Understanding the waste pyramid – how to monetise waste materials through molecular reconstruction
Recycling has two major limitations, the first is that the less value a waste material has the more energy is needed to recycle it. The second is that the collection and processing of worthless materials involve competing challenges with the scale of operation.
One of the main problems with waste is sorting it out; separating the many different materials people throw away. There are many materials which are recycled or re-used without resort to any form of separation. These are high-value goods such as jewellery, antique furniture, high-fashion clothes and so on. Then there are materials which are scrapped or recovered for re-moulding, re-melting or, in the case of paper and card, processed in some way but without chemical transformation.
The lowest value category requires some sort of chemical conversion for recycling. This could include for example feedstocks such as un-sorted municipal refuse, hospital waste, unusable clothing, and ocean plastics - which have no market in their current form. The Avioxx process addresses this with its process and technology for their molecular breakdown and reconstruction.
We make high value fuel out of non-recyclable or reusable materials
At Avioxx, we are concerned with the very real problem of how many wastes are dealt with by incineration and landfill. Incineration creates enormous carbon emissions and is happening on a large scale all over the world. Landfill disposal also has its downsides such as methane gas produced from landfills, and the escape of plastics into the oceans causing significant ocean CO2 absorption rate decline.
Recent reports of the burning of clothing sent to Africa, intended for re-use, have shone a light on an expanding fast fashion sector. Charities and other benevolent agencies wishing to help less advantaged people, are finding their efforts going up in smoke, literally. As production expands and re-use markets become saturated, an increasing volume of unwanted and valueless materials face disposal.
Confronted with the prospect of large quantities of their products being ultimately burned to produce carbon dioxide and other harmful pollutants, the fashion industry is one of many sectors, keen to find a solution which reflects its customers’ and shareholder concerns for the global environment.
The recycling pyramid
The Avioxx solution
The Avioxx process is a way of converting carbon-containing materials, including household wastes and other hydrocarbons into sustainable aviation fuel. The use of biologically derived material in the feedstock offers the prospect of its classification as “sustainable”. Sustainable fuel must adhere to strict regulatory requirements to allow it to be categorised as net zero or sustainable. Using this process to make aviation fuel avoids the emission of carbon dioxide and other pollutants and is clearly a beneficial solution without having to re-invent and replace the current global fleet of aircraft.
Aviation fuel made this way will displace fuel derived from fossil sources and have a very positive impact on global emissions whilst also addressing a number of important secondary environmental benefits.
The unique Avioxx solution has six main elements:
- Waste collection
- Sorting
- Pre-treatment
- Chemical breakdown
- Chemical rebuilding
- Distribution and sales
A. Waste collection
The economies of scale favour large scale processing units, but this imposes high collection, transport, and handling costs. Local authorities have historically bourn the burden of municipal waste collection. They have increasingly promoted the pre-separation of wastes by householders. The recycling of glass, metals and paper/card has become firmly established as a result.
The recycling of plastics is more problematic because of the wide variety of types and their recyclability. Consequently, a substantial residual of unrecyclable household waste remains to be dealt with. Much of this still finds its way to landfill and incineration via fairly large-scale collection centres operated by a handful of large waste management companies.
In the case of some industries, such as vehicles and tyres, the industries have fostered their own recycling solutions. However, the fashion and clothing sector have yet to get to grips with an ultimate disposal strategy.
The evolution of charity shops and more recently pre-loved clothing websites has been an interesting development. Charities have relied upon the generosity of volunteers to operate the collection service, but not all materials are saleable, and the disposal of rejects, alongside arisings from local authority disposal points, present an environmental challenge and costly burden.
As the volume of these low value items increases, the costs of transport and handling severely erode any potential future revenue. Increasing proportions of the mix will remain unwanted and a low-cost means of recycling will become urgent. This will require collection strategies to be reassessed.
