"Alternative" energy has been a popular topic in homestead circles for 30 years, but this generally implies solar or wind. We seldom hear about steam -- a simple technology that is more dependable and, in some cases, more practical. This article will help you decide if steam is right for you.
In an era when homesteaders and others interested in renewable energy can buy a wide variety of photovoltaic and wind electric converter components off the shelf, steam power seems to be somewhat quaint and old-fashioned. But in reality, steam might have many more practical applications for homesteaders than solar or wind.
Steam obviously wouldn't be practical in areas where sunshine is ample but water and fuel are scarce. On the other hand, areas where sunshine is limited (especially during the time of the year when energy needs are highest) and winds are unreliable often have ample supplies of both wood and water. In such places, steam power certainly deserves consideration.
The Great Lakes region, with as little as eight hours of low-angle daylight during the winter (and much of that cloudy), a heating season of six months, and abundant supplies of wood and water, appears to be ideally suited to steam power.
The uses of steam
Both PV arrays and wind electric converters transform solar energy into electricity, which is then used to perform useful work. Steam can do the same, and without regard to the weather, time of day, or time of year. But steam can also do much more.
The first steam piston engine was developed for pumping water (in 1690). It can still do that, either directly or by running an electric pump. Thousands were used on small farms for this purpose, well into the 20th century.
Steam engines were also widely used to thresh grain, and to grind it. They cut firewood and made lumber and shingles. They provided power for plowing and other farm chores, for boats and ships, and of course, for railroads. Before electricity became widespread, steam powered most factories, often with a system of shafts, pulleys and belts that could be connected to a wide variety of machines. And earlier in this century more than 100 companies manufactured steam powered automobiles. Even today steam is widely used to generate electricity (sometimes using nuclear power), to cook and process food, and in other applications.
In other words, steam can do everything wind and solar power can do ... and more ... and with greater reliability. But there is an even greater plus for those cold, dark, northern regions: Steam power produces heat.
Skip Goebel, of Sensible Steam, Branson, MO, goes so far as to suggest that producing electricity with a steam engine isn't practical, or at least not nearly as efficient, unless you have a use for the "waste" heat. But at the same time, solar and wind power seldom produce enough power to provide any heat. Therefore, most homesteaders using those forms of energy use solid fuel burning appliances in addition. In these cases, steam power does indeed seem to be "sensible."
Advantages and disadvantages
There are, of course, pros and cons regarding steam power. Just as steam doesn't make sense in a desert region with plenty of sunshine but no wood or water and a limited need for heat, and a lot of sense in places with the opposite attributes, there are many other considerations as well. Most are trade-offs: you give up one benefit to gain another.
A steam engine can be fired up when there is no sun or wind, because it rises solar energy stored in wood, coal, oil, or other fuel. For most homesteads this means wood, which is "free." The trade-off is that wood has to be cut, hauled, split and dried, usually involving being handled several times. It has to be stored.
In addition, steam power requires -- demands -- close attention and supervision. Unlike a solar panel or windmill, or a gas or diesel generator, you don't just install a boiler and steam engine and walk away. This also implies that you need to know a lot more about the technology. The trade-off is that when your neighbors' generators run out of gas or diesel, you'll still be burning wood, or anything combustible.
Compared to a gasoline engine, a steam engine will last practically forever. (One reportedly ran 24 hours a day for 150 years, from 1800 to 1950.)
Therefore, the inconvenience of dealing with an unrefined fuel, the need for a certain amount of knowledge and skill, and far more time spent operating the system, (and some would also include the greater potential danger) is offset by having power on demand regardless of the weather; using a readily available, renewable and "free" fuel; and a durable, easily maintained, long-lasting machine.
Clearly, steam power isn't for everyone. For others, it might be a wise choice ... a choice not only with present and future possibilities, but a romantic past.
The history of steam power
For those of us of a certain age who fondly remember the awesome power in the chugging of a massive steam locomotive and the spine-tingling wail of its mournful whistle, the romance of steam can be even more appealing than its current practical value. The same can be said of even older men (usually) who recall the boyhood excitement when the steam threshing machine arrived at their farm. It can be said that the steam engine played a major role in the development of America and the Industrial Age, but the story begins long before that.
