Energy storage costs: Are they really on the slide?

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We hear every day that the cost of storage is falling rapidly, with obvious implications for the prospects of renewable power generation. I accept that most of these statements are made in good faith, but some are clearly optimistic. Where can one find objective expert information about the cost of storage?

I was pleased to read a recent report (PDF, 12 MB) [1] from the Sandia National Laboratories that gives detailed information about the costs of various forms of storage. The Sandia Laboratories were originally formed for nuclear research and still have major involvement with nuclear weapons, but they also undertake other forms of research, including energy and climate. I would say Sandia has exceptionally high credibility.

The Sandia report is dated July 2013.  The authors first describe various uses of storage in the electricity system:

• bulk energy services (energy time-shift, supply capacity)
• ancillary services (regulation, spinning reserve, voltage support, black start, load following, frequency response)
• transmission infrastructure services (upgrade deferral, congestion relief)
• distribution infrastructure services (upgrade deferral)
• customer energy management services (power quality, power reliability, retail energy time-shift, demand charge management)

They then survey the actual cost of installed systems. In their words:

“More than 50 battery original equipment manufacturers (OEMs), power electronics system providers, and system integrators were surveyed and asked to provide performance, cost, and O&M data for energy systems they could offer for various uses of storage.”

Although some of the data comes from 2010 and 2011, all costs are expressed in 2012 USD.  The comprehensive cost estimates include:

• energy storage system (equipment, installation, enclosures)
• owner interconnection (equipment, installation, enclosures)
• packing and shipping
• utility connection (equipment, installation)
• Balance of Plant costs (civil engineering only)
• general contractor facilities
• engineering fees
• project contingency (@ 0-15% of install)
• process contingency (@ 0-15% of battery)

The Sandia report thus gives a snapshot of storage costs in the US, as best as could be done in mid-2013.  Different metrics are provided such as round trip efficiency, installed cost in $/kW or $/kWh, and LCOE in $/MWh.

The figure below was prepared from data sheets in Appendix B of the report.  It shows the initial installed capital cost in $/kWh for 19 different types of storage installations.  The technologies do not include thermal storage of energy as in Concentrated Solar Thermal installations.  I have also omitted results for flywheel storage, as this is so expensive as to be off-the-scale in the figure.

Initial capital cost for storage systems (2012 USD / kWh).  Categories described below.

The categories are:

1          greenfield pumped hydro (bulk storage)

2          compressed air energy storage (bulk storage)

3          Na-S (bulk storage, utility T&D)

4          Na-Ni-Cl (bulk storage, utility T&D, commercial and industrial)

5          Va-redox (bulk storage, utility T&D, commercial and industrial)

6          Fe-Cr (bulk storage, utility T&D, commercial and industrial)

7          Zn-Br (bulk storage, frequency regulation, utility T&D grid support)

8          Zn-Br (distributed storage, commercial and industrial)

9          Zn-Br (small residential)

10        Zn-air (bulk storage, utility T&D, commercial and industrial)

11        advanced Pb-acid (bulk storage)

12        advanced Pb-acid (frequency regulation)

13        advanced Pb-acid (utility T&D)

14        advanced Pb-acid (distributed storage)

15        advanced Pb-acid (commercial and industrial)

16        Li-ion (frequency regulation, renewables)

17        Li-ion (utility T&D grid support)

18        Li-ion (distributed storage)

19        Li-ion (commercial and industrial)
It is important to note that project lifetimes differ for the various technologies – it’s 60 years for pumped hydro, 40 years for compressed air energy storage and 15 years for all the battery technologies.

The initial capital costs for pumped hydro (Category 1) and compressed air energy storage (Category 2) are very good.  (Incidentally other energy storage metrics, particularly Energy Stored on Energy Invested, are also very good for pumped hydro and compressed air energy storage.)  Category 6 (Fe-Cr technology) has good results for installations dating back to 2011.  Results for Category 10 (Zn-air technology) seem good, but the report notes these are for systems that might be built in the future.

Lead-acid systems (Categories 11-15) were still cheaper than Li-ion systems (Categories 16-19) at the time the report was completed.  The flow batteries (Categories 5 and 7-9) give mixed results, which one imagines will be improved with further development.

Conclusion

According to the Sandia report, battery storage costs are still quite high when all costs and the project lifetimes (15 years) are taken into account.  Battery technology is clearly developing quickly, and I look forward to follow-up reports from Sandia or other sources.

Anthony Kitchener is thanked for mentioning this report to me.

Reference: [1] A.A. Akhil et al., “DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA”, Sandia Report SAND2013-5131 (July 2013).

This article was reprinted with permission from www.sunoba.blogspot.com