Just another quick Sankey diagram before the weekend. This beautifully crafted black&white diagram is from a scientific article ‘Exergy assessment of a cogeneration system with micro-turbine and absorption chiller’ by Martínez Reyes et.al. published in Proceedings of COBEM 2005 (18th International Congress of Mechanical Engineering).

This is for a cogeneration system with a 30 kWe gas micro-turbine and a 35 kWt absorption chiller. Flows are in kW with a scale of 1 cm = 100 kW in the original size. Good handling of the loop flow.

The Australasian Institute of Mining and Metallurgy (AusIMM) is an association of the minerals industry. In this AusIMM Bulletin article titled ‘From Waste to Wealth’ they talk about metal recovery and recycling in Australia.

This Sankey diagram (actually two Sankey diagrams) from the article visualizes metal flows in Australia in 2012/2013 based on data from Golev & Corder (2014).

The smaller yellow diagram section on the left actually just shows mining activities in Australia and the fact that the largest portion of mining output (ores) are exported. Only 7.5 Mt are processed within Australia. This Sankey arrow is then blown up and corresponds to the yellow input stream into the second diagram [a similar solution to decouple diagrams with different scales was presented in yesterday’s post].

In the metal production process there are losses, and material is being exported and imported. The annual increase to the Australian ‘in use stocks’ (i.e. metals being used infrastructure, buildings and products) is 12 Mt, possible only thanks to 7 Mt metals imports. Some 7 Mt of metals are also released annually from ‘in use stocks’.

The dotted lines signal that there are possible routes, but either outside the scope of the Australian market or no reliable data is available (new scrap from the manufacturing step being fed back to the smelting).

In this post on rare earths I have recently featured an alluvial diagram depicting rare earths use from a presentation by T.E.Graedel (Yale). That same presentation also lead me to another article by X. Du & T.E. Graedel titled ‘Uncovering the Global Life Cycles of the Rare Earths Elements’ (open access) that has a number of circular flow diagrams I would call “REE wheels”.

The article describes how quantitative data on rare earths is available for mining and processing, but “very little quantitative information is available concerning the subsequent life cycle stages”. Also, data is mostly available for the overall REE production, but not individually for every single rare earth element. They therefore aim to estimate and approximate the quantities for ten REEs, based on sources from China and Japan.

Here is the REE wheel for Yttrium (element Y) from the article:

The diagram can be read from 7 o’clock to 5 o’clock in a clockwise direction. The processing steps are “Mi” (mining), “S” (separation), “F”(fabrication), “Ma” (manufacturing), “U” (use) and “W” (waste management), thus showing the flow of the rare earth element through the economic cycle.

I did a Sankey diagram version of the above Yttrium REE wheel to have the arrow magnitude representing the quantities. Flows are in Gigagrams (million metric tons) per year.

Due to the fact that the arrows connect horizontally and vertically to the node (and do not run diagonally like in the original) my remake looks less “circular” somehow… in fact it resembles more one of those retro indoor AM/FM loop antennas you would hook to your HiFi. So I am not fully satisfied with the outcome. Would it be better if the nodes were tilted 45°?

What’s nice is that the extraction of ore (17.4 Gg) can be directly compared to the 2.9 Gg Yttrium release to the environment. I switched ore input and tailings output at the mining node to have them side-by-side.

Comments and improvement suggestions welcomed.

I had previously reported on Sankey diagrams being used in articles on circular economy (earlier this year in January and back in 2013). Researchers in the field of MFA, circular economy and urban mining apparently love to use them…

Here is another one from an article by Willi Haas et.al. published a few weeks ago (How Circular is the Global Economy?: An Assessment of Material Flows, Waste Production, and Recycling in the European Union and the World in 2005; DOI: 10.1111/jiec.12244).


Open Access @ Journal of Industrial Ecology, via Green Manufacturing blog

The answer to the question raised in the title is answered visually: Not very circular!

The above Sankey diagram is for “all societal material flows globally”, world mass flows moved by mankind. 62 gigatonnes (Gt) of material processed, out of which 58 Gt are newly extracted, and only 4 Gt recycled. “From such a system-wide metabolic perspective, the degree of circularity of the global economy measured as the share of actually recycled materials in total processed materials appears to be very low, at 6%.”

