Convert Horsepower-Hours to Petajoules
Convert Horsepower-Hours (hp·h) to Petajoules (PJ) instantly and accurately.
Conversion Formula
PJ = hp·h × 2.684519538e-9
About Horsepower-Hours
A horsepower-hour (hp·h) is the energy from one mechanical horsepower (745.6999 W) for one hour - exactly 2,684,519.54 J ≈ 2.685 MJ. James Watt coined the horsepower to compare his steam engines with mine horses; billing in hp·h preceded the kilowatt-hour tariff. The metric horsepower (PS = 75 kgf·m/s = 735.499 W) gives a slightly smaller metric-hp·h = 2,647,795 J, used in European and Japanese engine datasheets. Today the hp·h appears in marine engineering logs, mining energy accounting, and vintage industrial equipment. 1 hp·h = 2.6845 MJ = 0.74570 kWh = 641.19 kcal.
About Petajoules
A petajoule (PJ) is 10¹⁵ J - the national energy policy scale. IEA reports primary energy in PJ/year: Sweden ~600 PJ; Germany ~12,500 PJ; the United States ~93,000 PJ. World total primary energy supply is ~605,000 PJ = 605 EJ. The 1883 Krakatoa eruption released ~200 PJ ≈ 48 megatons TNT. A 1-megaton nuclear weapon releases 4.184 PJ. Global annual steel production embeds ~38,000-47,000 PJ of energy. 1 PJ = 10¹⁵ J = 277.78 GWh = 238.85 ktoe = 23.88 ktoe.
Quick Reference Table
| Horsepower-Hours (hp·h) | Petajoules (PJ) |
|---|---|
| 1 hp·h | 2.685 × 10-9 PJ |
| 2 hp·h | 5.369 × 10-9 PJ |
| 5 hp·h | 1.342 × 10-8 PJ |
| 10 hp·h | 2.685 × 10-8 PJ |
| 25 hp·h | 6.711 × 10-8 PJ |
| 50 hp·h | 1.342 × 10-7 PJ |
| 100 hp·h | 2.685 × 10-7 PJ |