new videos
hot off the press!  
    more about rocket
mass heaters here.

more videos from
the PDC here.
  • Post Reply Bookmark Topic Watch Topic
  • New Topic

Wood gas for heat and electricity  RSS feed

 
Justin Jones
Posts: 54
Location: Lake Arrowhead, CA
9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Many of us live in forested environments. When I look around me, the resource in great abundance is... wood products! Live trees and brush of course, but also lots of detritus, old logs, branches, lots of pinecones. This woody biomass contains a great deal of stored solar energy. And I want to tap into that efficiently and effectively.

I want to know - NEED to know - if there is a home-scale system that will accomplish these basic parameters:

Input: woody biomass

Output:
- char
- heat (in the vein of RMH)
- electricity (charge batteries via generator)

Being a forest resident, this is my ultimate energy challenge. I suspect that I will pursue the best solution for the rest of my life.
 
Justin Jones
Posts: 54
Location: Lake Arrowhead, CA
9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
For my purposes, heat and char production are of primary importance. My electricity needs are relatively small and can be met by a stationary bicycle generator, though I understand there's a lot of sweat involved for even small yields, so a cogeneration system is definitely more desirable.
 
Steve Hoskins
Posts: 65
Location: NW lower Michigan
1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I have been thinking about this for a while and also dwell in the forest.

There are a few commercially available stoves which also produce electricity, one is called the Kimberly, i think. None of them (that i have seen) seem perfect to me.

I'll be watching this thread with interest.
 
Marcos Buenijo
pollinator
Posts: 583
Location: Southwest U.S.
12
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Justin Jones wrote:For my purposes, heat and char production are of primary importance. My electricity needs are relatively small and can be met by a stationary bicycle generator, though I understand there's a lot of sweat involved for even small yields, so a cogeneration system is definitely more desirable.


Why char?

How much heat do you need (i.e. northern climate with harsh winters)? Is space cooling necessary during summer months? What about food storage - a freezer is probably the best thing for long term food storage, and that's a substantial electrical load. It seems you'll be using a laptop computer at the very least - well, what about internet connection? This will require additional electricity. Try to get a realistic estimate on the electrical loads you expect to need, and do not low ball there - if anything, be conservative in the estimates. I don't expect even the most modest off grid homes to get by on less than 3 KWh daily.

In my opinion, solar panels are the most practical means to generate electricity in a remote setting, at least in most settings. If a solar array and battery system can meet your electrical needs most of the time, then it makes practical sense to keep a tank of propane to run a small backup generator (assuming infrequent use - that is, only when required to bulk charge the battery and protect from a dangerously low state of charge). I suggest propane because it stores indefinitely vs gasoline or diesel fuel, and I see your electrical demands as very modest. A small Honda generator is a good choice for a very small system (like an EU1000).

Now, let's assume you want to get away from commercial fuels entirely and use wood for electricity generation. In that case, there are three options (well, only two really). A wood gas engine system, a charcoal engine system, or a small piston steam engine.

1. Wood Gas Engine System - The best example of which I know is the system developed by Ken Boak of the UK. See description here: http://www.powercubes.com/listers.html . Mr. Boak has the system set up to run the engine for part of each day on wood chips. Heat exchangers on the system pick up the heat from the cylinder cooling water and the engine exhaust to heat a large store of water in an insulated vessel. The heat is transmitted to the home using a hydronic heating system (pumping hot water into the home for heating applications). The down side of this is primarily the fuel processing required. A second down side is the necessity to operate the system at a fairly high rate to keep temperatures in the gasifier high enough to generate a clean fuel gas. On this last point, Mr. Boak uses most of the electricity generated in electric space heaters just to load down the engine and help keep the gasifier temps up. It's possible to run a smaller system, but the smaller the system the more fuel processing is required - sort of a catch 22.

This system seems overkill for your application. Also, the fuel processing required to run a system like this for primary heat would be daunting. A better configuration for making use of a wood gas engine system would be to use traditional firewood for heating applications, then process only enough wood fuel as required for use in a small backup generator system - sort of like making small wood chips or chunks for a small engine wood gasifier in lieu of storing propane. However, you would need solar/wind/hydro for primary electricity.

2. Charcoal Engine System - This process entails processing wood to charcoal, but capturing the heat from the process and storing in a thermal mass such as water. The heat can then be used for heating applications, and the charcoal can be stored for use in small engines as required. I don't know of a viable system in operation, at least not on a residential scale, but it's clear that it's possible. Note that charcoal can run very small engines more easily and more cleanly than wood.