B. Sorting
Chemical transformation often involves the input of significant amounts of energy. For this reason, it is sometimes worth putting some effort into sorting the materials so that a higher proportion can be transformed physically, as in the case of remoulding plastics, processing paper and card and so on.
Artificial Intelligence (AI) has created opportunities to make this easier and largely automatic. Here at Avioxx we have been researching the use of AI to analyse the composition of waste. Cameras can automatically recognise shapes and a database can easily be set up so that different waste items on a conveyor can be identified along with their potential energy content. This has several benefits.
Firstly, the data can interact with robotic or mechanical separation systems to pick items from the feed belt and deposit them into a separate stream, enabling automatic picking, and effectively adding value to the waste. This also reduces the energy costs of its transformation. Alternatively, it enables a more tailored or specific treatment which will add more value.
Secondly, it means that the average aggregated properties of the waste stream can be estimated at any one time. This means that the energy content and chemical composition can be continuously determined. These data can be fed into the control system of the chemical processing system to ensure stability and optimisation.
Another important reason for sorting is to remove materials which could damage the process either through attrition, or by forming compounds which are corrosive or poisonous to the catalysts and other sensitive components. Magnetic or weight-based sorting systems are an obvious option, but other measures may be appropriate and worthwhile.
C. Pre-treatment
Shredding - The Avioxx process is a continuous flow system and feedstocks need to be able to be handled easily and automatically. Shredding improves the options for transport and handling in the process. Shredding systems are commonplace within the waste processing sector. A system which is adequately robust and can achieve the necessary size reduction to be selected based on the waste properties.
Water removal – The performance of the system depends on the energy content of the waste material, and this can vary significantly with household waste as well as other materials. Waste heat generated in the process can be used effectively in drying the feedstock and in doing so raise its intrinsic energy value. Exposure to blown air may be quite effective in most cases.
Pelletisation – The formation of homogeneous mixtures of solid dry material is useful in enabling the feedstock to be fed by screw feeder or similar conveying systems. Machinery is available to do this, but the condition of the material is crucial to its efficient deployment. Measurement systems are also much improved when dry and flowing materials are being weighed for example. Specific wastes may require specialist processing to achieve the aim of their being able to be transported, stored, handled, and weighed efficiently.
Other – There are several other options for the pre-treatment of the waste feedstocks, depending on their nature. These include pyrolysis, whereby the waste is heated to a high temperature at which point it gives of a range of gases, tars, and pyrolysis liquors, together with char or pure carbon. These materials can then be processed separately into useful products, including via the Avioxx route.
D. Chemical breakdown
The Avioxx process is a brutal way to treat carbonaceous materials. It is a last resort in the absence of easier ways to recycle. The high temperature reaction with oxygen shatters existing chemical bonds and creates two basic components, carbon monoxide and hydrogen, often referred to as “syngas”. Other by-products are also formed due to the complexity of reactions taking place.
This process, called “gasification” or “partial oxidation” represents some of the most elementary chemistry, and is generally carried out using air. However, air consists of 80% nitrogen which would be carried through the process.
The Avioxx process by contrast uses pure oxygen. This has two clear benefits. Firstly, it provides a much more vigorous reaction, attacking materials normally hard to gasify, and secondly, it reduces the size of plant needed because of the vastly reduced gas volume. The oxygen is generated within the process using an electrolyser, and this is powered by a fuel cell system which uses the syngas as the fuel.
E. Chemical reconstruction
This final stage of the process involves the rebuilding of the molecules required to resemble the sustainable aviation fuel. It uses an iron or cobalt catalyst as a means of polymerisation, through the creation of long chain molecules or paraffins. It’s called the Fischer-Tropsch process, invented by two German chemists in 1925.
The conditioned syngas is fed over an iron and/or cobalt catalyst where an exothermic reaction takes place to form a mixture of paraffins and other hydrocarbons, referred to as FT crude. The reactor is cooled by water or other medium. The composition of this FT crude is sensitive to the reaction conditions and the catalysts used, so stability of the operation and the feed conditions is of crucial importance for quality control.
