A novel approach to hydraulic energy recovery: submersible Pumps As Turbines

Daniele Novara

Instead of a conventional “dry” Pump As Turbine (PAT) device for energy recovery, the Dŵr Uisce team is investigating the use of a “submersible” PAT in order to simplify the construction of the turbine house. Therefore, a prototype submersible PAT has been tested in the lab to determine its performances.

Figure 1: conventional PAT (as deployed at Blackstairs Gropu Water Scheme demonstration site)

Pumps As Turbines (PATs) consist of hydraulic turbines derived from standard water pumps whose flow direction is reversed with respect to pump operations. Therefore, instead of consuming electricity to move water around they can be used to generate electric power from a pressurized water flow. Despite the lower efficiency compared to conventional hydraulic turbines, the mass manufacturing process makes PATs several times less expensive to purchase and operate as demonstrated during the early phases of the Dŵr Uisce project.

The vast majority of PATs installed or investigated worldwide consist of conventional “dry” units which need to be housed in a protected location in order to avoid flooding damage. However, this can sometimes turn out to be expensive since in order to maximize the energy recovery the turbine should be located as close as possible to the downstream water body to which the fluid is being released. Furthermore, in order to avoid cavitation damage to the blades the ideal location of a turbine is slightly below the surface of such downstream water body.

Figure 2: submersible PAT being tested at Trinity College Dublin

As an alternative approach, the Trinity College team is investigating the use of a “submersible” type PAT (Figure 1) instead of the common “dry” type (Figure 2). The main advantage of a submersible PAT is that the turbine and electric generator are pre-assembled and housed inside a waterproof steel cylinder which can be conveniently lowered to the bottom of the downstream water body without fear of flooding damage. Instead, the rest of the electric equipment necessary for the power plant can be placed at a different nearby location above ground and away from flooding risk.

In order to determine the performances of a submersible PAT, a 3 kW prototype was tested on the hydraulic test rig at Trinity College Dublin.

The results showed a turbine mode mechanical efficiency comparable to that in pump mode as declared by the manufacturer (56%), which is a considerable result given the small size of the device.

Heat recovery from kitchen wastewater

By Ajeet Singh

Significant amounts of energy are consumed in the heating of water for food production and other activities in buildings. The energy embodied in hot wastewater associated with kitchen drains of the hospitality and food services sector in the UK was estimated 1.24 TWh/yr. The capture of this energy has the potential to reduce greenhouse gas emission by 344 k tons Ce/yr [2]. If this energy could be recovered, it would directly attenuate the heating load requirement of the building, and hence the electricity bills. The EU has officially recognized wastewater as a renewable source of energy [3].

The present research focuses on recovery of heat from hot wastewater, flushed into the drainpipes of commercial kitchens. A grease trap is a system one can find in commercial kitchens for the removal of fat-oil-grease (FOG) from the kitchen wastewater. Grease traps present a convenient location where hot wastewater is temporarily retained, from where waste heat could be recovered, in comparison to sewer drains where hot wastewater quickly runs away. My objective is to recover embedded heat from the kitchens wastewater by retrofitting thermal recovery unit inside the grease trap (GT) device. The GT device integrated with thermal recovery unit is referred as hybrid GT system.

Fig. 1. Experimental prototype GT system integrated with thermal recovery unit: (a) Side view of GT system; (b) Thermocouple placement for temperature measurement at different locations; (c) Heat exchanger unit fitted to GT system;

The assessment of the hybrid GT system was conducted through:

1. the development of a laboratory prototype GT system at full scale and assessing its thermo-hydraulic performance (Fig. 1);

2. the development of a numerical model of the experimental prototype to gain deeper insights into its performance; and

3. the design of a second heat exchanger using the numerical model to improve the overall thermal recapture potential of the system (Fig.2).   

A well devised methodology was followed in determining the performance of the hybrid GT system experimentally and computationally. The system integrated with the heat recovery unit was capable of recapturing a maximum heat of 1050 J per sec. The temperature of the clean water through the heat exchanging unit raised by 2-5 degrees Celsius and these results could facilitate preheating of cold water in buildings, lowering the primary heating requirement for conventional water heating devices.

About 20% of the heat was recaptured from the hot wastewater flowing through the GT system which earlier was going waste into the drainage system. At building level, about 21% of the hot water is consumed in kitchens [4]: mounting such a thermal recovery system could save around 20% of the energy from the high temperature kitchen wastewater. However, this research is in its development phase, and hence, it is very early to discuss its impact at building level.

Fig,2 Numerical model of the hybrid GT system

The preliminary results presented here were conducted using clean water to simulate the operation of the GT system, and future work is required to assess the performance of the system using wastewater containing FOG and to improve the design of the heat exchanger. Future work is also required to assess the impact of lowering wastewater temperature on FOG removal efficiency.

