Passive Solar for Heating Concentrate Pre-Boil

[jeugster]

Is anyone using passive solar to heat sap before boils? Seems like a low cost way to directly reduce fuel use. What do you think?

Are there any disadvantages to running an open system with sap running through rooftop collectors?

[Bucket Head]

I'm all for alternative energy sources. I find the small, hydroelectric turbines fascinating. I wish I had a water source with some drop on this property! But with that said, your best bet on warming sap or concentrate is to employ a pre-heater in a steam hood. You might as well use the lost heat from the pan to do something. And that will warm the sap to a much higher temperature a lot quicker, which will help the boil rate quite a bit.

But if you have some rooftop collectors that don't currently have a home......

Steve

[jeugster]

Definitely planning on getting a pre-heater. That heat is so precious. Is the one you fabricated working well?

I'd rather catch some sunshine than chop more wood. No solar water heater units laying around, but it could be a good investment.

There are some ridges on the property with good wind, hopefully I can justify putting some big turbines up someday.

I'm planning an operation from scratch, so it might as well be as efficient as possible right?

[maple flats]

I love solar, BUT I think the sun in maple season is not dependable or fast enough to be effective. if you have a large volume solar heater, you will degrade the sap, because in concentrate you have also concentrated the micro organisims. As such you must pre heat it fast and immediately get it boiling or you lose a lot of sugar to the micro organisims.
I built a pre heater that is in my hood and it works well, but not perfectly. It heats sap to about 170 when not drawing syrup and about 110-120 when in a draw. I should have made it a little bigger. I have 50' of 1/2" cu and 4' 1" cu in my 3x5 hood and I draw about 7-9 gph of syrup.

[jeugster]

Hmm... maybe you could get around the hungry bacteria problem by heating concentrate rapidly as it goes to evaporator. A sap pre-pre-heater if you will. Then you're left with the problem of how to collect a lot of sunshine fast, or finding a way to store heat that can be released quickly.

If the biggest costs for production are fuel then capital then labor it seems like good sense to use solar to reduce fuel and labor costs for a small capital expense. Of course the numbers might not add up like I hope, but it's a neat idea anyways.

[mellondome]

A preheater under a hood will cut down your wood usage far more than any solar heater you can fab up. Not sure how you plan to keep a roof top slow flow pool heatet mat clean on thw inside. Also with such a thin layer of sap, not sure how you plan on keeping it from freezing.
But if you can keep it clean on the inside, approved for human consumption, preheat sap to 190deg, and increase your boil rate by 15% on the same wood input, then maybe you have something. But if you spend couple hundred on a heater that is not made from food safe materials, freezes up all the time, ony heats your sap 5 deg on a hot sunny spring day, and is full of bacteria slimen then it might not be that good of an investment.

[jeugster]

Why not both preheater and passive solar? Maybe a closed loop system with glycol and another heat exchange would solve the bacteria problem.

[motowbrowne]

A preheater under a hood will cut down your wood usage far more than any solar heater you can fab up. Not sure how you plan to keep a roof top slow flow pool heatet mat clean on thw inside. Also with such a thin layer of sap, not sure how you plan on keeping it from freezing.
But if you can keep it clean on the inside, approved for human consumption, preheat sap to 190deg, and increase your boil rate by 15% on the same wood input, then maybe you have something. But if you spend couple hundred on a heater that is not made from food safe materials, freezes up all the time, ony heats your sap 5 deg on a hot sunny spring day, and is full of bacteria slimen then it might not be that good of an investment.

This. Keep it simple. Keep your eyes out for a used steam away if you want to get really efficient with your firewood. Then, maybe run the steam away blower on PV panels.

[Buffalo Creek Sugar Camp]

You aren't evaporating any sap with a preheater, just warming it. I think if you keep it warm for too long, it will darken the syrup. One preheater is plenty.

[jeugster]

It doesn't get much simpler than passive solar.

The steam-away heat exchanger captures heat that is already being produced in the evaporator to heat up sap. A solar heat exchanger adds external heat to the system. If the overall cost per BTU for passive solar is below the cost of the wood/labor/equipment and it can be done safely in line to the evaporator... why not use sunshine for heating?

