Why is the category in the general information for some processes different from that of the flows in the in-/outputs?

Question

Hello,

I have a question about the categories for two different processes.

For the process market for ethanol, without water, in 95% solution state, from fermentation | Ethanol, without water, in 95% solution state, from fermentation | Cutoff, U, the general information says that the category is 1072: Production of sugar. But in the inputs and outputs, all flows are categorized as 201: Production of basic chemicals, fertilizers and nitrogen compounds, plastics.

For the process market for ethanol, without water, in 99.7% solution state, from fermentation | Ethanol, without water, in 99.7% solution state, from fermentation | Cutoff, U it is exactly the other way around. In the general information, the category 2011: Production of basic chemicals is given. In the inputs and outputs, all flows are categorized as 107: Manufacture of other food products/1072: Manufacture of sugar.

Unfortunately, I don't quite understand this. I would be pleased if someone could explain this to me. Or is it simply an error?

Many thanks in advance

Leonie Drechsel

Answer 1

First of all, the processes are following the ISIC classification (https://unstats.un.org/unsd/classifications/Econ/isic) where the activities are sorted into their respective folder (classification) by ecoinvent. This ISIC classification is only meant to be for processes (activities) and not for products. Apparently ecoinvent sorted the 95% ethanol from fermentation into the manufacture of food categories and the 99.7% ethanol from fermentation into the basic chemicals categories. Of course, the choice is sometimes not straightforward, since you can use ethanol in high concentrations in chemical products, but it can also belong to the food sector where it is produced from fermentation. I guess, that they decided to put the high concentrated one into the chemical sector. You can also check where the reference products are used and you will see that the 95% from fermentation is only input into dewatering process to get higher concentrations, which then might be used in the chemical sector. And the high concentrated ethanol from fermentation is input into some chemical processes, so the different classification makes sense.

Secondly, the products could be sorted into the CPC system, which would result in completely different folder than the ISIC system for the processes and it would result in often only 1 product per folder and it would result in many more folders. That's why in openLCA it was decided to keep the folders from the ISIC system also for the products (although they are usually for processes). And because you can have a product used in very different processes, of course sometimes there might be product in a product-folder which does not correspond to the same process-folder.

Thirdly, it should be no drawback in modeling, since the folders are only for navigation and a quick classification of activities/products. You can always search all your products or activities over the search bar. You can also drag and drop the products or processes in any folder that you wish, since it will not affect any calculation.

Comments

Thanks for the reply, I think I need to be more specific with my question.

In general, of course, I understand that the 95% ethanol and the 99.7% ethanol are classified differently. And I also understand that the general information says that the 95% ethanol falls into the category "1072:Manufacture of sugar" and the 99.7% ethanol falls into the category "2011:Manufacture of basic chemicals".

However, if I look at where the reference products are used, as you also said, then I see in the dewatering process that a 95% ethanol in the category "2011:Manufacture of basic chemicals" becomes a 99.7% ethanol in the category "1072:Manufacture of sugar".

After what you have said and after the general information, shouldn't it be the other way around? So that a 95% ethanol of the category "1072:Manufacture of sugar" becomes a 99.7% ethanol of the category "2011:Manufacture of basic chemicals".

And I'm also confused in the markets. All flows in the inputs and outputs have the same category ("1072:Manufacture of sugar"), but in the general information the category is "2011:Manufacture of basic chemicals".

And as I said, the "market for ethanol, 99.7% - fermentation" is exactly the other way around. Are the categories of the two flows perhaps wrong?

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As Conrad mentioned, the categories for processes and product flows do not matter for calculated results, we take them as ecoinvent is providing them (since your processes seem to come from ecoinvent); both are also multifunctional processes I assume thus their products could be put elsewhere for that reason, but I am guessing.

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The flows (exchanges) that you see in the input and output have flow categories (folder for flows) which are independent of the categories for processes. In the original data from ecoinvent, this would be even a completely different classification system. As I said before, processes ISIC and products CPC.

But for openLCA we decided not to take the CPC folder for flows, since this would result in many more folders with most likely only 1 product in it. That's why we decided to sort the products into the same folders as processes. This is done automatically. If I'm right, the first process that appears with the corresponding reference flow (product output) will give its category to the product flow. The point is that there is no ISIC system for products, since this is only for processes. That you found a flow in basic chemicals (inputs and outputs) and not in food manufacturing is simply because this flow apparently appeared for the first time in an output of a chemical production, but it can also appear in outputs of food manufacturings.

By the way, in the CPC classification your "ethanol, without water, in 99.7% solution state, from fermentation" and "ethanol, without water, in 95% solution state, from fermentation" would be in the folder "35491: Biodiesel".