Some Power Sources Compared

by David Steinberg



Watt Reciprocating Steam Engine

Steam Turbine

Otto Cycle (4 stroke) Gasoline Engine

Diesel Engine

Various Rotory Engines (Wankel and others)

Stirling Engine

Gas Turbine


Fuel Cells

Electric Motor


Watt 2.5%

Multiple expansion steam engines greatly improved efficiency. Now about 17%

Steam turbines typically have a thermal efficiency of about 35 percent, meaning that 35 percent of the heat of combustion is transformed into electricity.

Most automotive and small aircraft engines have 25-30% thermal efficiency.

Ideal diesel efficiency of 56%

- large marine engines can exceed 50% thermal efficiency

- normally diesels achieve and efficiency of about 35%


Has the potential to be more efficient than a gasoline or diesel engine

-stationary gas turbines can reach an efficiency of about 40%

- They can be particularly efficient when waste heat from the gas turbine is recovered by a conventional steam turbine in a process known as a combined cycle. Efficiencies of 60%+ can be realized




James Watt -1736 - 1819

Sir Charles Algernon Parsons 1854-1931

Nikolaus Otto 1832-1891

Rudolph Diesel 1858-1913


Robert Stirling 1790-1876

See below



Michael Faraday 1791-1867

1888 - Nikola Tesla (1867-1943) invents the first practicable AC motor and polyphase power transmission system, which revolutionizes industry and commerce.

Key Dates

1776 – Watt built an engine with a cylinder of 127 cm diameter to pump water 1778 - final version of the new Watt engine

1782 -  Watt made his double-acting engine With this improvement the engine had double the power with the same displacement

1807 - First commercially successful river boat the North River Steamboat (often called the "Clermont").

1838 - The side-wheel paddle steamer SS Great Western was the first purpose-built steamship to initiate regularly scheduled trans-Atlantic crossings.

1882 – Parsons brought out his reaction steam turbine

1894 Parsons took out patent No. 394 for 'Propelling a vessel by means of a steam turbine….”

1897 – Turbinia demonstrates speed potential of marine steam turbine

1898 - HMS Viper first steam turbine powered warship

1906 Dreadnought, most powerful war ship in the world used steam turbines

1906-7 Cunard sister ships turbine-driven Mauritania and Lusitania fastest liners on Atlantic

1920-58 - Steam turbine locomotives a failure

first demonstrated by Nikolaus Otto in 1876

1885 Gottlieb Daimler and Wilhelm Maybach patented one of the first successful high-speed internal-combustion engines and developed a carburetor allowing use of gasoline as fuel.

- patent for the device on February 23, 1893 and building a functional prototype in early 1897 which went into production

- SELANDIA (1912)
Selandia, first oceangoing diesel engine
-powered ship.

- 1923/24 the first diesel-driven trucks

- 1936 series production of the first car diesel engine

- 1924 first diesel switching engines.

1930 Diesel engines suitable for main line locomotives developed in Germany and USA

1939 – GM started mass production of diesel mainline locomotives

1935 - first heavy-oil burning four-stroke diesel.


1816 he received his first patent for a new type of "air engine".

1791 - John Barber received the first patent for a basic turbine engine. His design was planned to use as a method of propelling the 'horseless carriage.' The turbine was designed with a chain-driven, reciprocating type of compressor. It has a compressor, a combustion chamber, and a turbine.

1872 - Dr. F. Stolze designed the first true gas turbine engine. His engine used a multi-stage turbine section and a flow compressor. This engine never ran under its own power.

1903 - Aegidius Elling of Norway built the first successful gas turbine using both rotary compressors and turbines - the first gas turbine with excess power.

1897 - Sir Charles Parson patented a steam turbine which was used to power a ship.

1914 - Charles Curtis filed the first application for a gas turbine engine.

1918 - General Electric company started a gas turbine division. Dr. Stanford A. Moss developed the GE turbosupercharger engine during W.W.I. It used hot exhaust gases from a reciprocating engine to drive a turbine wheel that in turn drove a centrifugal compressor used for supercharging.

1920 - Dr. A. A. Griffith developed a theory of turbine design based on gas flow past airfoils rather than through passages.

1930 - Sir Frank Whittle (1907-1996) in England patented a design for a gas turbine for jet propulsion. The first successful use of this engine was in April, 1937. His early work on the theory of gas propulsion was based on the contributions of most of the earlier pioneers of this field.


1936 - At the same time as Frank Whittle was working in Great Britain, Hans von Ohian (1911-1998) and Max Hahn, students in Germany developed and patented their own engine design.

1939 - Heinkel Aircraft flew the first flight of a gas turbine jet, the HE178.

1941 - Sir Frank Whittle designed the first successful turbojet airplane, the Gloster Meteor, flown over Great Britain. Whittle improved his jet engine during the war, and in 1942 he shipped an engine prototype to General Electric in the United States. America's first jet plane was built the following year.