The earliest use of steam power dates back to 130 B.C., when Hero of Alexandria built his aeolipile. The same principle is used today on lawn sprinklers. It produced very little power and was considered a toy or curiosity.
The first steam turbine was also a toy. Invented by Giovanni Branca in 1629, this device directed a jet of steam at a modified very small water wheel.
The first useful steam engines were used to pump water. In 1690 French physicist Denis Papin built a crude device that used steam pressure to force a piston upward. When the heat source was removed, the steam cooled and condensed, creating a partial vacuum, causing atmospheric pressure to force the piston down, performing work.
Just eight years later English engineer Thomas Savery patented a more practical steam pump, followed by the "atmospheric steam engine" built by Thomas Newcomen and John Calley in 1712. This was used to pump water from mines until as late as 1800, although Scottish instrument maker James Watt's well-known engine, which displaced it, was developed in 1765.
Some steam enthusiasts insist that Watt didn't invent anything: the credit goes to his business partner, Matthew Boulton. Watt certainly didn't invent the steam engine, and certainly not by watching steam lift the lid on his mother's teakettle, as many of us learned in school. But after being called upon to repair one, he is credited with making many improvements, including developing the crankshaft, which converted reciprocal motion to rotary motion; the double-acting piston, in which steam was alternately fed into both the top and the bottom of the piston-cylinder assembly to nearly double the power output; the governor, which regulated the flow of steam to the engine; and the flywheel, which smoothed out the jerky motion of the cylinders.
Watt and Boulton sold their engines on the condition that 1/3 of the fuel savings be paid to them -- and the fuel costs were 75 percent less than for the Newcomen engine.
Although Watt is said to have recognized the benefit of using steam at higher-than-atmospheric pressure, practical use of this knowledge awaited improvements in boiler design. These came by the end of the 18th century, in the form of both water tube and fire tube boilers. (See page 40.)
Improved boilers made possible the steam-driven carriage (1801) and locomotive (1803), both built by British engineer Richard Trevithick. (The locomotive boiler exploded.) The first truly successful traction engine was the famous Rocket, built by George Stephenson in 1829. After that, railways expanded rapidly, both in England and elsewhere.
While locomotives were being developed in Britain, Americans were concentrating on steamboats. John Fitch operated one on the Delaware River in 1787. Robert Fulton's famous Clermont, launched in 1807 (using a Watt and Boulton engine), ushered in the age of steamships.
Noncondensing high-pressure engines were developed and widely used in America. Although these were more powerful and efficient, boiler explosions were common during the early 1900s.
The most famous engine of the 19th century was a behemoth demonstrated at the 1876 Centennial Exhibition in Philadelphia. With cylinders 40 inches in diameter, a stroke of 10 feet, and a flywheel 30 feet in diameter, the two-cylinder Corliss engine delivered 1,400 horsepower to drive the 8,000 machines in Machinery Hall.
Within a decade this was dwarfed by a marine engine delivering more than 10,000 horsepower.
Steam engines became common in factories. Usually a single central engine delivered power to a number of machines by use of shafts, pulleys and belts, guaranteed to give any OSHA inspector nightmares.
After using steam to power stationary machines (including one that plowed, by means of cables), large farmers soon adapted steam traction engines ... eventually shortened to "tractors."
Meanwhile, steam power was being applied to automobiles. The Stanley Steamers built by twin brothers F. E. and F. O. Stanley beginning in 1897 became an American legend. They were more powerful than the "internal explosion" gas autos of the day, and because of their torque, required no transmissions. (They eventually used boiler pressures of up to 1,000 pounds per square inch!) Some of these reached speeds of over 100 mph.
During the late 1890s and early 1900s, more than 100 small factories were producing steam-powered automobiles. Most burned kerosene. Their popularity declined during World War I, and production ended in 1929. However, steam trucks were used in England through World War II.
