Brewery Upgrade: Heating 8,000 gallons a day on Solar?

[houseofancients]

I'm sure the shear volume of water required got some clicks!

I have been very happily running a ~1000W solar system on my Ford Transit for a few years. I don't own a home, so my list of solar 'projects' are relatively limited. However, I do own part of a large brewery, which uses a tunnel pasteurizer to process its beverages. Effectively, this is a very long sealed tunnel that heated water is pulled from basins, and recirculated over the canned beverages passing down a long conveyor. The cans are heated from cold (34F) to very hot (160F) for the purpose of killing any bacteria in the liquid or package. The primary heating function is a boiler fed by natural gas, but our usage is astronomical.

I'm curious as to the feasibility of installing solar (significant or insignificant amounts) as a way to supplement our boiler/natural gas use. The tunnel pasteurizer gets run all day, every day, through primarily solar generating hours (6AM - 7PM). Any heat that can be added to the system would be a benefit to our overall energy use and costs, and I do not expect to size the system to replace the boiler.

The advantage of this system is that it is relatively simple to install (power is in direct current, with no inverters or battery), with very little risk in undersizing. If it is cloudy one day, or we have lower output in the winter, it is all irrelevant as we still have the boiler to make up our heat needs.

I'm just starting here as a litmus test - is this even worth exploring, or a waste of time and money?

Thanks!

I would think that solar thermal ( and lots of it) would be a better investment.
More efficient and scales

 

[Bluedog225]

What’s your payback period on $200,000 in terms of gas savings?

 

[MisterSandals]

100 cubic feet (Ccf) of natural gas equals 103,600 Btu, or 1.036 therms

By quick math, no chance we are getting out of this less than $250-300K!

357,000,057 BTUs.

357000057 / (103,600BTU/1.036 therms) = 3570 therms

My january bill was $2.6 per therm
3570 x $2.6 = $9282 gas bill per month

What’s your payback period on $200,000 in terms of gas savings?

If you could produce power 25% cheaper with a $200k investment, break even would be:
$9282 x .25 = $2320 savings per month
$200,000 investment / $2320 = 86 months (7.2 years)

 

[Hedges]

GT PV solar is in the $1/W range, either hardware for DIY or utility scale including labor.
I think it quickly pays back vs. the electric rates some of us pay, slower where rates are lower.
But competing with natural gas is difficult, except when gas rates skyrocket.

Start by calculating $/BTU gas, $/kWh utility power, years amortization of GT PV to break-even with utility. Then consider heatpump efficiency.

Would a coal fired boiler and liquid-liquid heat exchanger be the cheapest?

 

[Shimmy]

The solar-thermal evacuated tubes are great for high temperature heat, and the heat pumps are great for lower temperature boost. I would expect you want both, but the natural gas is still going to do the heavy lifting to get the water to >175ºF.

I'd be curious how much make-up water is needed for the system and if there is any chance of recondensing the dryer air on the incoming cans for pre-heat.

 

[littleharbor2]

I'm probably way out there with this but what about a UV light like they use to kill bacteria in water filtration systems?

 

[Hedges]

That might even work if the contents was exposed to it. If beer bottles were made of quartz (not amorphous) glass, maybe it would work. Aluminum cans, not so much.

UV can also create vitamin D from oils. And it might denature the beverage in ways you don't want. But then, pasturization does too. Some orange juice tastes better than others which are overly cooked. Same goes for milk; raw tastes better.

 

[OzSolar]

What a fun thread! Side Note: Someone's got their priorities straight. Lives in van and owns part of a brewery.

Lot's of great ideas already!

From a shaky memory: (I'm about to invoke Cunningham's Law)
-Pool heating style panels (unglazed) are pretty much only good for pool heating since they can't heat the water much past 15 degrees above the ambient air temp
-Flat Plate - follow the below link
-Evacuated Tube - follow the below link

Actually I just I found this handy link from NREL that's easy to read and compares the type of solar water heating collectors. It talks about what type of collector you would use based on what you're trying to.

While we're brainstorming: How much of the brewery isn't air conditioned but could use some? If you put a heat pump water heater in those spaces you can get some cooling and some hot water.

I'm just starting here as a litmus test - is this even worth exploring, or a waste of time and money?

I will offer that I've personally been around and/or watched a lot biggish SHW projects over the years (30+ years....). They all share a few common traits which is that they never work as good as hoped and after a lot of fooling around and reworking, etc they eventually get abandoned for a whole bunch of reasons. So, IMHO which is based on a bit of actual experience, SHW won't even come remotely close to penciling out for what you're wanting to do which I is something I really hate say.

