Great topic. I would suggest using the metric U value system to estimate heating requirements, for some reason to me the metric U value makes more sense than the R value system, watts of energy transfer per square meter of surface, based on temperature difference inside to out. To come up with a heating requirement over a season you would then just need to know the approximate insulation value of the building, and the average temperature for that season x the hours of that period.
The heat pump systems are becoming more popular in the north, in principle they should give you about 4 watts heating energy out for each watt of energy to drive the system. As Tom cautions though, the mechanics of a system might be it’s downfall. I do know that the payback is very long even in a cold climate once you pay a contractor to install a ground loop. However, if you have ample well water, you can avoid the cost of a ground loop, and just use the ground, or a body of water as the energy source. http://wellconnectgeo.com/
I have been thinking for a long time that modifying the heat exchanger on a 10 or 12,000 btu ac unit to exchange heat from water would make a basic core of a unit.
No heat pump system is going to be practical for off grid, though in the north a cooling system is very easily achieved exchanging heat into cold well water, assuming a shallow well.
I have another idea that fits this topic, alluded to by Jo. Why not use the ground itself as the storage medium, rather than water tanks? Ground can be heated, or cooled to provide a highly efficient storage medium. Energy losses from a monolithic block of earth heated or frozen will be very low, and the larger the area used as storage the more efficient it will be.
In the case of Manitoba, our climate is extreme, deadly cold in winter, and often uncomfortably hot in summer. Often I have wished for a whisp of snow in July, or some summer heat on a day like today. Storing the cold and heat for later use would address our needs.
I was meaning to get a ground loop set up this fall for an offgrid refrigerator, but haven’t set it up yet. Our ground is cold enough at depth to serve for refrigeration, about 42F, or 5.5C. The idea is to bore 10 foot holes, and set 2 or 3 loops of 1/2" copper pipe into holes, then run glycol through insulated hoses to a steel / aluminum block inside a mini fridge, circulated by a 12v pump powered by a designated solar panel. During the winter when the cabin is at ambient temperature, the ground loop will eventually be frozen to perhaps -20C, then providing excellent refrigeration the following year. The only question will be how much ground loop for effective refrigeration.
A larger system could use a central air heat exchanger, or perhaps something larger, to exchange heat from a large mass of earth, producing a large block of permafrost.
The same concept will apply to heating. If coolant is used, (or perhaps steam), a mass of ground could be raised to very high temperatures for later use, if using an adequate heat source, say a charcoal kiln, solar flat panels or a solar concentrator array: http://www.builditsolar.com/Projects/Concentrating/concentrating.htm.
Interesting topic ChrisKY.
I like that you have as a practical matter simplified BTU’s to kilojoules.
Here is a fellow woodgaser/whole home woodheater guy in southern Oregon done what you postulate: www.mbryner.fatcow.com/docbryner/mossy_hollow/Home.html
Ground under the house water thermal storage is under the sub-section Thermal Storage. His current heat input is his masonry/mass wood-heater.
This link will put you up on his home page.
Super important to understand that he is trying to come up with a TOTAL off-grid energy living solution!
He has kilowatts of PV solar. Battery banks. An off-solar-season system recharging compression engine able to currently fuel off of pump diesel/vegetable oil/waste motor oil. “Waste” heat from this is not wasted but used to heat his PowerHouse for his current heavy-oils fuels and his battery banks.
Read his site projects and find that his micro-hyro has “failed” to reliably produce and deliver outside of a few weeks of spring flow.
Not stated, but work/efforts there set him back with house roof-top solar-thermal development.
He is on over a hundred acres, so compex-tech-idealism’s systems; good-bad-failed, are always able to be backed up with his always growing trees and brush.
Another proof-of-concept validation source of information is here:
Very, very information dense, four layers deep site.
Their 40,000 hour life engine system produces 4.4 kW/electric and 11.5 kW/thermal(in heated water flow) an hour just as long as you can feed it natural gas or propane.
Of course this could be woodgas fueled too.
Simple-is-best. Look at MB’s pictures and you can see it can get complicated and maintenance demanding real quickly.
Really for space heating nothing gets simpler than rural property owning and growing solid solar energy storage. Even after cut solid-solar-energy can be years stored without “corrosion treatments”, “fuel life extender additives”, “anti-algae treatments”.
