EIO-LCA Web Forum

How interpret results on energy consumption ?
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Author:  ColinJURY [ Thu Sep 24, 2009 4:05 am ]
Post subject:  How interpret results on energy consumption ?

Dear support team and forum users,

I am conducting a LCA and I would like to use results of the sector "Petroleum, Coal and Basic Chemical – Other Basic organic chemical manufacturing” from the US database.

Despite I carefully read the introduction on how to interpret results as well as several posts on this website, I have still some questions.

Total Elec Coal NG LPG MG Distil Kero Jet R
(TJ) (MkWh) (TJ) (TJ) (TJ) (TJ) (TJ) (TJ) (TJ) (TJ)
Tot all sect 21.7 0.92 4.95 12.3 1.5 0.4 0.92 0 0.2 0.45
Org chem 8.10 0.51 1.28 5.75 0.36 0.07 0.02 0 0 0

1) I wonder why the results displayed in the column “total” are not equal to the sum of the values of the corresponding lines. For instance, if I convert MkWh to TJ using the factor 3.6, the sum of the line "total for all sectors" is 24TJ and is 11% higher than the result in the column “total” (21.7TJ). If I do not convert MkWh, the sum is 0.5% lower than the result in the column total.
My questions are:
- Shall the sum of the values of a line be equal to the result in the column “total”?
- Do we have to consider the electricity used in the calculation of the total of energy spent? If yes, how (MkWh or TJ)?

Note: In the case of the Canadian database where the default unit for electricity is TJ, the sums of the values of each line are always higher than corresponding results in the column “total”.

2) I would like to be sure I can use those data to calculate the resource depletion using a LCA valuation method (Impact 2002+, Ecoindicator99, ReCiPe ...).
My questions are:
- Do the data correspond to the total consumption of fossil fuels along the whole supply chain, or should I have to consider the additional energy needed to extract and to refine fuels? I guess data are representative of the whole supply chain, but I would appreciate a confirmation.
- Should the fossil fuel consumption needed to produce electricity be added or is it already included in the results of fossil fuels?

3) Do the errata of the book “Environmental LCA of Goods and Services” are available, please?

I would be very grateful for any hints.

With kind regards.


Author:  hscottm [ Fri Sep 25, 2009 9:40 pm ]
Post subject: 


1) The disconnect is that the total is not the sum of the columns. if you hold the mouse over the column headers you get more info, one of them is how the total is calculated. in short we only count the energy of part of the electricity because counting all of the fossil electricity would double count energy use.

2) These numbers already count everything along the supply chain. For example, energy needed for making electricity are included in that row. The energy to refine said petroleum is included in the petroleum row.

3) Re: errata the only relevant one is related to the construction chapter, and is included on the forum.

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