Merian who runs the Boreal Perspectives blog posts on a Sankey diagram that visualizes academic career paths.

This was originally shown in a 2010 Royal Society policy report entitled “The Scientific Century: securing our future prosperity”. Merian raises concerns about the quality of the diagram. She goes: “So what’s so bad about the chart? Some obvious issues:

  • It is unclear what goes in on the left and to a lesser degree what is covered by the end points. The report indicates in a footnote that the term “science” is used “as shorthand for disciplines in the natural sciences, technology, engineering and mathematics,” but the three documents used for input categorise the fields in different ways, and there is no indication which fields exactly would have been selected.
  • Line thickness is not proportional to percentage weight. The 26.5% and 30% streams have the same thickness, and the 17% stream is much less than half the thickness of either. The 3.5% stream is more than half the thickness of the 17% stream.
  • Why does “Permanent Research Staff” not end in an arrow? And why does the arrow from “Permanent Research Staff” to “Careers Outside Science” bend backwards (to suggest it is a step back in one’s career, that is, an implicit value judgement?) and then not even merge with the output stream?
  • Does it really mean to suggest that no one goes from “Early Career Research” (that is, a post-doc) to “Career Outside Science” (or to industry research)? In my experience, watching post-docs, that is quite a common choice for post-docs precisely because non-academic jobs may be offering better pay and conditions, or because they don’t have a choice at that stage.”

She then presents a remake of the above diagram made using the Sankey plugin for d3.js

Indeed, the distribution diagram without the arrow heads seems to be better suited. The overall appearance is much more calm.

Merian, however, concludes “no graph would have been more useful”.

Ecowest’s Marc Tobin has this video on Sankey diagrams up on his Youtube channel. He uses LLNLs energy flow diagrams to explain differences in the energy pattern in the 11 western states.

I particularly like it when he comments that Sankey diagrams are much appreciated by “data visulization nerds”… (check out from 0:28).

Browsing my previously bookmarked Sankey diagram samples I came across this one which I find interesting. The diagram was shown in a Green Cars Congress blog entry in 2010 and illustrates a study that finds that “large scale biofuel production can be successfully reconciled with food production through the use of land-efficient animal feed technologies and double-cropping”. The authors of the study are Dr. Bruce Dale and colleagues at Michigan State University.

As always I refrain from commenting the underlying content as I am not a domain expert. Rather I would like to focus on what makes this Sankey diagram special.

These are actually two diagrams that are “flipped” over at a vertical center line. The left half of the diagram has a right-to-left orientation and shows the “114 million ha of cropland used now to produce animal feed, corn ethanol, and exports”. Some cropland sits idle and is not used productively. The right half is a second Sankey diagram and shows a different use of the cropland with “major crops and outputs for the maximum ethanol production scenario”. No units in the Sankey diagram but the central columns seems to represent the land area (million ha), while the two outer vertical columns (Crops, Output) show mass (tonnes?) on a different scale.

In contrast to the first scenario it can be observed that “30% of total US cropland, pasture and range, up to 400 billion liters (106 billion gallons US) of ethanol can be produced annually”. Ethanol can be used as an alternative non-fossil car fuel. CO2 emissions are also higher but this is from biogenic sources.

Have you ever heard of the city of Issaquah, WA? To be honest, I hadn’t heard of it until I read this post on the New Energy Cities blog.

Issaquah is one of ‘New Energy Cities’ in the Northwest that has created an Energy Map and calculates the carbon emissions it is responsible for based on the fuels used. The role model for these Sankey diagrams are the ones published by the EIA.

Elizabeth, the author of the post, writes:

“Total carbon emissions are depicted in the gray flow lines, by both source and end use. The blue flow line represents hydropower energy used for electricity generation; the green represents non-hydropower renewable energy used for electricity generation; the brown represents nuclear energy used for electricity generation; and the red represents coal energy used for electricity generation. The orange flow lines represent natural gas used for electricity generation and direct heating. The pink flow line represents petroleum used for transportation. The dark gray flow lines represent electricity consumption by residential, commercial, and industrial user categories.”

Wow! I’ve seen those energy Sankey diagrams for the world, for nations and for federal states. But this one for Issaquah is definitely the one that covers the smallest geographical and administrative entity.

Yale School of Forestry & Environmental Studies and The Connecticut Energy & Environmental Protection Agency have conducted a study on waste flows titled ‘Unlocking the Value: Transforming the Connecticut Materials Economy’.

The study features two Sankey diagrams that show the present situation (2010) and a an alternative scenario, where much of the materials are recovered.

This is the current situation in which only 25% of the 3.16 Mt of waste (Building C&D Waste not considered) are recycled.

The authors explain that

“Each year Connecticut residents and businesses generate more than three million tons of munici pal solid waste (MSW, or “regular trash”). Currently existing recycling and reuse programs capture a portion of the value of Connecticut’s waste, while waste-to-energy facilities process and recover energy from most of the MSW that is not recycled. With our recycling infrastructure underutilized, and resource recovery facilities at capacity, there is vast potential to transform our management and processing systems to further unlock the economic potential of waste.”

The optimized scenario with much increased recycling of materials (almost 80%) is shown in this diagram:

Connecticut is looking into the environmental and economic benefit of a recycled materials econonmy.

via Talismark blog

Following up to my last post, here is another Sankey diagram for phosphorus flows. This one is by Jason Pearson, TRUTHstudio and can be found in the ‘Visualization’ section of his website. Jason is also the designer of the Economy Maps (see this March 2012 post).

Jason says that “the diagram demonstrates the key point: that only 15% of the phosphorous in the US food supply chain is ingested, with the remainder ending up as waste. The diagram also shows the proportion of phosphorous used or wasted in non-food supply chains”

This one is more colorful than the Dutch one. Flows are in kt (kilotons). It has a left-to-right orientation (the other was vertical) and is very compact with almost no space betweend the bands, almost like in a block-style diagram. As a concession to this dense style, diagonal arrows don’t maintain their width.

As promised in this post on U.S. 2010 Energy Flows here are some other Sankey diagrams from a July 2012 publication by Eric Shuster, NETL/DOE. These diagrams show world trade flows for coal.

The first one features the top coal exporters and their 2010 exports of coal to the regions America, Europe and Asia. This does not include domestic production, but just export. Indonesia and Australia are clearly the main exporters. Unit is in Mio short tons.

The other coal Sankey diagram is for U.S. coal imports and exports in 2010. Here the unit is in 1,000s of short tons, hence the two must not be directly compared. Also, the inset of the yellow arrow for domestic production in comparison to U.S. import/export is not to scale with the other flows shown on the flow map. In fact, all the blue Sankey arrows appear as a small export flow (81,716) in the yellow Sankey miniature, and all red flows on the world map are summarized as the tiny import flows (19,353).

The U.S. is primarily using its domestic coal and still able to export the surplus.

Stay tuned to see the world’s natural gas flows from the same publication

Dug out a folder on the hard disk of my old computer where I had stored many Sankey diagrams. Great stuff there I had saved years ago. Problem is that at the time I didn’t label the diagrams properly, so that I am now trying to trace where I got them from.

Here is one I like quite a bit. It is featured on p. 24 of the Alsaka Energy Plan (available on the Alaska Energy Authority (AEA) website / directly access large PDF)

Alaska Energy Flows for 2006 in trillion BTU. Forget about the other fuels, this state’s energy is almost entirely based on crude. And – despite being an importer of oil – AK is primarily an exporter of oil. All other energy flows really seem to be insignificant because of the dominance of oil. Losses are not shown with streams, but rather are given as text on the node.