Water Lifting Water: A Comprehensive Spatiotemporal Review on the Hydro-Powered Water Pumping Technologies

Round 1

Reviewer 1 Report

Revision of the paper “Water lifting water: A comprehensive spatio-temporal review on the hydro-powered water pumping technologies”

Major revision

The issue addressed by this paper is interesting as it focusses on the review of hydro powered pumping. Nevertheless, the novelty of this work should be further detailed, its practical value and its scientific added value should be highlighted.

The authors did not critically analyse the limitations of using a google search. Especially if when considering older documents.

Lines 124-127 – I did not understand this paragraph.

Lines 128-136 – There is no need for this paragraph, the authors can just say that several keyword in other languages than English were searched.

Why did the authors limit the search to these specific languages? Does this has influence on the results of the analysis?

The authors do not explain why the number of documents is important. If the analysis was restricted to scientific literature, the number of papers published for a given technology would be important, but it does not.

Then for the spatial analysis, the authors mention the number of reported cases, how does these numbers relate to the number of documents? It’s not clear.

Author Response

Point 1: The issue addressed by this paper is interesting as it focusses on the review of hydro powered pumping. Nevertheless, the novelty of this work should be further detailed, its practical value and its scientific added value should be highlighted.

Response 1: Two sentences were added (lines 72-78); they highlight the novelty of the review paper, with respect to the knowledge fragmentation and gap, as well as the value for different fields / audiences.

Point 2: The authors did not critically analyse the limitations of using a google search. Especially if when considering older documents.

Response 2: One sentence was restructured (lines 113-115), explaining how authors accessed sources of information not reachable through Google Scholar / Google search engines. Moreover, a new sentence (lines 121-123) explains the triangulation of sources carried out, in order to overcome such limitations.

Point 3: Lines 124-127 – I did not understand this paragraph.

Response 3: The corresponding paragraph (lines 139-146) was restructured, and an actual example was included. If these terms were not ruled out in some search iterations, the inaccuracies of results (technologies out of scope) was considerably higher in those cases.

Point 4: Lines 128-136 – There is no need for this paragraph, the authors can just say that several keyword in other languages than English were searched.

Response 4: The authors respectfully propose to keep that paragraph, as it is, due to two reasons: 1) as shown in Fig. 10 of the manuscript, there are technologies whose documents, either scientific or non-scientific, exist (almost) exclusively in non-English domains; and, 2) as a consequence of the first reason, it is of utmost importance to explicitly state those non-English keywords and terms, so the consequent data and later results become findable and reproducible, respectively.

To exemplify this explanation, technologies such as the Aerohydraulic water lifter, Hydraulic converter and Vietnamese hydraulic pump (amongst others), would be completely neglected in the results after those keywords are not known. Moreover, the results of the e.g. Chinese water turbine-pump (in both documents as well as cases of application) would vary significantly if non-English documents, only reachable through its corresponding Mandarin term, are not considered.

Point 5: Why did the authors limit the search to these specific languages? Does this has influence on the results of the analysis?

Response 5: The authors did an exhaustive search involving as many languages as possible, particularly when certain technologies—or their concentration in a specific area worldwide—were limited to specific non-English ones. However, it is impossible to cover the total universe in this respect; therefore, a disclaimer sentence was added to the text (lines 155-158).

Point 6: The authors do not explain why the number of documents is important. If the analysis was restricted to scientific literature, the number of papers published for a given technology would be important, but it does not.

Response 6: A new paragraph (lines 486-492), explaining the relevance on the interpretation of these numbers, was added to the document.

Point 7: Then for the spatial analysis, the authors mention the number of reported cases, how does these numbers relate to the number of documents? It’s not clear.

Response 7: The paragraph explaining the two datasets (documents and reported cases) their source of data, and their construction, was restructured (lines 183-198). Its last three sentences (lines 192-198), particularly, states the relation between the documents and the reported cases that derived from the former.

Reviewer 2 Report

The paper is a comprehensive review of small hydro-power applied to recover energy for water pumping. The topic is of interest because of the new interest in renewables and in a more sustainable use of energy in the wwater networks.

The positive aspect of the paper is the large data base of technologies built up during the research project. Very interesting is also the final spatial and temporal analysis on hydro power applications.

