Comparison of the running costs of engines
Historical-Comparison-of-the-running-costs-of-caloric-engines
Running costs of a small steam engine
| Kind of expense for 1 hors power | Costs in Mark |
|---|---|
| Amortization for purchase price for a low expansion machine without condensation, Installation costs including creation of a solid base and chimney of about 1,400 Mark; Interests and repair costs 12% per year; spread over 300 working days, 10 hours per working day | 0,056 |
| Costs for 4.5 kg of coal per hour | 0,09 |
| Worker for heating and maintenance; 3 Mark for a 2 horse power machine per day (=10 hours) | 0,15 |
| Lubrication, etc | 0,02 |
| Total costs per hour | 0,316 |
Running costs of an atmospheric gas machine
Due to the overwhelming better efficiency the atmospheric gas engine of Otto-Langen has become so popular that the gas machines of Lenoir and Hugon have lost any economical significance.
| Kind of costs | Cost in Mark |
|---|---|
| Purchase price of 1,500 Mark, 15% per year for amortization, interest and repair for one horse power and hour | 0,075 |
| 0.8 m3 illumination gas per horse power and hour, 0.175 Mark per m3 | 0,14 |
| maintenance | 0,02 |
| lubrication | 0,02 |
| Total costs per horse power and hour | 0,255 |
The atmospheric gas engine of Otto-Langen may also be fueled by petroleum, in which case the running costs are lower by 0.02 Mark per horse power and hour.
As we can see, for small power needs, the atmospheric engine of Otto-Langen not only provides a 20% cost advantage, it is also smaller than a comparable steam engine with a boiler, it only consumes energy when it is switched on, it needs not the attention of a boiler man, it needs no preparation time to get the water boiling and it does not require any regulatory approval.
Running costs of a high power steam engine
Small steam engines are quite inefficient and were running at an efficiency rate of about 2%. In bigger, more powerful steam engines, the losses in the boiler and the cylinder were lower and thus were more efficient. Even the price of bigger engines decreased per horse power with their size.
100 horse power engine with large expansion and condensation:
| Running costs per horse power and hour | Costs per hour in Mark |
|---|---|
| 11% for amortization of a purchase price of 900 Mark per horse power, interest and repair, per horse power and hour | 0.033 |
| 1,5 kg coal per horse power and hour | 0.03 |
| personnel costs for maintenance and heating 12 Mark per day for a 100 horse power steam engine | 0.012 |
| lubricant | 0.01 |
| Total costs per horse power and hour | 0.085 |
We can see that with using only 1.5kg coal instead of 4.5 kg coal per horse power and hour a big steam engine is three times more efficient than a small steam engine. Gas machines for that amount of power did not yet exist, the biggest Otto-Langen atmospheric gas engine provide 4 horse power break power.
Running costs of water engines
Water motors are driven by the pressure difference of the inflowing water and the outflowing water. Their purchase price is relatively cheap compared to steam engines or gas engines. They are small, not noisy and do not pollute the air, so they can be used at home, for example as a motor for a sewing machine.
| Kind of costs | Costs in Mark |
|---|---|
| 10% for amortization of purchase price of 750 Mark, interest and repair, | 0,025 |
| 9 m3 operating water at a pressure of 4 atmospheres per horse power and hour, 0.10 Mark per m3 | 0,90 |
| Maintenance and oil (lubricant) | 0,03 |
| Total costs for 1 horsepower and hour | 0.955 |
9 m3 of water at a pressure of 4 atmospheres (= 400 kPa) per hour is equivalent to 1 m3/s * kN/m2 or 1 kNm/s = 1 kW = 1.36 horse power of power supplied for 1 horse power of work generated. This is equivalent to an efficiency of 73.5%.
Despite the high sufficiency the cost to supply water at this pressure is relatively high, as the work has to be done remotely by pumps, operated probably by steam engines.
Running cost of electrical motors
In 1888 electrical motors were not given a bright future as the cost for supplying an electrical motor with a zinc battery was at least 20 times higher than for a steam engine.
The costs for a horse would be 4.50 Mark for a 10 hour working day or 0.45 Mark per hour. To achieve the same power 8 men would be needed. A laborer has a daily rate of 2.50 Mark, which results in 8*2.50/10 =2 Mark per hour. In this respect the water engine is still cheaper.