3. Piston Steam Engine - Personally, I believe this has the most promise. However, it's not practical due to the lack of hardware. There are decent small engine expanders available that are very durable, but one would have to engineer a steam generator with control system and an efficient small wood gasifying furnace to operate unattended - possible, but not for the faint of heart. The benefit of this system is primarily the ability to use wood with very little processing, and the ease in heat recovery (most of the heat is available at the steam condenser). It can also be very quiet and operate at a low output for long periods. Steam engines have also earned a reputation for longevity.

In my opinion, I say stick with PV/wind/hydro with battery system, and use a small propane fueled backup generator as required. Use wood only for heating applications.
 
Justin Jones
Posts: 54
Location: Lake Arrowhead, CA
9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Marcos Buenijo wrote:Why char?


I'd much rather use the carbon skeleton to build soils than burn it for energy production.

Marcos Buenijo wrote:How much heat do you need (i.e. northern climate with harsh winters)? Is space cooling necessary during summer months? What about food storage - a freezer is probably the best thing for long term food storage, and that's a substantial electrical load. It seems you'll be using a laptop computer at the very least - well, what about internet connection?


The winters here in Montana are long and harsh. An efficient wood stove will be essential. Cooling will not be necessary. Food storage is taken care of in the buildings at base camp - so no refrigerator. I have calculated my energy requirements:

- netbook laptop: 30 W x 10 h = 300 Wh
- stereo: 50 W x 5 h = 250 Wh
- modem: 24 hrs x 7 W = 168 Wh

Total: ~720 Wh at maximum usage

Light at night will be provided by candles (which also produce heat). A 12V deep cycle lead-acid battery rated at 130 Ah, discharged to 50%, supplies 780 Wh. With the inverter running at 92% efficiency these power needs could be met with a single battery. I would probably add a second one to cover further inefficiency and reduce strain on the batteries.

Not looking good for the bicycle generator. At 100 Watts production, I'd have to pedal maybe four hours a day just to be able to use my laptop and the modem for six hours.

Please let me know if there are faults in my math.
 
r john
Posts: 134
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
This is the biomass CHP system I am viewing next week.

http://www.volter.si/biomass-chp-micro-cogeneration-products-en-3.html

Looking in particular at how we can utilise the kiln drying facility.
 
Marcos Buenijo
pollinator
Posts: 583
Location: Southwest U.S.
12
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Justin, the math is fine - but I am wondering about the underlying assumptions. Note that a small inverter is probably more like 85% efficient, but the effective efficiency is often much less when used with low loads. An inverter often has a certain minimum draw that can be a significant proportion of a low load, and this can take the effective efficiency (eff) to much lower levels. Also, it's necessary to consider the inverter loss in addition to the load - so, 720 Wh/eff would be the actual load on the battery since the inverter loss is taken from the battery. More important, I'm wondering about additional loads? Fan(s)? Water pump(s)? These can be DC, so that helps.

Definitely it seems a larger battery is desirable. I suggest sizing the battery for 3+ days capacity. I wouldn't suggest this for a high electrical demand. Otherwise, a very large battery would be necessary. Consider that during an extended period of inclement weather it will be necessary to bulk charge the battery with a small generator when it reaches a low state of charge. This will not be efficient and it will be hard on the battery if it's a particularly small battery, and you would have to do it daily. Also, you want to conserve fuel and labor by avoiding the generator until it's absolutely necessary. A larger battery buys time for solar/wind to start producing. There is also the matter of battery charging being very inefficient while the battery is at a high state of charge. Bulk charging a larger battery is a lot more efficient. A common strategy is to not use the generator until the battery is at a fairly low state of charge, then bulk charge up to absorption - let solar/wind take it to float to avoid fuel consumption. Again, propane would solve a lot of problems, but I am assuming you want to stick with wood fuel. If I were in your position (at least as I understand it), then I would go with a "small" 12v forklift battery or pallet jack battery. One model of which I'm aware stores 8 KWh at the 20 hour rate and is rated for 1500 full cycles. This should buy you several days of zero charging if necessary, and it can go a few weeks without a full charge without significant damage. If you were to only bulk charge such a battery when required to protect against a low state of charge, then get it to float and perhaps a short equalization once a month, then I think this would work out very well. I expect such a battery to last many times longer than alternatives you might have considered.

