Javier Dufuor on the madrid+d Energía y Sostenibilidad blog reports about a novel lignocellulose biorefinery process developed by Prof. James A. Dumesic at the University of Wisconsin-Madison. This so-called TriVersa process can yield up to 80% of biomass from birch wood as marketable products.

The Sankey diagram for the TriVersa process shows carbon in biomass flows. Values are in percent, starting with the 100% C molecules in birch wood being used as feedstock.

An interesting detail about this Sankey diagram is that it additionally uses the process “nodes” or “boxes” to indicate operating cost and annualized capital cost. No numbers are given here, but the height of the process box indicates the overall cost (in a kind of stacked bar chart).

Another example for a Sankey diagram on a map from an article ‘Exergoecology Assessment of Mineral Exports from Latin America: Beyond a Tonnage Perspective’ by Jose-Luis Palacios (Escuela Politécnica Nacional, Quito, Ecuador) et al. published in Sustainability 2018, 10(3), 723 as open access article distributed under Creative Commons Attribution (CC BY) license.

I had not heard of the term ‘exergoecology’ before:

Exergoecology is the application of the exergy analysis in the evaluation of natural fluxes and resources on earth. The consumption of natural resources implies destruction of organized systems and dispersion, which is in fact generation of entropy or exergy destruction. This is why the exergy analysis can describe perfectly the degradation of natural capital.
The thermodynamic value of a natural resource could be defined as the minimum work (exergy) needed to produce it with a specific composition and concentration…
(Source: Exergoecology Portal)

The authors of the article argue that the Material Flow Analysis (MFA) approach should be combined with a measure for the thermodynamic quality of minerals, “especially when dealing with non-fuel minerals”. They propose to use the indicator exergy replacement costs (ERC) from exergoecology because it “considers the scarcity degree of the commodities in the crust and the energy required to extract them. When a mineral is scarcer and its extraction and beneficiation processes are more difficult, its ERC value becomes higher”.

These two sets of Sankey diagrams visualize this approach:

The two Sankey diagrams on the left are for Chile, the two on the right for Mexico.

The figure at the top is a common mass-based figure, showing minerals production, imports, domestic consumption and exports for certain minerals. The unit of measure is million tonnes per year (in 2013).

The one at the bottom shows exergy replacement costs (ERC) measured in million tonnes of oil equivalent (Mtoe). For each mineral an energy indicator in GJ per tonne of element has been applied, representing the work (energy) to extract the mineral.

In the case of Chile we can see for example that iron, copper and salt are the minerals mined in largest quantities (mass-wise). However, iron and salt only make up a small fraction of ERC, while copper and potash dominate the picture. In other words: Potash has a high exergy replacement cost to produce given the work effort required to mine it and in face of its scarcity. Copper comes in second.

For Mexico the figure a the top and below look pretty similar in regard to the proportions of each of the colored flows. One could say that the minerals are similarly difficult or expensive to extract. Coal (yellow band) is comparatively wider in the mass flow diagram than in the exergy replacement costs diagram, so it is “cheaper” in regard to exergy cost to be mined.

Many more interesting details to discover and the article is well worth reading. In my oponion a fascinating blend of two approaches and a great use for Sankey diagrams.

This Sankey diagram visualizing the energy balance for the French island Réunion has already been published back in 2010 in an article on reliability of supply in future power systems. (Mathilde Drouineau, Nadia Maïzi, Vincent Mazauric, Edi Assoumou. Long term planning tools and reliability needs: focusing on the Reunion Island. 3rd IAEE Rio 2010 International Conference “The Future of Energy: Global Challenges, Diverse Solutions”, Jun 2010, Rio de Janeiro, Brazil. 14 p., 2010). Access article here.

The flows are in Mtoe for the year 2007. The authors have been using the Markal/TIMES models to obtain data and study alternatives for future energy scenarios for the Réunion Island.

The EU funded PROSUM research project looks at ‘Prospecting Secondary raw materials in the Urban mine and Mining wastes’. The more than 15 institutions participating in the project have recently published their findings in a final report.

The report has some interesting Sankey diagrams on market input, stocks, waste generation and waste flows for product groups such as vehicles, batteries, precious materials and selected critical raw materials (CRMs) contained in batteries, electrical and electronic equipment (EEE) and vehicles.

Here is the diagram for vehicles in the EU28+2 (=EU28 plus Switzerland and Norway) market. Data relates to the year 2015.

Flows are in tons and ktons, blending two scales in one diagram. This merits its own post, I think. (read it here)

The electric vehicles currently driving on the roads are shown as “Stock”, meaning that the materials are in use and that they could eventually be recovered at the end of the life of the vehicle. This is the large stackd bar between “POM” (placed on market) and “De-reg Vehicles”. Again this stacked bar uses two different scales (tons and ktons).

Official report citation: Jaco Huisman, Pascal Leroy, François Tertre, Maria Ljunggren Söderman, Perrine Chancerel, Daniel Cassard, Amund N. Løvik, Patrick Wäger, Duncan Kushnir, Vera Susanne Rotter, Paul Mählitz, Lucía Herreras, Johanna Emmerich, Anders Hallberg, Hina Habib, Michelle Wagner, Sarah Downes. Prospecting Secondary Raw Materials in the Urban Mine and mining wastes (ProSUM) – Final Report, ISBN: 978-92-808-9060-0 (print), 978-92-808-9061-7 (electronic), December 21, 2017, Brussels, Belgium

Ann Arbor based consulting firm RRS has published a Sankey diagam visualization of the plastic streams in the United States. This is from their Data Corner blog.