 

[Hedges]

Far more important is to give customers the product they want.
And even more important, don't kill them!
(Ok to add renewable energy heat somewhere, but any rearranging of the line or water flow carries risks.)

Some places have tried to use antibiotic cleaners and sterile plastic cutting boards, instead of those filthy wooden ones. Let's just say it didn't work out quite they way they envisioned.

Also issues with quench tanks and other processing modifications.

 

[Hedges]

So, IMHO which is based on a bit of actual experience, SHW won't even come remotely close to penciling out for what you're wanting to do which I is something I really hate say.

Hey, what's the location, and the solar potential, anyway?

This application being different from others, it could well be that water piped straight through evacuated tubes, then through existing gas heater, would be very practical and cost effective.

A large solar thermal array, only supplementing power that is needed continuously during sunshine.
Leave the pumps running 24/7 and no freeze issues. Have a bypass valve that allows drainback in case there are issues.

 

[Supervstech]

Heat pumps certainly are a good way to generate hear, unfortunately they aren't great at heating water. They make fine preheaters so, say 20% reduction in heating needs...
Other incentives may payback though.
Energy companies frequently offer massive rebates for changing or supplementing for natural gas usage... and epa tax incentive programs as well...

Look into say 100K solar/heatpump investment, with 30% tax credits, and similar energy rebates...
Combined with fuel reductions could make a good break even plan...

 

[OzSolar]

Hey, what's the location, and the solar potential, anyway?

This application being different from others, it could well be that water piped straight through evacuated tubes, then through existing gas heater, would be very practical and cost effective.

A large solar thermal array, only supplementing power that is needed continuously during sunshine.
Leave the pumps running 24/7 and no freeze issues. Have a bypass valve that allows drainback in case there are issues.

I think you'll be hard pressed to find even one example of successfully integrating SHW into a manufacturing process. I'm talking about a 10yr or longer case study based on actual results. Not the glossy marketing piece about what it's going to do (AKA LEED Platinum, etc)

Energy costs are most often in the single digits of total operation costs, typically less than 5% of the total. COGS and salary costs dwarf energy cost so a plant manager with any experience will immediately balk at allowing anything into thier facility that will it make harder to product a consistent product.

 

[Madcodger]

I think you'll be hard pressed to find even one example of successfully integrating SHW into a manufacturing process. I'm talking about a 10yr or longer case study based on actual results.

A 10-year case study? I think you'd be hard-pressed to find that for any technology that is rapidly advancing, such as solar. The cost per watt of energy produced has been falling dramatically in recent years, so any case study from more than a decade ago would likely have exceptionally high costs.

Energy costs are most often in the single digits of total operation costs, typically less than 5% of the total.

Energy costs are becoming a very significant part of a brewer's worries, and a big reason we'll likely see more breweries turning to solar where and when possible, to at least partially offset costs.

I seriously doubt most breweries will be able to rely solely on solar. But encouraging through efforts such as net metering could do much to make brewing more profitable while reducing its impact on climate worries. I don't know if the OP's original concept is workable, but I do hope that brewery continues to explore ways to use solar.

 

[Doggydogworld]

A 10-year case study? I think you'd be hard-pressed to find that for any technology that is rapidly advancing, such as solar. The cost per watt of energy produced has been falling dramatically in recent years, so any case study from more than a decade ago would likely have exceptionally high costs.

That comment was about solar hot water -- pumping the water through evacuated tubes to be directly heated by the sun. Those costs haven't declined dramatically in recent years. Heck, they've probably risen.

As for photovoltaic, it's easy to take a 10 year case study and substitute today's lower upfront capital cost and higher interest rates.

 

[stienman]

I think you'll be hard pressed to find even one example of successfully integrating SHW into a manufacturing process.

If it's going to be done, though, I think this is the way to do it - start with an existing, no-solar plant, and bring in a small amount of solar to supplement the heating system. Check the results over time to see what cost savings is acheived, and if good then expand. If not it's no big deal - only a little was spent, and the system can continue to be used if it offsets the heating enough to pay for continued maintenance, or abandoned if it doesn't.

I suspect that a glazed solar system will work well. It isn't as efficient as the evacuated tubes, however all it needs to do is take the coldest water coming off the line - under 40C - and raise it as much as it can before it goes back to the boiler.

