MadSci Network: Engineering

Re: Why is steam power being ignored for alternative fuel vehicles?

Date: Wed Aug 25 13:11:21 1999
Posted By: Adrian Popa, Directors Office, Hughes Research Laboratories
Area of science: Engineering
ID: 934993372.Eg


There are many types of engines for doing work and they all have one thing 
in common, they convert high temperature liquid, solid or gas materials 
into low temperature liquid, solid or gas materials and they extract power 
to they do  useful work in the process. These processes are based in the 
laws of THERMODYNAMICS. Generally, the greater the difference between the 
high and low temperatures, the greater will be the useful power output and 
efficiency of the engine.

Engines that run on gasoline, methanol and diesel fuels are called internal 
combustion engines (ICE) and they use the rapid explosion, heating and 
expansion of a compressed fuel air mixture in an enclosed cylinder to drive 
a piston downward during the power stroke. Currently internal combustion 
engines have a number of advantages over external combustion engines with 
the explosive fuel being part of the heating process being a major 

Steam engines are external combustion engines (ECE) and they use an 
external fuel combustion process to convert liquid water to high-pressure, 
high-temperature steam in a boiler. The high-pressure, high temperature 
steam is then transferred into the cylinder to drive the piston during the 
power stroke. However, a steam-generating boiler and heater also have to be 
added to the vehicle to run an ECE engine. Because steam engines run at 
lower pressure and temperature differences than ICEs, they must use larger 
diameter pistons (greater volumes of gas) to produce the same amount of 
drive power and thus they are less efficient. 

The inability to rapidly build up steam pressure from a cold start has 
always been one of the drawbacks of steam engines and a number of flash 
heating concepts have been tried and proposed. See the laser flash heater 
proposal in the Mad Science archives (Rick Hall, Wed Aug 18 12:56:52 1999. 
Engineering: Re: Use laser(s) to flash heat water in a small tube(s) to 
power a car? )

As you suggest, fixed rate of combustion processes for steam boilers and 
also for hybrid electric vehicles can be designed to generate far less 
pollution that current ICEs. Here in California, to reduce air pollution, a 
number of manufacturing plants now use pure oxygen instead of air with 
petroleum based fuels for their ICEs and heating systems. This combustion 
process eliminates the harmful nitrogen compounds released when using air 
as an oxidizer. However, the oxygen must be stored in large cryogenic 

The hydrogen/oxygen fueled engine and or boiler would be one of the 
cleanest engines with water and steam being the residue from the process. 
One of the problems with these engines is to safely store hydrogen fuel and 
oxygen oxidizer. In California we have a number of hydrogen fueled busses 
operating which use the oxygen in air as an oxidizer. They are very clean 
but do produce some nitrogen compounds. The busses use large hydrogn fuel 
tanks filled with hydrogen absorbing materials such as nickle hydride to 
reduce the pressure in the fuel tanks. 

Hydrogen/oxygen fuel cells that can generate electricity in a clean process 
is another concept being studied for electric vehicles. Currently, cost 
effectively generating, storing and delivering hydrogen gas is an important 
part of the fuel cell concept being studied. A search of the Mad Science 
archives for fuel cells and hydrogen will return a large number of 
questions and answers that address the problems and potential of using 
these environmentally clean processes for motor vehicles, spacecraft and 
for aircraft.

Currently, research on fuel cells, new batteries and hybrid vehicles are 
the concepts most favored by the world’s automotive industry for future 
clean vehicles. The infrastructure to deliver the fuel to the consumer is 
also an important part of the process.

Best regards, Your Mad Scientist
Adrian Popa 

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