I think that the paper could become very significant but some additional work is necessary. I view the following obstacles to the publication:

- the Authors mixe up technologies at an industrial, at rural, or at conceptual stages. I think that you have to reorganize the technologies on the basis of the stage of progress.

- in an engineering paper I think that an enginnering based comparison will be necessary. This means that you have to incuede a range of flow rate-head in Table I for the energy recovery part and the pumping part of each device.

- another problem is the lack of efficiency values and cost for each technology. Phisycal principles do not allow comparisons, we need an efficiency value. Of course, if you make separate part for industrial, rural and conceptual technologies, you will supply data only from the first two lists.

These three points are on the paper data and organization.

Now some specific comments:

Line 59: 24/7 please be more clear 24 four hour a day and 7 day per week?

Line 37-75: The introduction is very poor. Please anticipate and introduce here part of the consideration and of the references that you include in Chapter 3. Many technologies, applications and worldwide analyses are already discussed in papers and books. Here the impression is that you are the first to talk about a topic...

Line 228 Hydro pneumatic water lifter. As far as I know, this technology is very old. I remember a Table and a description in a G. Venturoli book (Elementi di Meccanica ed Idraulica, Vo. II, 1818) but the first applications are of the hydraulic ramare of 1772.

Line 249 3.1.3 Hybrid turbine-pumps. I see only conceptual examples, but there are for sure some industrial products. I know of a Wortighton industrial turbopump of the sixthies (see attached paper).

Line 266 3.1.4 The description of WTPs is not clear. Is this device composed by a pump and a turbine on the same axis? Please carify and add a technical draw if available.

Lines 365 and 394 Here there is a good example of how generic could be the paper at this stage. Integration of PAT and pumps on the same axis are very efficient, with advanced theory and applications (see ref. 167). Bunyip and Filardo pumps are unknown tech. They can't be discusse din the same way....

Line 587. I think that the concept of a unique machine for energy recovery and production is a bit restricting in a world where multiple energy production point and anergy uses are possible. You have to cite new projects on energy recovery in water distribution networks, like:

https://www.redawn.eu/

http://hydro-bpt.bangor.ac.uk/index.php.en

Finally a list of achronyms is necessary.

Comments for author File: Comments.pdf

Author Response

Point 1: the Authors mixe up technologies at an industrial, at rural, or at conceptual stages. I think that you have to reorganize the technologies on the basis of the stage of progress.

Response 1: Amongst the selection criteria (section 2.1), technology development stage was not considered a discrimination factor, thus enabling a broad range of (old and new) HPP technologies to be part of the review’s scope. In that sense, according to the authors, classifying the technologies based on that criterion will imply a main pitfall: very few branches (e.g. commercial, commercially extinct, rural / non-commercial, conceptual) will group up too many technologies, too different in nature between themselves, whose only common point is only such criterion. For instance, industrially manufactured HPPs will encompass HSP, HRP, CWTP, High Lifter, Bunyip pump, amongst others. On the other hand, non-commercial ones (neither rural nor conceptual) will comprise the CWL, the Vietnamese hydraulic pump, HT. In turn, this will rather unnecessarily increase the complexity in the further analysis and interpretation of data.

Because of the aforementioned reason, stage of development / progress / commercial status  was only considered as another “characteristic” or “feature” of the technology, as pointed out in Figure 1 (with restructured title). Moreover, due to the inconveniences in choosing a single criterion to group and eventually classify all the screened HPP technologies, a combination of properties—related to the morphological / mechanical properties—was used to perform such a task (as stated in restructured paragraph in lines 178-182).

Point 2: in an engineering paper I think that an enginnering based comparison will be necessary. This means that you have to incuede a range of flow rate-head in Table I for the energy recovery part and the pumping part of each device.