Back to the original thread - if you are looking to make use of wood for electricity and you desire a commercial product to meet your needs, then I see only a small wood gasifier as a possibility. These products might interest you: http://northernselfreliance.com/get-the-nsr-hardware/isabella-gasifier/ , http://vulcangasifier.wix.com/vulcangasifier#!product/prd15/1585769955/m-series-ii-gasifier-refinery-system . Of course, you would need a small generator, and a Honda is best in my opinion. There is also wood processing equipment required. You could process fairly thin branches by cutting into small chunks. However, I suspect this would get old really fast if you were to rely on wood as a primary source of electricity. For backup power only, and with very low electrical loads, then maybe it would be doable. You would need on the order of 10 pounds of green wood (that must be dried before use) to generate one KWh electricity for end use - assuming a reasonably efficient and very small system, and considering all the losses involved. Most of the heat from the system could be captured for use, so that's a plus. There are no micro scale systems that are turn key, so you would have to develop something (not terribly difficult with the gasifier and engine already had). If you're willing to do this, and if you're dedicated, then you will get something impressive with time.

Now, if you are considering long term prospects, then I suggest a small piston steam engine system as a superior possibility for your particular application. However, that's a more difficult prospect since there's nothing suitable on the market. You would have to do some development work. The reason I consider this prospect to be a good match for your setting is the combination of plentiful wood fuel, low electricity requirements, and high heat requirements. Also, the fuel processing required for a small steam system would be a great deal less than a wood gas engine system. It could be made to use small seasoned wood splits. If you're going to be burning firewood for heat anyway, then a micro steam engine system could give you the heat and the electricity you need.
 
R Scott
Posts: 3349
Location: Kansas Zone 6a
32
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I, too, have looked for the "Mr. Fusion" of woodgas, just stick anything in from sawdust to firewood and magically get clean power and biochar and heat.

All Power Labs power pallet is the closest turn-key. Does power out of the box, can be tuned for more char production and easily extract domestic heat. Not cheap. but it is the closest you can buy to what you want in one package. Bigger than you want. They are also open-source so if you can weld you can copy the heart of their system. If I wanted an offgrid house with AC or shop in the deep forest and I had the budget, this would be part of the system.

There are lots of smaller experimenter's systems out there, most of them are not very efficient--they are simply too small to keep the temperatures you need, and not that much cheaper when you get it all together (usually way more $/watt).

Bigger problem overall is material handling--to burn all that stuff you have to get it to your machine or your machine to it, you need to get it consistently dry (easier where you are at but still not a given), you need a consistent SIZE--too small will choke the machine and too big won't fit or burn correctly. There are machines to do this at an industrial scale and ways to do it at a hobby scale, but not a great and affordable solution for homestead scale. Wayne Keith's chunker is probably the closest but it only works on specific types of feedstock. Many of the methods take more time or power than you get out of the woodgas. Even when you get past that, just the volume of material you have to deal with is daunting. A pickup load a day, EVERY day, gets old. If you live somewhere wet, you need to be able to dry and STORE your feedstock all the way through the wet season.

Try breaking up the problem. You will want WAY more biochar than you want power, so work on a large biochar reactor and a small woodgas unit.

Make the woodgas unit multipurpose--put it on an old tractor and get a PTO generator. That way you can haul wood or build gardens or charge batteries all with the same tuned engine/gasifier combination. Or put it on a small truck but add high output alternators so you can charge your battery bank quickly.
 
John Polk
steward
Posts: 8019
Location: Currently in Lake Stevens, WA. Home in Spokane
289
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I have been intrigued by this DIY wood gas generator set up.
http://woodgasifier.org/

If anybody has any personal experience with it, please chime in.

 
Marcos Buenijo
pollinator
Posts: 583
Location: Southwest U.S.
12
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Justin, I lifted this just as one example (see link below). It's a dc voltage booster for using laptops and other electronics from a 12 vdc source. It's designed for automotive use. This should lessen losses. I expect efficiency is on the order of 85% like inverters, but this should be verified. Note that electronics run on dc. So, using an inverter goes from battery dc voltage, to inverter ac voltage, then back to laptop dc voltage. There are unnecessary losses there.

http://www.powerstream.com/Produz10.htm

NOTE: I don't know much about these devices, I am only listing it to make you aware they exist.

 
William Bronson
Posts: 1416
Location: Cincinnati, Ohio,Price Hill 45205
18
forest garden trees urban
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Charcoal power might be your best fit.
You want char anyway, a tlud could be set up to charge a rocket stove style adobe bench, or bell,the modifications to the IC engine are ludicrously simple compared to those needed for woodgas,and char has a plethora of other uses.
But for everyday? Solar makes sense to me.
 