The more solar area the better. Even on cloudy cool days these will produce a little temperature rise.

They don't need to bring it from 40C to 60C - even just bringing it from 40C to 50C will reduce the boiler's energy consumption.

A simple control system, a booster pump, and some pressure/pumping calculations should be all that's needed to automate it so when the panels aren't raising the temperature then nothing flows through them.

If there's a reservoir in the system, then a gravity drain system could be designed so when they aren't being used the water doesn't sit inside them - if cold weather is a possibility for your region. Adding a reservoir would allow for this if the plant doesn't already have one - it needs to contain enough water to fill the solar panels and pipes - but it would cost some floor space. Of course with this type of plant throwing the water away when the system isn't needed and bringing in water from the supply when it is might not be a significant cost compared to having a reservoir.

A well designed thermosiphon system would eliminate the need for pumping, but has higher maintenance and design costs.

All that said, solar water heating is very expensive compared to photovoltaic solar cells, due to the low volume of solar water heater manufacturing relative to the high volume of solar cells. While an evacuated tube has a theoretical efficiency of above 90%, in real world use you will find that doesn't mean you'll get 90% of the 1kW of solar energy available per square meter of solar water heating tubes. Light passes through, there is space between the tubes, and a number of other factors reduce the efficiency. Not quite down to the level of photovoltaic, but the cost differential, maintenance, and lifetime all add up to make solar water heating a difficult sell in terms of cost/savings relative to photovoltaic.

If you go with solar electric, use air to water heat pumps to get the most out of that energy as you can. This will effectively multiply the energy depending on the outside air temperature.

 

[OzSolar]

A 10-year case study? I think you'd be hard-pressed to find that for any technology that is rapidly advancing, such as solar. The cost per watt of energy produced has been falling dramatically in recent years, so any case study from more than a decade ago would likely have exceptionally high costs

Cost per watt? I'm talking about solar thermal.

Solar hot water has been a mature technology since the 1970's with essentially no substantial technology advances in at least 40 years. Even evacuated tubes have been around since the early 80's.

The sort of case study I'm referring to would discuss much more than costs. It would include all sort of details but particularly what % the system was designed to offset vs. what % it actually did and what sort of maintenance costs during a statistically valid time period.

As I already tried to point out in #28, if there's an example of SWH being successfully integrated long term into a manufacturing process it should be easy to find. Sure, on paper it can work, but in practice it hasn't panned out yet.

I'm very much in favor of trying to make solar thermal work in any application. I've been around many really sharp people that have spent a lot of time and money trying to make it work in an industrial application and none have succeeded. That's not an opinion, it's just a fact.

If it's going to be done, though, I think this is the way to do it - start with an existing, no-solar plant, and bring in a small amount of solar to supplement the heating system. Check the results over time to see what cost savings is acheived, and if good then expand. If not it's no big deal - only a little was spent, and the system can continue to be used if it offsets the heating enough to pay for continued maintenance, or abandoned if it doesn't.

I suspect that a glazed solar system will work well. It isn't as efficient as the evacuated tubes, however all it needs to do is take the coldest water coming off the line - under 40C - and raise it as much as it can before it goes back to the boiler.

The more solar area the better. Even on cloudy cool days these will produce a little temperature rise.

They don't need to bring it from 40C to 60C - even just bringing it from 40C to 50C will reduce the boiler's energy consumption.

A simple control system, a booster pump, and some pressure/pumping calculations should be all that's needed to automate it so when the panels aren't raising the temperature then nothing flows through them.

If there's a reservoir in the system, then a gravity drain system could be designed so when they aren't being used the water doesn't sit inside them - if cold weather is a possibility for your region. Adding a reservoir would allow for this if the plant doesn't already have one - it needs to contain enough water to fill the solar panels and pipes - but it would cost some floor space. Of course with this type of plant throwing the water away when the system isn't needed and bringing in water from the supply when it is might not be a significant cost compared to having a reservoir.

A well designed thermosiphon system would eliminate the need for pumping, but has higher maintenance and design costs.

All that said, solar water heating is very expensive compared to photovoltaic solar cells, due to the low volume of solar water heater manufacturing relative to the high volume of solar cells. While an evacuated tube has a theoretical efficiency of above 90%, in real world use you will find that doesn't mean you'll get 90% of the 1kW of solar energy available per square meter of solar water heating tubes. Light passes through, there is space between the tubes, and a number of other factors reduce the efficiency. Not quite down to the level of photovoltaic, but the cost differential, maintenance, and lifetime all add up to make solar water heating a difficult sell in terms of cost/savings relative to photovoltaic.

