As the Chilean system moves towards a 100% renewable mix, episodes of low or very high generation appear that can last hours, days, weeks or months. This document answers two questions about that problem: how much long-duration storage the system needs and what it is worth. It defines LDES as a service rather than a technology: the one any storage —pumped hydro, compressed air, gravity, flow batteries, Power-to-X— provides for long enough to avoid load shedding or thermal backup.
How much is needed by 2030
The simulations use AMEBA's capacity and transmission expansion model, over all 8,760 hours of 2030, across four thermal retirement cases and an emissions tax of 35 USD/tCO2eq.
- Base case. With the retirement of 2 GW of coal between 2023 and 2030, about 7.6 GW of additional wind generation and 1.2 GW of storage are required, concentrated in 12-hour pumped hydro.
- Deeper retirements. Storage reaches almost 6 GW in the full thermal retirement case, and LDES enters more intensively: from 0.4 GW of 48-hour CAES up to 1.5 GW of between 48 and 72 hours.
- Curtailment. All cases end up at around 6-9%: it is cost-efficient to oversize wind and solar and complement them with storage.
Ruling out long-duration technologies makes the solution worse: in the coal retirement case storage investment rises from around 2 GW to 3 GW of BESS used at partial load, and under deep decarbonization solar has to be replaced by geothermal and CSP, which are more expensive. Measured in total cost —investment, operation, cost of unserved energy and emissions— including LDES saves between 2% and 5.3%.
Why it does not get built on its own
The current design does not send signals that reflect that value. The document proposes five long-term mechanisms: regulated auctions with renewable profile requirements; longer-term reserve contracts procured by the National Electrical Coordinator; capacity payments that recognize prolonged outages and the correlation between scarcity events; storage-as-a-service contracts paid for by those who benefit; and infrastructure tenders with cap-and-floor schemes.