Foot pounds-force minute to Terawatt
ft·lbf/min
TW
Conversion History
| Conversion | Reuse | Delete |
|---|---|---|
| No conversion history to show. | ||
Quick Reference Table (Foot pounds-force minute to Terawatt)
| Foot pounds-force minute (ft·lbf/min) | Terawatt (TW) |
|---|---|
| 100 | 0.00000000000225969658 |
| 1,000 | 0.00000000002259696581 |
| 5,000 | 0.00000000011298482903 |
| 10,000 | 0.00000000022596965806 |
| 33,000 | 0.00000000074569987158 |
| 100,000 | 0.00000000225969658056 |
| 330,000 | 0.00000000745699871584 |
About Foot pounds-force minute (ft·lbf/min)
Foot pounds-force per minute (ft·lbf/min) equals approximately 0.02260 watts. It is used in US mechanical engineering for low-power applications and in the historical definition of horsepower: one horsepower was defined by James Watt as 33,000 ft·lbf/min — the rate at which a horse could lift coal from a mine. This unit is now mostly encountered in legacy engineering references and historical machinery specifications.
One mechanical horsepower = 33,000 ft·lbf/min. A hand-cranked generator might produce 2,000–5,000 ft·lbf/min of mechanical power output.
About Terawatt (TW)
A terawatt (TW) equals one trillion watts and is used to express global and continental energy consumption and total planetary power flux. Total human civilisation energy consumption is approximately 18 TW. The Sun delivers about 173,000 TW of power to the Earth's surface. National electricity grids operate at tens of gigawatts; continental-scale grids and global energy statistics require terawatt-scale framing. Ambitious long-term energy transition scenarios describe targets in terawatts of clean capacity.
Global electricity generation capacity is approximately 9 TW. Total human energy use (all forms — electricity, heat, transport) is about 18 TW.
Foot pounds-force minute – Frequently Asked Questions
Where does the number 3,960 come from in US pump sizing formulas?
The pump horsepower formula HP = (GPM × Head in ft) / 3,960 hides a chain of unit conversions. Water weighs 8.33 lb per US gallon. Multiplying GPM × Head × 8.33 gives ft·lbf/min. Dividing by 33,000 ft·lbf/min per hp gives horsepower. So 33,000 ÷ 8.33 ≈ 3,960. The number is so ubiquitous in US mechanical engineering that pump designers recognize it on sight, yet few remember the derivation. It breaks down for fluids other than water — multiply by specific gravity for anything denser or lighter.
What real-world tasks produce 33,000 ft·lbf/min?
Lifting 330 lbs (150 kg) at 100 feet per minute — roughly the speed of a slow freight elevator. Or lifting 33 lbs at 1,000 ft/min (a fast dumbwaiter). A human on a bicycle sustainably produces about 5,000–10,000 ft·lbf/min (0.15–0.3 hp). A small outboard boat motor produces about 165,000 ft·lbf/min (5 hp). The unit makes intuitive sense for lifting and hoisting — the original application Watt cared about.
Why use ft·lbf/min instead of ft·lbf/s?
Historical convention and practical timescale. Mine hoists, waterwheels, and early steam engines operated at rates naturally measured per minute — the machinery completed one cycle every few seconds to minutes. Watt himself measured horses per minute because that's how mine work was timed. The per-minute unit also gives larger, more manageable numbers: "33,000 ft·lbf/min" is easier to work with than "550 ft·lbf/s" when you're doing longhand arithmetic in 1780.
How much ft·lbf/min can a human sustain?
A healthy adult can sustain about 4,000–6,000 ft·lbf/min (roughly 90–135 W or 0.12–0.18 hp) of useful mechanical work for hours — think steady cycling or rowing. Short bursts reach 15,000–25,000 ft·lbf/min (0.5–0.75 hp). Elite cyclists sustain 12,000+ ft·lbf/min (0.4 hp) for an hour. By Watt's definition, a horse sustains 33,000 ft·lbf/min, meaning one horse ≈ 5–8 sustained humans. The ancient rule of "ten slaves per horse" wasn't far off.
Is 33,000 ft·lbf/min still used in any modern calculations?
Yes — it's embedded in US pump and fan engineering. The formula for pump horsepower is: HP = (GPM × Head in ft × Specific Gravity) / 3,960, where 3,960 = 33,000 / (8.33 lb/gal). The number 33,000 ft·lbf/min lurks inside every US pump sizing calculation, even if the engineer never writes it explicitly. It also appears in ASME standards for hoists, cranes, and elevators — anywhere lifting power needs to be specified.
Terawatt – Frequently Asked Questions
How much of the Sun's power hitting Earth would we need to capture?
The Sun delivers about 173,000 TW to Earth's surface. Human civilisation uses roughly 18 TW total. So we'd only need to capture 0.01% of incoming solar energy to power everything — an area of solar panels roughly 400 km × 400 km, about the size of Montana. The challenge isn't total energy availability; it's cost, storage, transmission, and the fact that sunlight is spread thin and intermittent.
What does 18 terawatts of human power consumption actually mean?
Imagine 18 trillion light bulbs burning continuously, or 9 billion people each running a 2 kW heater non-stop. That 18 TW figure includes everything — electricity, transport fuel, industrial heat, cooking, heating. About 40% comes from oil, 27% from coal, 24% from gas, and the rest from nuclear and renewables. The US alone accounts for about 3 TW despite having only 4% of world population.
How many terawatts of solar would end climate change?
Replacing all 18 TW of human energy with clean sources would require roughly 60–75 TW of installed solar capacity (accounting for ~25% average capacity factor). That's about 40 times current installed solar. At 2023 installation rates of ~0.4 TW/year, it would take 150 years — but installation rates are doubling every 2–3 years. If that exponential trend holds, we could theoretically reach 60 TW of solar within 15–20 years.
What is Earth's total internal heat flow in terawatts?
Earth radiates about 47 TW of geothermal heat from its interior, driven by radioactive decay and residual primordial heat. That's 2.5× human energy consumption, but it's spread across the entire surface at extremely low density (~0.09 W/m²). Iceland, sitting atop a mantle plume, exploits geothermal for 90% of its heating. Globally, geothermal electricity capacity is only about 16 GW — a tiny fraction of what's theoretically available.
Has human power consumption always been measured in terawatts?
No — the terawatt scale is a very recent phenomenon. In 1800, global human power consumption was about 0.5 TW (mostly biomass burning). By 1900 it reached 1 TW with coal industrialisation. We crossed 10 TW around 1985. The jump from 1 to 18 TW in just 120 years tracks almost perfectly with global population growth times rising per-capita energy use. Pre-industrial humans used about 0.1 kW each; Americans now average 10 kW per person.