Pressure Reducing Valves (PRV) have been widely used as a device to control pressure at nodes in water distribution networks and thus reduce leakages. However, an energy dissipation takes place during PRV operation. Thus, micro-hydropower turbines and, more precisely, Pump As Turbines (PAT) could be used as both leakage control and energy generating devices, thus contributing to a more sustainable water supply network. Studies providing clear guidelines for the determination of the most cost-effective device (PRV or PAT) analysing a wide database and considering all the costs involved, the water saving and the eventual power generation, have not been carried out to date. A model to determine the most cost-effective device has been developed, taking into account the Net Present Value (NPV). The model has been applied to two case studies: A database with 156 PRVs sites located in the UK; and a rural water supply network in Ireland with three PRVs. The application of the model showed that although the investment cost associated to the PRV installation is lower in the majority of cases, the NPV over the lifespan of the PAT is higher than the NPV associated with the PRV operation. Furthermore, the ratio between the NPV and the water saved over the lifespan of the PAT/PRV also offered higher values (from 6% to 29%) for the PAT installation, making PATs a more cost-effective and more sustainable means of pressure control in water distribution networks. Finally, the development of less expensive turbines and/or PATs adapted to work under different flow-head conditions will tip the balance toward the installation of these devices even further.

Despite the existence of a vast scientific literature on the subject of hydraulic energy recovery from water pipelines by means of micro- and pico-hydropower using pumps as turbines (PAT), such technology has found a very limited application thus far in practice. In fact, the selection of a pump as turbine for a specific site is a matter of nontrivial trade-offs between a variety of technical and economic parameters and this aspect has not been sufficiently captured and integrated into a reliable, proven, and practical selection methodology available to designers and practitioners. Hence, a multi-objective PAT selection software was developed and utilized to design a 3 kW energy recovery installation at a rural Irish water network. The performance of the scheme was monitored over 13 consecutive months, resulting in the generation of nearly 16,000 kWh of electricity and validating the output from the PAT selection software.

Pumps As Turbines (PATs) are a class of unconventional hydraulic turbines consisting of standard water pumps working in reverse mode as the prime mover. Such devices can be well suited for either in-pipe energy recovery or small-scale hydropower, but their practical application is hampered by the lack of comprehensive guidelines able to assist the designer in the determination of the optimal plant layout and the choice of equipment. In fact, the performances of a PAT will depend on factors such as its construction type, its size and the flow conditions under which the machine is expected to operate. Ultimately, the design of a PAT-based hydro scheme is a matter of trade-offs which are in most cases not trivial. An innovative software was developed in order to assist hydro designers and provide a visual aid when choosing between different layouts of the analyzed hydro scheme (e.g., more than one PAT in series/parallel, different shaft speeds), and has been applied to a real case study of energy recovery in a water network.

The global water crisis, an enormous concern according to the World Economic Forum, poses a significant challenge to long-term sustainability, exacerbated by the high energy demand associated with water supply and treatment. As the renewable energy sector grows, the need for green technologies to support the water-energy nexus becomes evident. However, mere technological advancements are insufficient to address complex water-related challenges. This paper presents a transdisciplinary collaborative effort involving engineers, geographers, management researchers, and environmentalists working with practitioners in a cross-border network. The study explores through action learning research how, in a transdisciplinary partnership, network action learning influences the exploration and implementation of novel green technology and the development of innovation capabilities. The research is structured around three themes: green technology platforms, policy support and guidance, and dissemination and collaboration. It identifies the factors impacting technology exploration and application and how concurrently green innovation capabilities are developed. The study emphasizes the significance of transdisciplinary collaboration and offers valuable insights into addressing UN Sustainability Goals related to clean water, sustainable industry, and partnerships. It contributes to innovation capability theory and provides practical guidance to researchers, practitioners, and policymakers, emphasizing the need for holistic approaches to address the water-energy crisis and achieve sustainable development.

REDAWN project will foster the adoption of hydropower energy recovery technology in built water networks in the Atlantic Area (AA). REDAWN will develop an adequate institutional, social and technological environment to foster greater resource efficiency in water networks. Pumps working as turbines (PAT) and other converters (wheels) became attractive to improve the water sector energy efficiency. However, the behavior of these devices are complex and it is difficult know its behavior. To overcome this problem, computational fluid dynamics (CFD) models were used in conjunction with the conceptualization and laboratory tests to explore its performance. Different modes were tested and simulated: single PAT mode and in parallel in pressurized pipe systems and a wheel in an open channel flow.