Green Steam Energy
Robert Green, an American Inventor, has developed a brand new technology which generates kinetic energy through the conversion of waste heat (as well as many other fuel sources). The Green Steam Engine is piston powered and designed for a wide assortment of practical applications. These steam engines are easy to build and can be used to power boats, electricity generators, air or water pumps, water distillers, heat pumps, air conditioners and a wide array of other small to medium sized appliances. How-To Plans and Components can be ordered directly through the Green Steam Engine website.
YouTube: Flexible Rod Steam Engine | More Videos
One of the more unique advantages of the engine is its ability to generate energy from the waste heat of engines. Essentially, waste exhaust heat from a vehicle engine can be converted into energy used to some of the vehicle’s cooling systems and pumps. The design is lightweight, small and quiet - making it perfect for many small space situations. This green engine will boost the efficiency levels of any vehicle or machine system it is installed on.
The revolutionary new patented design converts reciprocating movement into rotary movement, greatly streamlining the piston design and allowing for more versatility and project flexibility. There are limitless possibilities and advantages for clean steam power. Some of the main advantages are: less air and noise pollution, high torque at low speeds, multiple fuel capabilities, and long life with low maintenance.
About the Flexible Rod Transmission (from Green Steam).
The properties of the patented crank mechanism (called a “flexible rod transmission”) invented by Robert Green, provides this engine with the advantage of eliminating the typical crankshaft and cam that requires lubrication and precision machining. It also provides the unique configuration whereby the cylinders are aligned in the same direction as the main shaft. The result is a compact, lightweight and slim engine that is extremely simple to construct and assemble.
The pistons and valves operate off a short piece of flexible shaft. Because the flexible shaft is fixed and cannot rotate, the piston rods and valve push rod are held in position while being reciprocated. The cylinders float, attached to a swivel ball fitting at their base. Much of the structure and weight of a typical steam engine has been eliminated.
The unique feature of the “Flex Rod Transmission” is that it produces an intermittent movement whereby the valve movement is stopped in its open and closed position during the power and exhaust strokes. This gives prolonged, fully opened valve timing. In compliment, the pistons are held stationary while the valve moves between phases. The output shaft continues rotation while the pistons stand still. The result is that the efficiency is increased dramatically. The overall friction of the engine is reduced due to the small number of light weight moving parts, and the use of ball bearings throughout. The flex rod is nearly frictionless as the flexing is like a spring in which the energy required to flex it is returned in equal amounts.
This engine may be made in a variety of configurations and sizes. For example, one can change piston size and stroke length in a matter of a couple of minutes. One cylinder may be substituted for an air pump cylinder to provide air or water pumping. It can have one or a plurality of cylinders without increasing the number of bearings.
Green Steam Engine - Plans and Products
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November 6th, 2006
There is a reason it’s called “waste heat.” No heat engine can reach what’s called Carnot efficiency. Carnot efficiency is determined by: n = (Th-Tc)/Th
Where:
n: efficiency
Th: Hot temperature of working fluid
Tc: Cold temperature of working fluid
Th and Tc are both in degrees absolute (Kelvin or Rankine). If your waste heat is 100C and the ambient temperature is 25C then Th=373K and Tc=302K. Tc is greater than 302K because the exhaust temperature of a heat engine is always greater than the ambient temperature. So the maximum possible efficiency is: (373-302)/373 = .19
It gets worse. The Carnot cycle assumes an isentropic process, so the 19% above can only be acheived if the two conditions are met: exhaust gas temperature is the same as the ambient temperature (never happens) and the entire process is isentropic (also never happens). The reality is going to be more like 5%-10% efficiency, with 10% unlikely.
I’ll also point out that this is nothing new. Dual fluid turbines were old when I was in college, decades ago. This is just a variation on a dual fluid turbine.
The next argument will be “well, even if the efficiency is low, it’s still using waste heat, so it must be good because we’re using something that would otherwise be thrown away.”
This argument has some merit, and if a device can be made cheaply enough, using it would be a good thing. The problem is that when you start to consider the cost ($ and energy) of building and maintaining a low efficiency device, it typically becomes clear that the “solution” is worse then the problem. The exceptions tend to be where one is “off the grid” for personal or political reasons, or where there is no grid.
I don’t know where the Green engine will fall out on the energy balance, but so far, very few devices to utilize waste heat are able to do so in a competitive manner.
October 23rd, 2007
If you use a fresnel lens or reflector you could use solar radiation to power the engine. The energy is free so efficiency is not a major issue.
