Oxfordshire County Library – a potential battery

This trial aims to learn if it’s possible to use buildings as batteries to provide flexibility to the electricity network.

Background

Project LEO is investigating how buildings can be used as batteries to provide flexibility in a low carbon future. LEO partners, Oxfordshire County Council and the University of Oxford, are working together to test this technology at the Oxfordshire County Library. The Library is the main public library in central Oxford and holds over 500,000 items available for loan. The Library is owned and run by Oxfordshire County Council.

This building is of particular interest to LEO as libraries tend to have relatively low, non-critical, uniform use throughout the week and as such, presents an ideal environment for testing the provision of flexibility services. Secondly, a library, through the very nature of the building and its contents, has a high thermal inertia (acting as a heat battery) which affords the building internal resistance to temperature and air-specific changes. This presents the potential opportunity for providing flexibility with minimal disruption to the building’s services and users. 

Aim of the trial

We are running MVS trials at the Oxfordshire County Library, testing how a building can provide flexibility to the electricity network by altering the time of use of electricity (by changing the demand for air conditioning) within the building. The trials will explore and unlock the potential of the building to play a part in delivering flexible energy. 

The core idea is to temporarily shift (or modulate) the use of air conditioning, for example, making sure that demand does not occur at times when the grid is congested. Coordinating this operation to make use of the buildings thermal mass, even if the chiller is switched off in the summer, the temperature inside the building should not rise immediately due to the energy stored within the walls and contents of the building. 

Switching off the air conditioning can bring about a large reduction in the electricity consumed by the building. This contributes to relieving the stress on the electricity grid, helping to maintain stability of the network in a way that removes or delays the need for network upgrades. 

What we hope to do

Through the trials being conducted on this building, we hope to increase our understanding of just how much flexibility this building – and others alike – could provide the electricity network with. The trials will allow the team to develop a business case for enabling similar assets to provide a flex market services. 

Initial trials are also trying to understand the amount of data, metering and monitoring required throughout the building in order for any potential flexibility service to be appropriately managed and validated. 

The team also hope to learn if altering the temperature set points of the building will affect building users and if so, understand the upper and lower limits of any temperature changes to minimise impact on users whilst still being able to provide a flexibility service.

How the trial works?

The trials undertaken at the Library will involve a series of tests which turn up and down the energy demand of the building through either changing the temperature set point (increasing/decreasing air conditioning use), or fully deferring the air conditioning load for some time intervals during the day. 

The team have collected data from the Building Management System (BMS) as well as from additional ad-hoc prepared temperature and electrical load sensors to understand patterns of energy use of the building and to synthesise and validate a theoretical building model to be use in the optimisation of the flexibility service delivery. 

Who is involved?

Oxford University is running this trial with the support of Oxfordshire County Council. 

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.

Background

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.

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.