Fossil fuels (yellow) are converted to energy, most biomass (green) ends up as gaseous emissions or solid waste. Construction materials are in orange and metals in blue and these add to stocks of buildings, infrastructures, and other goods with a lifetime longer than a year. The two red arrows are for industrial minerals and “waste rock” (would that be tailings from mining?). Note: The legend is cut off in the screengrab above (please check the original article, page 6).

Interesting article, make sure you read it (open access). It also features a second similar Sankey diagram for Europe (EU-27). Beautiful and intelligent use of a Sankey diagram.

Yesterday it became known that the European Commission would shelve their circular economy package of waste, recycling and incineration laws for now, in favour of an even more ambitious legislation to be presented by end-2015 (read here or here).

That led me to browse tweets using the hashtag #circulareconomy, and I ended up unearthing two nice Sankey diagrams…

The first one is by WRAP UK, showing the EU-27 material flows estimated in 2020. This is not for a specific type of material, but all material.

Flows are in million tonnes, with the 2020 values in blue, and the current (2010) figures in brackets below for comparison. There are three nodes: ‘Direct Material Input’, ‘Domestic Material Consumption’ and ‘Waste’. Unfortunately the size of the node icons is too large, and the flows are difficult to see. But still, this is a nice idea!

The main message is that in comparison to 2010, Europe could have 350 million tonnes of recycled material in 2020. Check out these Sankey diagrams by WRAP UK that basically convey the same messsage, but are less infographic.

Another Sankey diagram I found when browsing through the tweets was this one below. The title of the diagram is “How circular is th UK?”.

I found it in a blog post ‘Designing Out Waste Consortium’ by Ramon Arratia on Interface’s Cut The Fluff blog on sustainability, but it is originally from this Green Alliance blog post by Julie Hill.

No values shown along the flows in this Sankey diagram, but neatly shaped circular flows. The question raised in the title is answered prominently with the message that 19% of the material in the UK is led in a loop (pink flow).

Austrian technical consulting firm pro-wel offers process engineering services to its customers. Their website features two Sankey diagrams, one of which is a rare circular one with curved arrows (see others).

I also like the technical frame around the diagram, a must have in engineering and architecture.

While some of you might think of their favourite lunch time snack, in the UK the term WRAP refers tp the ‘Waste & Resources Action Programme’, an independent not-for-profit company.

WRAP now presented their vision for a circular economy in the United Kingdom by 2020, using Sankey diagrams:

The material flows for the baseline year 2000 are shown in a first diagram here:

In that year, apparently, 212 Mt of material were disposed of as waste (orange arrow), while only 47 Mt were recycled.

The situation in 2010…

… and the vision for 2020 (from this page):

The goal is to use less input materials, to reduce waste output and to recycle 3/4 of the materials.

See diagrams in high resoultion directly on their website.

After writing about VisioGuy’s radial Sankey diagram idea, I went through my bookmarks and collection of Sankey diagrams in search of further candidates for this special class of circular flow graphs.

Here are two goodies… 😉

Below is a black/white Sankey diagram of energy fluxes in a chemical loop combustion cycle from an Imperial College website. It is similar to the radial one Chris designed, however it is not exactly circular. Not all of the entries and exits of the cycle are shown as Sankey arrows. The exit of the arrow labeled W is to the center (would one call this anticentrifugal?). The methane input makes a U-turn before entering the loop.

The other Sankey diagram is from this website of a U.K. based company, and shows greywater recycling. The average consumption of freshwater per person / per day in the UK was 130 litres in 1996.

The water from wash-basins, shower and bathtub could go through a recycling stage and be reused for flushing and watering the garden. The designer gave it a roller coaster style loop, which sure doesn’t add to the information content of the graphic, but immediately draws the reader’s attention to the recycling. I am not sure where the third flow coming from the right goes to. It represents the potential savings of 45 litres/day, but kind of disappears behind the loop.

I’ll post more of these as I come across them.