A modern 72%-80% efficient multi zone woodstove. A modern double wall insulated SS chimney system; and good to go, simple and direct.
Now past a grow-your-own-trees, simple-and-direct approach . . . .
A fully self-standing home energy system.
We all need some daily electrical power.
We all need some daily mechanical power.
We all need some daily HOT potable cleaning/washing water.
We all need some annual space heating.
Most will need some annual space air cooling/dehumidifying. (this Marathon engine design was originally by Briggs& Stratton for one of the big HVAC companies systems for off-grid resorts applications.
Solar as PV and direct water heating can do some of this. But only part of the year.
Wood could do this as heat making and engine fuel all of the year. But the “heat waste” in the not space heat needed times of the year.
MASS waste heats storing of this gasifer and engine heats from times of not-need. To times of need-more-daily than a small resonable engine-generator system can daily produce is what give’s Chris’s topic merit.
This has been modern era proposed off and on since at least the late 1980’s in Europe.
Integrated home energy systems WITH a small efficient internal combustion piston engine able to home sully all of the home needs for electricity, mechanical power, domestic hot water, and space heating.
Systems actually trial designed in Italy and Germany.
Eroded sunk thier by Greens.
Eroded sunk here US and Canada by traditional Grid and Big-Energy suppliers. They directly attack bidding up “standards”. Indirectly erode by “Greens-Initives” funding.
Expect to see these types of systems instread coming out of Japan and Korea.
Honda and others are already 2/3rds the way there with their now offered up for use in the greater Asia and Micronesia areas.
The learning information exchanged between their hybrid vehicles and whole-home energy systems is what is push/pulling their advancements.
DIY you can achieve with current off-the-shelf components the majority of benefits of a factory designed system.
But only if you approch from a Total Annual Home Energy NEEDS honest approach from the get-go.
THEN an energy excess at one time more easily appreciated as a needs full-filler for a time of lacking!!
Our CHP systems have three sources for waste heat to water systems. The engine coolant is the simple one, that just has a flat plate heat exchange unit or you can bypass that and go direct if you have a pump that can supplement and keep enough GPMs going into the engine.Something to think about when taking engine heat, you can not take all the heat. the engine needs to run at 160* this the tolerance they are designed to run at. If you could heat an engine up and supply it with oil presure you could free wheel it quite easily. The Exhaust has a multi pass heat exchanger this is a drain dump system but could use antifreeze if desired. The third is our liquid cooled gas chiller. All three can be tied together, separated or any combination of the three. Applications and the ways of doing this are endless. There is a fourth system and that is simply removing heat from our enclosure and that can be used for fuel drying. Instead of venting it out with the stock fans. I was thinking when we get ours if we ever get one, we will install multiple hot water heaters and the waste heat will be the driver for the heat into them. However since our system will not be full time they will draw some electric to maintain them during off times.
Net search up “Honda CHP Systems”.
Reference links and youtubes of their systems developments from 2003 thru 2012. Smaller and smaller. The later versions with system supplied battery pacs and independent from grid capability after the Japanese earthquake.
They claim 60,000 systems put in place world wide in a 2012 newsletter.
Similar systems are becomeing more and more popular here.
My coworker built a house a few years back, his heating is similar to your idea.
He digged channals 5m deep(just under the ground water level) with a surface area of about 2x the surface area of the house. Ha layd pp pypes on the bottom and filled them with antifreeze.
In the house he has a heat pump. Water circulates trugh the ground, sucking energy from the water/ground, and the heatpump thain collects all the energy.
He is pleased with the resaults. Its quite an investment but he says it will pay off within l think about 10 years.
A nother way is to dig a well far enough from your house, and a deel well near your house. You pump the water from the house well, put it trugh the heat pump, and return the water trugh a pipe in a far away well. Its a cheaper solution but all this depends on if you live in a right location.
My father has such a well type heat pump system at his, he runs a big cafeteria so he needs a lot of hot water. The heat pump l think produces about 3 or 4 kw worth of hot water for every 1kw of electricity the pump consumes. Quite some saveing
Steve, whatś your opinion on the Stirling?
I often thought if I ever were to live off-grid that would be a good alternative for battery charging. Could run of the waste exhaust heat from a boiler or a stove. Swedish submarines use Stirlings. More suitable small 750 W Stirling generators I´ve seen used in Germany.
