Is there a future for plastics?

August 30, 2018 by Jannick Schmidt

Plastic is a ubiquitous material with many benefits such as low price and weight and an extreme functional versatility. Plastics are pervasively used in modern society.

However, the uses of petro-based plastics present us with some serious problems. First of all, we are talking about huge amounts of plastics. The approximate global production is around 480 mio tonnes of plastics produced every year (2011 data[1]) and is expected to double within the next 20 years. Currently the production of plastics accounts for around 3% of global GHG emissions[1].

Research from the past decade has demonstrated plastic contamination from micro-plastics being washed out as products are produced and used[2]. Microplastics are now routinely found in marine food chains[3], and the situation in terrestrial and freshwater ecosystems might be the same, as recent research demonstrates[4]. Furthermore most of us have seen troubling pictures of ‘macroplastics’ contaminating oceans, landscapes or cities around the world. Plastics in the environment cause serious ecological problems, but also represent a substantial economic challenge, as materials are wasted and fisheries and tourism are negatively affected.

In January 2018 a strategy to turn the ‘plastics economy’ into a circular economy was put forward by the European Commission as one of the solutions to the environmental problems of the production and use of plastics[5]. In a circular economy, focus is on keeping the values in the economy for as long as possible by keeping them in the ‘loop’ by reuse and recycle initiatives, as well as to minimise the materials (waste) that goes out of the loop[6].

For plastics, special attention is on reducing the waste component, as around 95% of plastics are only used once. Improving designs and options for consumer sorting and recycling can be an important part of the solution. Similarly there is a potential to improve the economy of post-use plastics as the market lacks unified standards and infrastructure for reprocessing[7]. A final approach that is often mentioned is to innovate various non-petro plastic systems, leading to products that are bio-degradable.

While the circular economy thinking intuitively makes sense to consumers and decisions makers, there are quite a few pitfalls seen from the life cycle assessment (LCA) perspective. When real life causalities are not appropriately investigated and considered, I am left with such questions as: Is recycling always a good idea? How do we compare single use vs. multiple use solutions? Are the alternatives to plastic really better for the environment?

Unfortunately, these questions are often not addressed. In the supermarkets, I begin to see bio products being labelled with blatantly incorrect claims, such as being 100% CO2 neutral. Let us remind ourselves that the old adage ‘there is no such thing as a free lunch’ is true here as well – producing and using bio plastics has environmental implications just as the petro plastics have.

Luckily, we have the tools to arrive at a more balanced view of the pros and cons by applying LCA that provide answers to the above question (and more). Some of my rules of thumbs are:

  • Always consider the trade offs (What is being replaced? Pick the solution that is actually best for the environment, avoiding suboptimisation)
  • For recycling, consider what is replaced (i.e., can reuse replace equal materials or products – avoiding down-cycling?).
  • Biomaterials or products are not inherently free of GHG implications, land use effects, or biodiversity concerns (look at the full picture).
  • Be critical – find the relation between causes and effects (e.g., marine litter is not caused by plastic production, but a missing waste management)
  • Realize that sometimes more investigations are needed to reveal the true consequences of product choices.

As sustainability professionals, we need to support the decision makers and consumers to ask for truly sustainable designs and material choices. Sometimes this implies saying something that goes a bit against the grain.

It is important to distinguish between micro-plastic and “macro-plastic”. Micro-plastics, e.g., micro-beads used as scrubbers and micro-fibres from washing of synthetic textiles, pass unaltered through most waste treatment systems, and end up in the environment. Micro-beads have no options for recycling, and biodegradable alternatives are available. Thus, there are obvious reasons for banning such products, as has already been done for their use in cosmetics and personal care products in a number of countries.

For synthetic textiles and macro-plastics, the picture is quite different. When considering the alternatives, petro-plastic based products often turn out to be better for the environment, as long as it is collected and properly treated after use, so that it does not end up to decompose in nature. Capturing micro-fibres directly from the washing process therefore appears a necessity. When suggesting designs for recycling we need to make sure that fractions are clean or can be easily separated, so that downcycling is avoided as far as possible. In some situations switching to selling ‘a service’ though rental, instead of selling ‘a product’ can be a game changer, as rental comes with built-in repeated use of the product. Take-back systems also need to be investigated further, and those that actually work for the environment should be chosen over those that miss the point.

I believe there is a sustainable future for plastics, when we seriously consider the facts that we have at hand.



[2] Law K L 2017. Plastics in the Marine Environment. Annu. Rev. Mar. Sci. 9:205–29.

