Updated on February 17, 2019
Resource Hierarchy Explained
Within the Circular Economy people often refer to the waste hierarchy as main guideline. The higher up the hierarchy, the less energy and material is spilled and therefore achieving a higher level of circularity. However, there are a various number of versions of that hierarchy and a more in-depth analysis is often lacking. In this post I will introduce the various takes on the hierarchy, collect them into a single resource hierarchy and give an initial analysis.
For the visually minded, here is an infographic of the complete resource hierarchy that I have developed:
Various Takes on the Resource Hierarchy
With the newly proposed circular economy package of the European Commission, understanding and applying the waste hierarchy is becoming more important. The European commission refers to its definition of the waste hierarchy several times
Back in 1979, the Dutch politician Ad Lansink, proposed one of the first waste hierarchies. Busy with waste management he noted down the various ways to process waste. He ordered them in a way such that the best possible option was at the top. For example separation at the source is better than separation at a later stage. Within the proposal the hierarchy use the letters A-F, a grading system that has been used for many other environmental guidelines such as energy efficiency.
Even though the proposal was approved, it was only embedded within legislation 13 years after, again 13 years later the European commission embedded Lansink’s Ladder in their waste directive.
Prevention is about avoiding the initial use of resources. Hence, if yo limit or avoid resource usage they will also not become waste.
Reuse is about postponing and substitution. When reusing products no new materials are needed to fulfill the need (substitution) and the reused product will have an extended life therefore only become waste later down the line (postponing).
Recycling is generally the physical and chemical process of turning the material back into its pure and fluid state. From there on it can be used to produce new virgin-like materials or building blocks.
Energy, this step states that energy generation from waste is preferred over lower levels of the hierarchy. Energy can be generated through incineration or gasification. It often comes at the cost of destruction of the material.
Incineration is similar to the energy production level, but is about getting rid of the material by destroying it. Incineration has several by-products such as heat generation, gas emissions and ash.
Dump (land fill) is the excretion of obsolete materials from the economy back into ecological spheres of the Earth. This can also be air fill such as emissions, waste water or forms of energy such as heat.
Also called Moerman’s scale or the food waste hierarchy, is all about avoiding food waste. Except for the name, aim and basis of the ladder, I could not find the origins of the scale. So if any one knows its history please leave a comment!
Moerman’s ladder is adapted from the more general Lansink’s ladder. It focusses on food waste and hence the biological cycle. It states that the use of biological material for food is preferred over the use of biological material as industry feedstock or for energy generation. It consists of the following levels:
Avoid food waste is mainly about reduction of food loss through more efficient use and more effective supply chain. Most food waste is generated either in the chain or after sales at the consumer.
Human food. In case prevention of food waste is not possible, it would be second best to still use it as human food without any processing. For example through redistribution.
Convert to human food. Sometimes the food isn’t good enough to directly use it as human food, conversion of the food waste could be an option. Processing could be simple heating to make jam to creating oils or other food extracts from the waste.
Animal feed, if the quality of food is too low to use it for human consumption, the next option can be to create or process it into animal feed. For example chaff and leaves or bones and marrow for cattle and pet feed.
Raw materials. If there is no food to be made from the food waste or other biological materials, the next best option is to process it into feedstock for industrial processes and non-edible products. For example bio-plastics or perfumes.
Make fertiliser. Once the material cannot be used for direct economic purposes you can process it to make fertiliser for cofermentation, which can result in additional energy output, or to make fertiliser through composting.
Use for sustainable energy. The next step is to gain energy from the biological material that is left and cannot be used anymore for any of the options above. The aim here is to retrieve as much energy from the material in any form possible such as heat and gas.
Burning as waste. The last option is to get rid of the waste as composting or using if for energy production is not efficient or applicable. This can be the case for material from which all nutrients are extracted or they are contaminated with non-biological or toxic materials. In this case controlled incineration is often applied with the aim to destroy the material. Energy that is retrieved from this process is a by-product.
3R, 6R and xR approach
Since the circular economy has gained attention, several people started to refer to the 3R’s or 6R’s. In China the 3R approach is common and refers to reduce, reuse and recycle. The 3R approach strives to reduce harmful impacts of economic activities on the environment by minimizing impacts throughout the product life cycle (production, distribution, and, consumption). The 6R is an extension of the 3R with additional steps that define recover, remanufacture and redesign.
Comparing the 3R and 6R with Lansink’s or Moerman’s ladder they are basically the same. Instead the 3 and 6R approaches use words that start with the re- prefix. This helps to remember that all things you can do to improve the sustainability of products and services may start with words that use this prefix. This has started a race to the top of scales that use 7, 8, 9, 10 or even more verbs that follow this line. For example Jacqueline Cramer published a list of 7R’s, but also one of 10R’s (both in Dutch). Each list that is being published is different but the approach and principles are the same. The unfortunate thing is that nearly never a more thorough analysis is given except for an explanation of the terms. Things are therefore getting more cloudy instead of useful…
Zero Waste hierarchy
Zero Waste Hierarchy of Highest and Best Use is a hierarchy that is similar to the 3R’s. However, where the 3R has a manufacturer perspective, this hierarchy has a more governmental perspective. It was developed by the Zero Waste International Alliance (an alliance of governments, NGO’s and businesses) in response to the European waste hierarchy that was not found to be ambitious enough. The European only “focuses on designing waste out of the system instead of trying to perfect bad ideas such as incinerators or landfills”.
