Power in your hands

So I was standing in the gas station, hose in hand, idly counting the seconds to fill my tank.   About 80 for 12 gallons, or 9 gallons/min.  I see that gas pumps are limited to 10 gallons/min, so that’s about right.   I see that gasoline holds about 130 megajoules per liter, so what’s the above flow in power terms?

10 gal/min * 4 liters/gal * 130e6 joules/liter / 60 sec/min = 87 megawatts!

That’s enough to power a small city!   That’s the engine power of a modern destroyer.  And there it is, flowing between my fingers.  What would that be in electrical wire terms?  A typical extension cord uses 16 gauge copper wire 1.3 mm in diameter, and can handle 15A at 110V, or 1600 W.  To handle the above power it would need to be:

((1.3 mm)^2 * 87 MW / 1600 W)^0.5 = 300 mm in diameter

That’s a solid copper rod a foot across.   No wonder they’re worried about how long it takes to charge an electric car!  No cable can deliver the power flow that you get from a small gas hose.

OK, so how about a big gas hose?  The Trans-Alaska pipeline is 4 feet in diameter and 800 miles long.  It carried 320,000 cubic meters per day of crude oil at its peak in 1988.  Oil weighs about 0.7 kg/liter and contains ~42 Mjoules/kg.  All together that’s:

320 Km^3/day * 1e3 liter/m^3 * 0.7 kg/liter * 42e6 j/kg / 86,400 sec/day = 110 gigawatts!

That’s a hundred nuclear reactors.  It’s 6X the electrical output of the world’s largest dam, Three Gorges.   It’s twice the power consumption of Great Britain.  It’s about equal to all the wind turbines in the world.  No wonder the oil companies really, really wanted to build that pipeline.  No wonder Alaska basically lives off the taxes collected from it!

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