References

[1] J. R. Mihelcic and J. B. Zimmerman, Environmental Engineering: Fundamentals, Sustainability, Design, 2nd Edition. Wiley Global Education, 2014.

[2]  Jan Spriet, Aonghus McNabola. Decentralized drain water heat recovery from commercial kitchens in the hospitality sector. Energy & Buildings 194 (2019) 247–259.

[3] DIRECTIVE (EU) 2018/2001 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 11 December 2018 on the promotion of the use of energy from renewable sources.

[4] https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/48188/3147-measure-domestic-hot-water-consump.pdf

Our Autumn Newsletter is out now!

Our Autumn Newsletter is out. You can view it here.

Welcome to our Autumn 2021 Newsletter, bringing you up to date on the Dŵr Uisce project.

The publication in late summer of the 6th Intergovernmental Panel on Climate Change assessment report has sent out to the world a clear and powerful message: we need to take ambitious action against climate change now. The Dwr Uisce team has continued in its commitment to provide solutions to improve the sustainability of the water sector and to spread the message. Individually and collectively, we have engaged in numerous activities: from delivering outreach events to launching a Citizen Science project, from designing a new webinar to presenting our findings at research conferences and online meetings.

In this Newsletter, you can read about our call to action for Irish households to contribute to the reduction of greenhouse gas emissions in Ireland, and the launch of the survey on Water￾ Energy efficiency in Irish households. Then, Dr Nathan Walker takes us through the lessons learnt from international energy benchmarking of wastewater treatment. For an insightful economic assessment of the water sector in Ireland and Wales, do not miss Dr Annum Rafique’s piece. Finally, you can read the latest research updates and publications from our researchers, including Dr Richard Dallison’s timely findings on the impact of future climate change on water resources.

We take this opportunity to wish all our followers and cluster members a climate action-filled Autumn!

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Croeso i'n Cylchlythyr Hydref 2021, i roi'r wybodaeth ddiweddaraf i chi am brosiect Dŵr Uisce.

Mae cyhoeddi 6ed adroddiad asesiad Panel Rhynglywodraethol ar Newid Hinsawdd ddiwedd yr haf wedi anfon neges glir a phwerus i'r byd: mae angen i ni gymryd camau uchelgeisiol yn erbyn newid yn yr hinsawdd nawr. Mae tîm Dŵr Uisce wedi parhau yn ei ymrwymiad i ddarparu atebion i wella cynaliadwyedd y sector dŵr ac i ledaenu’r neges. Yn unigol ac ar y cyd, rydym wedi cymryd rhan mewn nifer o weithgareddau: o gyflwyno digwyddiadau allgymorth i lansio prosiect Gwyddoniaeth Dinasyddion, o ddylunio gweminar newydd, i gyflwyno ein canfyddiadau mewn cynadleddau ymchwil a chyfarfodydd ar-lein.

Yn y Newyddlen hon, gallwch ddarllen am ein galwad i weithredu i aelwydydd yn Iwerddon gyfrannu at leihau allyriadau nwyon tŷ gwydr yn Iwerddon, a lansiad yr arolwg ar effeithlonrwydd Ynni Dŵr ar aelwydydd yn Iwerddon. Yna, mae Dr Nathan Walker yn ein tywys trwy'r gwersi a ddysgwyd o feincnodi ynni rhyngwladol ar gyfer trin dŵr gwastraff. I gael asesiad economaidd craff o’r sector dŵr yn Iwerddon a’r DU, peidiwch â cholli darn Dr Annum Rafique. Yn olaf, gallwch ddarllen y diweddariadau a'r cyhoeddiadau ymchwil diweddaraf gan ein hymchwilwyr, gan gynnwys canfyddiadau amserol Dr Richard Dallison ar effaith newid yn yr hinsawdd yn y dyfodol ar adnoddau dŵr. Manteisiwn ar y cyfle hwn i ddymuno Hydref llawn egni i'n holl ddilynwyr ac aelodau clwstwr!

Congratulations to Dr Nathan Walker on his recent achievement

Nathan, from our Bangor University team, defended his PhD thesis successfully at his Viva on the 28th of May, passing with minor corrections.

His thesis, ‘Analysing the water-energy nexus: Benchmarking efficiency in water services’, explores and pushes the boundaries of how efficiency is measured via methodological testing and sustainability-focussed metric use. The thesis yielded four publications, which can be found on our website here: dwr-uisce.eu/peerreviewed

Looking back over his time during the PhD, Nathan commented, “I’ve loved the past few years, it was a real privilege to be able to research such interesting topics with such a talented team. From delivering academic outputs on sustainability performance assessment and water efficiency to developing my research skills, and meeting some incredible people along the way, the time has flown by.”