Response 2: Although the authors considered this a very relevant remark, it is worth noticing that the scope of the article, as it was conceived, does not cover comparison / benchmarking of the technical performance of 30 screened HPP technologies. As a matter of fact, with respect to this topic, it would be necessary to carry out different studies to properly address such information, due to the following reasons:

1) Many technologies (e.g. HRP, CWTP, WDP, TDP, PAT-P), even within a single manufacturer, bear several models that are suitable for different contexts. For instance, some aim to higher pumped flowrates or higher pumped heads, to the detriment of the corresponding pumped heads and flowrates, respectively. Plus, these technologies and models have evolved (and improved) over time, which is one of the analysis lines of the present article. It is so, that highlighting ranges of working / pumping conditions per technology, in a single table, can mislead to (i) to assume that the bigger the number, the better the technology, and vice versa, and (ii) to benchmark such raw numbers directly one another, disregarding a whole set of other key factors, as explained below.

2) Pump head and flowrates values are intrinsically related to the optimal working conditions (which might be different between technologies), as well as to the hydraulic energy harnessing capacities of each hydro-mechanical concept itself. Therefore, and to avoid misled messages by showing only ranges in a table, it is preferable to conduct benchmarking analysis based on performance curves. Nevertheless, and despite that sound option, it would be misleading as well to do such a study comparing technologies very different in nature (i.e. GT, Hydrobine and PAT-P). In consequence, an ideal alternative would be to analyse the technical performance of those technologies that are in a similar range, for instance, WCTs, WTPs.

3) If the analysis is meant to be more detailed, and more technologies to be benchmarked, then it should even include: efficiencies, power generation, investment costs, and thereafter power unit / pumped unit costs. Only then it would be possible to generate a whole panorama of comparative costs / benefits of HPP technologies, much beyond than the ranges initially requested.

Point 3: another problem is the lack of efficiency values and cost for each technology. Phisycal principles do not allow comparisons, we need an efficiency value. Of course, if you make separate part for industrial, rural and conceptual technologies, you will supply data only from the first two lists.

Response 3: Similarly to the previous point, this is certainly a key remark. Nonetheless, it is addressed in the section 3) of the previous answer as well.

Point 4: Line 59: 24/7 please be more clear 24 four hour a day and 7 day per week?

Response 4: The expression was clarified.

Point 5: Line 37-75: The introduction is very poor. Please anticipate and introduce here part of the consideration and of the references that you include in Chapter 3. Many technologies, applications and worldwide analyses are already discussed in papers and books. Here the impression is that you are the first to talk about a topic...

Response 5: The introduction was broadened (lines 71-78) to explain the existing knowledge gap due to the temporal-spatial fragmentation of information.

The authors acknowledge the existence of other studies on RE-based water pumping, as well as (old) reviews on HPP technologies (lines 67-72). However, and to the best of our understanding, this is the first worldwide-scale study of its kind addressing: 1) many different HPP technologies, some of them absolutely overlooked in previous studies; 2) a thorough analysis of their origins, evolution and fate); and, 3) their integral depiction, in space and time, of their development and application throughout the history. If the reviewer knows of a similar previous document / study, whose content deserves to be considered to strengthen the present review, we kindly would like to ask for further information on it.

Point 6: Line 228 Hydro pneumatic water lifter. As far as I know, this technology is very old. I remember a Table and a description in a G. Venturoli book (Elementi di Meccanica ed Idraulica, Vo. II, 1818) but the first applications are of the hydraulic ramare of 1772.

Response 6: Certainly. The non-automatic HRP was invented in 1772, and the first self-acting HRP was invented in 1796 by Joseph Michel de Montgolfier. This is considered in both Appendix A (bibliography and application cases) as well as Appendix B (evolution of HPP technologies). Additionally, this is reflected in the literature analysis – Figure 11 (3.2) and temporal analysis (3.4).

Point 7: Line 249 3.1.3 Hybrid turbine-pumps. I see only conceptual examples, but there are for sure some industrial products. I know of a Wortighton industrial turbopump of the sixthies (see attached paper).

Response 7: Neither the Hydropulsor nor the HT are/were conceptual. As a matter of fact, the Hydropulsor was industrially produced in Germany, marketed by the company Ottensener Eisenwerk, A.G., and applied in a number of cases in Germany and Poland (see Appendix A and Appendix B). The HT, on the other hand, although initially constrained to lab research in the 1940s (doctoral research of Aurel N. Bărglăzan), during the 1990s was applied to actual agricultural setups in the outskirsts of Timișoara, Romania (see Appendix A and Appendix B).