Why did steam power lose out to gasoline? Not because the internal explosion engines were superior. Steam autos had more power, no clutch or transmission, no ignition. No spark plugs, no carburetor, no radiator. Although many people feared boiler explosions, this proved to be groundless. The inconvenience of waiting for the engine to warm up was largely negated by the flash boiler. But that came too late to save steam.
Marketing apparently played a role. Some might liken it to MS-DOS crushing the superior Mac computer operating system. The more powerful promoters of gasoline autos got the upper hand on steam, and ran with it. There is little doubt that if the same amount of time, money and creativity that has been expended on internal combustion engines had been invested in steam, the situation today would be reversed.
But steam still has possibilities. Richard Stegeman, a retired NASA engineer, is one who thinks so. In fact, he has gone back beyond the steam engine, to Newcomen's atmospheric engine, to develop an engine that runs on solar power. (See box)
The parts of a steam engine
The internal combustion engine has become exceedingly complex and ever-more high tech. The source of its fuel is extremely limited geographically, and that fuel is highly refined. It is also a dwindling and nonrenewable resource, susceptible to shortages, and a pollutant. It is, in other words, a good example of high technology and its effects, requiring considerable division of labor, hidden costs and disregard for the environment.
Steam engines are simpler.
Although the heart of a steam system is the boiler, the guts are the engine itself. And since most people find that more interesting, let's start there.
The basic parts of the steam engine are the the cylinder, cylinder heads, piston, piston rod, cross-bead and connecting rod.
The cylinder is a single piece of cast iron, bored out smooth.
The cylinder heads are flat disks or caps bolted to the ends of the cylinder itself. Sometimes one cylinder head is cast in the same piece with the engine frame.
The piston is a circular disk working back and forth in the cylinder. It is usually a hollow casting, and to make it fit the cylinder steam tight, it is supplied with piston rings. These are slightly larger than the piston and serve as springs against the sides of the cylinder. The follower plate and bolts cover the piston rings on the piston head and hold them in place.
The piston rod is wrought iron or steel, and is fitted firmly and rigidly into one end of the piston. It runs from the piston through one head of the cylinder, passing out through a steam-tight "stuffing box." One end of the piston rod is attached to the cross-head.
The cross-head works between guides, and has shoes above and below. It is essentially a joint, necessary in converting back-and-forth motion into rotary. The cross-head itself works straight back-and-forth, just as the piston does, which is fastened firmly to One end. At the other end is attached the connecting rod, which works on a bearing in the cross-head, called the wrist pin, or cross-head pin.
The connecting rod is wrought iron or steel, working at one end on the bearing known as the wrist pin, and on the other on a bearing called the crank pin.
The crank is a short lever which transmits the power from the connecting rod to the crank shaft. It may also be a disc, called the crank disk.
How steam power works
Steam leaves the boiler through a pipe, controlled by the throttle valve. It passes on to the steam chest, usually a part of the same casting as the cylinder. It has a cover called the steam chest cover, which is securely bolted in place.
The steam valve (or valve) serves to admit the steam alternately to each end of the cylinder in such a manner that it works the piston back and forth.
There are many kinds of valves, the simplest being the D-valve. It slides back and forth on the bottom of the steam chest (the valve seat), and alternately opens and closes the two steam ports, which are long, narrow passages through which the steam enters the cylinder, first through one port to one end, then through the other port to the other end. The exhaust steam also passes out at these same ports.
The exhaust chamber is an opening in the lower side of the valve, and is always open into the exhaust port, which connects with the exhaust pipe, which finally discharges itself through the exhaust nozzle into the smoke-stack of a locomotive or traction engine, or in other types of engines, into the condenser.
In most engines the valve is set so it opens a trifle before the piston reaches the limit of its movement in either direction, thus letting some steam in before the piston is ready to move back. This opening, which usually amounts to 1/32 to 3/16 of an inch, is called the lead. The steam thus let in before the piston reaches the limit of its stroke forms a cushion, which helps the piston reverse its motion without any jar. The cushion must be as slight as possible or it will tend to stop the engine.