Nathan is continuing on the Dŵr Uisce project as a postdoctoral researcher where he will extend some research concepts developed during his PhD around efficiency analysis and benchmarking across various sectors.

Nathan would like to thank his supervisors, Dr Prysor Williams and Dr David Styles, his Viva committee, Professor Julia Patricia Gordon Jones (Chair), Professor Yener Altunbas (Internal Examiner), and Professor Gustaf Olsson (External Examiner), and the Dŵr Uisce Project funders, the European Regional Development Fund through the Interreg Ireland-Wales Cooperation Programme, for their diverse support.

How can households take climate action and help contribute to reducing greenhouse gas (GHG) emissions?

Aisha Bello- Dambatta and Roberta Bellini

It is clear that climate change is happening, and it is likely that most of us have already directly felt some of its impacts.

Flooding in London, August 2021 (BBC)

The extreme events like the recent catastrophic floods in central and western Europe, the wild fires raging in Canada and the western U.S. states, and in the entire Mediterranean region are projected to increase in both likelihood, frequency and magnitude in the future and will continue to do so unless we do something to limit emissions. And these are just a few of the extreme weather events that occured in this month alone!

Scientists warn in the recently published Intergovernmental Panel on Climate Change (IPCC) special report published of increasing extreme heatwaves, droughts, and flooding; and the real risk of the Paris Agreement to limit global warming to well below 1.5°C above pre-industrial level being broken in just over a decade.

The UN Secretary-General calls this report a “Code Red for Humanity”, stressing the overwhelming evidence of human influence on GHG emissions.

We all have a role to play in helping avoid exceeding the 1.5°C threshold, but we must all act immediately and ambitiously to slow the accelerated warming of recent decades.

Wild fires in the Mediterranean (Reuters, August 2021)

So, how can Irish households reduce their energy consumption and help Ireland reduce its emissions?

We can start taking immediate action right now in our homes. One way to do this is through water use efficiency. This is because water production, treatment, and distribution is highly energy intensive, and on average between 2 – 3% of the world’s energy use is used to treat water to potable quality, deliver it to consumers, and to process and dispose of wastewater. In Ireland for example, Irish Water is the biggest electricity consumer. However, this consumption represents only a portion of total water-related energy use, with the majority attributed to water use – particularly for hot water use and space heating in buildings. Recent research from Trinity College Dublin estimates up to 86% of household energy use can be attributed to water use. Click on the infographic below for more insights and tips!

GET INVOLVED! We have launched a Citizen Science project on Household Water-Energy Efficiency as a call to action for Irish households to take climate action through water-energy efficiency at home. Our main aim is to engage and collaborate with the public in improving our understanding of, in the first instance, the public perception of water and energy use at home, how they relate, and the most effective means of improving the efficiency of both water and energy use at home.

On August 23rd 2021 two of our team members, Roberta Bellini and Nilki Aluthge Dona, met with the first participating community group for an informal presentation about Dŵr Uisce and the water-energy nexus, the citizen science project and the survey. Residents of Kilcronan Court in Clondalkin (Co. Dublin), part of Co-Operative Housing Ireland, had a lot to share and a lively discussion covered many different issues such as carbon footprint, water scarcity, water quality, plastic packaging, fast-fashion and more. Guided through an idea storming session, they quickly realised how all these issues are interconnected and complex to solve. It was uplifting to experience their positive outlook and eagerness to do more. All participants had ideas about how to save water and energy; they also shared what they are already doing in their households and community. Inputs about the need water and energy businesses, food producers, and supermarket chains to step up to the challenge and offer more sustainable options that can be afforded also by lower income families were those with the highest consensus. When invited to play a quick game to guess the amount of water needed to carry out a number of activities, they all took on the challenge. Many were surprised by the amount of water used in a power shower for 5 minutes and when doing the math for the weekly and monthly amount pledge to shower less… or not to shower at all!

We take this opportunity to thank the residents of Kilcronan Court for their engagement. They have set the agenda for our next interaction with the wider community.

We hope that more communities will participate in the initiative and we are available to organise a similar event (in person or online) in you community.

The survey part of the project launches in early September 2021 and will be open until 31 October 2021. More details soon!

For more information and to get involved, you can contact Aisha at the following email address: a.bellodambatta@bangor.ac.uk.

Learning from international wastewater treatment energy benchmarking

Nathan Walker

The team have conducted an international energy efficiency benchmarking exercise on wastewater treatment. The results showed that EU states have the highest electricity intensity (kWh/m3) seemingly due to higher wastewater effluent standards however, the impacts on greenhouse gas emissions are widely varied depending on individual country fuel mixes. These findings inform future research by suggesting improvements around data reporting and sharing, particularly influent vs effluent, and gross vs. net energy consumption data.