Justin Jones
Posts: 54
Location: Lake Arrowhead, CA
9
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
William Bronson wrote: Charcoal power might be your best fit.
You want char anyway, a tlud could be set up to charge a rocket stove style adobe bench, or bell,the modifications to the IC engine are ludicrously simple compared to those needed for woodgas,and char has a plethora of other uses.
But for everyday? Solar makes sense to me.


This discussion has mainly been focused on my specific energy requirements and how best to meet them. I agree that one the scale of a single person, solar is probably the best option for electricity generation.

However I would like to steer this thread in a more general direction, attending to the question of 'What is the best way to generate electricity, at the home scale, from woody biomass?'

It seems that there are two primary candidates: a steam engine, powered by anila-type char/ rocket stove on the one hand, versus a wood gas internal combustion engine on the other hand. This is really what I am interested in exploring.
 
Justin Jones
Posts: 54
Location: Lake Arrowhead, CA
9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John Polk wrote:I have been intrigued by this DIY wood gas generator set up.
http://woodgasifier.org/

If anybody has any personal experience with it, please chime in.



Now that's more like it! This is exactly the sort of thing I've been looking for. All the other wood gas engines look much too complex and shiny for any diy potential.
 
John Polk
steward
Posts: 8019
Location: Currently in Lake Stevens, WA. Home in Spokane
289
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
This is exactly the sort of thing I've been looking for.

He has built his on a cart, which makes it quite handy, but if it was mounted on a small trailer, you could even tow it to a more remote site with a truck/tractor/golf cart/ATV. Power tools, anywhere on the site, or at the least, the ability to charge batteries in a remote cabin setting.

I believe that on his older site, he claimed something like a chain saw could produce enough chips in one hour to fuel it for seven hours. If that thing could be operated on waste materials, it could 'pay itself off' real quickly.

I would love to hear a review from somebody that has actually built and used one.
If it performs as claimed, it would be a no-brainer to build one in a wooded region.
In the dead of winter, solar panels may not be enough, but if you could take a 5 gallon bucket of wood chips or pine cones and top off your batteries at any time, that thing would be a godsend.

 
Marcos Buenijo
pollinator
Posts: 583
Location: Southwest U.S.
12
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Justin Jones wrote:What is the best way to generate electricity, at the home scale, from woody biomass?


Wood gas engine system used to bulk charge a large battery system.

While steam has the potential to be better in many respects, there is not suitable hardware available.

I suggest a wood gasifier that can handle fairly large wood pieces to lessen fuel processing requirements (imagine 1-2" diameter branches cut in 1-2" lengths). The larger the chunks, then the less fuel processing required - and the larger the gasifier/engine/battery system required. If your electricity demands are modest, then you could set up a system to charge the battery on a weekly basis. By all accounts I have seen, the forklift battery is the most cost effective battery alternative.



 
John Polk
steward
Posts: 8019
Location: Currently in Lake Stevens, WA. Home in Spokane
289
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
While steam has the potential to be better in many respects, there is not suitable hardware available.

The construction/operation of steam engines is not for the inexperienced.
Without proper training, steam engines can be quite dangerous.

the forklift battery is the most cost effective battery alternative.

I worked on a ship that had electric forklifts for each hold. We were set up for underway replenishment of munitions...no room for error. I was greatly impressed by the amount of work that they could perform before it was time to switch in a new one...not an easy task on a ship at full speed at sea, with about an extra inch of clearance. Those buggers were heavy !

 
Marcos Buenijo
pollinator
Posts: 583
Location: Southwest U.S.
12
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John Polk wrote:The construction/operation of steam engines is not for the inexperienced.
Without proper training, steam engines can be quite dangerous.


I agree. Old school steam systems with their large boilers can be dangerous (and expensive!). Joe Blow shouldn't mess with it. Of course, Joe probably shouldn't be doing anything remotely DIY. Until a commercial system becomes available, or unless an individual is willing to build and test a suitable small furnace and safe monotube steam generator for a low power system, then a wood gas engine system is the only thing going for wood => electricity. Hopefully, there will be a commercial small scale steam option in the near future as it is better suited for micro scale CHP with biomass. Something like this would be ideal: http://uniflowpower.com/.

John Polk wrote:
I worked on a ship that had electric forklifts for each hold... Those buggers were heavy !