If a closed system was used to power the engine, the formula for the Carnot system no longer holds as the exhaust energy is reused and is not wasted as in an open system.
November 3rd, 2007
I am looking for a wood fired steam plant and engine to generate electricity power about 25 kva.
info@wisemansbridge.com
Dylan Chivers, Zambia
November 10th, 2007
Hey GEOTHERMAL, your argument against this engine based on efficiency has no merit, all the electricity we get now is heat engine generated and subject to the same rules anyway: nuke, oil, coal power plants all use steam.
February 10th, 2008
Yeah this is just a stirling engine. Jerry E. Howell, a model builder builds some really nice engines based on the same principles, even has a candle powered fan that makes me drool :P. http://www.jerry-howell.com/index.html#a2
February 22nd, 2008
It may be similar to a stirling but it definitely looks easier to build. I can see this with a parabolic solar concentrator on sunny days and a hydrogen boiler (utilizing hydrogen stored on sunny days ) keeping a battery bank powered up. Small space requirement, low maintenance, little to no emissions.
March 15th, 2008
The plans are rubbish, the claims for 10 hp are rubbish, the design is weak and no better than a standard steam engine. Small steam plants, and 10 hp is VERY small, are lucky to get 10% efficency with a high temperature differential. Extracting “waste” heat means low temperature differentials which hammers efficiency. So you build this rubbish at some considerable cost in either time or money and you can light a 3V torch bulb. Some things are just NOT WORTH DOING.
Cheers Mark
Currently building a Green Steam Engine for a friend and HATING IT.
March 26th, 2008
Rubbish is a pretty strong word…
I think the value of this engine is that it can be built by people that don’t own a CNC machine, with parts that are very easy to source, is fairly reliable and it can be repaired easily.
I am about to try to get approx. 500 Watts (net) out of a system using a simple solar panel as a preheater, a fresnel lens focused on a simple heat exchanger to flash off the steam. I would recycle the condensate into the system.
To get the same power with PV panels, the panel cost alone would be approx. $2,500 USD. So anything better would be nice.
I would like to offer the design to people in impoverished areas that have lots of sun, such as in the Dominican.
Advice??
Will.
April 21st, 2008
Advice?
Do the numbers work out the theoretical system efficiency with a non superheated 20psi steam feed?
Re read what I wrote, you need a lathe and be competent with it, preferably a mill, the ability to silver solder, and it’s still cack, moose drool, garbage, junk etc etc. O-rings sealing 6mm thick pistons is stupid and has absolutely zero chance of handling much over 20psi. No provision for lubricating the alloy cross head with steel piston rod. A brass valve body and steel rotating valve with no lubrication provision. NO insulation on the cylinders so the heat losses are horrific. Miserable control of valve cutoff. Lousy porting and steam losses.
The plans are pictures with arrows describing the parts, crucial dimensions are missing. There is not one dimensioned drawing in the CD. I have built slide valve steam engines from old refrigeration compressors in a weekend using a drill press. They were pretty average but 20 times better than the Green Steam Engine.
Look round the web. Claims of 500hp engines, three factories geared up for production in 2004 (yeah right) 24% efficiency bwahahaha. Stupid fantasies with no basis in reality.
The simple measurement of the water rate (pounds of water per hp) would show just how awful this piece is. Yes there is a patent and my Aunt Agnes has one for reversible bloomers and she’s nuts also.
Cheers,
Mark
June 11th, 2008
Mark -
I’ll give your comments more weight than any of the others, since nobody has yet seemed to offer any comments based on experience versus based on hand-waving, guesses, and Internet surfing.
I’m interested on your thoughts on this engine not as “designed” (since it sounds like there are no designs provided on the CD, only vague drawings) but on this engine as a concept. While 6mm may be insufficient to handle >20psi, is there a design modification that would make this more feasible? Can the pistons or entire engine be easily insulated to retain heat losses? Is it that the idea of this engine at any “reasonable” efficiency is impossible, or are there modifications that would make it at least useful?
It seems to me that this engine has three main features that are appealing:
1) Low pressure operation (I know that means low power, but if you increase piston size and stroke, maybe this gets better.)
2) Ability to use saturated steam (see #1)
3) No requirement for piston lubrication in the oil, allowing for closed-loop (or nearly closed-loop) recirculation without an oil separator
Other benefits (not primary)
A) No high-precision parts
B) Can be started from cold without petcock valves or risk of condensation damaging the piston
C) Apparently simple and inexpensive construction and maintenance
For a small (<6kw) powerplant, this actually might be reasonable. Capturing and converting ANY high-heat source into DC power as an adjunct to other power input sources seems like a win for me, even if it’s only run for a few hours a day. Certainly, not having to build a high-pressure boiler (and get certification for same) also seems like a win.