Additional steps are then taken to refine the FT crude by reaction with hydrogen. Hydro-treatment and hydrocracking provide a mixture of components which more closely match those found in conventional jet fuel.
F. Distribution and marketing
The location of the Avioxx plants is crucial to achieving the optimum scale and the minimisation of collection, storage, handling, and transport costs of the feedstock. It is also important to be able to integrate the supplies into the existing aviation fuel distribution system.
In the short-term blends with traditional aviation fuel of 10% are foreseen, rising to 100% over the longer term. This may change as price and quality competitiveness may accelerate demand. Airline customers may optionally wish to pay a premium to fly sustainably with Avioxx sustainable aviation fuel. As higher quality sustainable aviation fuel is produced at lower cost a straight fight with fossil fuels may offer the prospect of rapid expansion and displacement of traditional competitors.
Whilst optimisation of the supply chain and excellence in process operations are vital, this will be supported by investment in corporate awareness and brand building, both within industry circles and the end-customer base. The use of book-and-claim systems whereby airline customers can request Avioxx SAF is quite feasible and will motivate airline customers to seek our products directly.
Making the economics viable
The scale of the process is a key area for consideration. The economies of scale apply to the capital and operating costs and favour building large plants serving wide areas and able to compete with fossil-based supplies. However, the collection and transport costs form a significant component of the raw material cost, as do the distribution costs of fuel to the airline customers. It is clearly sensible to size the plant to be consistent with the availability of raw material at the collection points. The proximity of the plant to the existing fuel blending or logistics infrastructure is also a consideration.
The main competition is from fossil-based fuels, produced from crude oil by distillation or from gas-to-liquids plants. These latter use the Fischer-Tropsch process but consume natural gas as feedstock and operate on a vast scale. They are generally located in the middle east and are transported to consumer markets.
Our Avioxx plants are of a size which is consistent with the availability of feedstock at typical collection points and are but a fraction of the size of the largest fossil-based gas-to-liquids plants in the middle east. Nevertheless, the low value of the waste material we use will largely offset scale effects of processing, provided the plants are well-located to minimise logistics costs, operate automatically with low overheads, and are reliable.
One key feature is the control system we are developing. This is designed to ensure the gases fed to the FT section are of consistent composition, temperature, and pressure, despite the very varied composition of the waste material being processed. The work on AI and machine learning will have an important bearing on the success of the operation.
Finally, the Avioxx process offers the prospect of delivering better fuels to the airline businesses, fuels which are more energy efficient as well as being environmentally beneficial. This means that they will be able to command a premium in the market vis-à-vis traditional supplies.
Our SAF will contain a different mixture of components than distilled petroleum product by virtue of its manufacturing route. There is scope for fine-tuning of the process to minimise the harmful components, including those most inclined to produce contrails for example, and maximise those giving efficient and effective combustion. The Avioxx products will need to meet the tight specifications for Jet fuel.
Steps towards value creation and a circular economy
The Avioxx process offers the prospect of creating a competitive route to the manufacture of aviation fuel from waste materials, which is sustainable. The company aims to stimulate the development of the circular economy by designing a system at an appropriate scale, consistent with the needs of the waste industry. The immediate objective is to design, build and operate a small-scale system which demonstrates the core functions of the Avioxx technology. The next is to achieve the qualification as a sustainably sourced fuel. The third is to design a large demonstrator plant (ca. 5,000tpy) which mirrors a commercial unit of 32,000tpy fuel. Each of these steps represents a significant valuation gain for the business.
The work in progress includes several wide-ranging technical challenges, from understanding waste and how it is managed, to the highly regulated aviation fuel business. It offers an opportunity to apply the immense skills of the team, and the exploitation of intellectual property which sets this venture apart from any competitor and provides the assurance of healthy growth and profitability over the longer term.
For more information about our work at Avioxx please contact us on info@avioxx.com and we’d be delighted to hear from you.