Very heavy! Good news is there is a nation wide (U.S.) company (GB Industrial Battery) that manufactures and sells forklift batteries with pricing that includes delivery in the 48 states. They will also pick up a discarded battery free of charge (for the scrap). Even if one must transport the battery, then I still consider it worthwhile due to how long these units seem to last in the stationary RE setting. I've seen many accounts showing 15-20 years, and even 10+ years on some accounts that started with a used battery. More important, they seem to be the most cost effective alternative.

In my opinion, if one desires to generate electricity in a remote setting and using only wood fuel, then using a wood gas engine system to periodically bulk charge a fairly large battery system seems the most practical alternative. I think it could be a reliable and even practical set up when electrical demands are low. Justin, I suggest you take another look at Ken Boak's system. Now, he has a much higher electrical demand than you expect to require. However, his basic configuration is what I suggest. Incidentally, Ken also has a small wood furnace for supplemental heat. He uses a central hot water storage tank and provides most of the heating in the home with a hydronic heating system. I like this idea for use with a low power fan coil unit using a DC mag drive pump and DC fan. Sure, it's an additional load, but if you're running a wood gas engine system to charge a 24 volt forklift battery, then you'll have a little more capacity. The engine system should be used to heat the thermal mass whenever battery charging is done. When additional heat is desired, then a more traditional furnace can be used. One might go with a different thermal mass such as those used in rocket "mass" heaters, and there has been some discussion of using the heat from an engine to charge this kind of mass as well. A benefit of this approach is that the intensive fuel processing required for the gasifier is limited by the electrical demand. A low demand means less fuel processing. So, much or most of the wood fuel consumed can be used for a traditional furnace, and this means wood splits.

I'll provide an estimate on fuel consumption for a good wood gas engine system, assuming it operates at an optimal rate for good efficiency. Expect roughly 15% efficiency in the engine system (fuel to shaft work). Battery efficiency is a conservative 80% (assuming bulk charging at a modest rate from a low state of charge). Alternator efficiency can be 80% with a good permanent magnet unit. Throw in a 0.8 factor as some systems would require a dc converter or small inverter, and there is some battery self discharge. This corresponds to roughly 7.7% conversion of wood fuel to end use electricity. This is a realistic estimate assuming a good system, and it's fairly conservative for a good system running at optimal output while battery charging. Green wood provides roughly 4400 btu per pound, so one needs to prep about 10 pounds of green wood for every KWh of electricity consumed. This is an estimate, of course, but it's based on data that I've gleaned from real world units.



 
Justin Jones
Posts: 54
Location: Lake Arrowhead, CA
9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Marcos Buenijo wrote:
I'll provide an estimate on fuel consumption for a good wood gas engine system, assuming it operates at an optimal rate for good efficiency. Expect roughly 15% efficiency in the engine system (fuel to shaft work). Battery efficiency is a conservative 80% (assuming bulk charging at a modest rate from a low state of charge). Alternator efficiency can be 80% with a good permanent magnet unit. Throw in a 0.8 factor as some systems would require a dc converter or small inverter, and there is some battery self discharge. This corresponds to roughly 7.7% conversion of wood fuel to end use electricity. This is a realistic estimate assuming a good system, and it's fairly conservative for a good system running at optimal output while battery charging. Green wood provides roughly 4400 btu per pound, so one needs to prep about 10 pounds of green wood for every KWh of electricity consumed. This is an estimate, of course, but it's based on data that I've gleaned from real world units.





Wow, that is a chilling reality check. Really puts the value of solar into perspective
 
r john
Posts: 134
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Justin Jones wrote:
Marcos Buenijo wrote:
I'll provide an estimate on fuel consumption for a good wood gas engine system, assuming it operates at an optimal rate for good efficiency. Expect roughly 15% efficiency in the engine system (fuel to shaft work). Battery efficiency is a conservative 80% (assuming bulk charging at a modest rate from a low state of charge). Alternator efficiency can be 80% with a good permanent magnet unit. Throw in a 0.8 factor as some systems would require a dc converter or small inverter, and there is some battery self discharge. This corresponds to roughly 7.7% conversion of wood fuel to end use electricity. This is a realistic estimate assuming a good system, and it's fairly conservative for a good system running at optimal output while battery charging. Green wood provides roughly 4400 btu per pound, so one needs to prep about 10 pounds of green wood for every KWh of electricity consumed. This is an estimate, of course, but it's based on data that I've gleaned from real world units.





