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January 2, 2012 at 2:00 am #36978
Anyone considered making a small steam powered generator?January 2, 2012 at 4:40 am #42149
You can do that, It would not be as efficient as in converting that same fuel to a gas and powering a combustion engine generator however. I think it would require 1.5 times as much wood to produce the same amount of electricity using steam power as wood gas for example. Or said another way using the same amount of wood you would get 2/3s the power from steam as from wood gas combustion. That’s a crude estimate by the way.
This problem wouldn’t stop me from doing it though. I have seen kits for twin piston steam engines on the net that run on 25 psi.. $200 roughly.January 2, 2012 at 9:32 am #42150
When most people think of steam they think of the older designs that are open circuit. A great deal of waste heat escapes by being vented to the atmosphere. Closed loop systems were developed for ships and research continues to this day. Gizmag recently carried a story of one new prototype with 37% efficiency that developed 100 HP. A bigger design for 350 HP is already bheing made. The expectation is a 50% efficient version is feasible but it is somewhat high tech because it involves heat recovery and condensing spent steam back into water. Not exactly suited to your typical DIY homebrew machine. However for someone with the requisite machining skills and the necessary machining facility it is feaSIBLE.January 2, 2012 at 4:46 pm #42151
I wasn’t even aware of wood gas ability to run engines. Very cool, thanksJanuary 5, 2012 at 10:31 pm #42161
Steam engines dating from WW2 and newer require water of high purity quality. Mineral laden well water or creek quality would in most cases cause undesirable build up of calcium and other dissolved minerals.
Older steam engines dating from 1850 – 1930 era had extremely low efficiency. This resulted in extremely high fuel consumption be it wood, coal or lastly some form of fuel oil.
Steam power continue to be used in US naval ships although the oil burning heat source has now been replaced with a nucllear furnace. It was the need for frequent refuelling that prompted a shift to nuclear power but not before all the woodland along our rivers had been consumed by the voratious steam engines of the paddle steamer era.
The lack of fresh water also prompted sea going ships to develop extremely efficient steam power with triple and quadruple expansion piston engines and later steam turbines with condensate recovery to minimize loss of steam quality pure water.
A tiny high pressure steam turbine would likely be a viable off grid generator in areas with access to cheap firewood or coal.
In our area many of the mills developed cogeneration steam plants to generate the power and heat needed by the mills. A scaled down version of a cogeneration plant might still be a viable power source for an off grid homestead. Don’t forget all these remote mills were in effect off-grid even if their size is more like a small town. There is a forum dedicated to micro-cogeneration and this forum featured an article about one of the micro=cogen list members living in the UK about a year or so back.
In a nutshell many of these members focus on running a 15 HP twin cylinder motor turning an AC generator while recovering all the waste heat for house heating. It does not have the sex appeal of a solar panel system and does require considerable technical expertise but it does work.January 6, 2012 at 9:03 pm #42162
Here is the link to the steam engine I was refering to.January 30, 2012 at 3:46 am #42233
I have been tinkering with a steam engine made from an opposed twin kohler with a 20 inch heavy flywheel. I’m using an old portable air tank for the pressure vessel and directly plumbed into the sparkplug holes. runs strong at 40psi and runs a single wire delco alternator up to 35amps 12 volt charge power for batteries. Although crude stages of building now I know that I can charge batteries in the event that diesel fuel is not available. As far as efficancy goes i live in the woods and the trees offer plenty of branches to collect and burn for free.February 3, 2012 at 6:40 pm #42253
Instead of burning wood to make steam, consider using a Stirling engine to generate the power from burning wood. Although the resource of natural wood is available, its the time needed to gather the wood and keep feeding the fire that is wasteful. Time better spent in other activity such as food production and storage.February 4, 2012 at 2:12 pm #42255
Yes a solar powered Stirling engine would be cool but I haven’t seen one yet that is twenty hp. Or that is in my price range..Like free. Like most folks we only run the genny when we have no wind or sun, So it is not that big of a deal. As I said it is just something that I’m tinkering with, Crap that I found for free.February 4, 2012 at 10:51 pm #42256
SES out in California is scrapping their entire stirling solar power system so maybe you could scrounge something there. They don’t want to be bothered with the mechanical maintenance. These units were on trackers.
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