The collection, treatment and disposal of wastewater is a significant consumer of energy, with estimates suggesting that more than 2% of the world’s electrical energy is used for water supply and wastewater treatment (Olsson, 2015). Kenway et al. (2019) report that wastewater treatment plants (WWTPs) can consume over 20% of electrical consumption within municipalities. Reducing the energy consumption of wastewater management is integral to efficient resource use within a circular economy and to reduce greenhouse gas (GHG) emissions.

This task is more difficult considering WWTP electricity demand within developed countries is expected to increase by over 20% in the next 15 years as controls on wastewater become more stringent (Wang et al., 2012; Hao et al., 2015); with the same trend expected in developing countries as wastewater quality becomes a greater priority (Lopes et al., 2020).

A valuable tool for improving wastewater energy intensity amongst water companies is benchmarking. By utilising key performance indicators, it is possible to find the optimal performers and evaluate companies against similar entities or standardised values (Torregrossa et al., 2016). By doing this, companies can identify and prioritise areas for improvement and learn from best practices (Walker et al., 2021).

We conducted an international benchmarking exercise on wastewater energy intensity, measured in kWh/m3, in attempt to understand who the best performers are and the reasons behind their performance. The core sample included 321 companies from 31 countries, however, to analyse regional differences, 11 countries from an external sample made up of various studies of WWTPs was also used in places (Figure 1).

Figure 1. Energy intensity (kWh/m3) and associated greenhouse gas emissions (kgCO2e/m3), stiped bars are from external data sets (individual, treatment plant studies).

EU states had the largest average kWh/m3 with 1.18, which appeared a result of the higher wastewater effluent standards of the region. This was supported by Denmark being the second largest average consuming country (1.35 kWh/m3), since it has some of strictest effluent standards in the world. All other regions averaged much lower, ranging between 0.58-0.64 kWh/m3, apart from Russia and the former states of the Soviet Union who averaged 0.82 kWh/m3. This appeared to be a symptom of the energy data being gross consumption (as opposed to net) and there being a disparity between wastewater quality standards, since energy production at WWTPs was not captured and the lowest energy consumers had some of the worst standards, and vice versa. It is expected that as regions with lower effluent standards improve to similar levels of advanced economies, their energy consumption will increase too.

The influence of energy consumption on GHG emissions was diverse owing to interaction with widely differing emission intensities of grid electricity: Poland had the highest carbon footprint with 0.91 kgCO2e/m3, whilst Norway emitted just 0.013 kgCO2e per cubic meter of, despite consuming 0.60 kWh/m3, showing the importance of energy intensity on particular infrastructures. Although this study provided some valuable quantifiable results, the conclusions stemming from the limitations of carrying out the benchmarking exercise are just as crucial.

There is a lack of quantity, quality, and granularity in existing global wastewater data, making it difficult to fully analyse the impact and potential paths to improve wastewater treatment. A lack of data generally leads to a lack of representativeness of certain regions, skewing comparisons with limited sample sizes.

The two changes that would have the most significant impact for future analyses are to have influent vs. effluent quality and net energy consumption data, which would increase the accuracy of studies, circumnavigating varying legislative effluent standards and compliance rates.

References

Hao X, Liu R, Huang X (2015) ‘Evaluation of the potential for operating carbon neutral WWTPs in China’. Water Res. 87, pp. 424–431. https://doi.org/10.1016/j.watres.2015.05.050

Kenway, S.J.; Lam, K.L.; Stokes-Draut, J.; Twomey, K.S.; Binks, A.N.; Bors, J.; Head, B.; Olsson, G.; McMahon, J.E. (2019). Defining water-related energy for global comparison, clearer communication, and sharper policy. J. Clean. Prod. 236, 117502.

Lopes, T. A. S., Queiroz, L. M., Torres, E. A. and Kiperstok, A. (2020) ‘Low complexity wastewater treatment process in developing countries: A LCA approach to evaluate environmental gains’, Sci. Total Environ. 720, 137593. doi: doi.org/10.1016/j.scitotenv.2020.137593

Olsson, G. 2015. Water and energy: threats and opportunities, second ed. London: IWA Publishing.

Torregrossa, D., Schutz, G., Cornelissen, A., Hernández-Sancho, F. & Hansen, J. (2016) Energy saving in WWTP: daily benchmarking under uncertainty and data availability limitations. Environ Res, 148, pp. 330–337.

Walker, N. L., Styles, D., Gallagher, J. Williams, A. P. (2021) ‘Aligning efficiency benchmarking with sustainable outcomes in the United Kingdom water sector’, J. Environ. Manag., 287, pp. 112317. doi: 10.1016/j.jenvman.2021.112317

Wang, X., Liu, J., Ren, N-Q., Yu, H-Q., Lee, D-J., and Guo, X. (2012) ‘Assessment of multiple sustainability demands for wastewater treatment alternatives: a refined evaluation scheme and case study’, Environ Sci Technol., 46(10), pp. 5542-5549. doi:10.1021/es300761x

The contribution of the water sector to the economy of Ireland and Wales

Annum Rafique

The water sector plays an integral role in the economy by providing clean and safe drinking water to households and businesses. They are responsible for collecting, storing, extracting, pumping, treating and distributing water and wastewater from homes and industry.

