Organic waste – a new resource?

Materials World magazine
1 May 2018

Guglielmo Carra, who leads Arup’s Materials Consulting team in Europe, tells Gary Peters why organic waste should be used as a vital resource in the future. 

Tell me about your career to date.

I am a civil engineer and materials scientist. I earned my masters degree in engineering from the University of Pisa, and my PhD from the Polytechnic University of Milan, Italy. I also spent some time in the USA, where I worked in New York, as well as a visiting student and subsequently a visiting scholar at MIT, where I started working for Arup.

During my years in Italy, I earned a MSc in Yacht Engineering from the Department of Aerospace from the University of Pisa. This course was where I started to think about cross-sector opportunities by understanding the potential offered by composite materials in construction. I am now based in Arup’s Milan office, where I lead the Materials Consulting team in Europe.

What has been a career highlight for you?

The proudest achievement to date has been leading the design, engineering, and development of the first self-supporting bio-composite façade panel in the framework of the EU funded R&D project, called BioBuild. 

What are the possibilities of regenerative resources?

Arup has been active on the topic of bio-based opportunities within construction for a long time now. For example, we were the lead designers for the solar-leaf building in Hamburg – the first building worldwide to employ the use of algae in façade panels. We have also worked on other demonstration projects such as the Hi-Fi temporary building at the New York MoMa, which was made of mushroom bricks.

It stems from an understanding that the construction industry needs to change and consider solutions with a lower impact on the environment. Even more important is the understanding that traditional raw materials and resources used today are limited.

It is our responsibility to identify and develop future opportunities to exploit regenerative resources, such as plants. Additionally, there are large waste streams coming from agriculture and forestry that are not used efficiently.

What challenges are there for implementation?

The challenges mainly relate to educating those in the supply chain and the availability of regulations that would support such transition. Of course, large development of bio-based technologies also requires investments in R&D and new players within the
supply chain. 

There is a need for clear governance strategies and plans. Recent European regulations relating to construction products, as well as guidelines on the circular economy are already pointing in this direction.

How does the process of turning waste into building materials work?

This depends very much on the specific waste residue and the final product to be produced, as well as the specific application for the end product. Currently, most of these products are primarily processed using a heavy press and water, energy, and pressure, in addition to the residue itself. 

In future, I see opportunities in applying more advanced manufacturing techniques to organic residue – one example could be 3D printing of natural materials.

It’s stated that peanuts, rice, and bananas could be used as building materials. Is that truly feasible on a large, mass-produced type scale?

I think one of the big opportunities of organic waste lies in the fact that it is largely and globally available. This allows us to think about scalability where different development models can be foreseen. 

Large companies could start producing bio-based products relying on solid waste streams, or the scalability could be provided by an incremental development of small and medium sized companies developing bio-based products. In both ways, I do not think that scalability will be an issue considering the large amount of resources available. More pressing is the need for investment to boost development.

What other types of organic waste could be used as building materials? 

Any product containing lignin and cellulose. It could be leftover tree branches, orange skin residue, tomato, peanuts, or potato skin. Each of these base materials could produce end products with different performances.

What needs to happen to shift the viewpoint of waste so people see it as a resource?

It’s all about going back to the roots. Our grandparents were used to seeing waste as a resource. I think the mentality has been distorted over the past 30–40 years due to a capital intensive industry and the illusion of an abundance of resources.

Nowadays, there are tools to revert this logic in a much more conscious way, by using and implementing technological advancements – gathering and using large amounts of data. A change of viewpoint is well on the way. However, to make this transition complete, there is a need for all stakeholders to be engaged, and education should take both a top-down and a bottom-up approach. 

Things are improving. For example, Ikea has a take-back programme for used furniture, and in 2015, the EU first published its directives on the circular economy.

What barriers are preventing more organic waste being used as building materials?

A need for regulations to cover this area and investments allowing the industry to grow.

What are the most common uses of materials made from waste?

Typical use relates to interior finish such as partition walls, floor systems, and acoustic ceilings. Furniture could be an interesting opportunity, and there are also applications related to the façade industry for low-rise buildings.

Where in the world is most advanced in terms of using organic waste as materials?

There are a number of very interesting companies in the USA, who are involved in exploiting agricultural waste for construction products. In addition, Germany is advanced.

How do you think the use of waste as building materials will develop in the coming years?

This is dependent on a number of factors. Regulations are the first barrier. In some countries, organic waste is indeed waste and in some cases it is treated as such with very stringent procedures. As for many other waste categories, there is a need to gain the end-of-waste status, in order to be reused and processed in future products. 

Then, the applicability of such bio-based products needs to be competitive from a performance standpoint with other benchmark products on the market, for example in respect to fire performance or durability. As soon as this is better understood, there will be the opportunity of exploiting the untapped value of the organic resources in construction.