1942 - Dr. Franz Anslem developed the axial-flow turbojet, Junkers Jumo 004, used in the Messerschmitt Me 262, the world's first operational jet fighter.


1821 – Faraday’s first motor 1834 -Davenport, invented an electric motor in  and began a small electric railway in 1835.


The reciprocating steam engine powered the industrial revolution.  As latye as World War II it was being us3ed to power Liberty Ships.  However, it seems to have no future even though, using modern materials the steam locomotive might be made competitive with today’s diesels (see A blast from the past, Economist

Dec 17th 1998). 


Steam turbines are no longer competitive with diesel units for commercial marine propulsion or with gas turbines for non-nuclear naval ships.

 In nuclear ships, all of which are naval, nuclear energy is used to generate steam to power steam turbines.  However, nuclear energy does not seem set to be used in commercial shipping.

Combined cycle gas and steam turbine systems may have a future in shipping.

Being challenged by fuel cells in the key automotive sector.

- Diesel engines have become dominant for railway and marine propulsion, heavy machinery and heavy vehicles. 

- Outside of North America, electricity is preferred to diesel on high volume railway lines.

- the future role of diesels in light vehicles and small-scale power generation is unclear


Continue to be used for specialized tasks

The two major application areas of gas-turbine engines are aircraft propulsion and electric power generation. Gas turbines are used as stationary power plants to generate electricity as stand-alone units or in conjunction with steam power plants on the high-temperature side. In these plants, the exhaust gases serve as a heat source for the steam. Steam power plants are considered external-combustion engines, in which the combustion takes place outside the engine. The thermal energy released during this process is then transferred to the steam as heat

Gas turbines, in the form of turbofan engines are dominant as aircraft power units.  Combined cycle power plants are well established in power generation and gas turbine emergency generators compete with diesel units.  Gas turbines have not competed successfully with diesel and electricity in railway oservicerailways.












Frequently the output of diesel (eg. locomotives), steam turbine (power plants) and gas turbines (small generating sets and combined cycle power plants) are converted to electricity which may be used to drive electric motors.  This is almost always true for locomotive diesels.

David Steinberg

Sept 2004


All of the marine power plants currently in use and under contemplation for future use can be classified according to the following basic thermodynamic cycles:

1. Rankine cycle-Steam turbines of 2,000-100,000 SHP/unit

2. Brayton cycle-Gas turbines of 500-40,000 SHP unit

3. Otto cycle-Reciprocating internal-combustion gasoline engines of 10-2,000 SHP/unit

12-20. Speed-power trends for ship-type ranges

4. Diesel cycle-Reciprocating internal-combustion

diesel engines ….


The steam turbine is well suited to the largest power plants, produces a uniform turning effort, burns the least expensive fuel, and is capable of relatively high efficiencies, long endurance, long life, long mean time between overhaul (MTBO), and reasonable maintenance. It has the inherent disadvantages of large space requirements, a large watch-standing force, slow response time, being slow in getting under way, intermediate energy conversion with its secondary working substance, mechanical non-reversibility, and high turbine speed. These latter two disadvantages necessitate a separate, low-efficiency astern turbine of reduced power and large, heavy reduction gearing to the propeller shafts. The speed reduction is needed to allow both the turbine and the propeller to operate in their most efficient speed range.


Gas turbines are powering an increasing number of high-speed displacement ships and the majority of high-performance vessels. This is because they have the lowest ratio of machinery weight to horsepower (specific weight) of any of the marine power plants. Gas turbines are very reliable , provide quick response after a cold start, and are adaptable to remote-control operation with a small watch-standing force. There is little maintenance between overhauls and most installations are designed to replace the entire engine, much like the aircraft jet engine from which it was derived. The disadvantages of gas-turbine propulsion include a large volume for the total plant, most of which is taken up by the inlet and exhaust ducting for the large quantities of air and exhaust gases. Although the gas turbine is reasonably efficient at the design power rating, it has a very high specific fuel consumption off the design rpm. It also has no reversing capability, so controllable pitch propellers are almost always found in gas-turbine powered ships. To improve fuel consumption at cruising speeds in twin-screw vessels, one of the controllable pitch propellers is often "feathered," or aligned with the flow, so the shaft does not rotate and all of the propulsion comes from the remaining shaft.

Gas turbines are perhaps most sensitive to atmospheric air temperature. Their power output will drop as inlet air temperature climbs. At the same time, the steam cycle's efficiency drops when the cooling water temperature in the condenser rises, which is also a function of its operating environment. It should also be pointed out that gas-turbine costs may be as much as 30 percent greater than those for steam power plants, since the gas turbine burns a higher grade fuel.


The low-speed, direct-coupled diesel engine is the most efficient of all the marine power plants, with specific fuel consumptions as low as 0.29 Ib/hp-hr. it is being used to power most new merchant ships .”



