Selecting a suitable waste-to-energy (WTE) technology for a specific region, such as the Greater Beirut Area, is a complex decision that involves various criteria and factors. The Analytic Hierarchy Process (AHP) is a decision-making methodology that can be applied to prioritize and select the most suitable waste-to-energy technology. Here's a step-by-step guide on how you might approach this using AHP:

1. Define Objectives and Criteria:

Objectives:

• Generate energy from waste
• Minimize environmental impact
• Maximize economic viability
• Ensure technological feasibility

Criteria:

• Technology efficiency
• Environmental impact
• Economic factors (cost, revenue potential)
• Technological feasibility
• Social acceptance

2. Identify Alternatives:

• List potential waste-to-energy technologies such as incineration, anaerobic digestion, gasification, and landfill gas recovery.

3. Establish a Hierarchy:

• Set up a hierarchical structure with objectives at the top level, criteria in the middle, and alternatives at the bottom.

4. Pairwise Comparison:

• Use pairwise comparisons to assess the relative importance of criteria and sub-criteria. For example, compare "Technology efficiency" against "Environmental impact" and assign a relative importance score.

5. Create a Comparison Matrix:

• Construct a comparison matrix for each level of the hierarchy based on the pairwise comparisons. Normalize the matrix and calculate the priority vector for each level.

6. Calculate Consistency Ratio:

• Evaluate the consistency of the judgments by calculating the Consistency Ratio. Adjust the pairwise comparisons if needed to improve consistency.

7. Aggregation:

• Use the priority vectors to calculate the overall priorities for the alternatives at the bottom level.

8. Sensitivity Analysis:

• Perform sensitivity analysis to assess the robustness of the results to changes in the input data or judgments.

9. Decision Making:

• Summarize the results and make an informed decision based on the priorities assigned to each alternative.

10. Documentation and Reporting:

• Document the entire AHP process, including criteria, alternatives, judgments, and the final decision. Provide a clear rationale for the chosen waste-to-energy technology.

Additional Considerations:

• Engage stakeholders, including local communities, authorities, and environmental experts, to gather input and improve the accuracy of judgments.
• Consider the specific waste composition, regulatory environment, and energy demand in the Greater Beirut Area.
• Periodically review and update the decision-making model to reflect changes in technology, regulations, or other relevant factors.

Remember that the success of waste-to-energy projects depends not only on the technology itself but also on factors like public acceptance, regulatory support, and economic viability. The AHP process helps in systematically considering these factors for an informed decision.

Dear Md.

Thank you for your reply

Since you are kind enough in replying my comments, something that I very much appreciate, you don’t refute any of them; you are just doing a description of the AHP method, which, by the way, is the best known and used MCDM method, and adding nothing new. It is very well known after more that 40 years.

If I can I would like to pose a question. Would you be willing to support your work when the stakeholders will be asking questions that you cannot answer, like for instance, if you say that criterion C5 is three times more important than criterion C3?

Thy will ask "Based on what?"

On intuition? Do you think they will be willing to spend millions of dollars based on a such a weak response?

EPP - Dear Dr Munier, thank you for the interest on Mr El-Toufaili’s paper, and for the time you dedicated to reading it.

NM- Dr. Padoano, thank you for your answer

EPP -There are some aspects that could surely be improved in the study; however, as Mr Al-Amin mentioned, the setting where a problem takes place is a key factor.

NM- I agree, but it does not mean addressing the problem with a MCDM method that is not suited for the job.

Really, section II looks more a description of the method than supporting its validity. Since when pair-wise comparisons between criteria are valid? Where is the proof of that? Why the consistency of the DM’s invented weights is important?

I agree that it is important for him, but not to the problem, the article refers to. The authors take the method at its faced value without analysing if it is realistic or applicable to their problem.

EPP -In the specific case, the idea was to start a discussion on the problem showing that stakeholders’ points of views can actually be taken into consideration.

NM- Sorry, where is that really important fact?

In Figure 8 all authors seem to ignore that for instance, criteria Health and Pollution are related, as well as Solid Waste and Energy Production or Energy Generation related to Capital Cost, when Saaty himself established that criteria must be independent, and he was absolutely right? which is not the case here. In my humble opinion this is an aspect not to be blamed to the AHP method, but to its correct use by practitioners.