The water sector also contributes to the economy directly through the employment of individuals, taxes paid to the government, purchases made from other sectors, assets acquired and, indirectly, by providing water as a resource required by other industries.

The linkage between the water sector and the economy is considerable. When mapping the overall contribution of the water sector (in monetary terms) to a country's economy, we looked at all the possible impacts on the sector's economy.

The water sector contributes to the economy in three main ways:

1. Intermediate consumption (IC), which consists of the value of goods and services consumed by the water sector to produce their own output. It thus implies that by increasing intermediate consumption in the water sector, the water sector is purchasing or consuming more of the output of other sectors in the economy (electricity or chemicals, for example);

2. Employee compensations (EC), where the sector pays the salaries and wages of its employees. The income generated by the employees is then consumed in the economy through the purchase of goods and services as well as taxes payable to the government.

3. Fixed capital (FC), which implies acquiring fixed assets such as land, machinery and equipment, and capital acquired via loans for further investments. Thus, a rise in the consumption of fixed capital may imply that the water sector is expanding its infrastructure through additional investments.

We looked at those three contributors in Ireland and the Wales (UK) and how they have changed over time using data for the period 1985 to 2018 from Eurostat, to compare and contrast the water sectors in these two countries. Figures 1 and 2 illustrate the per capita amount of IC, EC and FC for Ireland (in €) and the UK (in €), respectively.

Figure 1: IC, EC and FC per capita for Ireland, 1995-2018 (Eurostat, 2021).

As shown in Figure 1, the overall per capita contribution of the water sector in Ireland rose from €84 in 1995 to €254 by 2009 but then declined to €124 by 2018. The decline sector's contribution was due to austerity measures introduced in Ireland in 2009 (McIntyre, 2014). The austerity measures introduced by the IMF had the most significant impact on IC and EC, which implies that the sector reduced its reliance on employees and purchases from other sectors. Over the years, IC has had a more prominent role in the Irish water sector than EC and FC.

Figure 2: IC, EC and FC per capita in the UK, 1995-2018 (Eurostat, 2021).

As opposed to the Irish water sector, the overall per capita contribution of the water sector in the UK remained relatively unchanged over the years ranging from €174 in 1995 to €167 by 2018 (Figure 2). The average annual growth rate of per capita contribution of the UK's water sector was less than 1%, which implies that the sector moves slowly. This may be because of the structure of the UK's water sector. Compared to Ireland, the UK privatised their water sector in 1989, leading to the creation of local monopolies where commercial and domestic users have no choice in their supplier. Since then, the sector is subjected to economic, environmental and quality regulations by a regulatory authority. This has allowed the individual water companies to reduce their control on the monopoly, which may have lead to inflated water prices (Pointon and Matthews, 2016; Ofwat, 2015). The overall per capita contribution of the water sector in the UK is higher than that in Ireland, implying that the water sector in the UK contributes more to their economy than the water sector in Ireland.

In terms of the water sector providing benefits to the economy, the water sector in the UK outperforms the water sector in Ireland. When comparing the two, studies have found that the UK's water sector has better water quality, wastewater treatment and customer services compared to the Irish water sector (GWI, 2018). Furthermore, the UK's water sector has fewer water losses due to leakage, faulty meters or unauthorised use than the water sector in Ireland (GWI, 2018). The water infrastructure in Ireland is 65 to 85 years old, compared to 36 years old European average, and so is in dire need of repairs and replacements (OECD, 2016).

Since individuals in Ireland do not pay directly for the water like individuals in the UK via water bills, there has been limited funding to improve infrastructure to reduce losses. Furthermore, the approach to control leakages also plays a vital role in reducing losses. Mainly, only reported leakages are repaired, and water utilities do not generally carry out any regular form of tests to monitor or control leakages. The UK water sector reports less leakage than the Irish water sector due to funding available for the water utilities to replace and repair supply pipes (GWI, 2018). It is possible to improve water services in Ireland by introducing water pricing, which may help to inject more capital into the sector. However, water pricing in Ireland has not been a popular opinion with their population in the past. Any government planning to introduce such policies may face serious opposition. For the Irish water sector to improve and become on par with the UK's water sector, continuous investments are required to improve their services and infrastructure.

References

Eurostat (2021) 'National accounts aggregates by industry (up to NACE A*64)'. (Accessed on 30/07/2021).

GWI (2018) International Comparisons of Water Sector Performance.