On another note. How is this for a heat sink/storage?
This example was being developed as a CHP system, though it seems it wasn’t marketed for long, if at all. The gas bearing linear Stirlings promise exceptional lifespans, and in fact are being used on deep space probes because of their mechanical reliability and efficiency. Even for grid tie purposes I think such a system would be a dream, distributed power production, grid resiliency, greater efficiency by avoiding line losses. For an offgrid system, 1 kw would go a long way. Especially with battery storage for peak draw it should provide enough for most household needs.
From this information it appears that the Microgen home CHP system might be available. It shouldn’t be hard to convert one from running on natural gas to wood gas.
J.O. the “problem” I have had with Stirling engines is the lack of widespread deployments. Those offered up are at gov’mint’s and enthusiasts forced costs-plus, put into use.
There is an American woodgasing concern named Community Power Corporation. Dr Tom Reed was part of their advisory board. They make very expensive community sized CHP in all SS using chipped woodfuels.
Why, we no see? They cater to gov’mint compliance projects. Our US gov’mint Greens hate internal combustion engines. In love with anything else “as better”, like fuel-cells, external heat source engines (to be able to be hydrogen fueled).
This may now be Net disappeared. Community Power Corp wasted away a few $100,000’s of developmental moneys back in the Clinton-Era 1990’s with one of the US Stirling engine promoter companies trying to make Stirling engines work with their gasifacation system. Failed. Woodgas was life shortening the flexible metal seals engine membranes.
They could have instead been selling and deploying for this same effort and money, many community power systems just using off-the-shelf converted natural gas piston engine systems from Caterpillar and Cummins.
Same waste away, only now MILLIONS $'s of investor and public moneys occurred in the same Clinton’s era 1990’s in the Connecticut (state) woodgas power project. They had the dead, dying too-crowded, re-growth trees. The means to harvest, and chip process all worked out. Even had the large scale gasifier system prototype built and trial-proofed gas-making… Whole endeavor collapsed. Why? The insistence on using gas-turbine generators for the electrical power makers. They just could not get the woodgas clean enough to not deposits enbrittle and misbalance those turbine blades.
Kawasaki of Japan, Hyundai of Korea, GE/Jenbacher of Austria, and again Caterpillar USA; make lots of BIG 20 cylinder IC point-of-use gaseous fueled generating systems and would have loved to fill that need. AND They, take responsibility for gasses cleaning up for gasses from coal/coke making off-gasses, to landfill-off-gases, to actual woodgas. They practical only clean good’enough for an annual 7,000 hour engine rebuilds. Make those rebuilds cost afforable. Use three engine systems so always 2/3rds capacity available, uninterrupted.
Real easy to kill off any local sourced alternative fuels initiative. Just put in place someone who will specify a killing/impossible standard, or mandatory requirement. Just “one”, is all it takes.
Ha! Man-cave iron-mass thermal storage is right!
Now my wife will not even let me put “an ugly black-box” fully advanced 21st century stove into our living spaces.
No-o-o-o. Has to be “pretty” cream colored porcelain enameled dust-catcher, beauties. Sigh. Possible. For a 30% greater price. An ~10% loss in transfer efficiency. Picture in my old DOW photo album.
Nice links you put up Gary Tait.
Follow the embedded link highlighted Rankine cycle Engine there for the, why-not, story.
Woodgas fellow I will not mention drove me nuts for years insisting an Organic Rankine Cycle engine was the way to go.
Basically a liquid to gas refrigerant phase change external applied heat source engine.
A heat-pump ran backwards to make mechanical power
They never have yet broken out of single digit thermal efficiency. The last, best, deployed steam engines with triple expansion cylinders did 16% thermal conversion efficiency.
The simplest, piston, valve-in-block, fixed timings. internal combustion gas fueled piston engine does at least 25% thermal conversion efficiency.
Current small Honda’s are 40% thermal conversion efficient. Next-gen, true mechanical crankshaft Atkinson cycle Honda’s will break into 50% conversion territory.
Now for the same costs, ease of worldwide practical deployments try to eveneven match that Green-Steam sucking down investors money’s.
Costs. Costs. Costs. Serviceability. Serviceability. Serviceability. Sucks on all woo-woo power engine wonders.
