- Advanced Energy Storage 2026
- Annex A
Methodology
How the edition was made: methods, the model card, the evidence cut and its age, the acceptance record and the glossary.
Contents
- ·Edition home
- ·Executive summary
- 1Storage is grid infrastructure and a supply chain
- 2Key findings
- 3Systems and sectors at baseline
- 4Risks and capability
- 5Grid dependence on batteries while supply is restricted
- 6Readings from the other desks
- 7The 2027 agenda
- 8Systems in depth
- AMethodology
- A.1 Methods
- A.2 Model card, Energy storage System Model v0
- A.3 The baseline evidence cut
- A.4 Evidence age and coverage
- A.5 Evidence cards, two anchor sources
- A.6 Publication acceptance record
- A.7 Status words
- A.8 How the edition is made, released and corrected
- A.9 Glossary and abbreviations
- A.10 Technical annex
- BData appendix
- CReferences and record
- ·Complete edition, for print
A.1Methods
The global baseline uses published values and four simple derivations. Each is shown in full so that any reader can reproduce it.
| No. | Derivation | Calculation | Result |
|---|---|---|---|
| (1) | Battery storage added in 2024 implied by 40% growth | 108 ÷ 1.40 | ≈ 77 GW |
| (2) | Fall in installed cost, 2010 to 2025 | 1 − 140 ÷ 2,634 | about 95% |
| (3) | US utility-scale capacity at mid-2026 | 43.6 + 8.3 | ≈ 51.9 GW |
| (4) | US additions planned from the second half of 2026 to 2028 | 14 + 26 + 14 | 54 GW |
| Strength | Definition |
|---|---|
| STRONG | a disruption in the source system has historically changed the target system’s service or output within one season, in more than one region |
| MODERATE | an effect is documented but buffered or slower |
| WEAK | an effect is plausible but not documented at global scale |
| Label | Rule |
|---|---|
| Reported | value as issued by its source, with year |
| Inferred | reasoned from cited evidence; never a measurement |
| Estimated | Nexus analytical value with stated method |
| Scenario | conditional on stated assumptions |
| Expert input | structured editorial judgement awaiting evidence |
A.2Model card, Energy storage System Model v0
- Model ID
- MDL-XT16-STORAGE · v0.1
- Purpose
- represent advanced energy storage as infrastructure coupled to power systems, minerals, trade, finance, safety and recycling
- Family
- graph-based system of systems
- Inputs
- the cited sources of this edition; no proprietary data
- Method
- expert-specified coupling strengths (STRONG · MODERATE · WEAK) from assessments and analogue events
- Validation
- none yet, first validation against federation evidence in 2027
- Uncertainty
- qualitative; strengths are hypotheses, not measurements
- Domain of validity
- global scale; not for asset-, site- or country-level use
- Reproducibility
- strength table and sources published in this edition
20couplings
typed in v0
0strong
documented within one season
0moderate
documented, buffered
20weak
plausible, undocumented
A.3The baseline evidence cut
Every Nexus edition is published from a frozen evidence cut. The global baseline cut is documentary: it pins the exact edition of every source cited. Federation cuts begin with the first national Foundry cuts in 2027.
- Cut ID
- DC-XTECH-STORAGE-GLOBAL-2026-B0
- Type
- baseline documentary cut
- Resolution policy
- pinned · as of 30 September 2026
- Sources pinned
- 48 cited sources, each at the edition and access date in the references
- Model runs
- none at baseline, analytical values are stated with their method
- Digest
- computed at freeze and recorded in the publication record
- Supersedes
- nothing, first cut of the series
- Superseded by
- the 2027 energy storage annual cut
Lineage
- 01
source edition
- 02
pinned citation
- 03
finding
- 04
page
- 05
publication record
| Element | Baseline 2026 | 2027 global annual |
|---|---|---|
| Sources | cited global publications, pinned by edition | national, regional and sector cuts through one graph |
| Analysis | stated methods and editorial estimates | typed analysis specifications |
| Models | Energy storage System Model v0 specification | model runs with receipts |
| Findings | twelve baseline findings | findings re-bound to federation evidence |
| Review | five passes scheduled | five passes on the exact digest |
A.4Evidence age and coverage
A 2026 global edition rests on evidence observed in many different years. This page shows each time base, so that no single year label hides older evidence.