Wow, that is a chilling reality check. Really puts the value of solar into perspective


Its a chilling reality check because it is so way off the mark. If you check out the details of the Finnish CHP system above which I visited yesterday then fuel input is 189kw electric generated 40kw and useful heat 90kw as listed in there sales brochure with actual performance 5-10% better than that due to our strict advertising laws. Woodchip consumption of approx 43 kg per hour running a 6 cyl gas engine.
 
allen lumley
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
58
books fungi hugelkultur solar wofati woodworking
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
r john : That is a great system, it is also a great big HUGE system, What do you want with such a big unit ! You could run a small motel, and dump the waste heat into
an olympic swimming pool !

I would be very happy with a 2.5 KWatt per hour plant running 12 -24 Volts directly with some battery back up ! I could live with a unit 1/2 that size with 1 cylinder and
the possibility of the future ability to have a PTO!!

I seriously expect that 1 man would be needed for several hours daily to make sure the wood/biomass fuel was conditioned to burn, and then there is 'hauling the
ashes', and loading the feed box, Watching this leviathan would not be the same as sitting beside a rocket stove and dropping in another chunk or three when the
pitch of the dragons roar changes !

The amount of wood consumed for the rating seems reasonable, if you wanted to both heat and run a machine shop, But it appears to be way over the top for most
of the needs of your Fellow Members !

Just my two cents worth ! Big AL
 
r john
Posts: 134
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
allen lumley wrote: r john : That is a great system, it is also a great big HUGE system, What do you want with such a big unit ! You could run a small motel, and dump the waste heat into
an olympic swimming pool !

I would be very happy with a 2.5 KWatt per hour plant running 12 -24 Volts directly with some battery back up ! I could live with a unit 1/2 that size with 1 cylinder and
the possibility of the future ability to have a PTO!!

I seriously expect that 1 man would be needed for several hours daily to make sure the wood/biomass fuel was conditioned to burn, and then there is 'hauling the
ashes', and loading the feed box, Watching this leviathan would not be the same as sitting beside a rocket stove and dropping in another chunk or three when the
pitch of the dragons roar changes !

The amount of wood consumed for the rating seems reasonable, if you wanted to both heat and run a machine shop, But it appears to be way over the top for most
of the needs of your Fellow Members !

Just my two cents worth ! Big AL



Allen
We are very fortunate in the Uk in that we get paid by the government for renewable energy. For electricity it is by what they call the Feed in Tariff (FIT) and for heat the Renewable Heat Incentive (RHI). So long as you follow the strict rules then you will be paid for the heat and electric recorded on the meters. The size of the system becomes irrelevant in individual terms as your needs are covered and any excess is exported into the National grid reducing our reliance on fossil fuels. I was looking at the system as a solution for woodchip drying using the German Hook Bin system outlined in the brochure I referred to earlier which there is a link to in the brochure. With respect to time needed the woodchip required for a month takes less than 1 hour to process with a chipper into IBC containers. Refuelling is 5 minutes per day tipping an IBC container into a hopper with a fork lift using a pallet rotator. Monitoring can all be carried out remotely by mobile phone with any error messages automatically sent by SMS text to your mobile and the factory.

Maybe it is a bit OTT for Fellow Members but I am just reporting how much more advanced Europe is in respect of weaning itself of Fossil fuels compared to the power hungry USA.

Nearly forgot in respect of ashes the 45 gallon drum collecting ashes requires emptying on average once every 3 months.
 
Andrew Ray
Posts: 165
Location: Slovakia
1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I saw this thread awhile ago. Right now, for various reasons, I'm looking at the alternative to grid electricity. Obviously solar is cool, but not so much in Dec. and Jan. especially. I remember, perhaps after reading the above reply about steam turbines, thinking "it would be cool, when will it be available". So today I googled "microturbine" and found some company in India making them, starting at 1kW capacity with relatively low pressure (5 bar).
http://mizun.trustpass.alibaba.com/product/108351168-0/Micro_Steam_Turbine_Generators_from_1_KW_to_50_KW.html

According to wikipedia, dry wood has an average of 4.5kWh energy per kilogram. I wonder how much of that energy can be captured by a rocket stove for boiling water into steam?

I just googled "rocket stove steam boiler" and found this: http://www.kimmelsteam.com/ryanboiler.html

That website has a ton of information on steam engines from old tractors and cars.

