the pressing phase, avoids the formation of internal tensions within the panel, thus guaranteeing the quality and flatness of the panel. This method is suitable for wet and dry processing of orange biomass, ensuring a continuous panel production cycle. Furthermore, the hot pressing occurs at temperatures lower than conventional.

The performances obtained with the panel according to this technology are as follows:

• Density equal to 558 kg/m3, measured on dry material
• Thermal conductivity equal to about 0.066 W/mK, measured at a temperature of about 10°C
• Flexural strength equal to 1.61 N / mm, measured by breaking test

Advantages:

• Natural material with similar characteristics to cork
• Reuse of agricultural by-products
• Reduction of CO2 emissions
• Reduction of energy and costs
• Eco-sustainable and recyclable material
• Excellent thermal conductivity and sound absorption make the material comparable to the products currently on the market

Potential Applications

• Eco-architecture and buildings
• Improvement of the building’s energy and environmental performance
• Use as thermal insulation panels for external infill walls of buildings
• Can be used as ceiling or cladding panel, be inserted inside the walls as insulation or used as a suspended panel
• Can be used in the furniture and design industry

Customer Benefit

The construction sector is carrying out a migration process towards new techniques and materials that meet the latest sustainability requirements. The ecological transition is increasing the demand for ecological materials such as natural insulation for buildings. Excessive demand translates into an increase in cost and difficulty in finding products. A sustainable approach sees the production of materials within a short distance, with attention to local resources. The use of citrus fruit processing by-products guarantees economic savings thanks to the elimination of disposal costs and allows a significant economic increase in waste.

Currently, the technology has undergone investigations and prototype testing, where the application in the laboratory has been validated. Future developments see the validation of the material in the industrial field, with the help of industrial partners who can evaluate the application of the most suitable commercial sector. Validation and production of the building panel will require additional investments. In particular, the analysis of the process and industrial production represents an important step for the industrialization of the product. In addition, product certifications and environmental labelling will be required for the marketing of the new material. The development of the project through an industrial partner would allow to adapt the production of the material to the traditional equipment in possession and to reduce the necessary investments.