Sandford Hydro trials

How can we store electricity generated by the hydro?

This trial is looking to see if we can use the river as energy storage and provide flexibility to the energy network.


Sandford Hydro is a hydroelectric power plant on the River Thames near the village of Sandford, just south of Oxford. In 2016 Low Carbon Hub opened a community energy share offer and raised the funds to build Sandford Hydro. The hydro uses three Archimedes screws (similar to the one in operation at Osney Lock Hydro) to generate electricity from the flow of the river water.

Key Sandford Hydro facts

  • Fully commissioned in August 2017
  • 440kW installed capacity
  • 1.6GWh annual generation of clean electricity
  • 1.1 tonnes CO2 emissions prevented every day
  • 500+ households supplied with clean energy
  • Fish pass allows all species to travel up river for the first time in 400 years

Aim of the trial

Since the start of 2021, Low Carbon Hub Operations Manager, Harry Orchard, has been carrying out Minimum Viable System (MVS) trials at Sandford Hydro as part of Project LEO. The trials at Sandford will explore and unlock the potential of the hydro to play a part in delivering flexible energy. This means being able to increase or decrease energy generation or turning up and down energy demand.

A Minimum Viable System is the minimum set of participants, technologies and practices required to test a new process, service, or asset. Referred to as MVS trials, our experiments help us to explore how effectively flexibility services can be delivered and highlight the benefits these provide to the network and the trial participants and wider community.

The MVS process allows us to test the flexibility services in a step-by-step fashion, helping us to thoroughly understand what does and doesn’t work well. We can then review the process, ironing out the bugs before rolling out flexibility service participation to a wider audience.

What we hope to do & learn

We already know that energy storage will be a large part of how we use energy as a society in the future. The most obvious form of storage is a battery but using Sandford Hydro we are exploring a different way of storing energy for use at a later time – using the river. By slowing down one or more of the hydro’s screws, we can slowly build up a reserve of excess water upstream of the hydro, which can then be utilised to generate extra power when required by simply speeding the screw(s) up again.

The MVS trials that are taking place at Sandford Hydro largely consist of slowing down the screw(s) by a certain amount for a certain period of time, before speeding them up again, all the while measuring the impact on the hydro’s power output and the river level upstream. This allows us to measure how much energy can be stored in the river, and for how long we can use this additional power to provide flexibility services. With hydro generation being very seasonal (peaking in winter and lowest in summer), doing trials regularly throughout the year helps us to build up a picture of how best to utilise the hydro to maximise the benefit to the electricity network.

Who is involved?

These trials are managed by the Low Carbon Hub.