Our recent developments in steam power are exciting. We are committing to the first prototype of a stationary, distributed power generator. This is our high-appropriate technology route to biomass-based power systems, while higher tech, proprietary systems like the Cyclone steam engine have already proven several improvements over gasoline engines: (1), higher efficiency; (2) clean burn; (3) complete fuel flexiblity; (4) and water lubrication that displaces the need for engine oil. While not as high tech as the Cyclone – our initial prototype of a stationary power generator is only a beginning. Hear a discussion with Tom Kimmel, Steam Automobile Club of America (SACA) President – on the prospects of steam, distributed generation, and building from there:
SACA’s Tom Kimmel on Distributed Generation from Marcin Jakubowski on Vimeo.
The good news is that SACA is a goldmine of talent, they are willing to share openly, and to us it’s clear that we should take advantage of this opportunity before it disappears with the aging of SACA members. We’ll keep you updated on developments, such as itinerary planning for our steam tour across America, as well as technical developments.
Distributed power generation is a clear goal – the next major field of endeavor for Factor e Farm, which would allow us to fuel our operation for free – from agriculture, off-grid fabrication workshop, to living and transportation.
We’re now completing the LIfeTrac II/Power Cube II/Soil Pulverizer II product ecology and beginning prototypical, modular CEB construction – and by next year, our goal is to have an initial prototype of the LifeTrac tractor running on steam power – even if slowly. It’s just a matter of evolving a system for higher power. We already know that steam tractors were responsible for opening up this continent to agriculture at the beginning of the last century, and we know that the Land Steam Record is about to be broken next year by other people from SACA.
I’m very encouraged to see you focusing on micro steam power. The problem with power generation has been that it is dependent on specific kinds of fuels or large scale infrastructure. The ability to burn about anything to generate usable power will be a foundational building block to Open Source Ecology.
I think you’re going in the right direction.
Very excited about the steam project here and to that end I’ve been reading up on thermodynamics. I found a treasure of a book, Principles of Thermodynamics by George A. Goodenough. (with a name like that how can you go wrong) Published in 1920 and available on Google books, he devotes chapters to steam flow, steam engines, and steam turbines.
I’ve read enough of the book to experience a revelation. The revolutionary potential afforded by modern materials and micro processor control is not in a reciprocating engine, it’s in a single stage impulse turbine.
It’s like this; yes the Arduino and a solenoid valve will give us infinitely variable cutoff, but the old-timers could adjust cut-off very well too. And we’re constrained by the same thermodynamic cycle efficiencies they were. But when we consider a small impulse turbine we have advantages over the old-timers.
Paraphrasing Goodenough: the most efficient impulse turbine will have a peripheral velocity 1/2 that of the steam velocity from its nozzles. The steam velocity is a function of the difference in temperature from the boiler to the condenser, and as we all know the higher the difference in temperature the more efficient the engine.
Then, as now, impulse turbine peripheral velocities ought to be as high as 520m/s, but the old-timers didn’t have materials which could stand that kind of load, we have carbon fiber. They didn’t have bearing which could spin at 40,000 rpm (necessary to achieve 520m/s peripheral velocity with a .25m turbine), we have foil air bearings. They didn’t have a good way of efficiently throttling the engine to produce partial loads, we have Arduino running solenoid valves at whatever duty cycle is appropriate.
The old-timers built turbines with multiple stages of large wheels to overcome their limitations. Today we can do better, much better. Modern materials and controls will make possible, for the first time, a small, single stage, variable load, impulse turbine. Consult Goodenough for the efficiencies of such an impulse turbine, and you’ll see the revolutionary potential.
Tell us more about the bottom line efficiencies of the single stage impulse turbine. It was my impression that reciprocating engines show better efficiencies at scales under 500 hp. We agree completely that at this upper level, turbines are the way to go – but are you suggesting that they should be applied in much smaller cases? There is mechanical efficiency and thermodynamic efficiency to consider – are you considering both in the equation?
Both the reciprocating and turbine engines are based on the Rankin cycle, so the thermodynamic efficiency is the same. Each engine, given ideal conditions, can produce equal work with a given mass of steam and entropy difference. The question becomes, which engine can make a better small motor?
The largest efficiency loss, according to Goodenough, in the reciprocating engine is steam condensation and subsequent re-evaporation on the cylinder walls. The process has no effect upon total heat but it does convert a considerable portion of heat available to do work into heat unavailable to do so. This inefficiency is multiplied is a small engine because a smaller cylinder has a greater ratio of surface area to volume than a large cylinder. Therefore, condensation losses are greater is a small engine.
The greatest efficiency loss in a steam turbine is leakage around and friction between the steam and the several stages of rotors and stators. The proposed impulse, some say velocity, turbine is a single stage affair, with proportionately less leakage and friction than a multiple stage commercial turbine. A small, single stage, turbine minimizes the leak and friction inefficiencies of the engine.
You see what I’m getting at here? Building small exacerbates the weaknesses of the reciprocating engine while minimizes that of the turbine. Only material deficiencies prevented single stage impulse turbines from being developed in the heyday of steam.
Ok, you want numbers.
The impulse turbine has two major parts to consider, the nozzle which converts pressure to velocity, and the turbine rotor which converts that velocity into angular velocity. With fast enough turbine speed it is possible to transfer into the high eighties percent of the kinetic energy in the steam into the rotor. A practical number is 86%. The nozzle is isotropic and given that we only have to design for one pressure (thanks to the Arduino controlled valve) we can realistically achieve 90% efficiency pressure to velocity. Friction in the bearings will be minimal, as will be steam friction against the single rotor, so our mechanical efficiency can be 75%.
Set the condenser temperature to 68F, (293.15K) and super heat the steam to 250C (523.15K) and we have thermal efficiency (Qa) at 44% x 75% = 33%. Not too shabby.
Is not the mechanical efficiency of a steam engine in the 95% efficiency range or higher?
There are projects in Israel, Spain, and California using steam boilers using the suns’ rays, focused on them by large mirrors.
a turbine setup could use an old turbo charger with the oil bearings. I know a lot of gas turbine (jet engine) builders use those for their off the shelf turbine parts.
I question the efficiency of a turbine at low HPs, as well as the long-term durability of 40,000+ rpm vs 500 rpm.
When can we expect to see a basic steam prototype? And what size are you hoping for, 1 hp? 10hp?
[…] Distributed power generation is a clear goal – the next major field of endeavor for Factor e Farm, which would allow us to fuel our operation for free – from agriculture, off-grid fabrication workshop, to living and transportation. […]
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