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Published:3/1/2007

Pat Belrose has 75,000 sq. ft. in Missouri. John Bonner has 5 acres in Ohio. But they’ve got one thing in common: Both are finding success using alternative heat sources for the greenhouses¬—Pat is burning a mixture of corn and wood chips in his rustic-but-serviceable 1910 boiler, while John is burning biomass (including cow chips from his family’s cattle ranch) in a brand new $750,000 system from Hurst Boiler Inc. Together, they prove there’s an alternative fuel in the future of nearly any grower.

Fahr Greenhouses’ corn/wood combo

Ever since natural gas prices started going skyward, Pat Belrose has been looking at alternative fuels.

“We originally looked at burning either waste oil or vegetable oil, but those had a lot of environmental risks and problems that I didn’t feel real comfortable with,” Pat says. But some internet research, plus knowing folks who burned corn at home, got him looking at corn. Via the Web, he got help from a Penn State researcher who gave him some cost analysis info.

“At that point we were looking at $2 a bushel for corn, and Wow! That looked fantastic over $11.25 per therm natural gas.”

Pat’s old coal boiler had sat inactive since the late 1980s. A call to the Will-Burt Stoker company, the manufacturer of his coal stoker, revealed that they didn’t know how to successfully burn corn in it, due to improper air/fuel ratios. Pat’s brother-in-law came up with a solution using a DC motor to feed air into the fire box; with some tweaking, they soon were burning corn quite successfully. Pat says corn burns clean, with little smoke or ash.

But then corn got expensive—up to $3.50 a bushel now. So it was back to the Internet, where Pat found a source in St. Louis for ground-up wood pallets. The stuff is so abundant, he only pays for the trucking—about $600 for 100 cubic yards of chips.

The problem with burning straight wood is that is doesn’t flow easily from the hopper to the boiler, whereas corn is extremely fluid, so Pat experimented with a blend of corn and wood, settling on one part corn to two parts wood. With that, he can heat 35,000 sq. ft. of greenhouse at a savings of at 25% or more over natural gas (he calculates his cost per million BTUs at $11.93 for natural gas when gas is a 90 cents per therm, and at $8.66 for a 50/50 mixture of corn and wood, when corn is $3.30 a bushel).

For additional savings, Pat has lined his entire greenhouse with a layer of 3-mil winter poly. He calculates that that saved him $4000 in fuel last winter.

“My goal is to maintain or reduce fuel cost without having an adverse effect on the environment,” Pat says. “We hope by conservation and alternate fuels to take out the dramatic shifts in fuel cost from year to year so we have a more stable cost structure.”

Eagle Creek’s Biomass Boiler

John Bonner, general manager of Eagle Creek Growers, calls his new biomass boiler, just installed last fall, a “viable alternative” to traditional fuels. “It takes our raw fuel cost - say we’re paying $10 per million BTU to the gas company or $16 if we’re burning oil - it takes our raw cost down somewhere close to $2.50, or maybe $2 depending on what we’re burning.”

John’s system is a 300 hp Hurst “vertical underfeed” boiler that can burn nearly any fuel that has about 20% moisture content or less. John’s fuel of choice: cow manure from his family’s 1,000 acre farm, blended with sawdust or wood chips and shredded tires. A 50%/40%/10% mix seems to be working, although they’re still experimenting. He’s been running it since November; during the January cold snap when temperatures went down to 0F he burned roughly 35,000 lbs. of biomass per day.

The system heats water, which is then circulated through a 30,000 gal. insulated tank (an old propane tank) that acts as a buffer for when the greenhouse demands heat all at once when the sun sets. The whole deal is controlled by a Priva environmental control computer. The two existing boilers now serve strictly for backup, as John has enough capacity to heat 8 or 9 acres with the biomass boiler.

When asked about his expectations for the system, John replied that it depends on the cost of natural gas. But payback should be in four to five years, he says.

“It was a pretty easy decision for me: We’re either going to pay the gas and oil companies or we’re going to put in the infrastructure, pay the bank for 3 or 4 years and get the thing paid off. That will put us in a position to be responsible, conserve, have some sustainability here, and also stay competitive.”

It doesn’t hurt that two other large Ohio greenhouses, Willoway Nurseries and Green Circle Growers, have also recently invested in biomass boilers. The three openly share information about the technology.

Another benefit to low-cost heat: John doesn’t think about cutting corners with heat and sacrificing plant quality. He opens up greenhouse bays when he needs the space, and he doesn’t have to grow extra cool to save a degree or two. “The growers love it,” he says.

John may have a built-in supply of cow chips to burn, but does he worry that demand for biomass will push up the cost of even things like wood chips and shredded tires?

“That’s a great question, but I’m not worried about it,” he replies. “If I can get through four or five years and even just break even, then I have the choice to burn anything I want to burn—I can burn gas or oil if I want or cow manure and tires if I want.”