Tag: food

EU Food Flows 2011

This comprehensive and well-structured Sankey diagram on food production, waste and consumption is featured in an article ‘Quantification of food waste per product group along the food supply chain in the European Union: a mass flow analysis by Carla Caldeira et al. (published as open access article under CC BY license in: Resources Conservation and Recycling · June 2019). The paper “presents a high-level top-down approach to food waste accounting in the European Union.”

Flows are in megatonnes (Mt) wet mass for the year 2011. The diagram shows “feed and food flows, excluding soft drinks, mineral waters and some non-perishable foodstuffs (salt, coffee, etc.)”.

The figure is split in two parts. On the left we see the stages production, processing and distribution, with gaps between the streams to better be able to distinguish them. The food flows reaching the consumption stage (365 Mt) are bundled and shown in a much more compact diagram inset, but still on the same scale, it appears.
Here we can differentiate the amount going to food service (restaurants etc.) and consumption in private households. We also learn that approximately 60 Mt of what is being purchased for consumption still ends up as food waste.
In the other hand, a large portion of rejects and waste in the production stages is fed back into the system (chartreuse colored flow at the bottom) and being used as animal feed. Much more detail there to discover…

Check out this related Sankey diagram on Material Flows in the U.S. Food System

Dairy Supply Chain GHG Emissions

Rediscovered this Sankey diagram in a 2011 project report ‘Scottish Dairy Supply Chain Greenhouse Gas Emissions’ (Sheane, R., Lewis, K., Hall, P., Holmes-Ling, P., Kerr, A., Stewart, K., Webb, D.: Identifying opportunities to reduce the carbon footprint associated with the Scottish dairy supply chain – Main report. Edinburgh: Scottish Government, 2011).

Flows are in megatonnes of CO2-equivalents (Mt CO2e) greenhouse gas emissions (GHG) in 2007 related to the production of milk and dairy products in Scotland.

A total of 1.657 MtCO2e GHG emissions were caused along the dairy supply chain emissions, which was equivalent to 3% of Scotland’s direct GHG emissions. With a yield of 1.3 billion litres of milk on dairy farms in Scotland in 2007 this corresponds to 1.1 kgCO2e/kg of milk or 1.2 kgCO2e/litre of milk.
If you look at the origins of the emissions in the diagram you will see ‘enteric fermentation’ (aka ‘cow fart’) and liquid manure (‘cow poop’) as the main causes.

Read the full report here.

Losses in Fruit Production

Food loss or wastage has been a topic a previous posts here on the Sankey diagrams blog before (see here or here).

Here is another Sankey diagram from the dissertation ‘Environmental assessment of Catalan fruit production focused on carbon and water footprint’ by Elisabet Vinyes i Guix (p. 73). It visualizes losses in the production chain for apples and peaches in Catalunya.

For each kg of fruit arriving on the market (or at the point of sales), some 1.21 kgs of fruit are being cultivated. Losses occur in the farming process itself as well as along the retail system. Of the 1 kg fruit purchased by the consumer, only 83% is actually eaten. 17% turns into waste.

Global Food System Sankey

Food losses and food waste has been addressed in a number of scientific research papers in recent years. Peter Alexander et.al. write about ‘Losses, inefficiencies and waste in the global food system’ (In: Agricultural Systems, Volume 153, May 2017, Pages 190-200, doi.org/10.1016/j.agsy.2017.01.014)

The article contains two beautiful Sankey diagrams. The first depicts the global food system in 2011. Flows are shown as dry mass. Flows are not individually labelled with the underling quantity, but rather a scale at the bottom shows 5 representative flow quantities and their corresponding width.

(under terms of Creative Commons Attribution 4.0 License (CC BY 4.0))

Crop (yellow) and grassland (green) net primary production (NPP) are shown as sources for the global food system. Losses are branching out as grey arrows. These “inefficiencies” of the system are described in detail in the article. The authors observe that “44% of harvested crops dry matter are lost prior to human consumption” and that “the highest loss rate can be found in livestock production”.

