+2 votes

There is something funny about the economic / physical allocation that I don't understand and would appreciate any insights or tips. I'm using 1.8.0 (and loving the new features :) ) standalone (zip) version in Windows10. I was using the ELCD database but created processes and flows from scratch.

I create a product flow "Electricity_test" with "net calorific value" as its reference flow property and "Cost" as another flow property with conversion factors 0.04 EUR (i.e. 1MJ = 0.04EUR). I create another product flow "Heat_test" with "net calorific value" as reference flow property and "Cost" as another property but with conversion factor 0.02 EUR. I create a process called "CHP_test" from Electricity_test (i.e. that is the reference flow) that outputs 1MJ of Electricity_test and 1MJ of Heat_test. I save the process. When I go to the allocation tab, select "Economic" as the default method (I don't this should matter), and then click "Calculate default values", the split is 50:50 for both Physical and Economic allocation.

I would expect the split to be 67:33 for the Economic allocation? i.e. as that is 1*0.04EUR vs 1*0.02EUR?

Adding any of the "Price" economic flow properties (using same 0.04 vs 0.02 EUR values) to both flows doesn't fix this.

However, adding "Market value, bulk prices" (in "EUR 2000") does fix it. So that's a work around but I don't know what is going on.

Weirdly, I managed to get it stuck on economic values for the physical split as well a moment ago (until I deleted the economic flow properties from the flows, when both splits reverted to physical basis of course) but I can't replicate it.

EDIT - ok, if I create a new database (i.e. not based on ELCD), I see that the only flow property under "Economic flow properties", is the "market value, bulk prices" one. So I think that maybe the other ones (that I assume are added as part of ELCD) are not recognised for some reason.

EDIT 2 - Just in case it's helpful. I managed to replicate the situation where it would only give the economic split. Essentially, this was where the Electricity flow was from ELCD and contained physical flow properties that aren't in the default list (e.g. Exergy). I then added a Heat output flow and added price to its properties (but not the other physical flows like Exergy, it just had Net Calorific Value. The allocation is then done on the economic split and remains so even if the other flow properties are removed. However, if the other physical flow properties are removed before the default allocation is calculated for the first time, it gives just the physical split. So, my guess is that it uses the ELCD physical properties to link to the ELCD economic ones (or that this forces them to be recognised) but it doesn't have equivalent ELCD physical flow properties to do the physical split (even though both flows reference property is, in theory, net calorific value).
in openLCA by (2k points)
edited by
by (23.4k points)
Can you send us a link to your database (if that does not violate the EULAs of the database that you are using which should not be the case if it is indeed ELCD) - gd@greendelta.com (e.g. wetransfer, firefox send)

1 Answer

+1 vote
by (2k points)
selected by
Best answer
Hi Jonas, thanks for the reply. Happy to email if it would be helpful to have more info / discuss further but in terms of database, I've just replicated this with a fresh copy of ELCD 3.2 v2 in OLCA1.7 format downloaded from nexus a minute ago. Database restored into OLCA1.8 (i.e. not combined with another). Created a process from Electricity flow (UUID 890a70b7-b677-4e2a-8a1b-7d017e0a10ae  which I now realise contains economic and physical  flow properties that are specific to  using ELCD and aren't present if you just create a new database), added a heat output flow (both reference flows are Net Calorific Value) and then added one of the economic flow properties to the heat flow. Refresh etc throughout. This results in what should be the economic allocation being applied to both allocations.
If I use an electricity flow (e.g. 1ca6b4ff-e518-48f1-8012-82776ef15ef8) which only has "standard" flow properties (e.g. net calorific value) and add the "Price" economic flow property to it (i.e. an economic flow property that is from ELCD but is still listed as economic) and then repeat the process (create process, add heat as a coproduct flow with NCV as reference and price as an additional flow property), then I'm stuck with the ratio for the physical allocation for both.
If only "market value, bulk prices" is used for economic flow property (i.e. the only economic flow property if I were to create a new database and only one using "units of currency" rather than "units of currency 2002") then it all works fine :) so that is a work around for simpler systems.
We're just buying Ecoinvent from nexus, so hopefully be able to try that in next few days.