Material Insights · Understanding the Material World

Explosives and propellants: Engineering and performance

Release rate, magazines and safety distances, not efficiency

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

These stores are engineered for release rate and reliability; efficiency in the battery sense does not apply, and siting is dominated by separation distances and licensing.

Round-trip efficiency (energy release)

Unfavourable

There is no recharging, so round-trip efficiency does not apply. What matters is how much of the chemical energy does useful work, such as breaking rock or lifting a rocket. Blasting firms compete on blast design and electronic timing that get more useful work from each tonne; Orica, a large supplier, says its FY2025 margin growth came partly from greater uptake of premium products and advanced blasting technology (company statement).8

Power and energy decoupling (release rate)

Mixed

Energy and power are fixed by the material and the device: detonation releases its energy in microseconds, and solid rocket motors burn at a rate set by their design. Liquid engines can be throttled, so power is set by the engine and energy by tank size, the closest these stores come to decoupling.7

Footprint and siting flexibility

Unfavourable

Storage needs licensed magazines, separation distances from homes and roads, and controlled access. Cryogenic propellant stores are large: the new liquid hydrogen sphere at NASA's launch pad 39B holds about 4,700 cubic metres (1.25 million US gallons), versus 3,200 cubic metres for each Apollo-era tank.7

LC-39B LH2 sphere usable volume 4,732 m3 (1,250,000 gal)7 Apollo-era tank 3,218 m3 each7

Safety and thermal runaway risk

Unfavourable

Accidental initiation is the defining hazard. Beirut's 2020 blast killed 218 people, wounded about 7,000, displaced more than 300,000 and caused USD 3.8-4.6 billion of physical damage (World Bank estimate). In the EU, the Seveso III major-accident directive applies to sites holding 10 t (lower tier) or 50 t (upper tier) of the most hazardous explosive classes. For ammonium nitrate the thresholds depend on grade: 10/50 t for off-specification material, 350/2,500 t for technical grade, 1,250/5,000 t for high-nitrogen fertiliser grade, and 5,000/10,000 t for fertilisers prone to self-sustaining decomposition.34

Seveso III explosives (P1a) 10 t lower tier; 50 t upper tier3 Seveso III ammonium nitrate from 10/50 t to 5,000/10,000 t depending on grade3 Beirut 2020 deaths and damage 218 deaths; USD 3.8-4.6 bn physical damage4

Sources

  1. Directive 2012/18/EU (Seveso III), Annex I legislation.gov.uk (EU directive text as adopted), 2012
  2. "They Killed Us from the Inside": an investigation into the August 4 Beirut blast Human Rights Watch, 2021
  3. New LH2 sphere at LC-39B (Fesmire and Swanger, NASA Kennedy Space Center) US DOE / NASA, 2021
  4. Orica Annual Report 2025 Orica Limited, 2025