I can see how photovoltaic might be better since you can net meter year round, whereas with passive solar you would have a short and low solar intensity time period to take advantage of the investment. To mitigate that we are thinking of using passive solar to partially heat the sugarhouse, using a heat sink (in the foundation) to store solar energy in the summer months.

[mellondome]

Let us know how it goes....you planning on putting the 45k taps through this? You eoild be further ahead using black painted collection tanks with bubble wrap on the sap surface in direct dunlight...

in the meantime, I will save on natural gas by using the steam i'm creating to increase my boil rate via my copper preheater under my flue pan hood, thus decreasing the amount of gas use.

[motowbrowne]

Jonathan, maybe you could clue us in a little bit here. All we know is that you're on Wisconsin, you run 80 taps, and you want to multiply your operation by a factor of about 560. We also know that you might be pretty well hopped up on coffee :).

From your posts it's not clear if you've visited any operations of a similar size to what you want to do. That is step 1. Visit several. I'll be the first to tell you that it's a whole different animal at that level.

Cooking sap from 80 taps on a flat pan burning firewood is a fun hobby. Even relaxing. Sure there will be stressful moments, but the stakes are low. Dealing with 60,000+ gallons of sap every day on the other hand... I hope you like plumbing. Personally I like cooking sap, maybe you do too. At a certain point, though, you won't be doing any off that. You'll be trouble-shooting equipment. The amount of equipment required to handle that much sap is astounding. Pumps will fail, lines will burst, something will happen every day that demands your immediate attention. Obviously you will be paying several people during the season. Now, the stakes are high.

My question is, why so big so fast? Is this what you want? To design and install a huge facility and oversee several employees. Why not buy a used rig, set 1-5000 taps and run things solo for a few years? If you still like it, then start talking about dropping a million bucks into it. Personally, and I mean absolutely no offense, but (unless there's a LOT you aren't telling us) there's no way in heck I'd lend a guy in your position $1,000,000 to go from 80 taps to 45,000.

[BAP]

Jonathan, maybe you could clue us in a little bit here. All we know is that you're on Wisconsin, you run 80 taps, and you want to multiply your operation by a factor of about 560. We also know that you might be pretty well hopped up on coffee :).

From your posts it's not clear if you've visited any operations of a similar size to what you want to do. That is step 1. Visit several. I'll be the first to tell you that it's a whole different animal at that level.

Cooking sap from 80 taps on a flat pan burning firewood is a fun hobby. Even relaxing. Sure there will be stressful moments, but the stakes are low. Dealing with 60,000+ gallons of sap every day on the other hand... I hope you like plumbing. Personally I like cooking sap, maybe you do too. At a certain point, though, you won't be doing any off that. You'll be trouble-shooting equipment. The amount of equipment required to handle that much sap is astounding. Pumps will fail, lines will burst, something will happen every day that demands your immediate attention. Obviously you will be paying several people during the season. Now, the stakes are high.

My question is, why so big so fast? Is this what you want? To design and install a huge facility and oversee several employees. Why not buy a used rig, set 1-5000 taps and run things solo for a few years? If you still like it, then start talking about dropping a million bucks into it. Personally, and I mean absolutely no offense, but (unless there's a LOT you aren't telling us) there's no way in heck I'd lend a guy in your position $1,000,000 to go from 80 taps to 45,000.
Well said motobrowne. I used to do it commercially when I farmed with about 16000 taps plus milked 450 cows. Keeping several vacuum operations going plus R/O's, pumps and so on can be a full time job. As far as the solar goes, I don't know about the weather in Wisconsin, but here in New Hampshire, a lot of syrup is made when the sun isn't shining. A lot of the time it is cloudy, stormy or at night when there is the most sap to deal with.

[morningstarfarm]

OK can someone clue me into this idea please...how would passive solar ever be a good thing for us to even contemplate?...to ever get any amount of heat into the sap we would have to heat it slowly over a long period of time..last time I checked I was trying to keep it as cold as possible until the moment I boiled and ten wanted to go from sap to steam just as fast as possible...seems like it would be a phenomenal way for us to grow bacteria....or am I missing something....

[RileySugarbush]

....or am I missing something....


I don't think you are missing anything.

It's tempting to grab some "free" energy, but there are much better ways toe improve an operation.