Converting from fuel oil to propane is projected to save one grower more than $30,000 in less than two years. Even with the cost of new equipment, it’s a savings worth investigating.
Thirteen years ago, when Jaap Molenaar started the first growing season for his first 5,000-square-foot hothouse, a gallon of fuel oil cost 62 cents. While the cost of fuel was still a factor in his operating budget, at such a low price, the cost of oil paled in comparison to the value of the crops he was keeping warm. Fast-forward to today, where Molenaar now operates 40,000 square feet of heated beds, and the cost of fuel oil has seen highs of nearly $4-plus per gallon. The cost of fuel is now a major factor in his operating budget and quickly determines whether or not it is profitable to grow crops for the winter.
Pioneer Gardens had numerous aging oil-fired hanging heaters, which were becoming difficult to maintain.
PHOTOS COURTESY OF PIONEER GARDENS
Molenaar is the co-founder of Pioneer Gardens in Deerfield, Mass. In this region of the state, on fertile soil surrounding the Connecticut River, there are countless family farms and greenhouses growing everything including vegetables, perennials and even tobacco. However, Molenaar has found a unique niche in the horticulture industry for this region. Pioneer Gardens specializes in growing tissue culture and root cuttings for replanting and resale to wholesale growers throughout the U.S. and Canada. Bringing perennial plants like geranium, hosta and sedum to market by springtime means that his growing season begins in late fall and continues through the winter. Considering that Massachusetts just went through one of the toughest winters in recent memory, this job is no easy task – and keeping the greenhouses at precise temperatures can make or break the farm.
Out with the old
Unfortunately, the fuel oil equipment that was new back in 1998 was showing its age and putting the farm at risk: Not only was the cost of fuel increasing, but the system was also a maintenance nightmare. “During the past two winters we have had at least one piece of equipment down each week,” says Molenaar. “The maintenance of 19 oil burners on aging equipment was becoming prohibitive, and their reliability was risky as the change in temperature could quickly destroy our crop.”
Pioneer looked at several alternatives to their current equipment. They even contemplated staying with fuel oil. “Back in Holland, where I am from, there is a great deal of new technology for oil burners, because fuel oil is double what it costs here,” Molenaar explains. “However, the equipment is just not ready or available in the U.S.” The consideration had been made to look at geothermal, as well. “We had a study done through a matching grant by the local university in 2001 to evaluate geothermal. At that time, the return on investment was 17 years, and we simply could not get financing for such a long payback.” And finally, a proposal for renewable biomass fuels: “I have seen numerous large growers install big woodchip boilers,” Molenaar says. “On their scale, the cost is effective, but for me, the cost of equipment, manpower, EPA approvals and the time to get it up and running was too great.”
Pioneer Gardens currently operates 40,000 square feet of hothouse space and is expanding to 120,000 square feet. Watering and moving the beds is performed electronically.
In addition to the current 40,000 square feet of growing beds, the farm was looking to triple the size of the heated beds to over 120,000 square feet over the next few years. Therefore, Pioneer Gardens decided to take a new approach to heating the houses. The previous system used in-ground radiant heat combined with hanging heaters to keep the houses warm. “We realized that the in-ground radiant was taking the heat away from the plants,” says Molenaar. “And while the hanging heaters kept the houses at 65° F, the beds only got to 55° F.” As luck would have it, Pioneer Gardens had built their current greenhouses from second-hand houses, which came with thousands of feet of 2-inch steel pipe. “I liked the idea of radiant heat, but the previous system just did not work,” Molenaar adds. “We decided to reuse all of that pipe in an under-bench radiant system to efficiently get the heat directly to the plants.”
Pioneer Gardens was able to reuse more than 4 miles of steel pipe for the underbed radiant system.
The entire heat delivery system was redesigned to use more than 4 miles of radiant piping, requiring a modern system to meet the demand for heat but also to modulate and provide lower temperatures required for radiant. The high cost of fuel oil and the limited efficiency of the existing equipment made it unfeasible to reuse the old boilers, and the farm needed something more reliable and better able to control the precise temperatures needed in the new radiant system.
“Ultimately, I decided on propane because it is a domestic fuel, the cost of the equipment was feasible, we could have the installation up and running by winter and it would give me the reliability and efficiency I wanted,” Molenaar concludes.
In with the new
On a warm spring day, the solar curtains are closed to prevent overheating of the hothouses.
The new system uses three high-efficiency (96 percent annual fuel utilization efficiency, or AFUE) boilers sized at 399,000 BTU each to accommodate the heating need for current and future hothouses. Multiple boilers would also give the system flexibility for each boiler to modulate automatically with outdoor reset controls and cascade in unison based on the demand for heat. On warmer winter days, one boiler operates to meet demand, but as the sun sets, the other two boilers can come on automatically to maintain temperature. “In the old system,” Molenaar says, “we were mixing down all the hot water from 180°F to 125°F for the radiant, which is inherently inefficient. While we still do a little mixing, the new propane boilers are actually able to maintain those lower temperatures consistently.”
In addition, several loops of overhead pipe were installed to help boost temperatures on the coldest nights and for use with snow melting. “Using the hanging heaters is really ineffective, so we installed the pipes above to circulate hot water,” Molenaar explains. “It works very quickly and provides some radiant heat back to the plants below.” While the new propane system did not fully come on-line until November, the system has worked flawlessly while providing immediate savings. The new radiant system has shown consistent soil temps of 65 to 68°F with similar ambient temperature in the greenhouse; meaning that the heat is spread evenly among the planting beds and the surrounding space. As an additional environmental benefit, by switching fuels, the farm has reduced its carbon footprint by 43 percent, cutting over 100 metric tons in CO2 output annually.
An ongoing project
While upgrading to a more efficient and effective heating system has helped with the bills, Molenaar’s plan continues to be reducing the overall heatload of the building. Part of that began several years ago with the investment in heat reflection/retention curtains in the houses. “The curtains are used both in summer and winter,” Molenaar offers. “During the summer, we close the curtains during the day to reflect the sunlight, and at night open them to remove heat. In the winter it is the exact opposite, where the curtains help reflect and trap heat from below. A single set of curtains results in a 25 percent energy savings. So last winter, I doubled my investment and each house now has two sets of curtains.” In addition, Molenaar is experimenting with using hay as wall insulation between the houses: “I knew that back in Holland they have used hay bales as construction material for centuries. What I did not realize is that a hay bale has an insulation value of up to R-56! With some rodent prevention (of course) and double plastic walls, I really think we can make a serious reduction in the BTU load of the houses.”
Two 1,000-gallon propane tanks provide adequate, safe and environmentally friendly fuel storage.
Overall, the conversion to propane was a large undertaking with major investments in time and money, but all signs now point to the decision being the right one. And as Molenaar walks across his greenhouse in the summer heat, he stops to inspect several flats of Coreopsis that are being prepared to ship to a customer in California. A tag on one of the plants says that it was started at the end of November last year. Molenaar smiles and knows that only four months from now, the leaves will be turning, the nights will be cold and he will be starting his next crop.
The new boilers operate at a much higher efficiency than the previous fuel oil system, and are able to cascade and fully modulate up and down based on the demand for heat.
Part of the transition to propane included the removal of over 3,000 gallons of fuel oil storage.
Chris Kowalski is marketing manager for Osterman Propane in Whitinsville, Mass. He can be reached at firstname.lastname@example.org.
For more information on the use of propane for horticulture, and for links to rebates for demonstration purposes, visit the Propane Education & Research Council at www.agpropane.com.