Electrical energy storage for mitigating climate change - Grantham Briefing Paper 20

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Authors: Dr Sheridan Few, Oliver Schmidt, Ajay Gambhir

Headlines:

• Academic and industrial experts agree that effective electrical energy storage will play a crucial role in moving to power the world with low-carbon electricity.
• Irrespective of the need to meet climate change targets, electrical energy storage technologies are essential to further enable the current rapid growth in renewable energy technologies, alongside other technologies to balance supply and demand.
• The electrical energy storage technologies that will be in use on a large scale within 5-15 years are likely to have already been invented, except if innovation and commercialisation radically speeds up over historical rates.
• Such technologies include: pumped hydropower, compressed air, thermal storage, electrolysis, aqueous batteries (e.g. lead-acid), non-aqueous batteries (e.g. lithium-ion, sodium-ion and lithium-sulphur), flow batteries (e.g vanadium redox flow, zinc bromide redox flow), power-to-gas, supercapacitors and flywheels.
• On many small islands and in remote communities, renewable electricity coupled with electrical energy storage is already the lowest cost option for electricity supply.
• Reliable clean electricity can be produced at a competitive cost through a grid powered by a high proportion of renewable energy coupled with electrical energy storage, and other technologies to balance supply and demand.
• Mechanical and thermal storage technologies, such as pumped hydropower, compressed air or thermal storage, require less energy to build and use less toxic materials than is typical for electrochemical technologies such as batteries, but are so far only widely used at a grid-scale.
• Electrochemical energy storage technologies are likely to do the majority of balancing supply and demand ‘off-grid’, and can play an important role in balancing on a grid.
• The environmental impact of an electrical energy storage technology relates to the energy, and scarce and toxic materials used in producing it, recycling procedures and how long the device lasts. Academia, industry and regulators should give greater consideration to each of these environmental impacts in directing fundamental and applied research, product development and deployment.
• Accelerating the development and deployment of electrical energy storage technologies will require further fundamental and applied research and development, support to encourage deployment, removal of policy barriers and improvements to market structures.

Introduction

Electrical energy storage technologies - an introduction

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Electrical energy storage devices are capable of storing electrical energy for use when supply fails to meet demand. These devices are likely to play an increased role in a future energy system, where a higher proportion of electrical energy is generated using intermittent renewable technologies, such as wind and solar. Electricity from these sources is generated intermittently and they cannot guarantee sufficient supply of electricity on demand by themselves.

There are a number of factors that make it challenging to plan how electrical energy storage can contribute to a reliable, clean future energy system. Firstly, electrical energy storage technologies have not been trialled on a sufficiently large scale. Secondly, there are a wide range of storage technologies, and for many of these the costs and technical characteristics are not yet well-defined. Finally, there is much uncertainty around the structure of the future energy system so it is challenging to make decisions around the role for electrical energy storage.

In this briefing paper, we explore the role that electrical energy storage technologies could play in supporting a cost-effective transition to an electricity system that emits a lower level of greenhouse gases – a so-called low-carbon electricity system. We then outline the specific technologies capable of filling this role. We consider the environmental impact of these technologies potential routes for short- and longer-term technological developments, and the role of policy in supporting both their development and deployment. We have not considered other forms of flexibility, such as demand-side management, increased interconnectivity and heat storage in detail in this report but they could also play an important role in a rapid and cost-effective transition to a low-carbon electricity system.

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Find out more

• Find out more about research into energy storage technologies at Imperial
• View all Grantham Briefing Papers and Notes