Energy storage

As demand for energy grows globally, energy storage technologies are of increasing importance to ensure the security and reliability of supply. This is especially true as exploitation of renewable energy sources increases. Energy storage technologies can be used as a buffer between generation and consumption, thus mitigating the unpredictability and intermittency associated with many renewable sources.

There are several ways in which energy can be stored for later consumption. These include electrochemical storage, as in the case of batteries, hydrogen for use in fuel cells, and thermal energy storage.

Key Contact: Dr Xiaohong Li

Current projects

Zinc-Nickel redox flow battery (RFB)

RFBs utilize one or more redox couples to store energy in electrochemical form. Existing RFB systems, such as Vanadium and Zinc-Bromide, are complex and expensive, largely due to the employment of costly ion exchange membranes in the cells.

Our current research in this area is focused on the development of a membrane-free RFB system utilising a Zinc negative electrode and a Nickel positive electrode. In partnership with Imperial College London and the University of Warwick, the EPSRC funded research project Zinc-Nickel Redox Flow Battery for Energy Storage aims to improve the efficiency and performance of this system.

The focus of the project is on the control of electrodeposited zinc morphology, structure and material of the nickel electrode, optimisation of electrolyte flow regime and overall cell and battery design. This will allow the technology to be scaled up for grid applications in an efficient and cost effective manner, ultimately benefiting power producers, industry and domestic consumers.

Contact: Dr Kaipei Qui and David Trudgeon

Development of the oxygen electrode for alkaline systems

Oxygen electrodes have a major role in energy storage applications. They assist in hydrogen production in water electrolysers, transportation and power generation in fuel cells and large-scale energy storage in metal-air secondary batteries.

These applications face the demand for improved performance (i.e. durability, lifetime, efficiency, cost) for widespread commercialisation. In order to overcome the technical obstacles that hinder performance, low-cost, robust and viable oxygen electrodes must be developed for effective utilisation of both oxygen reduction and oxygen evolution reactions.

Since the rates of the oxygen electrochemical reactions are quite slow, efficient electrocatalysts are highly sought after to help speed up these rates to a practical level. Current research in the group focuses on the synthesis and characterisation of electrocatalysts such as metal oxides to relate their physiochemical properties to electrochemical activity. The understanding of this relationship can then be used to enhance performance.

Contact: Adeline Loh

Hydrogen production by alkaline SPE eectrolysers

Hydrogen is expected to play a key role in meeting the need for clean fuel for both energy storage and transport purposes. Electrolysis of water is a clean method of producing hydrogen fuel. Currently, existing electrolysis plants operate at low current densities (around 0.25 A/cm2) and can only achieve energy efficiencies of around 60%. Acidic solid polymer electrolyte (SPE) systems demonstrate a substantial increase in efficiency and are commercially available in small units, but are expensive.

Our research aims to develop alkaline SPE electrolysers which utilise non-precious metal catalysts and give lower overpotentials for oxygen evolution compared to acidic systems, whilst maintaining improved efficiency.

The focus of the work is on developing efficient, stable catalysts for both the anode and cathode, fabricating the nanostructures of the chosen catalysts to maximise active surface area, selecting suitable corrosion-resistant substrates, membrane development and design of the cell. Ultimately, alkaline SPE electrolysers can lead to cheaper hydrogen production.

Enhanced phase change material for temperature regulation of concentrating photovoltaic systems

Phase change materials (PCMs), used as latent heat thermal energy storage with concentrated photovoltaic (CPV) systems could increase the overall system efficiency by two means. Firstly, by acting as a heat sink for dissipating heat, thus reducing the CPV module temperature and improving overall CPV efficiency. Secondly, by acting as a heat storage system for the CPV tandem thermal devices (such as hot water, solar air heating, space heating and agricultural usage), thereby increasing the overall system efficiency.

Although PCMs are well known for their high heat storage density, the most commonly used organic PCMs exhibit lower thermal conductivity, a drawback which ought to be overcome by addition of a carefully selected nanomaterial.

Contact: Shivangi Sharma

Demonstration of community-wide renewable energy scheme

This research aims to demonstrate the feasibility of community-based renewable energy schemes. By the utilisation of renewable energy sources and thermal energy storage in a dedicated hot water tank it is hoped that 3,500 new homes can be supplied with clean, sustainable heat.

If successful, this could prove the potential of renewables-driven community energy schemes and pave the way for similar projects around the UK.