Tag: Latin America

Minerals Exports from Latin America

Another Sankey diagram from the article ‘Exergoecology Assessment of Mineral Exports from Latin America: Beyond a Tonnage Perspective’ by Jose-Luis Palacios I discussed in this recent post.

Non-fuel minerals exported in 2013 from Latin America to other continents. Flows are in Mtoe (for the reason why these flows are measured with a typical energy unit and to learn about the ERC approach read the article). Due to the scale, some minerals can not be seen as individual flows in the Sankey diagram and are thus grouped as ‘Rest of Minerals’ (black stream).

Minerals Exergy Replacement Costs

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.

Yet Another ‘Flujo de Energia’ Diagram

The INCyTDE blog article that featured the Energy Balance for Guatemala presented in a post last week also contains two other energy flow diagrams from other Central American countries.

Here is the energy flow Sankey diagram (Balance Energetico Nacional) for Costa Rica for the year 2010.

In contrast to the situation in Guatemala, the dominating fuel is petroleum. The other two important feeds are from hydro and geothermal. Wood is used as heat source in private homes (17,746 TJ), and, with about the same amount, biowaste (residuos vegetales) constitutes an energy source for industry (17,607 TJ).

Flows are in TJ. The diagram is provided by the Ministry for Environment, Energy and Telecommunications.

And this time the diagram is impeccable…

Energy Balance for Guatemala

The research institute with the hard-to-pronounce acronymic name INCyTDE (Instituto de Ciencia y Tecnología para el Desarrollo at Universidad Rafael Landívar in Guatemala) has published a Sankey diagram with the energy flows for their country for the year 2011.

In regard to design the diagram has many issues: Apparently it was created using a drawing tool that supports primarily horizontal and vertical arrows and Bezier curves. But the diagram loses a lot with branching and joining of arrows almost non-existent.

Flows are more or less to scale. The unit is not shown in the diagram itself, but explained in the text (kilo barriles equivalentes de petróleo, KBEP = kilo tonnes of oil equivalent, ktoe). Data is from national statistics published by the Energy and Mining Ministry.

The content of the energy balance diagram is quite interesting, especially if you compare it to similar diagrams of other countries or the world average.
Wood is the most important energy in Costa Rica (green arrow ‘Leña’, 37.251 ktoe in 2011). Bagasse from sugar cane (dark green arrow ‘bagazo de caña’, 8.696 ktoe in 2011) is used for almost half of the electricity generation. Petroleum and derivates (dark pink arrow, 24.903 ktoe in 2011) however do play an important role for vehicles (transportation).

Energy Flows In Peru

Came across this Sankey diagram showing the energy flows in Peru in an article on Renewable Energies in the Energy Strategy on Alberto Ríos Villacorta’s blog.

It has the typical structure of a national energy flow Sankey diagram as I have shown here on the blog many times. Flows are in terajoule (TJ) and have a general left-to-right orientation. On the left are the different energy carriers (primary energy), conversion in the middle section, consuming sectors on the right. Losses branch out to the bottom.

Unfortunately the streams are not to scale in this Sankey diagram. Compare for example the 80.149 TJ energy from “leña” (wood) in green to the 515.929 TJ of energy embodied in gas (sand color) right above. The gas arrow should be approximately 6 times wider – still it is drawn thinner. Even worse the situation for losses in gas processing where 241.007 TJ are “no aprovechada” while 274.922 TJ pass through gas processing (“planta de gas”). Roughly half of the energy embodied in gas is not used, but it looks as if that arrow branching out to the bottom represents some 10 to 15% of the total flow only. Many other examples of wrong arrow magnitudes can be found.

So, some very general basics of Sankey diagrams are ignored here. Readers should check the flow quantities carefully, and not rely on the perceived quantities represented by the arrows.