[3] Cole M, Lindeque P, Halsband C, Galloway T S 2011. Microplastics as contaminants in the marine environment: A review. Marine Pollution Bulletin 62(12): 588-2597

[4] Rochman C M 2018. Microplastics research—from sink to source. Science April:28-29.

[5] Communication from the Commission to the European Parliament, the Concil the European Economic and Social Committee and the Committee of the Regions. A European Strategy for Plastics in a Circular Economy.

COM/2018/028 final

[6] Ellen MacArthur Foundation 2016. The new plastics economy –rethinking the future of plastics

[7] Ellen MacArthur Foundation 2016. The new plastics economy –rethinking the future of plastics

Kick-off for the linking of SDGs to LCA

July 31, 2018 by Bo Weidema

My blog-post last October announced our SDG club – a crowd-funded project to place each of the 169 targets of the 17 UN Sustainable Development Goals (SDGs) into a comprehensive, quantified and operational impact pathway framework, as we know it from Life Cycle Impact Assessment.

Now, with co-financing from the UN Environment Life Cycle Initiative, we have added an elaborate stakeholder consultation to run parallel with the development work, and expanded the project by teaming up with PRé Consultants to cover also the more qualitative approach known from their Roundtable for Product Social Metrics.
To mark the start of this collaboration, we published yesterday a joint, free, 13-page report entitled “Making the SDGs relevant to business”, summarising the existing knowledge on the linking of SDGs to business needs and outlining the role of LCA in meeting the needs and filling the gaps.

We are now looking for businesses that are interested in taking part in the stakeholder consultations and industry case studies. Contact if you want to take part or know more.

PEF weighed and found wanting

June 5, 2018 by Maartjes Sevenster, Sevenster Environmental

Our guest-blogger today is Maartje Sevenster, Sevenster Environmental, who has followed and analysed the process leading to the recently published weighting method for the EU Product Environmental Footprint (PEF). Here she shares her serious reservations on the process and the results.

A weighting set for the EU Product Environmental Footprint (PEF) was published last month. The weighting factors have been developed by the Joint Research Centre via an elaborate approach that has attempted to separate value-based weighting into objective factors. Nevertheless, the result is a poor, semi-qualitative approximation that mixes characterization, distance-to-target weighting, panel weighting, and uncertainty. All in all, the approach comes across as a black box of flawed mathematical operations.

A PEF consists of a characterization result for each of 16 impact categories, a corresponding set of weighted normalised results, and one single-score result. The use of this weighting method and the resulting single-score will be a requirement in all PEF studies and is meant to facilitate interpretation.

The final weighting set is an average of three independently derived sets, with the average multiplied by a robustness factor. Two of three independent sets are derived via traditional panel weighting and the third is based on a hybrid ‘evidence-based’ approach.

The term evidence-based has a feel of objectivity about it, but in its first part the approach applies weighting to issues that could better be investigated by natural science, and in the second part – that necessarily must be based on subjective preferences – the chosen approach violates basic requirements for good valuation practice.

In the first part of the JRC approach, an expert panel was asked to score the below seven characteristics of impacts on a scale from 1 to 100:

  • Spread of impact
  • Time span of generated impact
  • Reversibility of impact
  • Level of impact compared to planetary boundary
  • Severity of effect on human health
  • Severity of effect on ecosystem quality
  • Severity of effect on resources availability

It is immediately obvious that many of these factors, such as time span, are already covered by the commonly used LCA natural science based characterization models, even if they are not always made explicit in the end results. In fact, Annex 13 of the JRC weighting report includes a similar criticism by Mark Goedkoop: “using a panel to link mid to endpoint is really weird. This means we replace science by the verdict of panellist. I am quite aware about some of the uncertainties in the mid to end point factors, but I always thought we prefer science over the laymen’s view. Uncertain science is always better than no science at all.” Another example: the use of GWP100 for characterizing global climate change impacts implies a natural science based assessment of the timing of the impacts for comparison of greenhouse gas emissions. Is it then valid to subsequently allow an expert panel to assign a zero weight to time span as a weighting factor, which was theoretically possible for the experts in this approach?

Only two of the seven factors are not part of LCA characterization models, namely reversibility and level compared to planetary boundary. Reversibility is also the only factor that is intrinsically categorical and therefore an excellent illustration of the artificiality of the approach. Is it valid to say that an irreversible impact is (only) a 100 times worse than an impact that can be reversed by natural processes within one year? It would certainly be useful to dicuss these factors prior to determining a multi-criteria type panel weighting per impact category.

