Project: Knoydart SLIQ Battery
Technology: Single liquid flow battery (SLIQ)
Location: Knoydart, Highlands
CARES funding: CARES Infrastructure and Innovation Fund £64,000
Partners: StorTera
Date installed: April 2017

Background

Knoydart is a remote peninsula on the west coast of Scotland with no road link – the only way of accessing the area is by foot or boat. Knoydart Renewables own and operate a 300kw hydro-electric system which supplies electricity – with diesel generators as back up – to Inverie, the main settlement. There is no connection to the national power grid and the system generates most of the village’s energy requirements.

Demand on the generator depends on the weather and seasonal needs, meaning Inverie can experience power outages when the electricity demand outstrips supply. Conversely, the hydro-turbine can also be underused during off-peak hours.

Every two weeks, diesel generators are used to maintain the hydro-electric system which disrupts to the community’s electricity supply as the system must be switched off for the generator to be used.

Knoydart Renewables wanted to develop a solution to these issues, and a single liquid flow (SLIQ) battery was identified as a potential way forward. An 8kW/30kWh SLIQ battery demonstrator was installed as a pilot with help from CARES Innovation Grant funding.

Project Aims and Objectives

The long-term aim of this project was for 100% use of the electricity that was generated by the hydro.

Outcomes and achievements

The outcomes of the project are still being gathered and more up to date information is available on StorTera’s website. However, at the time of writing:

  • The SLIQ battery helped keep the diesel generator shut-off at night during a hydro pipe failure and in three other consecutive grid failures in 2017
  • The SLIQ battery powers the system at night during normal operations, avoiding the need for a diesel generator
  • There was a recorded a coulombic efficiency (the charge efficiency of electrons being transferred in batteries) of 93%.
  • In October 2017, more than 820kWh of electricity was exported.
  • The frequency response, stabilisation and backup functionality has all been successful.

Lessons learned

  • Long term technical performance of batteries and other trial technologies should be tracked, with a service or support contract offered to the community.
  • This pilot project helped prove the concept worked, and supported StorTera – the energy storage company – to deliver larger, more complex projects, as well as allowing Knoydart Renewables the opportunity to consider a commercial SLIQ battery to produce electrolyte to sell to nearby fish farms.