We operate a three generation family farm on Maryland's Eastern Shore. Diversification and changing with the times are some of the keys to keeping a family farm afloat. In the past the main farm income sources were Laying chickens for hatching eggs and row crops. Over the years we also have dabbled with feeder pigs, truck crops, and aquaculture. Times change! The chicken companies moved their laying chicken operation down south and now a lot of our cropland is in Conservation Reserve (CRP). These days the farm income comes from 2 - 500 ft broiler chicken houses, 20 acres of hay, and a one acre wholesale production greenhouse. The greenhouse has been profitable but lately the high cost of propane for heat has cut into the bottom line. We decided to invest in a grain fired boiler to try to save money and to support the farm economy.
System Info January 2007
Here's some info on our Pelco model 2520 boiler setup. We found the Pelco distributor website after seeing one at a tradeshow. The distributor put us in contact with a Pelco owner near us. He invited us to visit his Turkey operation to see a Pelco in operation. He was most helpful and answered all our questions. We left his farm sold on the Pelco. We estimate that the boiler will supply 75% of our total heat load with the existing propane unit heaters picking up the rest. The total cost of the new heating system was $75,000. In the past the greenhouse used on average 30,000 gallons of propane in a season. We estimate a $21,000 yearly fuel savings with $2.75 corn and a return on investment(ROI) of 3.5 years. With corn at $4.00 the savings will drop to $14,000 and a ROI of 5.3 years.
The grain bin will hold about 900 Bu. We pickup about 650 Bu at a time at the local elevator. It looks like we will need loads every 10 - 14 days in the cold weather. Our first load was corn but to try to save money we decided to get some barley to try and it is burning fine. Seems to produce about the same heat although their is more ash. At $1.50 /Bu savings we will deal with the ash.
Greenhouses make great solar collectors and usually need to be vented when the sun is shining even in cold weather. We shut the Pelco down on sunny mornings and start it up again a little before sunset. Removing the clinker and starting the fire takes about 10 minutes. We start the boiler on low feed (1%) and go back an hour later and set the feed rate for the night. We have been using rates between 30% and 65%. We tried using higher rates on a few cold nights but we were getting smoke and no increase in heat output.
Heat distribution is by way of 8 - 300,000 Btu heat exchangers (boxes with orange pipes in photo above). The Pelco 2520 is rated at 1.5 million Btu so we only run 6 of the 8 heat exchangers at a time depending on where we have plants. Water is circulated through the system any time the boiler is running. Greenhouse temperature is controlled by switching the heat exchanger fans on and off. Our environmental controls have 3 stages of heat. The heat exchanger fans are controlled by stage 1 and the propane heaters will come on as stages 2 and 3 if the boiler can't supply enough heat. If the Pelco should shut down for any reason the propane will take over automatically.
The heat distribution system was designed by Rick Jones of St. Joseph Heating Solutions http://stjosephky.com/index.htm. The boiler system has a Primary loop with 2 pumps located under the boiler to maintain a 200 gpm circulation through the boiler. The pumps in the photo above are in the distribution loop and supply the head needed to push the water through the heat exchangers. The distribution headers are 2" and 3" CPVC and are rated for the 180 deg water temps. The pipe is expensive but installation went quick with just cut and glue joints.
First season in review June 2007
The Numbers
I got a chance to sit down and crunch the numbers for the season. We paid $4.25 for a lot of our corn so I knew the numbers were going to be less than our estimates.
We burned 6,300 Bu of grain this season at a cost of $22,000. We burned about 1/3 barley and 2/3 corn. We also burned 2,500 gallons of propane costing $4,000.
In prior years our propane usage ranged from 25,000 to 32,000 gallons. This year was a little on the mild side so if we were using 100% propane we would have been nearer to the 25,000 mark.
If we figure that we replace 3.5 gal of propane for every Bu of grain then 6,300 Bu replaced 22050 gal plus the 2,500 gal we did use puts us near 25,000 gal.
We paid $1.62 per gallon for propane this year. That works out to a fuel cost savings of about $14,000 for the season. With a system cost of $75,000 that puts the payback time at 5.5 years--not as quick as we estimated.
On the plus side we were hoping to replace 75% of our propane usage but we ended up replacing 90%.
Observations
-The boiler system integrated with the existing greenhouse environmental controls without any problems.
-We estimate the output from the boiler was 1.2 million btu with corn and just over 1 million btu with barley. These are just estimates as different loads of grain had noticeable differences in heat output.
-Barley produces 3 times as much ash and flyash as corn. Barley forms larger clinker chunks (photos below) and is easy to remove from the boiler. Corn clinker is more granular and has to be scooped out with a hoe.
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-Being able to shut the boiler down on most (sunny) days has made the clinker removal much easier.
-The chores of clinker removal, emptying the ash bin and lighting the fire have blended into the daily greenhouse work routine very well. Less than 15 minutes a day is spent on these chores.
Changes
There's nothing like a few months use to show the problems in a setup. In this case it became clear that a couple of things had to be changed. One problem was fixed with a little trial and error and a few parts from the hardware store. The other problem was one that could only be fixed by throwing a large pile of money at it.
The small problem concerned catching the flyash coming from the bottom of the cyclone. The cyclone was an accessory and not mentioned in the Pelco manual. Our first thought was OK just put an open drum under it and the ash will 'fall' into the drum. WRONG! With the power exhaust blower the exhaust blew out the bottom and spread the flyash everywhere. OK we can fix that lets just seal the bottom of the cyclone to the drum (left photo).
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The sealed drum worked well... until we had to empty it. Who knew 30 gallons of flyash weighed so much? Trying to empty the slippery barrel with no handles was almost impossible. On to plan B. We tried a rubbermaid trash can but the lid got soft from the heat and would pop off the can. Plan C... Plan C is in the photos center and right above. It is made from 8" stove pipe and fittings with a handle riveted on. It fits into the adapter attached to the cyclone and is held in place by a wedge placed under it. It holds about 4 gallons of ash and is emptied every day. Takes about 30 seconds. Problem solved.
On to the big problem. There are 6 grain elevators within 30 miles of our farm. So we never considered that picking up truckloads of grain when we needed it would be an issue. We found that the local elevators were not setup to sell grain on an as needed basis. They would sell to us only when they were shipping themselves. It was always a scramble to line up a truckload. To make matters worse all the elevators ran out of barley by mid January an we had to go back to $4.25 corn. We decided that to assure a supply of barley we would need to put in a 6,000 Bu storage bin. We paid $20,000 to have the GSI bin erected. It is a very long term investment. Problem solved.
Grain Bin Update July 2007
We were able to buy barley from a local farmer right out of the field. We filled the GSI bin with 6100 Bu. at $2.30 per Bu. This should save us over $20,500 next heating season and no more hassles with the elevator operators!
Issues with Pelco
Very few! 2 failed components covered by warranty were promptly replaced. All calls to the service department handled quickly by knowledgeable people. Never to busy to answer questions.
Contact
kcl@dmv.com