| Indicator | Observed | Released | Cadence | Next release |
|---|---|---|---|---|
| Deployment | 2025 | Global Energy Review 2026 | annual | next review |
| Installed cost | 2025 | IRENA July 2026 | annual | next cost report |
| US capacity | 2025 to 2026 | EIA August 2026 | periodic | next EIA note |
| Lithium and cobalt | 2025 | USGS 2026 summaries | annual | next summaries |
| Critical minerals outlook | 2025 | IEA 2026 | annual | next outlook |
| EU regulation | 2023 | Regulation text | periodic | delegated acts |
| Moss Landing record | 2025 | secondary summary | one-off | agency report |
| Export controls | 2025 to 2026 | IEA 2026 | per event | November 2026 review |
| System | Coverage | Thinnest dimension |
|---|---|---|
| Deployment | GOOD | regional data on a common basis |
| Cost | PARTIAL | common basis across sources |
| Supply | PARTIAL | recycling volumes |
| Governance | PARTIAL | status of delegated acts |
| Long duration | THIN | deployment by technology |
| Safety | THIN | incident rates |
| Skills | THIN | workforce numbers |
| Recycling | THIN | capacity and recovered volumes |
| Field | Source that would fill it | Blocker |
|---|---|---|
| Energy storage investment totals on a common basis | national agencies, market surveys, development banks | not retrieved; the cost survey behind the IRENA series was not opened28 |
| Long-duration storage deployment by technology and duration | agencies, system operators, hydropower association | only unit costs read2; the hydropower outlook report was not opened37; one vendor claim13 |
| Battery fire and thermal event rates on a common basis | EPRI incident database and agency reports25 | the database page returned no data; the Moss Landing record comes from a secondary summary14 |
| Recycling capacity and recovered volumes | national agencies, recyclers, European Commission | not retrieved; only regulation targets read10 |
| Sodium-ion performance and output from primary data | peer-reviewed tests, producer data, national agencies | secondary summary and vendor announcement only1847 |
| Water use of pumped storage and thermal systems | operators, regulators, peer-reviewed studies | not retrieved |
| Chinese storage capacity from national sources | national energy administration and industry bodies | not retrieved; the figure found is in a secondary source15 |
| Status of EU battery due diligence obligations after August 2025 | Official Journal and Commission notices10 | the regulation text read states 18 August 2025; later changes were not checked |
| Status of China battery export controls after November 2026 | Chinese ministry notices and IEA updates8 | the IEA outlook records a suspension to November 2026; no later source read |
| Grid service performance of large batteries from system operator data | system operator reports | the operator page returned an access error; secondary summary only22 |
| Field degradation and lifetime of installed systems | operators, peer-reviewed field studies | not retrieved |
| Storage workforce size and skills gaps | national statistics, industry surveys | not retrieved; capability rung stays LISTED |
| IEA batteries report text beyond the slide set | IEA Batteries and Secure Energy Transitions report9 | the report page returned an access error; slides read |
| Capability rungs beyond standards and planning | agencies, operators, laboratories | not reviewed |
A.5Evidence cards, two anchor sources
Published by IRENA in 2026. Annual report. Role: binds FIN-002 and the cost tiles. Coverage: global averages by technology; project mix varies.
EVD-XT16-001
Renewable Power Generation Costs in 20252
Published by the IEA in 2026. Annual report. Role: binds INF-001 and the deployment tiles. Coverage: global and regional additions in 2025.
EVD-XT16-002
Global Energy Review 2026, battery storage section1
| Dimension | EVD-XT16-001 | EVD-XT16-002 |
|---|---|---|
| Completeness | global averages; few projects for emerging options | global and regional additions |
| Timeliness | published about six months after year end | published within the following year |
| Revision | annual edition | annual edition |
| Method transparency | cost definitions stated | definitions stated in the report |
| External validation | attributed series from a market survey | agency review |
Evidence cards to follow in 2027
A.6Publication acceptance record
Editorial self-check at evidence close. Every applicable item carries a disposition; the remaining items are review, approval and deposit.
| Group | Area | Items | Pass | N/A | Pending |
|---|---|---|---|---|---|
| D1 | Identity and scope | 8 | 8 | 0 | 0 |
| D2 | Source and data | 12 | 9 | 1 | 2 |
| D3 | Analysis and models | 12 | 3 | 8 | 1 |
| D4 | Findings and claims | 9 | 8 | 0 | 1 |
| D5 | Figures, tables, maps | 10 | 6 | 2 | 2 |
| D6 | Editorial and citations | 10 | 8 | 0 | 2 |
| D7 | Review and approval | 13 | 0 | 0 | 13 |
| D8 | Artefact and design | 12 | 7 | 0 | 5 |
| D9 | Registry and release | 9 | 0 | 0 | 9 |
Publication gate
- Conditions met
- 14 of 23 at evidence close
- Blocking problems
- none recorded
- Open conditions
- reviews, approval of the exact digest, deposit, registry pointer
Not applicable at baseline
- Model runs
- first runs in Q1 2027
- Maps
- plates in Q2 2027
- Waivers
- none
A.7Status words
| Status | What it means |
|---|---|
| Observed | Measured directly and published by the source. |
| Reported | Published statistics of an official or institutional source. |
| Declared | Stated by the body concerned; not independently measured. |
| Estimated | A Nexus estimate from cited evidence, with its method in Annex A. |
| Modelled | Produced by a stated model from cited inputs. |
| Inferred | Reasoned from cited evidence; not measured. |
| Forecast | A projection by the cited source. |
| Simulated | A simulation result under stated assumptions. |
| Scenario | A conditional statement under stated assumptions; never a prediction. |
| Expert input | Expert judgement, recorded with its basis. |
| Candidate | Proposed for a later edition; not yet evidence. |
| Evidence-quality levels (EQL 1 to 5) grade the source behind a value; they are not a score of the subject. | |
A.8How the edition is made, released and corrected
Every edition is built from a sealed evidence cut, reviewed under three keys, signed and deposited before any site shows it as published; corrections go to Nexus Standards as change proposals and feed the next cut.