In Table I it appears that the Technology Readiness Level (TRL) meaning is ignored, because it is not measured by a set of attributes, but for the state of development of a method, as TRL clearly mentions (READINESS), and in all honesty, I do not think that AHP can be applied, considering that in the 80s Saaty judiciously decided to improve it creating ANP.

EPP -There are several situations in where that starting a discussion is more important than offering a ‘closed solution’ (which, according to some decision makers, could seem ‘imposed’ by an undefined authority).

NM- Yes, you are right, however where in the text are the discussions with the stakeholders?

What the paper shows is a very valuable discussion and opinions with experts who may or not be the stakeholders. In my opinion, normally, there is a government body that want to implement a system or perhaps staff of a company that wants to implant this system commercially, that is, interested parties. Experts are technicians but not involved in the problem

EPP -The results of the paper are far from being conclusive, but they made it possible to trigger a factual discussion, which just few years ago was not considered feasible.

NM- Yes, I agree with you in this, but this discussion was possible since Roy created his method, and even before, in the 50s, when C/B analysis was expanded under pressure fropm people, environmentalists, health professionals, etc. Regarding developing a hierarchy, this is a very good way to understand a problem, and it could be that Saaty borrowed this the idea from Systems' Theory and its Workd Brealdown Sructure (WBS).

EPP -Apart from that, there is a good number of studies (at least starting from Zeleny’s, Roy‘s and others) that underline the role of the ‘problem owner’ and open discussion among experts and stakeholders in strategic decision making.

NM-Yes, and the opinion of both researchers support what I said

Dr. Padoano, I already knew that you are a defender of AHP and even that you are a lecturer on this subject, and I am sure that you know that I am the opposite. I started criticizing this method since I joined RG about 10 years ago, and also, I had the privilege to discuss it with Dr. Saaty, in 2017, months before his passing away. I have always maintained that AHP might be useful when used for trivial problems, but certainly not for complex ones; It is not up to that job.

Most curiously, you do not reject, answer or refute any of my points.

It would be my pleasure to continue this discussion with you, if you are interested, of course.

Best regards

Nolberto Munier

Thank you Dr. Padoano

Don't be modest, you are a recognized researcher and of course you have the right to have your own opinions and preferences.

There is no doubt that AHP is comprehensive and useful in some cases.

It is very simple indeed, but in my opinion it does not mean that it is reliable. The fact that results are based on a DM intuitions, not even analysis, and can change if another DM performs the same, makes me think that there is something incorrect in the method.

If I may I would suggest to think these two questions, and perhaps you can find the answers that escape to my understanding:

1- Does it makes sense using pair-wise comparison? Yes, it is, but what does not make any sense is asigning a numerical value to the preference, taken from a table that does not have any support. That table attempts to be a simil to the results reached by Weber and Fecther, when they studied responses as a fuction of stimulus. It appears that for Saaty stimulus and intuition are the same thing.

2- What really puzzles me if how somebody may assume that what is in his mind is applicable to the real-life? On what grounds?

I have many more 'pearls' like these but I do noy want to abuse of your patience.

Withot intention for arguing I am puzzled when you say that the decision taken was the recommended by the method. And what does it prove? If a faulty theory says that 4 + 2 =9 , we should accept it?

Only because a method says something, the result is correct?

I believe that when a person reads these aspects in a 'mathematical' method like AHP, it is impossible not to think that they are incorrect. Why people do not reaction to that? Not only in AHP, the same in ANP, B&W, SWARA, and may others,where the opinion of the DM is taken as the real truth.

It is not a matter of misconceptions, but when you think about the methodlogy of the AHP method you have to recognize that it is deeply flawed

Regards

Nolberto

Dear Elio pls drop the Dr. and use my name

I am glad that you are in agreement with my concerns, however, in that situation, may I ask why do you continue defending and using a method that you recognize that is faulty and irrational?

I am not judging, only curious.

There are MCDM that are very good, like TOPSIS, PROMETHEE, ELECTRE that, as any other MCDM method, have also blunders and assumed dubious assumptions, but at least, they are RATIONAL. They demand an active participation of the DM. For instance, in PROMETHEE the DM must take a decision based on real values and act accordingly, selecting the most adequate probabilistic function, or exert the veto as in ELECTRE, or determining the positive ideal and negative ideal in SPOTIS.

In all of these methods the DM must think, reason, investigate, consult, something absent in AHP, and possibly one of the reasons of its great diffusion.

