Material Insights · Understanding the Material World

Fuel stocks and strategic reserves: Engineering and performance

Why drawdown speed, not size, limits a reserve

What this tab covers Engineering and operating performance: round-trip efficiency, whether power and energy can be scaled separately, footprint and siting, and safety.

Strategic stocks are sized for energy (months of supply) far more than for power (barrels per day), and their real limit is drawdown rate and logistics.

Round-trip efficiency

Favourable

Losses are small compared with any electricity store: oil is pumped in and displaced out with water, and gas storage loses some energy to compressor fuel. The bigger loss is time: it takes about 13 days from a US presidential decision for SPR oil to reach the market.4

SPR time to market about 13 days after decision4

Power and energy decoupling (drawdown rate versus inventory)

Mixed

Inventory and drawdown rate are set separately by caverns and by pumps, pipelines and terminals. The SPR's nominal maximum drawdown is 4.4 million barrels a day; at that rate its October 2026 stock would last about 64 days (calculated). In 2026 the IEA-coordinated release delivered about 2.5 million barrels a day of extra supply at its May peak, against a loss of Strait of Hormuz flows from about 20 to 2.7 million barrels a day.24

SPR max drawdown 4.4 million barrels/day (nominal)4 IEA release peak rate about 2.5 million barrels/day (May 2026)2 Hormuz flows about 20 to 2.7 million barrels/day (Mar-May 2026 average)2

Footprint and siting flexibility

Mixed

Salt caverns are cheap and secure but exist only above salt domes, which is why the US SPR sits on the Gulf Coast. India uses rock caverns at Visakhapatnam, Mangalore and Padur. Gas storage depends on depleted fields or salt; countries without them, as in much of South Asia, rely on tanks and LNG.49

India SPR phase 1 5.33 Mt: Visakhapatnam 1.33, Mangalore 1.5, Padur 2.59

Safety and thermal runaway risk

Mixed

Tank farms carry fire and explosion risk, gas stores risk well blowouts and methane leaks, and coal stockpiles can catch fire through self-heating. Large sites fall under the EU Seveso III major-hazard directive, which applies from 2,500 t of petroleum products (25,000 t for upper tier) and from 50 t of natural gas or liquefied flammable gases (200 t upper tier). Ageing equipment raises both safety risk and the chance a site cannot deliver in a crisis.1013

Seveso III petroleum products 2,500 t lower tier; 25,000 t upper tier13 Seveso III natural gas and LPG 50 t lower tier; 200 t upper tier13

Sources

  1. How global oil supplies have readjusted to help fill the huge gap left by the Strait of Hormuz shock International Energy Agency, 2026
  2. SPR Quick Facts US Department of Energy, 2026
  3. India taps ONGC to accelerate SPR expansion amid global oil supply disruption S&P Global Commodity Insights, 2026
  4. Energy Security: Congress and DOE need a unified plan to align priorities and investments for the Strategic Petroleum Reserve (GAO-26-106918) US Government Accountability Office, 2026
  5. Directive 2012/18/EU (Seveso III), Annex I legislation.gov.uk (EU directive text as adopted), 2012