It adds three additional levels of which two are in between the reduce and reuse and focus on encouraging different behaviour and design of the product, the third is at the bottom and focusses on regulation of disposal. Especially the level that focus on encouraging and regulation is somewhat abstract to be address by chain partners. However, the waste hierarchy is not simply about regulation as the other levels from the 3R’s are more applicable to manufacturers and the rest of the supply chain.
That design is in this hierarchy can also be questioned, for sure it’s position. If designed well, the entire product life cycle is addressed and thus supports all other levels in the hierarchies: it addresses the reduction of material and energy usage, it allows for reuse of the product or components, and it eases recycling by avoiding difficult disassembly or compound materials. And if design support all other levels, aren’t there any other elements that support them as well?
Looking at the various ladders and scales there are various observations that can be made. Most of them are similar but use slightly different terminology. They are based upon each other and further developed. Each of them seems logical and applicable. But the question is how and when to apply them?
Interestingly, the Ellen MacArthur Foundation developed a model of the Circular Economy that includes the idea of the resource hierarchy. Especially for technical materials their model distinguishes between various circles and states that inner circles are preferred over outer circles as the savings are larger due to more value preservation within the product. For the biological cycle there are no specific inner circles, but cascading is one of the key elements here. This refers to the Moerman scale approach.
Within the Ellen MacArthur Foundation’s model there is a clear separation of the biotic and abiotic or biological and technological materials. This idea of resource separation comes from the Cradle to Cradle paradigm. It is useful as for most* biological materials nature can be used to regenerate them. This is on a rather small time scale, from a few months to several years most biological materials can be regenerated. However, technological materials such as metals or man-made materials such as plastics and composites, nature can’t seem to regenerate them within a time-horizon that humans can oversee. Therefore it is reasoned to keep those materials separated: products should either be made from biological materials or from technical materials. In case they are combined disassembly should be easy.
But the question is whether distinguishing between only these two cycles is enough. Especially because it can be argued that the Earth’s system could als regenerate other materials. Processes taking place deep down in the Earth’s crust (lithosphere) or high up in the atmosphere can also help to regenerate and balance out certain materials. However, these processes are not well-known and their time-frame may be very different from the biological regenerative cycle.
This leads to the circular approach. Most waste hierarchies end with land fill or incineration. They do show the options of cycling materials longer within the economy through for example reuse or recycling. A proper answer is never given to what can be done at the end of the life cycle. Incineration and land-fill are said to be no-go’s, but at one point materials will be degraded so much that they can’t be given another purpose within our economy. Therefore the final stage is probably return to the Earth’s ecological systems. The return should be well considered since it should do no harm to these ecological systems and preferably even support them. In other words, each material may have a different place where it should be ideally returned.
Life cycle approach and resource usage
Like the Zero Waste Hierarchy, there are several other scales to be found that also list levels (such as design) that do not seem to fit within the hierarchy. Reinvent is also an example of this. These actions can be applied to any of the levels to improve the sustainability of a product. Therefore the hierarchy developed here is based on the physical life cycle process: the take, make, use and waste stages. When applying these to the hierarchy it shows that some levels or measures fit in a specific life cycle stage. This may help businesses that operate in a specific life cycle stage to focus on measures that mostly apply to them.
These measures can also be linked to the effect on resource usage. For example, rejection of materials has a preventative effect, while recycling increases efficiency of the material (it can be used longer). These material usage effects are also in relation to the life cycle stage and therefore indicate that further down the life cycle it becomes harder to have the best effect possible on material usage and preservation.
Two resource domains, materials and energy, are often referred to within the hierarchies. There are savings on these domains (in the prevention level), costs (energy used for recycling) or returns (energy from incineration). Sometimes other material resources are also mentioned separately such as water usage. Even though the effects of the hierarchy levels on these resource domains cannot be generalized, it seems that in some levels there is a higher possibility to have positive effects on certain resources.
To allow, support and encourage manufacturers to effectively apply a resource hierarchy the right conditions should be available. As discussed before, one of these conditions, or enablers, is design. Designing, redesigning or even reinventing allow the manufacturer to make more efficient, effective or even prevent use of certain resources. This will bring him higher up the hierarchy. Next to designing there are various other enablers that support technical, cultural or economic development in such a way that additional steps on the hierarchy can be made. For example supply chain integration, legislation or logistics.
An Integrated Waste Hierarchy
Combining the various hierarchies with the analysis a resource hierarchy can be developed that shows the hierarchy, the resource separation, the life cycle stages and resource usage as well as the various enablers that support implementation of the hierarchy.
Within this resource hierarchy the perspective of the physical parts of the supply chain have been included. All that does not fit within this supply chain is moved to the bottom as bricks that may support the implementation of the hierarchy. The number of levels has been chosen such that there are always some levels that apply to a certain industry or supply chain partner.
Is the Resource Hierarchy always applicable?
The general assumption of most waste hierarchies (whether it is Lansink, Moerman, or any other), is that they are always applicable. The idea that distinguishing between various measures and sort them by resource intensity results in a useful tool holds true for most materials. However, that does not mean that it works for every material. For example, products made from brittle materials may require a lot of energy to create the conditions that it can be repurposed or remanufactured. Therefore it may be better recycle them as the total energy required will be lower. Also the amount of materials lost may be less.
The idea of the waste hierarchy, or parts of it, apply to various sustainability or economic paradigms. The Ellen MacArthur Foundation already related the waste hierarchy to the Circular Economy, but more paradigms are somehow related: either directly represented in the levels of the hierarchy or through the enablers of the hierarchy. The extended hierarchy below shows this:
If you’d like to download the resource hierarchy or the extended version in pdf. Right below are the download links.