| Step | What happens | Source |
|---|---|---|
| 01 Evidence arrives from the pillars | Foundry seals observations and indicator series, Universe hands over after-action and scenario findings, and contributions are screened at every gateway, including this site’s. | |
| 02 The cut is sealed | On the cut date the evidence is pinned under one identifier, so anyone can rebuild the edition from exactly what it was built on. | |
| 03 The edition is assembled | The edition is drafted from its template and content pack. Agents may draft; they never publish and never decide. | |
| 04 The keys turn | At the publisher of record the truth key comes first: every value is checked against its source or stated method before the meaning and capital keys turn. No edition moves on until every key has been turned by a named steward. | |
| 05 The gate opens | A named approver releases one exact digest of the edition; any change after this point is a new version, never a silent edit. | |
| 06 Signed and deposited | The PDF, the web edition and the data bundle are signed together with a manifest and an RO-Crate description, and deposited on Zenodo with a concept and a version DOI. | |
| 07 Published on its desk’s site | Only then does the edition show as published on its desk’s Reports site, and the Collection lists it as a part. | |
| 08 Corrections go to Standards | Method and correction findings go to Nexus Standards as change proposals; citations, corrections and new contributions feed the next evidence cut. |
A teaching model of the process, not a forecast and not a record of any run; dates and counts on this page come from the programme record. Sources: Reports governance at GCRI Canada (2026); Zenodo, repository of record for Reports deposits (2026).
Lifecycle, one state at a time: Draft, Computed, Evidence bound, Reviewed, Approved for release, Published, Corrected, Superseded. This edition is a draft.
A.9Glossary and abbreviations
| Term | Meaning |
|---|---|
| Baseline Edition | the inaugural annual edition that fixes the reference state for the series |
| WEFH+B | water, energy, food, health and biodiversity, the national nexus core |
| Coupling | a typed dependency through which one system transmits to another |
| Protection gap | the share of losses not covered by insurance |
| Capability ladder | LISTED → EXISTS → ADEQUATE → TESTED → DEMONSTRATED |
| EQL | evidence-quality level, 1–5 |
| Evidence cut | a frozen resolution of exact sources and versions |
| NNC · NLC · NWG | National Nexus Consortium · National Leadership Council · National Working Groups |
| Abbreviation | Expansion |
|---|---|
| AAM | anode active material |
| BESS | battery energy storage system |
| CAES | compressed air energy storage |
| EIA | US Energy Information Administration |
| LCOE | levelised cost of electricity |
| LDES | long-duration energy storage |
| LFP | lithium iron phosphate |
| NMC | nickel manganese cobalt oxide |
| PSH | pumped storage hydropower |
| STEPS | Stated Policies Scenario |
| TIC | total installed cost |
| UPS | uninterruptible power supply |
A.10Technical annex
| Item | Annex | Contents | Status |
|---|---|---|---|
| A.1 | Indicator definitions | the global indicator set, with units and sources | IN THIS EDITION |
| A.2 | Coupling strengths | the twenty-cell matrix and its rationale | IN THIS EDITION |
| A.3 | Scenario specification | SCN-XT16-SUP-01 assumptions and signposts | IN THIS EDITION |
| A.4 | Capability placements | rung evidence for fifteen functions | IN THIS EDITION |
| A.5 | Model diagnostics | first runs and validation | 2027 |
| A.6 | Sensitivity analyses | influence of coupling strengths | 2027 |
| A.7 | Cluster notes | cards for the major storage and battery supply chain clusters | 2027 |
| A.8 | Review statements | pass-by-pass review record | AT RELEASE |
A.1 · indicator definition: installed cost of four-hour utility-scale battery storage
- Construct
- fully installed cost per unit of energy capacity for a utility-scale battery with four hours of storage at rated power
- Unit
- US dollars per kWh
- Method
- weighted average of reported project costs, as defined by the publisher
- Source
- IRENA Renewable Power Generation Costs in 20252
- Uncertainty
- not stated as an interval in the pages read
- Known limits
- turnkey price and battery cost indices measure different scopes and are not interchangeable
Notes
Numbers are the edition’s reference numbers, so a note reads the same in every chapter. The full list, with every source and its licence, is in Annex C. Annex C, references
