Energy Storage Technologies for Climate Change Mitigation

Dr. Sheridan Few, Research Associate in Mitigation Technologies

Oliver Schmidt, Greg Offer, Nigel Brandon, Jenny Nelson, Ajay Gambhir

Grantham Institute for Climate Change, Imperial College London, South Kensington Campus

Introduction

• What role could storage play in moving towards a low carbon energy system?

• What needs does the energy system have which can be fulfilled by storage?

• What energy storage technologies are available to meet these needs?

• What improvements in energy storage technologies can we expect in the next 5 – 15 years?

• What role can policy intervention play in supporting innovation in and deployment of energy storage technologies?

Literature Review

Establish background

on technologies

Technology Selection

Survey among UK

Energy Storage

Research Network to

identify most

promising technologies

Expert elicitation

Elicit predictions concerning

future developmen

t from technology

experts.

Energy System

ModellingUse elicited parameters as inputs to

energy systems models

Our approach

Importance of cost

Szabo S, Bodis K, Huld T, Moner-Girona M. Environ Res Lett. 2011; 034002(6).

Importance of cost

Sandwell et al., SOLMAT (accepted) 2016

a) LCUE and b) carbon intensity of a PV-storage-diesel hybrid system using c-Si andlithium-ion batteries meeting 100% of demand. White lines correspond to shortfall from the PV and storage system, which is now met by diesel generation.

The cheapest systems rely heavily on diesel power, and are among the most carbon intensive. Increasing the proportion of demand met by PV and storage yields lower specific emissions, provided the systems are correctly sized.

On an off-grid scale, which three electricity storage technologies could be the least expensive by 2030 for balancing intermittent renewables? (top) Number of respondents mentioning any technology in category, (bottom) total number of mentions of individual

technology

Academia Industry

Timescales for Innovation

Hanna, R.; Gross, R.; Speirs, J.; Heptonstall, P.; Gambhir, A. Assessment Innovation Timelines from Invention to Maturity. UKERC Technology Policy Assessment 2015.

Technology Innovation Pathways Schematic demonstrating the impact of policy and funding on technology development and costs.

Grubb, M. Keio Econ. Stud. 2004, 41 (2), 103–132.

Lead-acid Batteries

• Deployment Status Lead-acid batteries are the world’s most widely used battery type and have been commercially deployed since about 1890. It is estimated that in the USA alone more than 3,000 GWh of lead-acid batteries were produced as starter batteries for vehicles, back-up power supply or energy management systems.

• Why is it promising? Low capital costs (50 – 600 $/kWh), fast response times, low-self discharge, reasonable cycling efficiency (63 – 90%).

• What are its limitations? Relatively low cycling times (<2,000) and specific energy (25–50 Wh/kg) limit the applicability for grid-scale storage applications. Lead-acid batteries may also perform poorly at low temperatures. The usable capacity decreases at high power discharge or high depths of discharge due to the crystallization of lead sulphate.

• Possible Future Developments Material innovation could lead to performance improvements, such as extending cycling times and enhancing the deep discharge capability. Recent progress has only been incremental and may be best performed in an industrial context.

• Environmental Impact Lead is toxic and sulfuric acid is highly corrosive, requiring recycling and neutralization.

Redox Flow Batteries

• Deployment Status The US Department of Energy (DoE) identify a total of 20 MW/49 MWh of grid-connected VRB projects, and 1.0 MW/2.6MWh of ZnBr projects constructed worldwide.

• Why is it promising? Redox flow batteries have the potential to operate at a range of scales, including off-grid. The high cycle life of VRBs makes them promising in terms of cost for long-term applications.

• What are its limitations? Mass and volume densities are too low for mobile applications, capital costs remain higher than competing technologies.

• Possible Future Developments Fundamental scientific challenges remain in understanding flow and material behavior, understanding performance degradation, and selection of corrosion-resistant materials for pumps, pipes, etc.

• Environmental Impact High cycle life in vanadium-based systems could result in a relatively low impact over its lifetime. Vanadium exhibits modest toxicity to humans, the vanadium electrolyte does not degrade or require change over the lifetime of the battery, and will almost certainly be recycled to recover its valuable vanadium content (EPRI 2007).

Lithium-ion Batteries

• Deployment Status Relatively mature for consumer electronics, less mature for vehicles, and grid or off-grid stationary applications.

• Why is it promising? Lithium-ion batteries have relatively high cycle life, high volumetric and gravitational energy densities, making them suitable for vehicles. Costs of Li-ion batteries for EVs is decreasing rapidly.

• What are its limitations? Relatively high capital cost relative to incumbent lead-acid batteries, limited recyclability.

• Possible Future Developments Improvements in manufacturing procedures and basic chemistry could decrease cost and improve performance.

• Environmental Impact Relatively high cycle life could result in a relatively low impact over its lifetime. Remains could be toxic, and some controversy over possible cobalt and lithium scarcity, particularly if recycling procedures are not yet well-established.