I understand there is some risk of explosion with a boiler, but I wonder why over pressure valves, such as are seen on hot water heaters can't also work for boilers?
 
allen lumley
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
58
books fungi hugelkultur solar wofati woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Andrew R. : Our Rocket Stove/ rocket mass heater Forum Here at Permies.com, and our sister site Richsoil.com have a serious bent towards
safety. None of us want to be guilty of advising on a RMH built to a fellow Member and have a 3rd party come along and due to personal inexperience
attempt a build, or a modification of someones build (as he understands It) and Seriously hurt or kill himself or family !

When water dashes to steam it instantly expands 2700 Xs, this is a tremendous amount of energy released and is generally referred to as Boom-Squish
with you being the Squish !

Think Boston Marathon Bombing with more Deaths, injuries, and full thickness full body burns !

One only has to look at the Frankenstien-like machines of doom called rocket mass heaters by their creators, to wince. With the new posting of a
Video of one of these Abominations we can count on a steady stream of badly built Frankin-clones to follow !

This is where I say U-tube is full of crap ! and climb down off of my soap box ! For the Crafts ! big AL
 
r john
Posts: 134
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I must agree with Allen even though I work with steam on a daily basis. There is no such thing as safe steam but there is safer steam which is derived by coils and evaporators rather than use of a boiler. What it means in reality is theres not enough steam within the coils to cause an explosion unlike a typical boiler however it does still have the ability to cause serious burns so needs to be treated with respect.
 
Troy Rhodes
Posts: 626
26
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
"I understand there is some risk of explosion with a boiler, but I wonder why over pressure valves, such as are seen on hot water heaters can't also work for boilers?"


Boilers are far more dangerous that water heaters, even though they look and act very similar most of the time. A water heater safety valve isn't designed to deal with the phase change problems of steam. It vents far far before steam is ever produced.

Pressurized steam (to accomplish real work) is a whole different universe.

A gallon of saturated steam at useful working pressures contains about the same potential energy as a stick of dynamite. In the rocket mass heater discussions about hot water, one often hears the phrase, boom-squish. This energy potential is why.

If something bad happens to a steam pressure vessel (say a pipe breaks and the pressure drops suddenly to atmospheric) the result is almost always an explosion.

There is no safety valve in the world that can prevent that explosion when something breaks like that.

Boiler explosions almost universally look like a bomb went off.


Yes, there are lots of worthwhile safety protocols to reduce the risk of catastrophic steam problems. Most of them involve licensed boiler makers, and licensed boiler inspectors, licensed pipe fitters and licensed operators.

I say this as a libertarian who would like to see 80% of our government to go away. We'd still need boiler inspectors.

I have actually built some model steam engines and stirling engines. I have several books describing how to make small scale boilers.

I have considerable welding and fabrication skills. I was actually a licensed pipe fitter for a time.

Yeah, I can't get up the nerve to make a boiler...


This guy sells steam stuff in about the right scale for what is being discussed here:

http://www.mikebrownsolutions.com/mbsteam.htm



On a very good day, steam power with a reciprocating engine at this scale would be less than 10% efficient from fuel to useful electrical output.


Not meant to be discouraging, but don't want anybody to underestimate the risks either.


 
r john
Posts: 134
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Quite frankly there is no need in this day and age to operate anything with a conventional boiler. Most countries operate on the requirement that you require a qualified steam engineer to operate a steam boiler this has resulted in many companies investing in hot thermal oil systems which with thermal oil steam evaporators can produce steam on demand and the thermal oil is not held under pressure and therefore there is no requirement to employ a qualified steam engineer. Hot thermal oil typically 230C has its own unique problems but at least with good engineering can produce a very safe working environment.

As for efficiency my girls where the rolls royce of reciprocating steam and achieve about 15% electrical efficiency and 75% overall efficiency.

Just an example of what can happen when all the fail safe devices dont actually work its the 4th video on this site.

http://www.claytonindustries.com/clayton_v1_videos.html

The first video also shows how much safer a coil steam evaporator is on a test to destruction with all safety features removed.
 
R Jay
Posts: 34
Location: 54 North BC Canada
2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Steam and water under pressure can be a dangerous combination. www.combustionsafety.com/hot-water-heater-explosion-elementary-school/

This item is in almost every househod......a hot water tank.....

One teacher and six children dead....thirty-six injured.....from an 80-gallon hot water tank running at approx 130 degrees Fahrenheit.....due to untrained "maintenance" people and a lack of a PM--preventative maintenance program. 

Another website http://www.stjoechannel.com/news/local-news/hot-water-heater-causes-home-to-explode/162490349

Nobody was killed or injured....the entire house was destroyed and shrapnel from the explosion was found up to 250 feet away.