However, if there is no way to modify this engine to work at better than let’s say 10% efficiency, then it’s not much better than the refrigeration compressor route.
Are there solutions which compare favorably to the Green design with the 3 criteria listed above? Is it completely hopeless or is it just poor implementation in the designs you were provided?
JT
June 23rd, 2008
Hi JT,
Sorry for the slow reply I hadn’t ticked the follow up comments box.
Lets skip to a bit of theory.
IHP = PALN/33000
This is a tool to figure out the theoretical (Indicated) Horse Power of a stream engine per cylinder
P is mean effective pressure
A is piston area in square inch
L is stroke in feet
N is rpm
If we plug in some numbers 3″ diameter bore 2″ stroke 500 rpm Mean effective pressure 10psi (assuming steam admission shuts of at 50% stroke) and 2 cylinders we end up with about 0.35 hp. Which seems about right. It would push a canoe along.
The next step it to determine what water rate this occurs at which determines the fuel consumption and thus the efficiency. A good unit say 4 hp at 120 psi with a little super heat would be lucky to do 10% fuel to shaft hp. Have a look at Strath steam http://www.strathsteam.com/ they supply units for remote area power to give you an idea of what a unit looks like. You need a good supply of fire wood and preferably a way to use a bucket load of hot water.
If you want some sites to visit (expect to do a LOT of reading) and some references sing out.
Cheers, Mark
June 24th, 2008
Mark -
Thanks for the figures. I didn’t quite get the same numbers as you, though:
IHP=PALN/33000
IHP=( (10)*(3)*(2/12)*(500) )/33000
IHP= (0.076 per piston) * 2 = 0.152 for 2 pistons
Is my calculation for the “stroke in feet” off? 2 inches is .167 feet.
A rough re-calc says that at 50psi avg pressure, 9 cubic inches of piston area per piston, 4 inches of stroke, and 1000 RPM would give 9.09 IHP. Quite an increase in size/speed/pressure to get to that number.
Anyway, the calculation is kind of beside the point. Would you say that this engine method, even with larger pistons and stroke, is a lost cause? The two benefits I see (no lubrication required, saturated low pressure steam) might outweigh the detractions, but only if it actually -works- as advertised.
The Strath Steam stuff is interesting, but as as Mike Brown’s engines. However, they both require fairly high pressure and lubrication, which requires expensive certified boilers and non-recyclable feedwater respectively. I understand the efficiency problems with creating the steam - I’m not thinking that this system is any magic bullet for exceeding any Carnot ‘brick wall’ efficiency barriers.
Would it be worth scaling this engine up to a reasonable size (5-8 hp) or is it not worth the time in your opinion?
JT
June 24th, 2008
Hi JT,
I quoted piston diameter, not piston area in square inches in my preamble. (easier for me to visualize) so 3″ = 7.07 Sq inch.
And no I wouldn’t scale it up, the design is marginal at best and even at the as drawn size at 50psi it will simply flog out.
You don’t need lubrication in the steam at 120 psi as long as you have no super heat. I run our steam boat with no lube but I do lubricate at shut down to keep the rust worms away (Can’t afford an all bronze engine!). The boiler water no matter what pressure should be treated other wise you will lose the boiler to the corrosion worms at an appalling pace and even 20 psi is a boiler. A boiler at 20psi producing enough steam to run 5 hp is going to be a big piece of kit just to get enough heating surface, and will still hold a lot of energy. You don’t ever want it to let go. I’ve dealt with a 200L oil drum idiots had got up to about 10 psi due to chemical reactions inside it very very scary and it was only lukewarm.
There are ways round this ie monotube but to get then to run stably requires a LOT of faffing about, and probably sacrifices of virgin stokers over James Watts grave at midnight.
Do you have local steam boaters? regattas you can travel to? You can find a lot of hands on and any steam boat owner will happily bore your ears off. We love to talk steam
June 25th, 2008
Mark,
It sounds like you have a lot of experience with steam engines.
I am interested in the sites you mentioned and also any information you might be able to provide about converting another engine to a steam engine. I am interested in making an engine in the 5hp range or so.
Thanks
June 26th, 2008
Mark -
Thanks for summary again. Yes, I’ve got some steam classes under my belt now running traction engines at the NW Antique Powerland location - those are >250 gallon systems at 60hp or so.