With regard to the Worthington turbopump, the authors thank for the kind contribution about that technology It is an interesting one, and the authors were not aware of its existence. However, notwithstanding its design (which certainly fits in a hybrid turbine-pump concept), it has not been envisaged as a (potentially) applicable technology to supply water for human consumption / agricultural irrigation, nor applied as such. In point of fact, the recalled uses are drainage of ship hulls, and mix of chemical and petrochemical fluids (etc.), which will eventually require an externally pressurized fluid to drive the turbine. Therefore, similarly to what occurred with firefighter turbo-pumps, water-driven foam pumps, and hydraulic turbochargers (lines 104-105), it does not comply with the points 2, 4 and 5 of the HPP technologies selection criteria (section 2.1).

Point 8: Line 266 3.1.4 The description of WTPs is not clear. Is this device composed by a pump and a turbine on the same axis? Please carify and add a technical draw if available.

Response 8: The sentence providing the description of the WTP (lines 298-301) was restructured and simplified: “The water turbine-pump (WTP), largely referred to the literature as a machine unique to China, results from embodying in a single case, and coaxially joining—through a single shaft or transmission system—an axial-flow turbine (usually a Kaplan type) and a centrifugal pump”. Besides, a technical drawing has been added as requested.

Point 9: Lines 365 and 394 Here there is a good example of how generic could be the paper at this stage. Integration of PAT and pumps on the same axis are very efficient, with advanced theory and applications (see ref. 167). Bunyip and Filardo pumps are unknown tech. They can't be discusse din the same way....

Response 9: The authors completely agree with the comment; such different technologies, in terms of hydro-mechanical concept, benefits, efficiencies, and development stage, cannot be discussed nor benchmarked / compared to one another from the technical / economical point of view (see Response 2 as a complement). As a matter of fact, that is why the scope of the review is limited to understand the spatial and temporal application of all the screened HPP technologies, namely: what has been applied where and when, and for which purpose. Therefore, the discussion on how this HPP applications are comparable to each other in terms of efficiency, are not considered at all. Furthermore, regardless their efficiencies, the proposed classification was used to provide a logical structure to a plethora of inventions / systems / devices, thus enabling the analysis of hundreds of cases that fit within the proposed scope.

Point 10: Line 587. I think that the concept of a unique machine for energy recovery and production is a bit restricting in a world where multiple energy production point and anergy uses are possible. You have to cite new projects on energy recovery in water distribution networks, like:

https://www.redawn.eu/

http://hydro-bpt.bangor.ac.uk/index.php.en

Response 10: Undoubtedly, energy recovery in water distribution networks is a very relevant topic, particularly within the context of more energy-efficient systems, with lower carbon footprints and reduced dependence on non-renewable energy sources. That topic as such is, however, out of the envisaged scope of the present review, which is limited to hydro-powered pumping technologies. In consequence, the authors consider the projects / literature proposed by the reviewer are out of the scope as well.

Point 11: Finally a list of achronyms is necessary.

Response 11: Although not required by the editorial board, it is considered a relevant and useful remark. A list of acronyms have been added to the manuscript; its inclusion is put under consideration of the editorial board.

Reviewer 3 Report

This manuscript review water pumps. The contents are good and it may help the readers seeking well organized review on the water a lot.

My question,

Are figures 10-15 originally made by your research team? If so, please improve them to be optimal for the journal paper size (too small font size in the figures and the resolution of figure itself is too bad). If not, the authors should include the source and re-draw them with better resolution and improved font size.

Other than the problem on the figures, it looks sufficient to be published as ‘review’ manuscript.

Thanks for your big effort

Author Response

Point 1: Are figures 10-15 originally made by your research team? If so, please improve them to be optimal for the journal paper size (too small font size in the figures and the resolution of figure itself is too bad). If not, the authors should include the source and re-draw them with better resolution and improved font size.

Response 1: Figures were replaced, so now they show bigger font sizes. Resolution was confirmed to be good enough in both electronic and printed media. Thank you for your kind comments.

Round 2

Reviewer 1 Report

The authors addressed every point I've made. 

Reviewer 2 Report

The recommendations were not all properly considered, but I'ma partially convinced by the Authors' response.