“A fool and his money is easily separated” Yep. I’ve been that fool too. Electric cars 1970’s through the 1980’s. Wished I would have just bought Honda’s then. If 10-15 years younger now I WOULD buy a depreciated fully practical hybrid cycle Toyota Prius. Wifie and the NuroDoc.'s now eyeing to take my vehicle keys away . . . next.
Had to give up the last of my firearms last week to satisfy them, and I am really bummed now.
J-I-C Steve Unruh
Steve, the linear Stirlings I believe have efficiencies around or over 20%. But, I’m sure you were years ahead of me on this, in a wood stove using low grade fuel, the system efficiency can be viewed as the 80%, or whatever the stove system rating is. The Stirling will act as a mild refrigerator on the fire, but producing basically gold, ac power.
It’s disappointing to see that various working commercial grade products that were developed have been shelved or cancelled, especially for Europe and Britain, squeezing much greater returns from imported and dwindling natural gas seems like a strategic prize.
I agree with your observations about the IC generators, at some point you would hope the goal is to get 'er done. I have my suspicions that governments and their entrenched industry friends really have no intention of implementing any better systems while over consumption pads their profit margins. The track record of failures to launch is too big, too consistent and too convenient
Thanks, Steve!
Yeah, I guess about same reason I mostly owned old Volvos - lot’s of cheap spare parts at the junkyards.
I just don’t know what to say, Steve. Non of us do, I guess. Afraid to say something inappropriate.
I can at least pretend I don’t know your local code of conduct.
I try to look at it this way: We all have it - the 100% deadly disease. It’s called life. No one gets away with anything.
Keep up your library diet and keep up posting. Much appreciatied.
Ahhh. Fellows, before you get too worked up about my by-by boom-go-bangs. The “they” I was having to satisfy was my own wife ( a Geriatric care teaching Nurse) and my own NuroDoc. Need the Doc to keep getting my medications.
They fear now too sudden irrevocable decisions by people with brain deterioration.
Almost weekly here regionally someone who shouldn’t be driving anymore mistakes the torttle for the brakes; or listen’s to a years been passed away spouse and makes an acroos-traffic turn into hurting folks.
My guns went into an older B-I-L, and an adult Nephews safes. “Safe” from me. I retain all of the reloading supplies. That is still fun and challenging. Somehow they overlook the powders and primers as not dangerous.
Now-w-w-w. Have two sisters almost daily calling me “afraid” I have given away the last of what is important to me. This is on top of ALL of my auto professional diagnostic and specialty tools I dragged over there last summer.
Just things. Not used, best passed on to those who can.
Ha! Just can’t get ahead with my family.
(Nope. My last hurrah would be gifting out my selected, special books)
Back onto topic for SteveU brain stretching I’ll try putting up links to some of the commercially available Honda CHP systems.
One of the better Atkinson cycle Honda articles with a motion graphic:
Yanmar also making up ans selling CHP variable speed Inverter systems. Diesel fuel of course.
Kohler offering PV solar back up systems in 24 and 36 and 48 volt DC. Aircooled so not CHP.
Ha! I have the download from here printed off sitting here in my lap.
Yanmar model CP10WN, and a smaller CP5WN
Try searching these up for the specs and numbers.
Claiming 85 and 84% fuel heat to usable energy’s conversions.
Electrical generation conversion efficiencies of 31.5 and 28%.
10,000 hour system maintenance intervals. Engine life’s of 60,000 hrs/ 10 years.
I have woodgassed Kobota natural gas water-“Warming” engines. Worked fine.
We had a water to air heat pump growing up. It lasted about 35 years and still worked bit it was noisy when it was replaced with another. The key is getting one with a good scroll pump. There were some cheaper ones that I heard there were problems with. Most new ones use a closed loop system. I don’t know how hot you can get the water prior to entry into it. It is one of those unsolved questions I haven’t researched enough.
If I was going to do it. I would probably get like a 10k gallon fuel tank that they bury for gas stations. I would probably use like spray on urethane insulation or else you are just going to be heating the dirt as that will try to stay around 50.
One of the more ingenious solutions is using old 2l bottles around a pipe to make the solar heater. It is used for apartment hot water heating on the low income section. I think in South America. They actually use convection for the circulation in the tank. But that is a whee bit hard to do in the northern winter.
Not a bad solution for a pool type of heater though.
