4

This inquiry was triggered by the question What is the scrap value of wind renewables?.
The question essentially asks for the 'scrapping' part of the life cycle analysis of a wind turbine (a full LCA would include investigating alternatives like refurbishing, and would also take the contruction and usage into account).

Despite being limited to the 'scrapping part', trying to work this out is going to be broad.

There are more of these questions:
Do small portable solar chargers generate more energy than it costs to produce them?
How to determine whether hybrid cars are really more sustainable than traditional cars?
Whole-of-life impact of liquid soap vs solid bars of soap
Which is more sustainable: aluminium can, plastic bottle or glass bottle?
Which is more sustainable: Almond, Soy, Coconut, Cashew or Other Milk?
etc.
(Very often these would need several LCA's)

Answers are often limited: some other life-cycle aspects, it depends on ...

On the other hand, LCA is extremely valuable in the area of sustainability; personally I see answers to LCA questions as a major benefit for this site.

Yet I doubt that at the current stage/size we have enough people to come up with good LCA's - we're still beta ;-)

I can think of several ways to address these questions:

  1. If they cannot be narrowed down sufficiently, be strict and vote to close as 'too broad'

  2. Allow everyone to contribute whatever parts of the analysis (s)he can come up with; this often leads to questions with enough answers to satisfy the OP (given by an 'accepted' mark), despite not being a solid LCA.
    (This seems to be the mode we're operating in now)

  3. Steer the questions to "What aspects do I need to consider in the LCA of X?"

  4. Steer the questions to asking for external resources

Thoughts? Any other approaches you see/want?

Note: We do have a life-cycle-analysis tag, currently used in 18 questions, among them: What are freely available tools or databases for Lifecycle Assesment?

Somewhat related question: How do you identify what is sustainable without reverting to lists and other people's ideas?

1

They way I see it there are 2 types of questions here; questions about the sustainability, environmental impact, LCA, scrap value, etc. of something in general, or of a specific situation. I took a quick glance at the questions you are referring and it looks like those are more or less about general situations. However, we also have questions about specific situations which may actually be harder to answer (e.g. Is buying online more sustainable than in local shop next door? or Does it make any difference to charge my electronic devices using an USB port?).

General situations

I think the best answers to these questions discuss research studies that have been done on the topic at hand. I guess this is your point 4, but in the answer you summarize the main points found in the research. Your point 2 (everyone contributes parts of the analysis) or point 3 (list which aspects to consider) are also fine, but are probably of lesser quality. If research on the topic does not exist, an answer that points this out would IMHO also suffice.

I think that if exact numbers are not available, rough estimates are fine as well (as EnergyNumbers did in his answer to What is the scrap value of wind renewables?). I agree that it's undoable to perform an LCA to answer a question, because a) this is way too much work and b) most people here probably don't have the knowledge or tools to do so.

One potential problem with questions and answers about general situations is that they don't always apply. There are always exceptions, circumstances where the research studies do not hold. On the one hand I think this should be evident to the OP. On the other hand, it may be best if the exact scope of the discussed research studies are also mentioned in an answer. A good LCA study always mentions the geographical, temporal and technology coverage of the used sources, so you should be able to find this information in an LCA report.

Specific situations

Questions where the OP is asking about a specific situation are somewhat more difficult to answer because it's more likely that research studies didn't cover this specific situation and/or that the OP didn't specify all relevant details. I think these question can often still be answered in the following manner:

  1. Indicate to the OP what the most important factors are to consider and how they influence the result.
  2. Refer to research paper(s) in which a somewhat similar situation was analyzed and what the outcome was. The OP can then decide for him/herself if their situation is similar enough to the situation described in the paper(s).

In my opinion an acceptable answer addresses either point 1 or point 2 and a good or excellent answer addresses both points.

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