OECD (2016) Report on the Funding of Domestic Public Water Services in Ireland.

Ofwat (2015) The form of the price control for monopoly water and sewerage services in England and Wales - a discussion paper.

Pointon, C. and Matthews, K. (2016) 'Dynamic efficiency in the English and Welsh water and sewerage industry', Omega, 58, pp. 86-96

Climate Action through Water Efficiency: Dŵr Uisce Hackathon with young people from ECO-UNESCO

Roberta Bellini and Aisha Bello-Dambatta

Engaging young people during their summer break by sharing research findings while stimulating their creativity and fostering activism to combat climate change can sound like a day-dreaming objective. But when you put together over three hours passionate young people, enthusiastic academics and researchers, the outcome may positively surprise you: they can collaborate on practical solutions to raise awareness on the climate action potential of being more water efficient.

Last month, the Dŵr Uisce Team decided to host a Climate Action Hackathon aimed at young environmental activists from ECOUNESCO. Hackathons began as gatherings of data scientists, software developers, business people who worked collaboratively over a short period of time to produce a piece of software or hardware for a specific purpose. This format has proven very effective to drive innovation. In recent times, it has been used in many different fields to bring together citizens, academics, professionals and experts, to innovate and find solutions to pressing societal issues. Hackathons are inclusive, challenging, and a great opportunity for sharing knowledge, learning from others and feeling united on a common objective.

The Dŵr Uisce team designed and facilitated the Climate Action Hackathon to challenge young people aged 15-17 to explore the water-energy nexus. The objective was to find practical solutions to reduce water use; the associated energy required to provide, treat and use the water in society; and the amount of GHG emitted. In other words, it was a call to plan for climate action and raise awareness about the positive impacts of water-energy use efficiencies.

The event took place on June 29th and 30th 2021 as an online Microsoft Teams event. The one hour-long pre-event meeting on the first day was a briefing session to frame the problem. It was also an opportunity for the young participants to ask questions about the Dŵr Uisce project, interdisciplinary research, and the water-energy nexus. The Dŵr Uisce team members used polls to assess participant prior knowledge and understanding of the problem, of our project and their expectations from the event. The hackathon itself took place on Wednesday June 30th 2021. It was a highly paced event, with lively interaction, Q&A, feedback and, most of all, a fabulous outcome: great actionable ideas to encourage citizens to be more water efficient in their daily lives.

Two teams of young people took part to the event, and all the participants were involved actively in peer-education for sustainable development programmes with ECO-UNESCO.

They were familiar already with concepts such as climate action projects and how to plan for them. Both teams thought of developing an app as a tool to raise awareness about the importance of saving water, energy, money, and emissions; and to encourage citizens to adopt resource-efficient behaviours to take climate action.

The first team proposed the EireUisce app, which was imagined as linked to household water meters to help users to track their usage, get rewards for saving water and information about the importance of saving water in a climate action context. The young team proposed opportunities to incentivise communities to be more water efficient including setting up a competition, similar to Tidy Towns, to crown the most water efficient Irish town.

The second team proposed the Water Usage Rating app, which was based on the novel idea (for Ireland) of a water rating system for appliances and buildings. The objective was to make citizens aware of how much water is used in households by washing machines, garden tools and water fittings in buildings. The focus was on empowering citizens, as app users, to make resource-efficient choices.

All of the young participants worked energetically and displayed great skills and abilities in team working, critical thinking and in taking a holistic approach to problem solving. Both apps have huge potential to be further developed and the majority of the young participants were keen to take the ideas forward in collaboration with the Dŵr Uisce team. In truth, the Dŵr Uisce team was “blown away” by the outcome of the Hackathon. We all were impressed by the enthusiasm, skills and positive can-do attitude in evidence. As a result of attending the event, the young participants, as activists, felt that their understanding of water-energy efficiency and consequences on the climate crisis increased.

For the Dŵr Uisce team, the event was a success both for the level of engagement, the learning and awareness realised, and the link established with young people. They are now part of our network of stakeholders. From a science communication and educational point of view, the format of a hackathon was a great fit to our Dŵr Uisce project purpose as it delivered on a number of aspects: firstly it centred the focus of the event on the young participants rather than on the project; secondly it facilitated interaction and collaboration among young peers as well as with academic researchers and professors in an informal atmosphere; thirdly it gave us the opportunity to gauge the level of interest in what we do and how the Dŵr Uisce project work is understood and applied by a non-academic audience; and lastly it challenged participants’ creativity to come up with a practical solution in a short amount of time that could have far reaching impacts.

We are planning to roll out the Climate Action Hackathon to second level schools in Ireland and Wales, to reach out to more young people and raise awareness on the climate action potential linked to water-energy efficiency.