“It is probable that attention was first given to the idea of a practical internal combustion turbine in the early years of the present century. In 1906 M Rene Armengaud converted a de laval impulse turbine to operate on compressed air mixed with metered quantities of petroleum vapour, the mixture being fired by means of an incandescent platinum wire igniter The useful output was about 30hp.


“Inevitably, the designer came up against the problem of the high gas temperature which was to prevent any

significant advance in practical gas turbine design until the developments in metallurgy engendered by the 1939-45 war. Combustion took place at about 1800 deg C in Armengaud's machine, and the combustion

chamber was lined with carborundum. Steam produced in a steam coil within the chamber was mixed with the gas products to bring the turbine inlet temperature down to about 400 deg C.


“In addition to the work by Armengaud and others in France, the gas turbine received considerable attention in Germany, where in 1910 Holzwarth designed and built. with the help of Korting Bros and the Brown Boveri company, a vertical constant-volume turbine designed to deliver 1000hp; it was coupled directly to a dc  electric generator mounted above the turbine. Instead of the continuous-combustion principle of the Armengaud turbine, ignition in the Holzwarth machine was initiated by a spark generated by high-tension magneto, and the hot gases were passed to a two-stage Curtis impulse power turbine. Steam generated by otherwise waste heat was used to drive a turbo-compressor supplying the combustion air, absorbing a great part of the theoretical total output, and the useful power amounted only to about 160hp.


“Development work came to a halt during the 1914-18 war but it was resumed in 1918 in the wake of interest

shown by the Prussian State Railway administration. In the following year an order was placed for a 500bhp unit driving a dc generator. At about the same time consideration was first given to the use of an internal-combustion turbine for marine propulsion and in December 1920 a Holzwarth unit, arranged for mechanical drive through reduction gears instead of electrical drive, was delivered for trials.


“Like modern machines, the marine turbine had a number of equally spaced combustion chambers (in its case six) arranged around the horizontal shaft; as in the earlier Holzwarth design, the air compressor was driven by a steam turbine utilising the exhaust gas heat for steam generation.  The design of a … turbine of this type for marine propulsion was illustrated and discussed in The Motor Ship for May 1922, but at berst the machine was regarded only as a possible competitor for the steam turbine.


“As it turned out, the complexity of the Holzwarth design and doubts about its material reliability militated against any further commercial development of the marine gas turbine for another quarter of a century.


“Apart from the lack of suitable materials for use in a high-temperature environment, the early gas turbines also suffered from inefficient compressor design. Between the wars, however, the Parsons Marine

Steam Turbine Co in England, and others, devoted considerable effort to the development of axial-flow compressors. In 1938 the Parsons company built an experimental gas turbine employing an engine-driven

compressor of the axial-flow type and thus the way was opened for the development of the small gas turbine for auxiliary power drives.


“Elsewhere, with the added impetus generated by the impending war, the gas turbine was under development as an aircraft jet engine and in 1941 Sir Frank Whittle produced his first successful aero

gas turbine. In the meantime, however, research work continued on the development of what was essentially an internal combustion version of the marine steam turbine, since advantages were seen in its basic simplicity compared with the diesel engine and the fact that it could be run on a wide range of fuels. Compared with the aircraft gas turbine, such machines were heavy and comparatively slow running

but that was considered to be no great drawback; it was expected that engine life to worn-out condition would greatly exceed that of the aircraft jet engine and that on-board maintenance demands would be small.


“In Britain, Metropolitan-Vickers Ltd was well to the forefront in the design and development of gas turbines of the marine steam turbine-derived type. In 1951 a 1200hp unit was installed for comparative trials in place of one of the four diesel propulsion engines in the 12,000-ton (deadweight) single-screw diesel-electric tanker Auris …. The gas turbine unit, which burned diesel or the heavier residual fuel oils, proved reliable in service and in March 1952 the Auris crossed the Atlantic using only the gas turbine-driven alternator and burning furnace fuel oil. No great problems were encountered and the vessel was able to maintain an average speed of 7.25 knots.


“In all, the Metrovick machine ran for about 20,000 hours….”

From The Illustrated History of Ships edited by E L Cornwell, Octopus Books 1979







In the 1970s, a significant number of ships were powered by steam turbines. But during the 1980s and 1990s, diesel engines swept the field, because they permitted substantial savings in fuel costs. American President Lines next generation of container ships, the C-10's, are powered by diesels, and achieved a 60% savings in fuel use over the steam turbine-powered C-8's. The last edition of Containerisation International Yearbook, which lists all container vessels in mZmmercial service or under construction, reveals that only several hundred of the over 7,000 container ships in service were powered by steam turbine engines.”



There are no alternatives to small and medium size diesel engines in marine applications.

Over the last several years, gas turbine engines have begun to be used as an alternative to large slow-speed diesels. Gas turbine use of lighter distillate fuels provides lower emissions. Although gas turbines have been used in military vessels for many years, it is only recently that they are being installed in large ocean-going commercial vessels. Their commercial reliability is yet to be seen.”