Just some observations from a certified steam engineer who worked at BC pulp mill boiler rooms and on hi-pressure boilers in the Alberta oil sands.
 
Michael Deaves
Posts: 8
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Justin,

I am in a similar situation about deciding what to do with my electricity situation in an off-grid cabin I'm planning. I figure I need about 1.25 kWh per day of electricity to get by. One solution I have found is these guys,

http://www.devilwatt.com/

They make a little power bar thing that you screw to the top of your wood stove to generate ~ 70 W of continuous power, with no moving parts. You just need to supply cooling water, which could be done by gravity feed from a spring or roof top run off. I haven't seen any reviews of these things, so I don't know how robust they are. Just because they have no moving parts, doesn't mean that they don't break. 1.25 kWh/day is only 52 W continuous power.

If you are running the wood stove anyway then it might be a good solution for the winter months.
 
R Jay
Posts: 34
Location: 54 North BC Canada
2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Michael Deaves wrote:

I am in a similar situation about deciding what to do with my electricity situation in an off-grid cabin I'm planning. I figure I need about 1.25 kWh per day of electricity to get by.


Hi Michael

You wrote you need 1.25 kilowatts per _hour_ per day.  In  a 12-hour day that would be a consumption of 15 kilowatts.

52 watts of continuous power is 52 watts per _hour_.  I am curious to know what you plan to run off the your system.
 
Michael Deaves
Posts: 8
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Jay,

I meant 1.25 kWh, as in kilo-watt-hours, not kilowatts per hour. Kilo-watts per hour doesn't really make any sense, since a kilowatt is a unit of power, which is already a rate of energy consumption, so we don't need to make it a rate again by saying kilowatt PER hour (that makes as much sense as saying MPH per hour). A kilowatt-hour is the energy that is used by running something that has a power of 1 kilowatt for one hour.

I have no idea why battery and solar people talk in kilowatt-hours, it's just confusing to everyone involved. The SI unit of energy is the Joule, that is what should be used. Power is the rate of energy use, or Joules per second. We call this a Watt. So if you are using one Watt your are consuming energy at a rate of one Joule per Second. A Kilowatt is then 1000 Joules per second.

Now comes the weird part. A Kilowatt-hour, is the amount of energy used by running a 1 kilowatt appliance for one hour. Since a kilowatt is 1000 Joules per second, and an hour has 3600 seconds in it, a kilowatt-hour is actually 3600*1000 Joules, or 3600 kilo-joules.

I think the confusion is made worse by the cooling industry, which rates their appliances in BTU-hours, when in reality what they really mean is BTUs PER hour, which is 1055 Joules per hour, which is 0.293 Watts (Joules per second).

So in my post I say that in my home I will need 1.25 kWh per day, which is 4500 kilo-joules of electrical energy. A 52 Watt generator will produce 52 Joules per second, or 4500 kilo-joules in 24 hours.

I hope this makes sense.
 
R Jay
Posts: 34
Location: 54 North BC Canada
2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Michael Deaves wrote:

Hi Michael

So in my post I say that in my home I will need 1.25 kWh per day, which is 4500 kilo-joules of electrical energy. A 52 Watt generator will produce 52 Joules per second, or 4500 kilo-joules in 24 hours.

I hope this makes sense.


It makes sense...if you are running a 12 volt system and only producing 4.3 amps...that will give you 52 watts of power.

Joules per second....watts...power....equals product of voltage and amperage

You say one kilowatt-hour is 3.6 megajoules, or 3600 kilojoules which is the amount of energy converted if work is done at an average rate of one thousand watts for one hour.
In 24 hours that would be 86 megajoules.... 86 thousand kilojoules.

The requirement is 1,25kWh ..... 4.5 megajoules or 4500 kilojoules produced in an hour.....multiplied by 24 hours is 108 _Megajoules_.....108,000 kilojoules....

Or.....back to Ohms law...1250 watts of power needed---on a 12-volt system that would be 104 amps...on a 24-volt system-- 52 amps...on a.36-volt system--35 amps....

The Devilwatt stovetop thermocouple 70 watt unit produces a maximum of 18 volts at 4 amps

What you plan to run off the your system?
Ohms-Law-Formula-Wheel.png
[Thumbnail for Ohms-Law-Formula-Wheel.png]
 
Anything worth doing well is worth doing poorly first. Just look at this tiny ad:
Thread Boost feature
https://permies.com/wiki/61482/Thread-Boost-feature
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!