Thinking in AHP: None, only intuition, that can be different a minute later……

Reasoning in AHP: None. For instance, it is impossible to find the reason by which a DM prefers three times abstract concepts like love, and tenderness. Can you see the absurdity of this?

Investigation in AHP: None, because selection is at random and depends on the mood of the DM.

I agree 100% with you that MCDM only helps the DM; whatever the method used, it is only a tool. As that, they only serve as a ‘supposedly’ correct base for the DM to decide.

You talk about future discussions, fine.

If the DM comes with a solution and have to explain it to the stakeholders, and one of them asks “Can you tell me please why you say that criterion c4 is 2 times better than criterion c6?’ Where are the discussion and the analysis, as you say?

What is the DM answer? If he says that it was his intuition, most probably he will be fired. This is reality, Elio, not theory. Or suppose that the financial guy says to the production manager that he has no money to buy an equipment that the latter is asking? What is the solution given by AHP?

I see all of this every day in my comments on published papers in RG, more than a hundred at this time, needless to say, if I were a reviewer many wouldn’t be published. A clear example was your article; no reviewer saw that it contradicts Saaty statement that AHP must be only applied when criteria are independent.

Of course, many stakeholders approve what the DM result, because they probably think that he used a famous MCDM model - on which they don’t have the faintest idea- which is not a mathematical, physical or chemical formula, but an approximation to reality, and depending of one DM or even a group. If the stakeholders hire another DM and the result is different, what would they do?

If you use AHP for selecting a movie or a restaurant, it strongly depends onyou, and it could be very useful indeed, but not in the real-world. In the first case, the success or failure will affect the individual. In the second case it may affect millions and change their life, like selecting a place to build a power dam.

I do not know what is for you a manageable set of alternatives, of course, if there are say 200 alternatives, it would be very cumbersome solve the problem, probably not because the method, but for the workload. In that case you can reduce the number of alternatives to a manageable number, say 30, using statistics. But this reduction is made reasoning and mathematically, not because I do not like some of them

Just to finish, what is the gain in getting different practices, you will get back at square one?

You only need the best, and a ranking of the others, and as you know, in deceasing order of importance.

If, as you say, you get alternatives out of the scenario, which is reasonable, you are solving another problem, not related with the original, which is also normal.

I have participated in many real-life situations and yes, there are cases were new requirements may be added or deleted, and it is quite normal. If you use AHP, you have to start all over again.

Sorry for my extense answer

Best regards

Nolberto

EP-Dear Nolberto,

EP- thank you for your thorough reply. Just few answers to your comments.

NM- Dear Elio

Thank you for your appraisal and for your honest answers. You are one of the few persons that contact me back. You rightly defend your positions; it looks that many authors are afraid or cannot do the same.

‘may I ask why do you continue defending and using a method that you recognize that is faulty and irrational?’

EP- I have worked in teams in different companies with MCDA, and we presented and discussed different methods: in some situations, there was an agreement on using the AHP. We usually discuss and present pros and cons of methods with different theoretical backgrounds (SMART, PROMETHEE, ELECTRE, TOPSIS, VIKOR): PROMETHEE and TOPSIS have been selected in several situations.

NM- You say that in some situations there was agreement in using AHP. I have not doubt about it. If you are discussing hiring policies in the xx company, they are who best know what is needed, what people profile, and so on. If time shows that this policy was a success or a failure, both the merit and the blame will fall on the team.

I believe that it means something, and for me it is due that irrationality cannot be justified.

But if a government is planning to construct a power dam to generate electricity and has to decide the place among others, a common problem, the decision will affect many people that did not participate in it. In this case, you cannot use AHP, because you are not entitled to vote for others, that do not even select you to represent them, and this is what AHP does. You know that there is even a theorem, the Arrow Impossibility Theorem that calls this procedure a dictatorship.

I asked this same question tom a renown mathematician, and the answer was “Yes, but the people need to be taught”. I wonder on what and by who….

As you say, you discuss the merits and demerits of AHP. Its only merit is that it is well-known and it appears to be the reason to use it. I can show you 29 demerits, that even were published in an e book of mine two years ago. It took me four months of discussion with three Springer reviewers where every of mine assertions were discussed and further approved. At present, the book was accessed by 7,425 persons, according to Springer daily records. Do you know how many of them refuted what I said: NONE.