If you are interested in having your students participate in this, please contact Roberta Bellini bellinir@tcd.ie for more information.

We take this opportunity to thank Doireann and Dunchadh and all the young activists from ECO-UNESCO for their energetic participation.

Rethinking the analysis of future high flows in Wales

In the past few months, Richard, a postdoctoral researcher in our Bangor team, has been revisiting some analysis completed during his PhD with Dŵr Uisce. This work aims to improve our understanding of changes in the characteristics of high flow events in Wales under future climate change. It is important to understand such events, as very large streamflows can results in inundation and flooding, bringing economic and social costs, implications, and distress.

The analysis is based on the results of an extensive round of hydrological modelling completed for five catchments in Wales (Clwyd, Conwy, Dyfi, Teifi, Tywi) under a worst-case future climate change scenario (Representative Concentration Pathway 8.5 [RCP8.5]). Future climate scenarios were taken from the 2018 UK Climate Projections (UKCP18) data from the UK Met Office’s Hadley Centre, the most recent projections available. These were implemented at a daily timestep into the Soil and Water Assessment Tool (SWAT) hydrological model, in order to project future streamflows up to 2080.

Previous work focussed on analysis of change in the number of days per year and season where streamflow is greater than the 95th percentile value of the whole dataset, as well as change in seasonal and annual 1-day maximum flows. While these particular factors do give an indication of the future character of high flow days (frequency and severity respectively), it is not possible to take account of or characterise changes in prolonged high flow events, such as event severity and length. The graph in Figure 1 demonstrates the factors analysed in the original research, using an example dataset.

Figure 1. Example of previous analysis factors.

In order to better characterise high flow events observed in future streamflow projections, as opposed to just high flow days as previously studied, it is first necessary to separate one event from another, so that each event is hydrological independent. To do this, the method of baseflow separation was adopted, whereby the digital filter method is first applied to the streamflow timeseries to separate the baseflow (shown by the red line in Figure 2) from the overall streamflow (shown by the blue line). Following this, individual events with at least one day of flow above the dataset 95th percentile value can be identified, with the length of these being defined as starting when streamflow rises above baseflow levels and ending when the two are equal again (highlighted in Figure 2). This method therefore allows for the identification of multi-peak events, and marks a distinction from the previous analysis by not conflating an increased number of high flow days, with an increased number of high flow events, as the former maybe a product of longer and more severe events, rather than a larger number of events. By identifying individual events, it is therefore possible to gain a better understanding of how high flow events are changing. Changes in the frequency of high flow events, for example, can be calculated by totalling the number of individual events each year and season, and changes in the duration of events can be computed by taking the mean number of days between event start and end. Changes in the severity of events can also be studied, in two ways in fact, first, by calculation of the number of days per event where streamflow peaks above the dataset 95th percentile, and second, as in the previous analysis, 1-day maximum flow. Figure 2 provides a visualisation of the factors analysed, following the new methodology.

Figure 2. Example of the new analysis factors.

Figure 3. Seasonal and annual Mann-Kendall trend analysis results for Welsh study catchments.

As can be seen, the new analysis has the potential to provide a much clearer picture of changes in the severity, frequency, and duration of future high flow events. Indeed, the results of a Mann-Kendall trend analysis of this work (Figure 3) suggest that over the study period (2021-2080) several changes are projected, with varying patterns seen both between seasons and catchments. One of the clearest trends, with most agreement between catchments, is an increase in the severity (maximum flows) and frequency (number of high flow events) of high flow events in the winter and spring seasons. The least change is seen in the mean high flow event duration, with it generally decreasing across all seasons and annually, but only to a relatively small degree, and with the least statistical significance of all of the factors presented. As can be seen in all three factors presented, seasonal change is generally more substantial and significant than annual change, with large seasonal shifts often cancelling each other out in the annual picture. No statistically significant trends were found in the analysis of number of peaks above the 95th percentile per event, these results are therefore not included in Figure 3.

The results of this analysis have important implications for a variety of sectors, indeed anyone who abstracts from river systems or relies on their flow for other means could be impacted, as well as communities or individuals at risk of flooding. In terms of water resource use, hydropower operators in particular could be affected by the results presented, with two of the three catchments displaying declines in annual maximum flows. In addition, the increases seen in spring in terms of maximum flow volumes, and number of events, could also be worrisome for flood planners, as this has important implication for mitigation plans and measures. The impacts of changing high flow and flood events have far reaching consequences, it is for this reason that getting the best characterisation of future changes is important and is why this analysis has been strengthened.

We are grateful to Professor Neil Macdonald of the University of Liverpool for his suggestions for strengthening the analysis conducted. The improved analysis has been included in an article submitted to the Hydrological Sciences Journal and greatly enhances the results of this paper. Look out for news of this publication later this year, both here on our website, as well as on the Dŵr Uisce Twitter feed, @Dwr_Uisce.

