Choosing between flows types

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gnicki
Posts: 14
Joined: 27 Jan 2016 08:14

Choosing between flows types

Post by gnicki » 27 Jan 2016 08:34

I am stumped at a fundamental terminology question. In an agricultural LCA, I am adding inputs to my process. However, such inputs can be found under different flow categories. How do you know which type to choose? For example, I am assessing the impact of an agrichemical from its cradle then it being applied on the farm and the associated emissions. Choosing "Elementary flow" seems to make the most sense, however I am not entirely sure of the definition of an elementary flow from the help pages, which is: "Material or energy entering the system that has been drawn from the environment without prior treatment, or material or energy leaving the system that is released into the environment without subsequent treatment" -- what does that mean "without prior treatment"??
Any help would be greatly appreciated!

aciroth
Posts: 750
Joined: 09 May 2010 23:28

Re: Choosing between flows types

Post by aciroth » 27 Jan 2016 15:00

Hi, your question is about one of the fundamentals of LCA (I would say) - and the definition of an elementary flow can also be found in the ISO standards for example. Basically, an elementary flow is directly taken from nature, or released to nature. For example, water: groundwater (as input to a pumping process) is typically an elementary flow, drinking water (created using groundwater, but obtained by treating the water - cleaning with UV light, de-ironing, ...) is a technosphere flow or a product, since it has been "treated". An agrochemical is therefore not an elementary flow.
Hth,
Andreas

gnicki
Posts: 14
Joined: 27 Jan 2016 08:14

Re: Choosing between flows types

Post by gnicki » 29 Jan 2016 10:22

Thank you very much Andreas -- I had checked the wording of ISO as well. However, I was thrown off by the fact that almost all of my study's 25 specific agrochemicals are found under Elementary flows > soil > agricultural, whereas there are only generic chemical classes under Manufacturing > Manufacture of other chemical products > Manufacture of pesticides and other agrochemical products. So while of course it makes sense that chemicals should not be listed as an elementary flow (by its very definition), I am a bit stumped as to why they are there -- is there any application for them under this category?
I greatly appreciate your help.
Geoff

aciroth
Posts: 750
Joined: 09 May 2010 23:28

Re: Choosing between flows types

Post by aciroth » 29 Jan 2016 10:43

Hi Geoff,
well the flow "classifcation" (whether a flow is elementary or not) is a modeler decision. Chemicals can be elementary flows as well, if they are directly emitted (to soil or air, e.g. when spraying pesticides).
Hth,
Andreas

gnicki
Posts: 14
Joined: 27 Jan 2016 08:14

Re: Choosing between flows types

Post by gnicki » 29 Jan 2016 10:55

Thanks Andreas -- okay I understand. So if I wanted to add the input of 1 kg of chemical X being applied to a farm, I would include both 1 kg of it under an elementary flow, and in addition 1 kg of it from the manufacturing part (and the transportation part for that matter) -- is this correct?
Thanks for your patience!
Geoff

aciroth
Posts: 750
Joined: 09 May 2010 23:28

Re: Choosing between flows types

Post by aciroth » 29 Jan 2016 17:09

Yes, that's correct, the elementary flow is then an emission (maybe not 1kg as some parts stay on the plants which are harvested though?)

Nachhaltigkeit
Posts: 15
Joined: 03 Jun 2014 12:47

Re: Choosing between flows types

Post by Nachhaltigkeit » 31 Jan 2016 20:17

I know where the confusion stems from. There are only some inventories about production of specific pesticides in Ecoinvent. In most agricultural datasets "pesticide, unspecified" is used for the inventory of the production of pesticide "x".
There are inventories about the environmental impacts of specific pesticides if they run-off to soil (or ground water).

So if you have for example:
Inputs:
0,3 kg Pesticide A
0,1 kg Pesticide B
and the assumption that 100% of the used pesticides are leaching to soil, it would look like this in Ecoinvent:

Inputs:
0,4 kg Pesticide, unspecfied
Outputs:
0,3 kg Pesticide A, to agricultural soil
0,1 kg Pesticide B, to agricultural soil

gnicki
Posts: 14
Joined: 27 Jan 2016 08:14

Re: Choosing between flows types

Post by gnicki » 25 Mar 2016 06:30

Hi Nachhaltigkeit,

I have come back to the issue you raised a while ago, and have a further question. Thanks for your original post.
Nachhaltigkeit wrote: Inputs:
0,4 kg Pesticide, unspecfied
Outputs:
0,3 kg Pesticide A, to agricultural soil
0,1 kg Pesticide B, to agricultural soil
You say here basically that the elementary flows are outputs.

So, going with your example, in my process of "crop X production" I would enter the inputs/outputs as follows:

Input:
The manufacture of 0,4 kg "Pesticide, unspecfied"

Output:
0,3 kg Pesticide A, to agricultural soil
0,1 kg Pesticide B, to agricultural soil
1 kg of crop X

Is this really how I would enter it? Actually I have been confused here, having until now entered the "1 kg of crop X" as an output, while EVERYTHING else entered as inputs, like this:

Input:
The manufacture of 0,4 kg "Pesticide, unspecfied"
0,3 kg Pesticide A, to agricultural soil
0,1 kg Pesticide B, to agricultural soil

Output:
1 kg of crop X

Is this incorrect??? I'm sorry this is a very fundamental question, but of course very important!

Any help you could provide would be greatly appreciated!

Geoff

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