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Future cost and performance of water electrolysis: An expert elicitation study

The need for energy storage to balance intermittent and inflexible electricity supply with demand is driving interest in conversion of renewable electricity via electrolysis into a storable gas. But, high capital cost and uncertainty regarding future cost and performance improvements are barriers to investment in water electrolysis. Expert elicitations can support decision-making when data are sparse and their future development uncertain.

In this study we presents expert views on future capital cost, lifetime and efficiency for three electrolysis technologies: alkaline (AEC), proton exchange membrane (PEMEC) and solid oxide electrolysis cell (SOEC). Experts estimate that increased R&D funding can reduce capital costs by 0-24%, while production scale-up alone has an impact of 17-30%. System lifetimes may converge at around 60,000-90,000 hours and efficiency improvements will be negligible. In addition to innovations on the cell-level, experts highlight improved production methods to automate manufacturing and produce higher quality components. Research into SOECs with lower electrode polarisation resistance or zero-gap AECs could undermine the projected dominance of PEMEC systems.

This study thereby reduces barriers to investment in water electrolysis and shows how expert elicitations can help guide near-term investment, policy and research efforts to support the development of electrolysis for low-carbon energy systems. 

Figure - Elicited expert estimates for 2020 and 2030 capital costs without ( R&D) and with production scale-up (●RD&D) as a function of R&D funding (1x, 2x, 10x). Data points indicate 50th, uncertainty bars 90th and 10th percentile estimates. Expert C made 2020 estimates for AEC (R&D) or PEMEC (RD&D). Expert D made all estimates for AEC and PEMEC. Results are sorted by technology and in descending order for 50th percentiles without production scale-up ( R&D). 2016 reference values based on Table 1. No 2016 reference vales for SOEC as this technology is not yet widely commercialised.

Schmidt, O., Gambhir, A., Staffell, I., Hawkes, A., Nelson, J., Few, S. Future cost and performance of water electrolysis: An expert elicitation study. Int. J. Hydrogen Energy 42, 30470–30492 (2017). Publication

Prospective improvements in cost and cycle life of off-grid lithium-ion battery packs

This paper presents probabilistic estimates of the 2020 and 2030 cost and cycle life of lithium-ion battery (LiB) packs for off-grid stationary electricity storage made by leading battery experts from academia and industry, and insights on the role of public research and development (R&D) funding and other drivers in determining these.


By 2020, experts expect developments to arise chiefly through engineering, manufacturing and incremental chemistry changes, and expect additional R&D funding to have little impact on cost. By 2030, experts indicate that more fundamental chemistry changes are possible, particularly under higher R&D funding scenarios, but are not inevitable. Experts suggest that significant improvements in cycle life (eg. doubling or greater) are more achievable than in cost, particularly by 2020, and that R&D could play a greater role in driving these. Experts expressed some concern, but had relatively little knowledge, of the environmental impact of LiBs. Analysis is conducted of the implications of prospective LiB improvements for the competitiveness of solar photovoltaic + LiB systems for off-grid electrification.

Figure - Impact of increased R&D funding considering technical improvements alone and alongside other factors (OF), and an additional ten years of development from 2020 to 2030 on 50th percentile estimates of battery cost (academic and industrial experts aggregated). Median values for each percentile estimates with technical improvements alone under continued current funding are displayed, and median percentage reductions in cost as a result of each change are applied.

Few, S. et al. Prospective improvements in cost and cycle life of off-grid lithium-ion battery packs: An analysis informed by expert elicitations. Energy Policy 114, 578–590 (2018).  Publication

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