I’ve got myself a fairly small boiler that is “awaiting restoration” - see http://www.loligo.com/projects/steam/boiler/ and follow the obvious links for pictures. It’s not a tube boiler, and it’s terribly inefficient, but it’s a start - I’ll build a Yarrow boiler or something better after I get some more soot under my fingernails.
I’d never leave a boiler alone, no worries about that. My goal would be 75psi. And I’d treat the water in the boiler for anti-rust mixture, but being able to recycle the water without running it through an oil separator would be ideal. So I’m encouraged by your comments about running your engine without lubrication, but that goes against what I’ve learned and read.
Ideally, I’d like to use rainwater to avoid mineral buildup. I’d like to recycle the water without gumming up the boiler, since rainwater is a limited resource. This implies running without lube oil or getting an oil removal system, and I’m trying to avoid complexity and cost, hence my interest in the Green design.
Thanks for your comments on the Green steam engine. I’ll put my efforts first into my single-cylinder horizontal before I experiment with the Green system, but it sounds like you have little faith that the Green design could be used to efficiently get ~10hp.
JT
June 27th, 2008
I bought a set of plans out of curiosity and I have to admit that Mark is correct. The joints are crude and not steam tight. The great claims for the patented spring link are a bit of a joke.
Monotube boilers (flash steam) don’t need certification by the way and don’t need to run at high pressures. They do need some experimentation as there is little hard information about them. The most famous monotube was in the Doble steam cars. A great deal of info is available in older model engineering publications as flash steam boats used to hold all the speed records
July 5th, 2008
Hi, I’m a bit clueless on thermodynamics.
Anyhow, I have an unlimited suuply of wood.
I need at least 2 steam engines which are 35 hp.
Can anyone give me info on building them???
Thanks!
August 28th, 2008
Sir,
I am Rachin.UR B.Tech final year student. I am interested in taking a seminar about GREEN STEAM ENGINE. Please give me more detail about this engine. My email is “rachu0423[AT]yahoo.co.in”
Thank you,
rachin.ur
January 27th, 2009
I have built and operated a home power cogeneration plant, an automatic coal fired cogeneration system, using 135 psi steam in a small uniflow reciprocating engine, driving a generator. A paper was presented at the ASME Joint Power Generation Conference in 2003, giving details of the system, along with a diesel engine system of similar application. It is paper No. IJPC2003-40192, titled “Experience with Early Distributed Generation Systems”.
Having much experience with small generation systems and steam machinery, I must agree with virtually all of what Mark Stacey has presented.
Fred Rosse
February 22nd, 2009
What if you could power the generator with a closed system steam engine?
I have a way to generate incredible amounts of heat to drive the steam engine.
I wish I were an engineer so I could build a prototype.
How does a person go about obtaining a grant from the govt?
The only overhead involved is the original outlay of money for the engine, the generator and the land to place the units upon.
It’s hard to trust anyone these days. I am afraid that if I share my thoughts that my idea will be stolen and I will get nothing for the invention.
March 2nd, 2009
Hello Steamers-
Thanks JT and Mark for the discussion. I had high hopes for the green steam, but it is not sounding so great now….. Although I still may tinker around with recovering some energy from a shunt loop on a solar water heating system and trying to recover heat from the condenser. I was thinking of a closed loop (boiler-engine- condenser-pump ) that would contain a fluid with a boiling point of around 120 F. Any recommendations for a fluid with that kind of a working temp? As you can probably tell I’m new to the concept so any tips and pointers would be great.
Thank you!
June 2nd, 2009
Low temperature geothermal is being utilized right now to drive turbine generators at a site in Utah and the power is being sold to Anaheim, California. Raser Technologies utilizes a proprietary, low temp. process to boil a liquid (ammonia? freon?) to drive turbines in a closed loop system. There should be no such thing as waste heat.
August 24th, 2009
This is not a Stirling and is not rubbish. In fact this engine has been in trials with the US Army for some time, I have seen it running on a minimal heat source and not only does it work, it is instant-on and quite powerful while light-weight and nearly friction free.
Bottom line… Bob Greens inventions work and work well for not a lot of cost. His process and tech is always brilliant in simplicity.
November 6th, 2009
What differs this design from the old Steam Locomotive. See http://www.animatedengines.com/locomotive.shtml
Pistons attached to a mechanism that turns a flywheel. The multi-piston approach is worse because the more mechanical pieces you have the more friction there is. There are Rankine cycle turbines that can efficiently gather waste heat right now. Its just that they cost a lot and very little energy is recovered.
November 6th, 2009
Comment not, Tex, unless you have seen it for yourself. The 12 cylinder still has only 1 bearing!