- 28UNVERIFIED, not opened: BloombergNEF (ed.), Energy Storage System Cost Survey 2025, cited only as the source of the series reported by IRENA; not opened. BloombergNEF, London. Observation year 2025. Accessed 2026-11-03.back
- 2IRENA (ed.), Renewable Power Generation Costs in 2025, 2026 (installed cost of four-hour utility-scale battery storage about USD 140 per kWh, down close to 30%; total installed cost by storage technology; solar paired with batteries). International Renewable Energy Agency, Abu Dhabi. Observation year 2025. Accessed 2026-11-03.back
- 37UNVERIFIED, not opened: International Hydropower Association (ed.), World Hydropower Outlook 2025 (the page loaded but the report was not read; the 2025 pumped storage figure appears only in a secondary summary). IHA, London. Observation year 2025. Accessed 2026-11-03.back
- 13Form Energy (ed.), Battery technology page (iron-air system described as able to discharge for up to 100 hours). Vendor statement, weak evidence, not independently tested. Form Energy, Somerville. Observation year 2026. Accessed 2026-11-03.back
- 25UNVERIFIED, not opened: EPRI (ed.), Battery Energy Storage System Failure Incident Database (the page returned no data; incident rate figures seen only in a secondary summary). Electric Power Research Institute, Palo Alto. Observation year 2025. Accessed 2026-11-03.back
- 14Wikipedia contributors (eds.), Moss Landing Power Plant (fire of 16 January 2025; 300 MW and 1,200 MWh phase; about 1,200 residents evacuated). Secondary summary, weak evidence. Wikimedia Foundation, San Francisco. Observation year 2025. Accessed 2026-11-03.back
- 10European Parliament and Council, Regulation (EU) 2023/1542 concerning batteries and waste batteries (full text; battery passport from 18 February 2027; safety of stationary battery energy storage systems, Article 12; recycled content targets). Official Journal of the European Union, Luxembourg. Observation year 2023. Accessed 2026-11-03.back
- 18Wikipedia contributors (eds.), Sodium-ion battery (energy density figures; producer announcements of 2025; cost claims marked as needing update). Secondary summary, weak evidence. Wikimedia Foundation, San Francisco. Observation year 2025. Accessed 2026-11-03.back
- 47UNVERIFIED, not opened: CATL (ed.), announcement of the Naxtra sodium-ion battery brand, April 2025, known only from a secondary summary; the company news page was fetched but no article was read. Contemporary Amperex Technology, Ningde. Observation year 2025. Accessed 2026-11-03.back
- 15Wikipedia contributors (eds.), Battery storage power station (national capacities, cost series, incident trend, as reported from cited sources). Secondary summary, weak evidence. Wikimedia Foundation, San Francisco. Observation year 2025. Accessed 2026-11-03.back
- 8IEA (ed.), Global Critical Minerals Outlook 2026 (revised version, July 2026; concentration of refining, lithium price rise from January 2025 to April 2026, China export controls of 9 October 2025, LFP share of battery energy storage). International Energy Agency, Paris. Observation year 2025. Accessed 2026-11-03.back
- 22Wikipedia contributors (eds.), Hornsdale Power Reserve (150 MW and 193.5 MWh; grid service claims from cited sources). Secondary summary, weak evidence. Wikimedia Foundation, San Francisco. Observation year 2024. Accessed 2026-11-03.back
- 9Wanner, B. (IEA), Batteries and Secure Energy Transitions, presentation slides, Energy Storage Summit, London, 18 February 2025 (slides summarising the IEA special report of 2024; storage capacity needed for tripled renewables; stated policies battery additions to 2030; lithium demand measures). International Energy Agency, Paris. Observation year 2024. Accessed 2026-11-03.back
- 1IEA (ed.), Global Energy Review 2026, section Technology: Battery storage (108 GW of new battery storage deployed in 2025, 40% more than in 2024; about 80% utility-scale; lithium iron phosphate about 90% of deployments; China about 60% of additions; battery-based UPS additions up 30% to 45 GW). International Energy Agency, Paris. Observation year 2025. Accessed 2026-11-03.back
- 3US Energy Information Administration (ed.), Battery storage capacity averaged 70% growth over the last three years, Today in Energy, 7 August 2026 (43.6 GW at the end of 2025; nearly 52 GW at mid-2026; planned additions to 2028). EIA, Washington. Observation year 2026. Accessed 2026-11-03.back
- 5USGS (ed.), Mineral Commodity Summaries 2026: Lithium (world mine production 2025, end uses, prices, reserves). US Geological Survey, Reston. Observation year 2025. Accessed 2026-11-03.back