Setting a valve is adjusting it on its seat so that the lead will be equal at both ends and sufficient for the needs of the engine. By shortening the movement of the valve back and forth, the lead can be increased or diminished. This is usually done by changing the eccentric or valve gear.
The lap of a slide valve is the distance it extends over the edges of the ports when it is at the middle of its travels.
The steam engine itself is of no use without a boiler. (You can test, or play with one however, using compressed air.) Boilers are also simple in principle, but are apt to be more expensive than the engine itself.
The first boilers were merely pans, or kettles, and then wrought iron cylinders, with a fire beneath. These produced steam slowly and were very fuel inefficient.
By the end of the 18th century two distinct types of high-pressure boilers were in use: water-tube, and fire-tube. Both are still used today.
The names are quite descriptive. With a water-tube boiler, the water is in tubes, that are in a fire, or more accurately, in hot combustion gases. A fire-tube boiler is the opposite: the hot combustion gases go through tubes or large pipes that are surrounded by water.
The objective is simple. To make steam rapidly and economically, the heating surface must be as large as possible. Both the water-tube and fire-tube boilers provide far more heating surface than a pan or kettle.
Boilers can be either vertical or horizontal. The majority of small stationary steam engines use vertical boilers.
The most important parts of a boiler are not those that hold the water and fire, but the attachments. An understanding of these is essential for proper and safe operation of a steam engine.
The importance of boiler safety can be dramatized in a single sentence: There is a stick of dynamite in every gallon of water.
It's not enough to know that steam is dangerous. You should also be aware that at sea level a cubic foot of water equals 1,700 cubic feet of steam. (This tremendous expansion is what gives steam its power ... and it's also one reason a boiler should never be located in a living area.)
The first duty of the operator (engineer) is to make absolutely certain the boiler is filled with water. This is determined by the water level in the glass water gauge or sight gauge.
One of the first warnings Skip Goebel issues at a steam workship is that if the water level is low and there is no pressure, do not add water: Put out the fire and get out!
Boilers don't explode, Skips says: other things -- especially pipe connections and pipes -- go first. All safety devices should be doubled, even tripled, for insurance.
For example, in addition to the water gauge, a boiler should have 2-4 try cocks to ascertain the boiler water level. If water stands above the level of the cock, it will blow off white mist when opened; if the cock opens from steam space, it will blow off blue steam when opened.
Technically, if you can see it, it's not steam, according to Goebel: it's water vapor.
Try cocks (sometimes called gauge cocks) should be opened from time to time to be sure the water level is okay and that the water gauge is working properly.
The steam gauge is an essential part of any boiler. This is a delicate instrument that indicates the pressure of the steam in the boiler in pounds per square inch (psi).
It's essential that the steam gauge be attached to the boiler by a steam loop, a tube with a loop in it. This lets the steam work on the water in the tube, and the water cannot be displaced by steam, which might interfere with the proper working of the gauge due to excessive heat.
Arguably the most important part of a boiler or steam engine: the safety valve. This is a valve held in place by a spiral spring (or some similar device) set to blow off at a given pressure of steam. The safety valve has a handle, which should be opened from time to time to make sure the valve is working properly.
One other very important part of a boiler: the fusible plug. This is a plug filled with a metal that will melt at a comparatively low temperature. As long as it's covered with water, no amount of heat will melt it, since the water conducts heat away from the metal. However, when the plug is no longer covered by water -- that is, when the water level has fallen below the danger level in the boiler -- the metal in the plug will fuse, or melt, and make an opening through which the steam will be released. The plug should be inspected regularly for scale buildup.
While it does add an element of safety, the fusible plug should not be depended on to cover operator carelessness.
Filling the boiler
Before startup, a boiler must be filled either by hand or with some type of external pump. After steam is up, the boiler is supplied with water either by a pump driven by the steam engine itself, or by an injector. Most people dealing with steam power will understand pumps, but injectors are unique.
