Life Cycle Inventory

How does one partition by mass, energy, and economic value?

Make allocation keys: For mass and energy simply find percentage of each mass. For economic value multiply price by mass, then find the percentage.

What are approaches to avoid allocation?

System expansion can be done for products to see what products they would replace. A credit can then be calculated for moving away from a fossil based equivalent to the new product.

System subdivision can be done by dividing a complex process into smaller, sub-processes. You can then collect separate input and output data, avoiding the need to allocate shared environmental burdens.

Which allocation is most preferred?

According to ISO if allocation is going to be preformed it is best to do it based on physical properties, so mass allocation is preferred.

If a co-product has a much greater economic value than its other co-products, one may argue that economic allocation is motivated.

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