Waste could soon be harvested from farms and turned into building supplies like bricks, insulation and panelling, thanks to the advent of new research in the field. Roads & Infrastructure Magazine investigates.
Australia produces more than 5.3 million tonnes of food waste from households, the commercial sector and the agricultural industry, according to the National Food Waste Strategy.
Food waste ends up costing the economy $20 billion and is estimated to have released 7.6 million tonnes of carbon dioxide emissions in 2014-15.
Engineering and design firm Arup has been researching possible ways to take advantage of the opportunities presented by agricultural waste.
The Urban Bio-Loop report explores new avenues for the construction and infrastructure industries to take advantage of this untapped resource. By doing so, it would help build a circular economy – a system that attempts to reuse waste instead of throwing it away and eventually reaches a point where everything can be recycled.
The report outlines the main ways to get the most out of agriculture and creating building materials made out of biological matter, which are called biomaterials.
For example, flat boards made from agricultural waste can be used for decorative and functional purposes while remaining sufficiently stiff and durable. Natural fibres from plants like bananas can be used to create a variety of complex forms and surface finishes.
Acoustic absorbing components from highly porous waste materials can be used in insulation. Natural fibres from biomaterials provide low thermal conductivity for thermal insulation and can also be used to create carpets and envelope systems for a variety of interior and exterior applications.
One initiative forwarded by Arup was the BioBuild project. In collaboration with 12 companies and universities, some of the first systems for bio-composites were designed for construction projects in Europe and parts of the US.
An example of the technology produced was a brick grown and made from mushrooms. The bricks were suitable for interior finishes, provide acoustic absorption and were used in heating applications. They featured in an outdoor installation at New York’s Museum of Modern Art, needing to be protected by plastic or plaster, as water causes them to degrade over time.
Dr. Guglielmo Carra, Arup Europe Lead Materials Consulting, says the ability to find an alternative way to exploit agricultural waste increases its potential to be used in a variety of areas.
“With this research we wanted to tackle another very relevant issue which was: how can we exploit very valuable and abundant resources like the natural waste from the countryside and materials to make construction parts?” Dr. Carra says.
“Our research has found that using a kilogram of agricultural waste to create building materials had five to six times more value than if it were used to create energy from anaerobic digestion or incineration.
“Construction needs to optimise processes in the way we design our projects, buildings and infrastructure projects.”
Dr. Carra says one of the goals of the Bio-Loop report was to inform people about the value chain for waste and propose tangible applications and case studies.
“It’s an open call to the construction, waste and agricultural industries to join forces and make it a real opportunity for growth,” he says.
“The idea was to showcase the fact it is possible to use biomaterials in infrastructure, find elements that make it effective and make it open to the industry. One of the main drivers for the industry in this space has been the financial opportunities available.
“Scalability is the next big step for this kind of technology. Contractors, engineering firms and large companies dealing with food or agricultural waste need to all join up to start scaling up the technology that a few companies have been bringing forward.”
When it comes to seasonality in crops, Dr. Carra says there are a few ways to stop raw materials from flooding the market or not being available in some parts of the year, creating massive price fluctuations.
“Crops along the equator benefit from 365 days a year of the same types of growing conditions, meaning there’s lots of opportunities there to exploit the stable climate,” he says.
“For areas in the world without that luxury, there are methods to preserve materials for whole year-round production. One way to do so is to dry the materials and store them to use them for manufacturing throughout the year.”
Dr. Carra says it’s important to explore how the entire waste cycle can be exploited to turn unproductive waste into valuable resources sold as components.
“If waste can be harnessed at a very low price and used to create building materials, mixed with traditional components like steel and concrete, it becomes a cheaper and more environmentally friendly alternative,” he says.
“By diverting biomaterials away from landfill, composting and incineration, it lets them get more value before they can recycled or broken down to return nutrients to the earth.”
Dr. Polly Burey, Senior Lecturer at the University of Southern Queensland (USQ), says there are significant advantages to using food waste in construction.
“There’s a wide range of food waste streams available here in Australia that could be tapped into for construction. For example, seafood is quite a sizeable industry in Australia which produces shells as a waste by-product. Currently, there is research that is looking at how these shells could be used within concretes as an aggregate to strengthen the materials.”
Dr. Burey says to capture these waste streams the industry would need to target industrial agricultural waste to avoid contamination.
Capturing it from a single source would help reduce the 2.2 million tonnes of waste that she estimates comes from the commercial sector.
“To ensure this technology is successful, different stakeholders from across industries need to be in communication. We need to encourage researchers to talk to potential stakeholders about new technology to make full use of this innovation.
“There’s often a mindset issue when it comes to research like this. It can be hard to convince industry stakeholders that biomaterials could stack up against traditional materials,” she adds.
Dr. Burey says it’s important to properly use the inherent value of the waste that is currently being sent to landfill, composted or incinerated. She says that embracing a circular economy helps avoid losing value from produce.
“These materials provide functionality and can be used to create structural integrity, prevent water from permeating and could even be cheaper in some instances. When waste produce is used on a farm as animal feed and compost, it’s not returning the full economic and resource value, it’s just mainly being returned as nutrients. Some people within the food industry I have talked to maintain that it is an expensive form of animal feed with all the water and fertiliser resources sunk into it,” she says.
Bagasse, for example, is a byproduct of sugar cane harvesting and can be used to create stiff boards.
Australia plays a large part in the sugar cane industry, with 35 million tonnes grown annually, generating $2 billion for Queensland, according to the Australian Sugar Milling Council.
Dr. Burey says finding an alternative use for these by-products creates a safety net for the industry. A diversified market means farmers are able to be protected from the full brunt of an unexpected disaster.
“Cyclone Debbie was painful for a lot of farmers as it knocked down a significant amount of crops. When there is a variety of potential alternative sources, such as ethanol, or being used to create boards, it means that the industry can mitigate the effects of serious disasters on their business.
“A similar example is the recent listeria outbreak in melons. If there was a way to turn that waste not affected by listeria, which is currently just sitting there and rotting, significant value could be captured instead of lost.”
Sven De Wachter, an entrepreneur and Management Consultant for Wachter Oriental, has seen this technology at work in the banana industry.
French company FIBandCO has been taking advantage of the resources available from banana harvesting on the Caribbean island of Martinique and turns previously discarded banana plant pseudostems into 100 per cent natural panels, wallpapers and veneers.
“A typical banana trunk will provide around seven tonnes of natural fibre per hectare, more than flax fibre,” Mr. De Wachter says.
“Compared with harvesting timber, the banana alternative has no impact in the deforestation process. This is because of the banana plant’s rapidly renewable life cycle, which is able to reach full size in just nine months.
“If it was left in the field or turned simply into compost, it would create carbon dioxide. By turning them into a veneer, panels, acoustic panels, or even wall paper, it’s able to provide new resources and a diversified range of products for the banana farmer.”
Mr. De Wachter says because the harvesting process uses the pseudostem of the banana plant, it means the harvesting process doesn’t create any competition in the food chain.
He explains the best time to processes the pseudostem from the banana plant is within 24 to 48 hours after it is harvested. Mr. De Wachter says Australia’s banana industry would make it a great area to establish a banana fibre manufacturing unit for local growers.
“I believe it would be a good diversification for the sometimes challenging banana industry in North Queensland,” says Mr. De Wachter.