Factors such as reversibility and time span may well play a role in expert judgements of the severity of a certain impact as compared to others. However, the JRC approach first introduces a categorical scaling for each of those factors turning them into artificial ordinal variables. For instance, for time span the following categories are used:

  • Momentary [less than 1 month] = score of 1
  • Very short term [more than 1 month and less than 1 year] = score of 20
  • Short term [1-3 years] = score of 40
  • Medium term [4-30 years] = score of 60
  • Long term [31 – 100 years] = score of 80
  • Very long term [more than 100 years] = score of 100

Even though we know precisely that some impacts are instantaneous and others may be spread out over hundreds of thousands of years, such as those of radioactive radiation, the difference is here reduced to an arbitrary factor of 100. The bottom line is that most of the seven factors can be evaluated by natural science, albeit with considerable uncertainty, and do not need expert weighting. The scaling wipes out all scientific evidence and along with it any understanding of what a resulting indicator might really mean.

The second part of the JRC expert weighting procedure is a more traditional expert panel judgement of the relative importance of the seven factors. This leads us to another troubling aspect, which is that the seven factors are not completely independent as is required for proper evaluation of (compensatory) weights. Especially the “level compared to planetary boundary” overlaps with all other factors to at least some extent. Moreover, averaging categorical variables is mathematically meaningless, even when the categories appear to be “numerical”.

Finally, this weighting set from the expert panel is averaged with two other weighting sets derived via a different approach. This seriously undermines the transparency of the weighting, which should at all times be straightforward to interpret, not just a set of numbers to arrive at a single score. This is further aggravated by the use of a robustness factor to assess what is in essence uncertainty. Again, this factor involves three arbitrarily scaled ordinal variables that are averaged. The report shows some inconsistencies regarding the final choice for this robustness factor, which is apparently not considered very robust by JRC, since toxicity impacts have been excluded from the benchmark calculations in spite of already having a very low weighting due to their low estimated robustness. The semi-numerical approach gives a false sense of objectivity to this “uncertainty assessment”.

To summarize, the final weighting set is the result of so many mathematically questionable averaging, scaling, and multiplication steps that it is hard to take serious. To allow for proper interpretation of results, weighting sets should be based on clear and transparent principles. It is preferable to use a single-step conversion with a fairly limited but unambiguous perspective, such as weighting based on damage costs.

Previous blog-posts on PEF:

The clock is ticking for PEF
Harnessing the End‑of‑Life Formula

Is your pet a climate problem?

January 31, 2018 by Jannick Schmidt

The dog is said to be man’s best friend, but is it a climate enemy?

Dogs and cats are as fond of meat as are their owners. And therefore their CO2 emissions make up a substantial part of their owners emission totals. In fact, our calculation shows that a 10 kilo dog like the ones below on average emits up to 1.1 tonnes of CO2 annually, mainly through their meat consumption.

Last week I was called in as an expert for a radio programme: P1 – ‘Your dog, the climate enemy’. This segment is part of a series, ‘The climate testament’, that addresses climate issues and what each of us can do to alleviate some of the problems we face today.

The largest and most obvious problem with cats and dog lies with their meat consumption. As meat is produced, we see both land use effects and various greenhouse gas emissions, since the conversion from plant to animal protein is very inefficient, esp. for the bigger animals like pigs and cows.

For the radio programme, I had calculated emissions for three different dog sizes and I compared these to driving a car, where the emissions from small dog is equivalent to driving up to 1000 km in a average Danish car, while the big dog equals up to 5200 km driven, provided the dogs eat meat. I based these rough and average calculations on the current dietary recommendations for each of the weight classes given by professor Charlotte Bjørnvad. Bjørnvad is a professor in Internal Medicine at Department of Veterinary Clinical and Animal Sciences, University of Copenhagen.

Luckily for the environmentally conscious pet owner, Bjørnvad explained that a conversion to a more climate neutral diet is possible.

Dogs have had a long co-evolution with humans, eating the leftovers from our table. So in spite of their wolf ancestry, they can now thrive on a vegetarian diet. This is also a consequence of breeding, with all the genetic changes that this entails. Charlotte Bjørnvad explained how we could give them a protein base from e.g. beans combined with eggs, but let their main energy come from carbohydrates. In fact, a dog’s digestive system can handle carbohydrates and fibres from vegetables, provided they are heat-treated, just as is the case for humans.

So there is now enough knowledge to suggest it is safe to switch to a vegetarian diet for our canine friends. For cats, it remains a bit more tricky – a suggestion in the programme was to include insects as a source of animal protein for the cats, since they need a wider range of animal proteins in their diet, compared to both humans and dogs.

So starting from a rather polemic initial question; we arrived safely at the end of the radio programme at a solution that can be directly implemented in your dogs food bowl – next step is to push the pet food market in the right direction.


For those of you that understand Danish the podcast and Danish article is here.