Spreading the word to the future generation: Water-Energy webinars with the children of Rathnure Primary School, Co. Wexford (Ireland)

Roberta Bellini

Sharing research findings with the wider public is one of the objectives of the Dŵr Uisce project. In particular, engaging youth in activities that are educational but at the same time interactive, fun and stimulating, offers the opportunity to explore environmental issues and to appreciate innovative solutions. Furthermore, using a place-based learning approach in designing learning events, learners can connect the different topics and themes to their locality from an environmental, geographical and historical point of view. Embracing this educational challenge, the Dŵr Uisce Team, in collaboration with Blackstairs Group Water Scheme (GWS), looked at ways of presenting the recently installed pump-as-turbine (PAT) system at an age appropriate level to which the children could relate and link to their own lives and experiences.

 Following installation of an innovative pump-as-turbine energy recovery system at Blackstairs GWS, the Dŵr Uisce team had planned to organise in-school workshops and  site visits to the water treatment plant (WTP) for all three local primary schools served by the scheme: Rathnure National School, Caim National School and Donard National School. However, COVID-19 restrictions intervened. Undeterred, the team, in collaboration with Blackstairs GWS and local teachers, designed and delivered an online experience for primary school pupils. On May 31st 2021, the first three webinars were delivered to children of 4th, 5th and 6th class in Rathnure National School, Co. Wexford (Ireland).

 The webinars explored the water cycle, the water-energy nexus, the history and technical details of the Blackstairs GWS, and the innovative role of the pump-as -turbine system. To compensate for not physically seeing the WTP and for the lack of in-person interaction, each webinar included some fun and engaging activities and visualisation tools to help the children to connect with their locality, reflect on their water use behaviour and its consequences on the current climate crisis.

 Dr. Roberta Bellini, a Trinity-based team member, introduced the webinar ‘THINK WATER = THINK ENERGY’ and the Dŵr Uisce project. Dr. Bellini facilitated a group activity looking at what actions using water the children had carried out in the past 24hrs to immerse the children in the topic. To bridge with the second part of the presentation, the children were guided through the natural water cycle using an enquiry learning approach.

 From here, Ms. Dympna Skelton, Manager at Blackstairs GWS, presented an overview of the history of the Scheme, its geographical layout and its technical details such as pipe network, water treatment process and metering, and of the approach to climate action taken by the Scheme’s board of management. In particular, Ms. Skelton noted the collaboration between Blackstairs GWS and EPS, the WTP operator, to donate the financial savings arising from the Dŵr Uisce energy recovery system to the Wells of Life Ireland charity providing drinking water wells to rural communities in Uganda.

Figure 1: Ms Skelton presenting the Blackstairs Group Water schemes to the children in Rathnure Primary School

 To replace the site visit, pictures of the WTP were used throughout. A simple but very effective Google Earth image illustrated the hydrological contribution zone, pipes and other elements of the network in relation to the Rathnure school (Figure 2). When an image of a cartographic map of the network was presented, the children were able to position local places in relation to pipes, tanks and the whole network. The children were tasked to trace the pipes carrying water from the WTP to the schools in the area on a simplified map. Finally, they were encouraged to reflect on the need for energy to perform the different activities they had listed at the start of the webinar through a discussion and a group  activity.

Figure 2: Google Earth project showing the Blackstairs Mountain, some of the BGWS features and Rathnure N. S.

 To illustrate the part played by Blackstairs GWS in climate action, Ms Skelton invited to Dr. Daniele Novara, a Trinity-based Dŵr Uisce team member, to discuss the innovation enabling the carbon footprint reduction of the water treatment operation. Dr. Novara explained the underlying principles and technical details of the PAT-based energy recovery system, using diagrams and a picture of the actual PAT in place in Blackstairs. He concluded with the environmental and monetary saving realised by the scheme, highlighting the positive local and global impacts. The children came to understand how the monetary savings of the first 12 months of operation of the PAT-based system arose and were donated to Wells of Life Ireland. They were proud of the socially-responsible connection between their local community and another in Uganda.

 The children were wonderfully curious as they engaged in the webinar. They asked highly pertinent and detailed questions including the dimensions and costs of the PAT system, the length of time required from ideation to implementation, and the replicability of the scheme elsewhere. They were curious to know if there were other PAT systems in water networks in Ireland and, on learning that Blackstairs GWS currently operates the only one, it sparked in the most entrepreneurial children the idea for a potential tourist attraction!

 Feedback from children and their teachers has been extremely positive: they praised the group activities and the use of maps and aerial views for stimulating learning, critical thinking and creating a link with the local area.

 The Dŵr Uisce Team thoroughly enjoyed the engagement experience and we hope to deliver the webinar in two other local schools in the near future.