Methods for estimating future costs

• Learning Rates/“learning by doing”• Bottom-up technology assessments• Expert Elicitation• Hybrid Approaches

Expert Elicitations on Battery Cost and Performance

• Catenacci et al. (2013) interviewed policy and battery technology experts to elicit estimates of EV battery costs in 2030, and the impact of increased R&D funding upon these (preceded by Baker et al., 2010).

Catenacci, M.; Verdolini, E.; Bosetti, V.; Fiorese, G. Energy Policy 2013, 61, 403–413.

Expert Elicitations on Battery Cost and Performance

• Implicit that R&D is the most important factor in driving cost reductions and performance improvement

• Sparse on technical details of innovations• Battery specifications are often vague• Numerical ranges are often wide

Bottom-up estimates• Cluzel and Douglas use a bottom-

up model for Li-ion EV battery costs, identifying historical, and possible future cost reductions.

• Future cost reductions are chiefly based upon:– Cathode improvements

(voltage, capacity)– Anode Improvements (voltage)– Scale-up (reductions in pack

component costs as a result of industrial learning processes, alongside reductions in labor and financing costs)

Cluzel, C.; Douglas, C., Element EnergyCost and Performance of EV Batteries; 2012.

Learning CurvesNykvist & Nilsson 2015 show recent cost history, and a range of future cost projections for Li-ion batteries in battery electric vehicles. These results demonstrate:• A significant level of

uncertainty in current and future costs.

• Estimated market leader costs below most 2020 projections.

• A cost reduction rate which would result in battery costs of market leaders and the industry as a whole meeting at $220/kWh in 2020.

Nykvist, B.; Nilsson, M. Nat. Clim. Chang. 2015, 5 (4), 329–332.

Expert Elicitation on future cost and technical perfomance of Lithium-ion batteries: Our methodology

Elicitation of percentile estimates of costs and technical parameters for a Li-ion off-grid PV balancing system with specific requirements (15kWh, 3hrs, <1C) in:• 2020 and 2030

As a result of:• Technical improvements from R&D (only)• Technical improvements from R&D + manufacturing scale-up

Subject to a range of R&D scenarios:• 1x, 2x, and 10x current funding

Experts sourced from academia, industry, and consultancy

Expert Elicitations: Emerging Conclusions

• Most experts anticipate commercial off-grid li-ion batteries meeting will have similar chemistries to those currently used in EVs in 2020, but manufacturing and pack design may improve.

• Some experts anticipate game changing commercial post Li-ion technologies (LiS, Na-ion) are conceivable by 2030 under higher R&D funding scenarios

Cost• Impacts from increased R&D funding are likely to be small by 2020, but could have a significant impact by

2030 as innovations from R&D transfer to industry.• R&D having an impact by 2020 could be focused on manufacturing methods and pack design, rather than

basic cell chemistry.• “Learning-by-doing” likely to be important up to 2020 and 2030.

Lifetime• A lot of potential for lifetime improvements expected through R&D, via electrolyte stability improvements,

better cell design, and better thermal management (perhaps less important off-grid)

Environmental Impact• Most technical experts invterviewed have little knowledge of embedded energy and recycling procedures for

Li-ion batteries, but agree this is an area in which R&D could have a large impact.

Expert Elicitations: Emerging ConclusionsTimescales• Spending R&D funding takes time• Filling positions can be challenging, and training takes time even if individuals with suitable expertise are

available.• Question of how much extra research funding allows one to explore: “Three mothers can’t make a baby in

three months”• Connectedness and ensuring effective communication between stakeholders could be more important

than funding.How to spend additional R&D funding?• Types and timescales of innovation may be very different depending on where R&D funding is spent –

fundamental research, or research into manufacturing methods/small changes, demo projects & pilot lines.

• Incremental changes vs. breakthroughs.• Scale up – Allowing greater learning and automation, and further down supply chain, but also extra capital

investment in new factories and facilities.Other emerging conclusions• Many Li-ion factories are operating at under-capacity. If demand increases significantly, cost reductions

associated with learning may be partly offset by new capital required to build factories.• Large factories may not be as willing to take risks with innovative manufacturing methods as smaller

facilities.• Contract length could be important in determining which technologies develop, and how.

Summary

• Energy storage could play an important role in balancing renewables and decarbonising the energy system.

• Cost is an important factor in determining the likely success of energy storage technologies.

• Off-grid storage technologies are likely to be electrochemical, but not entirely clear which type.

• By 2020, most improvements are likely to be through learning-by-doing, and R&D funding is likely to have little impact.

• Historical technology development timescales suggest that widespread storage technologies by 2030 are likely to be already invented/commercialised to some extent.

• R&D funding and deployment support are both likely to be important in developing technologies to 2030 and beyond.

Thank you!

• Thank you for listening!• Oliver Schmidt, Greg Offer, Nigel Brandon, Jenny Nelson, Ajay Gambhir• Alex Cheung, Alyssa Gilbert, and Anthony Kucernak for help in developing

the infographic.

• Joint workshop with SUPERSTORE project on UK Energy Storage roadmap, Imperial College, expected June 27th

• Forthcoming Grantham Briefing Paper on “Energy Storage for Climate Change Mitigation”