What argument do you have to refute this? Just select two excellent methods that can do the job PROMETHEE or TOPSIS

Years ago, here in RG, I was requested for a practitioner to help him in an end of career project related to MCDM. When I saw the project, I recommended the practitioner to change the method because AHP was not up for the job, and of course, I gave the reasons. This person consulted his tuitor and he said that he MUST USE AHP. Why? Probably because it was the only method he knew

NM-‘If the DM comes with a solution and have to explain it to the stakeholders, and one of them asks “Can you tell me please why you say that criterion c4 is 2 times better than criterion c6?’ Where are the discussion and the analysis, as you say?’

EP-In our cases, the AHP scale is thoroughly explained as a means to compare objects: it takes the largest effort in the evaluation procedure (in our cases).

NM – The AHP scale, as I mentioned yesterday, is based on preferences and measured by a dubious Fundamental Scale that pretends to be a copy of the Weber-Fechter Law, that says that there is a log response to increasing stimulus. It is not my invention, Saaty says that he took as a model this law, and equating stimulus with intuition, which obviously are not even remotely related. You say ‘through explained’, may I ask what is to be explained, other than obey to emotions?

‘I see all of this every day in my comments (…). A clear example was your article; (…)’

EP-I usually don’t like to submit papers of this kind (and several companies don’t want to circulate the work), but I stay with the decisions of the team (I think that less than 1 out of 8 case studies we did has actually been submitted for publication).

NM- Well, but you do not explain why you submitted it, knowing that it was violating AHP procedure. Years ago, I made the same comment on a paper published by professors of two European university. Want to know their ANSWER?

“Yes, we knew that, but we decided not to consider”

As simple as that…..

‘If you use AHP for selecting a movie or a restaurant, it strongly depends on you, and it could be very useful indeed, but not in the real-world. In the first case, the success or failure will affect the individual.’

EP-The main fields of application, in our case, are design selection for products and services (by means of a panel of prospective users), supplier selection and technical asset selection: in many cases there are one or just a few company’s officers who are entitled to put forward a solution, usually in a limited time.

NM- Well, in your case it might make sense, however you admit in the paper that AHP is applied to ‘waste to energy’ which is not a service, but a complex undertaking involving, engineering, environmental, health and economic problems. The service will be the distribution of the energy produced. Decades ago, two students in the University of Milan, solved this type of problem using MCDM, certainly not AHP.

‘I do not know what is for you a manageable set of alternatives (…)’

EP-I don’t know for me, but for some of the companies where we worked this means having just few solutions (three? four?) that have very similar performances and features, and which can then be negotiated in terms of price (or cost of ownership). I have noticed that what Simon wrote in the 50s about bounded rationality and the firms’ decision process has been confirmed in many real problems…

NM – Well it makes sense, and you can use the ranking of alternatives.

Very interesting and useful your mention about Simon, and his work about bounded rationality. “This model suggests that decision-making is not always rational, but rather limited by the information available, time constraints, and cognitive limitations of the decision-maker, asserting that” the cognitive abilities of human decision-makers are not always sufficient to find optimal solutions to complex real-life problems, leading decision-makers to find satisfactory, sub-optimal outcomes” (Maillard, 2016) . Bounded Rationality and Behavioural Economics- Routledge

Needless to say, that I am in complete agreement, and glad that you brought it.

It reinforces the fact sustained by many researchers that MCDM most be done bottom up, not top down.

The reason is simple, if you have a mix of data with certain degree of uncertainty, as always happens, you do not improve it by multiplying to invented weights, as those from AHP, and proceeding to ‘solve’ the problem, and arriving at results that might be biased because the are grounded on altered data either quantitative or qualitative.

In my humble opinion, it will be better off, to solve the problem without any interference altering data .At the end you will have a result that possibly is if not optimal, at least convenient, using for instance TOPSIS.

It is here, at the bottom, where the participation of the DM is paramount. He inspects the result that again, have a solid mathematical base, and examines it. He can make several analysis using sensitivities analyses, consulting other experts about similar problems, examining the influence of exogenous variables in the results, etc. From there he can go up and add or delete criteria, modify performance values, add criteria say for cost with upper and lower limits simultaneously, check for rank reversal, etc.

This is rationality

If you find that this bottom-up process is reasonable, you will understand why you cannot use AHP.

Please don’t tell me that you can use AHP in sensitivity analysis because its process, using ceteris paribus for criteria is rejected by most economists.

Best regards and enjoy your beautiful city

Nolberto