I am not an engineer, nor a physicist, but I quibble with dldance above. The diesel has other stages of conversion unique to its electric nature that a steam engine does not face. That is, the combustive energy of the diesel, an already decidedly inefficient process in a reciprocating engine, must then be converted to DC and fed to torgue-generating motors. There is energy loss at that point. Dynamic brakes mitigate that to an extent.
A steam loco generates 100% torgue at stall, and it is torque, not HP, that gets a heavy train moving and that accelerates it.
Steam could be cheaper if diesel goes to $2.50/gal. Then again, British Columbia coal mines are at full tilt after a lull of about 8 years because China’s economic boom (and friends, it’s a whopper!) is making coal more economical to mine. If we returned to steam, we’d have to outbid the Chinese, a dim prospect at best.
If inflation is taken into account, crude at 53 US$ per barrel is still cheaper than in the late seventies.
I don’t know of any attemps by the coal-industry to have a modern steam-engine designed. in the late seventies, some test-runs have been made, but the results were reported to be non-conclusive.
it would be great to see main-line-steam again, but I don’t believe it will ever happen.
Once thing I’ve wondered about is the costs of producing diesel fuel from coal vs. the cost of producing synthetic “natural” gas (synthetic natural-talk about an oxymoron) from coal stocks. The latter has been done worldwide including in North America. There is dual fuel technology for burning gaseous fuels in large diesel engines. There is even Railpower’s proposals for gas burning turbine locomotives (as for a "turbine vs. diesel argument, I for one don’t want to go there.)
While you’re correct that starting torque (the power a machine develops at zero speed) is what starts a train or any other load in motion, your statement that a steam engine could develop 100% of its power at stall is not true.* Few (if any) machines develop full power at stall, and a reciprocating steam engine got nowhere near it .
The vaunted Big Boy, for instance, reached its maximum power output at something over thirty miles per hour. A diesel-electric with DC traction hits maximum output somewhere under ten miles per hour, and AC-traction locomotives do better than that.
In other words, the diesel-electric developed greater starting torque than a reciprocating steam engine - by a wide margin.
*(For those who don’t know the relationship between power, torque and speed: the Power (in HP) of any machine is calculated by multiplying Torque (in foot-pounds) by the Speed (in rpm) of the output shaft - in the case of a steam locomotive, the axle of the driving wheels; in a diesel locomotive, the crankshaft of the diesel prime mover.)
Actually:
Both AC and DC traction motors do develop their maximum traction at zero mph. However, sophisticated slip control devices limit that traction to the maximum value limited by adhesion. The difference between AC and DC traction is that the AC motors can tolerate the resultant high currents experienced during this mode of operation. The DC motors have be able to accelerate the train to at least ten miles an hour in order to avoid burning themselves out wheras AC traction motors can hold a train on a hill without the brakes, if necessary. As a result, AC engines can pull a train up a hill at run 8 while going only five mph or less. Do this with DC traction motors for more than 15 minutes and all of the traction motors will be fried.
I think that one of the factors greatly overlooked by history is the cost of abandonment of steam on an accelerated basis before the existing hardware was depleted, and the associated abandonment of stranded assets that followed.
A lot of good 5 year old engines got sent to the scrapper with 10+ years of useful life left in them.
The value of assets thusly abandoned should rightly have been factored into the cost of implementing diesel l.