SubScrewHydro Project

Submersible Screw Pump-as-Turbines: a low-cost fish friendly solution for micro-hydropower (SubScrewHydro Project)

Project Team:

Principle Investigators:


  • Dr Miguel Crespo-Chacon Easy Hydro Ltd
  • Dr Miguel Crespo-Chacon (Easy Hydro Ltd)
  • Ms Sinead Hogan (University College Dublin)
  • Dr Malabika Basu (Technological University Dublin)
  • Dr John O’Sullivan (University College Dublin)
  • Prof. Paul Coughlan (Trinity Business School)

Trinity Researchers:

  • Mr Calvin Stephen

Funding Agency: 

Science Foundation Ireland






Hydropower, Environmental impacts



SubScrewHydro is a collaborative project between Trinity College Dublin (TCD), University College Dublin (UCD) and Easy Hydro Ltd aiming at addressing the challenge of reducing the cost and impact of barrier removal in river systems (weirs, dams, etc). The advancement of hydropower as a leading source of renewable energy is challenged by its impact on the environment including the potential harm it poses to fish populations. However, one way of easing the regulatory burden on new hydropower projects is by using existing river structures such as old weirs, dams or mills. This eliminates the need to install a new barrier where its pre-existing, and reduces the creation of new environmental impacts. However, the new Nature Restoration Law requires a significant amount of existing barriers to be removed fully or partially to help restore ecosystems. This impairs the potential for new hydropower projects using existing barriers.
The removal or modification of existing barriers in rivers is very costly with considerable social and environmental impacts of its own, including increasing the risks posed by invasive species. On average, the cost of removing a single barrier is estimated to range between €250,000- €500,000. 
There are over 73,000 existing barriers in Ireland and due to social opposition, environmental impacts and costs, full barrier removal is impractical in many cases. Therefore, barrier modification to open up routes for fish and sediment movement is the most viable option but the costs require innovation to increase feasibility. 

The design of a river barrier modification system forms the focus of the SubScrewHydro project. The primary objective of this work is the adaptation of a submersible centrifugal screw pumps to act in reverse and offering a capability to pump water and fish and to produce energy and allow fish passage in reverse. 

The work includes experimental and field assessments of fish friendliness of the technology, and the assessment of the available resource for the maximization of the technology impact. 
If successful the technology can then be installed across thousands of sites in Irish rivers contributing towards reconnecting rivers by providing a safe route for fish passage and downstream, and sediment movement, while generating renewable hydroelectricity for rural communities and end-users.


National Challenge Fund, Government of Ireland, SFI and EU logos