If you go with solar electric, use air to water heat pumps to get the most out of that energy as you can. This will effectively multiply the energy depending on the outside air temperature.

All great points. May I offer that the biggest issue that I've seen is that any system, not just energy, that gets in the way of production more than a few times will get removed or bypassed very quickly? I've worked in a lot of facilities (as in thousands) and lost count of the great ideas that didn't make it because they weren't quite ready for prime time and left management with no choice to remove them.

Again, I'm not saying it can't work, just saying if it could work why can't anyone point to a success story?

 

[rustythorn]

besides heat you can also use cold to save energy. depending on what you are making and were you are located you can use the colder months for ice distillation. not many things benefit from distillation so best to experiment first but if you get into whiskey ice distillation can get you part of the way there for free. another item i've found that works well with ice distillation is mead, ice mead is a very dangerous thing [in a good way ]. also ice distillation is also good for cider.

i wish the alternative grass fuels would use ice distillation, it would make them more green.

 

[WindWizard]

I have both PV and also Solar Hot Water collectors. Evacuated tubes and flat collectors. They both work very well for what they were designed for. The PV's generate electricity and the Solar Hot Water collectors heat the water in my two tanks to 150 deg f on a sunny day.

If you fill the roof with Evacuated tubes and run a pump to pump the water, then you can get the water temperature hot and then supplement the boiler. We supplement our hot water needs with a wood or an oil boiler.

I think that integrating a hot water system into what OP already has should make it fairly straight forward.

The other ideas are good but I think they add a lot of unnecessary complexity.

If you are interested in heating water, then heat water with Solar tubes that are designed to efficiently heat water.

The Solar tubes should be setup with a circulator pump that only turns on when the temperature is higher on the tubes Vs the holding tank. You would need to run a closed loop of copper coils filled with a glycol mix into a holding tank of water to transfer the heat.

The heated water in the tank can then be used for your pasteurizer.

That is what I am doing now on a smaller scale. Not only do I heat the domestic water but I also heat our 17500 gallon swimming pool. I have achieved temperatures of 93 degrees f.

 

[n2aws]

That is the fun part - the water is continuously heating a stream of approximately 20 gallons per minute of cold (34F) product, entering the tunnel.

Just curious, is the water being recirculated? If it's being used to pasteurize, I can't imagine its cooling from 160F to 34F before "cycling back in", so I'd like to understand where the heat is going.

Is this just an open air environment? Would it be possible to enclose/encapsulate at least a significant majority of the water path to reduce thermal loss, before it gets back to the inlet? If it's not being recirculated, and always a fresh source.. Is there a way to convert to a recirculating system? Seems like this would reduce both the water bill, as well as the energy bill.

Give us some additional details! As someone mentioned.. heating water from 34 to 160F will take a significant amount of energy (as seen in your NG consumption numbers), But if it's recirculated and some of the thermal loss is controlled so maybe going from 120 to 160.. requires much less energy.

Deets please!

 

[SajgZi]

100 cubic feet (Ccf) of natural gas equals 103,600 Btu, or 1.036 therms


357000057 / (103,600BTU/1.036 therms) = 3570 therms

My january bill was $2.6 per therm
3570 x $2.6 = $9282 gas bill per month


If you could produce power 25% cheaper with a $200k investment, break even would be:
$9282 x .25 = $2320 savings per month
$200,000 investment / $2320 = 86 months (7.2 years)

No way they're paying residential rates. $2.6 / therm is #1 a lot, and #2, $26/MCF. Natural gas traditionally is priced in million BTU increments via futures and whatnot (henry hub - contract is for 10,000 MMBTU - https://www.cmegroup.com/markets/energy/natural-gas/natural-gas.contractSpecs.html).

Current price for natural gas is like $3.2 per MMBTU. Natural gas is frequently just above 1000 BTU/CF. 1000 makes the math easy.

They're likely paying closer to $4-6 per MMBTU, the base price + some pipeline transportation fees + delivery fees.

Source: I used to work for the 6th largest utility in the US doing gas SCADA + commercial/industrial gas nominations/allocation/billing support.

All this to say, gas is currently quite cheap. The payback will be long. Can they convince their customers to pay more for a "green"(ish) product?