Breakdown is in percentage values only. The amount of 8,300 MMT seems to be an aggregated figure for a 65 year period from 1950 to 2015. And 80% has ended up on landfills.

Original data is from a study ‘Production, Use, and Fate of All Plastics Ever Made’ authored by Roland Geyer of the University of California, Santa Barbara; Jenna Jambeck of the University of Georgia; and Kara Law from the Sea Education Association.

What would daily life in a ‘zero carbon’ Great Britain look like? Since 2007 the Zero Carbon Britain (ZCB) project of the Centre for Alternative Technology (CAT) has worked to “offer the hard data and confidence required for visualising a future where we have risen to the demands of climate science; to remove fear and misunderstandings and open new positive, solution-focused conversations.”

They have presented a Sankey diagram for the energy landscape in the UK, the way it could look like if Britain’s energy production was actually carbon free and 100% renewable energy.


via Open Energy Monitor blog, original image here (under CC BY-NC 2.0 license)

Flows are in TWh/year. The largest energy sources are wind and biomass. Some of the electricity is used to produce synthetic gas, synthetic liquid fuels and hydrogen (used mainly in the transportation sector). In that scenario there is even an electricity surplus that can be exported.

While I can not judge how realistic such a vision of the UK energy landscape is, I can at least say it is very different from the current situation (see here or here), and even from this UK 2050 energy scenario.

The European research project CASCADES’ objective was “to define the cascading use of wood and assess the environmental and socio-economic impacts of cascading, to identify and analyse the barriers preventing cascading”. As a central element of the project a wood flow analysis was conducted.

From page 26 the 2016 final report [Vis M., U. Mantau, B. Allen (Eds.) (2016) Study on the optimised cascading use of wood. No 394/PP/ENT/RCH/14/7689. Final report. Brussels 2016. 337 pages)] comes this Sankey diagram depicting wood flows in the European Union (EU-28).

All flows are in Mm³ swe (solid wood equivalent). No absolute numbers are given to quantify the flows, instead three sample arrows serve a reference to the scale (“Legend of dimensions”).

The wood biomass is either used as material (left branches) or as energy (right branch). On the material side wood industry (yellow path) and paper industry (blue path) take up most of the biomass. Residues of both industries along with a good chunk of the post-consumer paper waste are being recovered and led in a cascading loop, until they eventually shift to the energetic side.

A complex and interesting Sankey diagram with much to discover. The CASCADES report describes all the areas of the wood flow system, identifies hotspots and describes measures for optimization.

Europe’s Joint Research Centre (JRC) has published a new report on ‘Critical Raw Materials and the Circular Economy’ in December 2017.

The report also builds on findings from a 2015 study by BIO by Deloitte, where a Raw Material System Analysis (MSA) Framework had been introduced that “investigates the flows and stocks of 28 raw materials from ‘cradle-to-grave’, that is, across the entire material life cycle from resource extraction to materials processing to manufacturing and fabrication to use and then to collection, processing, and disposal/recycling”. I had posted about this here.

Like in the 2015 study the authors present MSAs for a number of critical materials (CRMs) within the EU-28 boundaries and are depicting them as Sankey diagrams. The authors then expand into how scarcity and price may impact certain industrial sectors or products (Automative, Electronics, Batteries, etc.). Best practices are suggested for recovering critical materials.

Here is the MSA Sankey diagram for Germanium (from page 41 of the report):


All flows are in kilograms per the reference year 2012. We can see that roughly 80.000 kg of Germanium entered the EU in the year 2012, and 15.800 kg were made available on the secondary material market within the EU.

For the individual industrial sectors, another type of figure is presented. This breakdown of how much of the CRMs is used in a specific sector gives a better understanding of the dependency on certain CRMs.

This Sankey diagram (from page 39 of the report) for the Electrical and Electronical Equipment sector shows, for example, that 87% of the Germanium (ge) entering the EU are used in the EEE sector, making it the largest consuming sector of Germanium. The remaining 13% are used in other sectors:

Crossing the information from the MSA Sankey diagams that show availability of a CRM, and the information from the Sankey diagram showing demands per sector gives a good understanding on why some materials are considered critical for industries, and measures for recovering more of them from tailings or waste are meaningful.

Source: Mathieux, F., Ardente, F., Bobba, S., Nuss, P., Blengini, G., Alves Dias, P., Blagoeva, D., Torres De Matos, C., Wittmer, D., Pavel, C., Hamor, T., Saveyn, H., Gawlik, B., Orveillon, G., Huygens, D., Garbarino, E., Tzimas, E., Bouraoui, F. and Solar, S., Critical Raw Materials and the Circular Economy – Background report. JRC Science-for-policy report, EUR 28832 EN, Publications Office of the European Union, Luxembourg, 2017, ISBN 978-92-79-74282-8 doi:10.2760/378123 JRC108710.

Access JRC report here (PDF).