Storage as transmission alternative: when BESS beats wires
Battery energy storage deployed as a transmission alternative — relieving congestion or deferring substation upgrades — is gaining regulatory acceptance in CAISO, ERCOT, and PJM. Where BESS can substitute for transmission investment, project economics often dominate wires-only alternatives by 30–60% over 20-year planning horizons.
In 50 words: BESS deployed as a transmission alternative — relieving congestion or deferring substation upgrades — is gaining regulatory acceptance in CAISO, ERCOT, and PJM. Where BESS can substitute for transmission investment, project economics often dominate wires-only alternatives by 30–60% over 20-year planning horizons.
The concept
Transmission-as-a-service traditionally meant adding wires, substations, and transformers. Battery storage can sometimes substitute for these — discharging during peak congestion to reduce required line capacity, or providing voltage support that would otherwise need a substation upgrade.
Where regulation has caught up
US FERC Order 841 (2018) and subsequent orders allowed storage to participate in wholesale markets. The 2024–2026 series of rulings has extended this to:
- Allowing storage to be classified as a transmission asset
- Permitting cost-recovery through transmission rates
- Defining hybrid asset structures (storage providing both market and transmission services)
When BESS beats wires
Storage typically wins when:
- Peak-only congestion: lines are needed only a few percent of hours; BESS can shift those hours' flow
- Deferral value: a substation upgrade can be deferred 5–10 years through targeted BESS
- Location-constrained: building new transmission faces siting/permit barriers; BESS can be sited at existing substation footprints
- Renewable integration: smoothing variability that drives transmission peaks
Real deployments
CAISO has approved multiple storage-as-transmission projects, including:
- A 230 MW BESS in Goleta, CA for substation deferral and grid stability
- Several distribution-level BESS as alternatives to substation upgrades
ERCOT and PJM have similar projects under construction or planning.
Indian implications
India hasn't yet formalised storage-as-transmission asset classification, but CERC discussion papers suggest movement in this direction. Storage co-located at transmission constraint points could be a meaningful tool for relieving renewable-rich state congestion (Rajasthan→load centres).
What developers should think about
For projects in markets with storage-as-transmission frameworks:
- Hybrid revenue structures combining market participation + transmission tariff recovery
- Longer revenue certainty than market-only BESS
- Different regulatory and operational obligations than market-only BESS
What to watch next
The first multi-hundred-MW storage-as-transmission project to commission in 2026 will reveal whether the regulatory frameworks deliver the operating economics that the planning documents promised.
Researched and drafted with AI assistance; reviewed and edited by the named editor within 24 hours of draft.