With an injector, steam from the boiler is led through a tapering nozzle to a small chamber in which there is an opening from a water supply pipe. This steam nozzle throws out its spray with great force, creating a partial vacuum in the chamber, causing the water to flow in. Because the pressure of the steam has been reduced when it passed into the injector, it can't force its way back into the boiler, and finds an outlet at the overflow. When the cold water comes in, however, and the steam hits it, the steam is condensed. The water and condensed steam are carried along toward the boiler with such force that the back pressure of the boiler is overcome and a stream of heated water is passed into it.
Needless to say, in order for an injector to work, its parts must be finely adjusted, and with varying steam pressures it can take some experience to get it started.
Usually the full steam pressure is turned on and the cock admitting the water supply is opened a varying amount according to the pressure.
First the valve between the check valve and the boiler should be opened, so the water can flow freely. Then open the valve(s) between the the steam supply pipe and injector. Finally, open the water supply valve.
If water appears at the overflow, close the supply valve and open it again, giving it just the proper amount of turn. The injector is regulated by the amount of water admitted.
Some traction engines have blast valves. This is located on a small pipe leading from the boiler into the smokestack. By opening the valve, steam is allowed to blow off into the stack, creating a vacuum and increasing the draft. This is used only when starting the fire, but also is of little use before the steam pressure reaches 15 pounds or so.
Blow-off cocks are used for blowing sediment out of the bottom of a boiler, or for blowing scum off the top of the water to prevent foaming. A boiler should never be blown out at a high pressure, because of the great danger of damaging it.
It should be obvious from even this brief discussion that using steam power involves a lot more than building a fire and opening a valve. It involves a whole new education.
So ... why steam?
So steam power isn't for everyone. But then, neither is "alternative" energy of any kind.
If you just want power on demand by flipping a switch, stick with the grid. If you don't trust the grid and expect power outages, get a gas or diesel generator. If you want a little more energy independence but still with a minimum of hassle, go solar, or buy a wind generator. And if you cannot or will not invest the time and effort to learn, as well as the money for the hardware, prepare to live with candles or oil lamps and hand tools.
But for anyone who wants to have power without being on the grid, steam certainly warrants consideration. Its biggest attraction today can no doubt be attributed to its use of wood or "waste" as fuel. The advantages of a fuel growing on your own land over gas or diesel are obvious. In addition, the simplicity and durability of the steam engine is a big plus.
But for those who are entranced by the romance of steam, thrilled by the sound of a well-tuned engine running on nothing but fire and water, and captivated by the relatively simple physics involved, owning and operating a steam engine can be its own reward!
There is a stick of dynamite in every gallon of water. One gallon of water turned into high temperature-high pressure steam will fill a 20' x 20' room with 300-degree steam, instantly killing all living organisms. No steam in the house!--from "Mike Brown Steam Engine with Basics of Steam Engineering"; Michael H. Brown, P.O. Box 4884, Springfield MO 65808
Mixing steam & solar
More than 15 years ago, Richard Stegeman noticed that the equipment used to harness solar power was too complicated to be maintained where it was needed most -- in developing countries. Being a mechanical engineer with NASA, he decided to do something about that. His goal was to design a solar engine so low-tech that it could be built and maintained anywhere, inexpensively, without complex tools and skills.
Now retired and living in Arizona (where he moved because of the insolation), Mr. Stegeman has built a prototype of the "Water Heart," the name coming from its resemblance to a human heart. It operates on the principle of the Newcomen atmospheric engine, which was abandoned in the 1700s in favor of the more efficient Watt and Boulton steam engine. Mr. Stegeman believes the atmospheric engine is still viable ... harnessed to solar power.
Instead of boiling large quantities of water to create steam to drive a piston, the Water Heart heats just enough water to create a pressure differential to move a piston. The prototype puts out 1.5 hp, enough to drive a pump for irrigation or clean drinking water. Its only fuel is solar energy; its only byproduct is distilled water.
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|Publication:||Countryside & Small Stock Journal|
|Date:||May 1, 1999|
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