Project lead: Power Migration Partners Ltd

Local Energy Challenge Fund award amount: £24,750

Area: Highland

Executive summary

Power Migration Partners (PMP) has developed a novel flow battery energy storage system and are planning a full scale installation to solve the current problems of the Knoydart community.

At present the Knoydart electrical grid uses power from a hydro-electric power scheme (hydro scheme) and a diesel generator during peak hours, which has a high levelized cost of energy (LCOE). But the hydro scheme does not get fully utilized during off peak hours. Future demand increase will force Knoydart Renewables (KRL) to run the diesel generator at all times to avoid blackouts. But a suitably designed energy storage system will allow KRL to remove the diesel generator from operation by storing hydro power during off peak times and using stored energy during peak times. In addition, a grid tied Smart energy storage system can be used to provide grid stability.

A prototype flow battery was developed during this feasibility study. Load and generation profiles identified in the Knoydart energy feasibility study were used to build a scaled down test bed which can mimic the Knoydart power generation system and electric loads. The ELTUN prototype was tested using this test bed to confirm the functional compatibility. A programmable Xantrex power supply was used to mimic the generator and a resistive load bank controlled by MOSFETs was used as the load. Load and generation profiles were controlled by a LABVIEW interface. This setup proved that the ELTUN flow battery can stabilise the Knoydart grid.

As part of this feasibility study, PMP carried out a detailed analysis of the Knoydart power generation and distribution system considering increased future energy demand and availability of emergency power. The technical and financial analysis indicated that an energy storage system with 400 kWh of output energy capacity and 75 kW of output power would best suit the Knoydart micro-grid.

The information below shows a comparison of the calculated LCOE at present, if the future demand increase is provided by the hydro scheme and diesel generator and finally, if the future demand is provided by the hydro scheme and the ELTUN flow battery.

  • Present energy generation with hydro scheme and diesel generator: levelized cost of energy = 13.7p/kWh
  • Increased future demand with hydro scheme and diesel generator: levelized cost of energy = 16.3p/kWh
  • Increased future demand with hydro scheme and ELTUN flow battery: levelized cost of energy = 12.4p/kWh

The main benefits the Knoydart community would gain from adding the ELTUN flow battery to their micro-grid are:

  • reduction of LCOE
  • grid stabilization due to the quick response speed and two way communication ability of the smart flow battery system
  • avoid use of the expensive diesel generated power and use power generated by the hydro turbine during off peak hours
  • emergency backup power during a grid failure
  • reduced carbon emissions
  • opportunity to develop green tourism
  • future potential to use the flow battery liquid to power inland vehicles.

Read the final project report.