Steam trains are wonderful to behold – to watch one go by is to experience the power of the machine. Unlike modern diesel locomotives which start instantly, never make a fuss, Steam locomotives take hours to get going, and must let off steam when being shut down – literally spewing energy away in a wondrous display of power and might. Worse, steam engines needed such a high degree of maintenance that they were in the shop 7 hours for every 3 they spent on the rails. So, it’s easy to see why they were replaced with technically superior, and aesthetically much more boring machines.
However, the high cost of oil prompted ACE to desing the 3000 in the early 1980’s. Never put into production, it was an attempt to exploit the differential between the costs of oil and coal to build a cheaper running freight engine. Impressively, it doubles the thermal efficiency of older steamers – up to 15% from just 7% when steam was being phased out in the 50s. Thermal efficiency means how much of the heat energy created by burning the fuel is turned into mechanical energy. 15% is impressive compared to your car, which is lucky to squeeze out 9% from its gasoline engine, but a bit crap compared to the 30% modern diesel locomotives achieve.
Half the therman efficiency means coal needs to cost half as much per energy unit for the machine to be profitable. In the early 80s, We should in no way desire this bank managers dream to come true. And it was true – to prove their case ACE took that pretty old Steamer you see above, and fitted it with various sensors, put it into service, and proved it was profitable to run at existing coal prices compared to diesel (in the early 80s), and this was with an engine running 6% thermal efficiency.
ACE’s project failed because the price of oil fell in the mid 80s. However, if the cost of oil climbs again to 150$ a barrel, you can be certain there will be renewed interest in the 3000. This should make us afraid, because Coal produces a lot more C02 for every joule of heat created than does oil, and this runs half the therman efficiency of a diesel loco. This means it produces at least 4 times as much C02 for the same amount of work done, and although that’s surely a lot less than moving things by truck, it is certainly not the direction we need to be moving.