The second Sankey diagram shows a section of the above figure, just the dry matter flows from crop harvest and processing, without any losses. This is interesting because it allows us seeing the share of processed and non-processed food being consumed by humans worldwide, and the the share of crop-based food intake (dark blue) compared to animal-based food intake (red). You could call this the veggie / non-veggie split. Based on dry matter that is.

(under terms of Creative Commons Attribution 4.0 License (CC BY 4.0))

If you want to see the corresponding global food system wet mass, protein and energy Sankey diagrams check out this interesting article. A recommended read for all of us eaters.

Feed-to-Food caloric flux Sankey diagram

Another way to look at energy flows! Here is a Sankey diagram of US feed-to-food caloric flux. This is from a paper by Shepon et.al. titled ‘Energy and protein feed-to-food conversion efficiencies in the US and potential food security gains from dietary changes’ published October 2016 in Environmental Research Letters (Environ. Res. Lett. 11 (2016) 105002 – doi:10.1088/1748-9326/11/10/105002) under Creative Commons CC 3.0

Flows are in Pcal (Peta calories, 1012 kcal). Production figures are based on data from U.S. National Research Council and a “Mean American Diet” (MAD) with an average consumption of 2500 kcal per day is used. We can see energy in three feed classes being transformed into energy in edible animal products. The authors explain:

“On the right, parenthetical percentages are the food-out/feed-in caloric conversion efficiencies of individual livestock categories. (…) Overall, 1187 Pcal of feed are converted into 83 Pcal edible animal products, reflecting a weighted mean conversion efficiency of approximately 7%.”

In light of this, energy conversion efficiencies of 30-40% seem to be fantastic…

Check out the article for another Sankey diagram of protein flux.

Energy Flows in Styrian Dairy Production

Styria is the second largest state of Austria, in the south eastern part of the country. It is famous for its beautiful mountains, its wines and some decent yodelling 🙂

It is also home to green tech industries, in fact “Styria is home to more than 150 clean technology companies … [whose] revenue totals €2.7 billion. This equals to 8 percent of the Gross Regional Product (GRP), and is one of the highest concentrations of leading clean technology companies in Europe.” (Wikipedia)

The ‘Styrian Promise’ is a project aiming at the implementation of energetically and economically meaningful energy efficiency concepts in Styian production companies. Case studies from food, textiles, metals and other industries are presented on the project wiki.

Above is a Sankey diagram depicting the energy balance at Obersteirische Molkerei Knittelfeld (Upper-Styrian dairy in Knittelfeld). Flows are in MWh per year. The main energy requirement is steam from natural gas: Whey drying and steam for milk pre-heating are the largest consumers of process heat. Read more detail on the dairy production here.

Food Waste in Germany

A rather simple Sankey diagram. It can be found on p. 195 of a study on Food Waste in Germany by ISWA, Stuttgart University comissioned by the Federal Ministry of Food and Agrriculture (BMEL). Flows are in million tons per year (averaged for the five-year period 2003 to 2007).

The yellow streams represent food delivered to individual housholds (“Haushalte”) as well as to commercial (large scale) users (“Grossverbraucher”) such as restaurants. The orange arrows show food waste (10 mo. tons p.a.). Note that individual households have a higher reject rate.

Energy Efficiency in Food/Beverage Industry

In a presentation on “Low CO2 production in European food and beverage industry” the author Christoph Brunner from AEE – Institute for Sustainable Technologies (AEE INTEC) suggests process flow sheets and Sankey diagrams as tools used for energy efficiency analysis.

This Sankey diagram is used as an example for the creation of mass and energy balances and the visualization of the production process.

The diagram is from Austria and thefore in German. From translating some words I understand this is probably for a food/dairy industry. Flows are in MWh, but without a time span. Two steam generators (one run with natural gas, the other with petroleum) supply heat to different processes. The cooking chambers (“Kochkammern”) require most, followed by “Selch” (?) and heating of a “KSPW Tank”. Some heat is recovered from condensate.

Sankey diagrams can help understanding the energy flows of process systems and detect hotspots for optimization.