Agriculture & Landscape Program
Green Energy

Ravenwold Farm Case Study

Ravenwold Farm has been a family farm since the early 1900's. It was originally primarily a dairy farm, but they made the switch to vegetables and bedding plants in 1993. They now focus primarily on bedding plants and vegetable starts, and hanging baskets, as well as growing about 30 acres of vegetables and sweet corn. They have four greenhouses, one 53'x96', two 30' x 96', and one 17' x 96' gothic styles hoop houses covered in 6ml double layer inflated poly. They use the smaller greenhouse for starts and keep it at about 62 degrees, then quickly expand into the other greenhouses which are kept closer to 56 degrees (night temperatures). They used to start their greenhouses in February, but have started buying plugs rather than starting from seeds so they could shift production into March to save on heating costs. Their greenhouses are mostly filled with annuals (~80% of the bench space); the rest is vegetable starts and hanging baskets. Prior to 2009 they were heating all of their greenhouses with oil. The greenhouse where they installed the corn furnace is 30'x96', starts up in March and was typically kept at 56 degree night temperatures. With the corn unit in place, they've been keeping it a warmer with 60 degree nights and 65 degree days. Up until now it has been heated with two Sundair oil furnaces – one rated for 300,000 btu's and the other rated at 180,000 btu's. The 180,000 btu furnace will remain the greenhouse to be used as a backup.

Saving money and keeping themselves insulated from fluctuations in oil prices has been their primary motivation for experimenting with corn as a fuel source. They also have the potential to grow their own corn if they can work out how to dry and store it, and have access to a steady supply of woodchips that they could eventually burn in their corn stove if they can come up with an economical way to pelletize them. Because of the potential for eventually using pelletized woodchips, one of their main criteria is that the stove be able to burn other pelletized biomass fuels and not just corn.

They quickly narrowed their choices down to a 100,000 btu furnace from J-Ran Enterprises in MI and and the LMF Amaizeing heat furnace. The Ja-Ran unit is rated at 100,000 btu's with a 12 bushel hopper, a 1/3 horsepower blower, and will burn corn, wood pellets, and other pelletized fuels. The LMF furnace is rated at 80,000-165,000 Btu’s, with a 14 bushel hopper, a ½ horse power blower, and will burn corn, pelletized wood, and other pelletized biomass fuels. They eventually decided to go with the LMF Amaizing heat model because of the more powerful blower and higher btu rating. They purchased the unit directly from the manufacturer for $4275 plus $200 freight. In addition to the furnace, they purchased a digital corn thermostat that helps give them more fine grained control over the furnace. The thermostat is a Corn-Trol unit, which helps to provide some fine-tuned temperature regulation. Without the corn-trol unit, the only real control you have over temperature with the stove is to manually set the on/off interval for the feed auger and adjust the air damper on the blower. The corn-trol unit will vary the speed of the fan and the on/off interval of the auger dynamically, based on the current temperature and how close it is to your set point. It is fully programmable and can handle different settings for day & night. They claim that it can keep the temperature within +/- 1 degree F and reduce fuel usage by an average of 11% by lowering the temperature of the low-fire mode and reducing temperature swings.

The Adams haven't had any issues with lighting their stove, as the idle mode has been working fine so far without generating excess heat – possibly due to the corn-trol. They fired up their shiny new LMF Amaizeing heat furnace at 5pm on March first. All in all, they felt that it took about a month to really get used to the furnace and get all the setting tuned to their liking.

In 2008, they used 750 gallons of oil to heat the greenhouse, for a cost of about $2,500. They're on track now to burn about 6 tons of corn over the heating season which began on March 1. At current market price of $220/ton for corn, that puts them at about $1320 for heat. This is $1180 less than what they paid for oil last year when it was over $3/gallon, and they still saved a few hundred dollars over what they would have paid for the same amount of oil at today’s lower prices, even with keeping the house at the higher temperatures.

They purchased their corn from Rolling Acres Farm in Southampton, MA, Five Point Farm in Northfield, MA, and from Zgrodnik Tobacco in Hadley for an average of $220 per ton. They get about one pound of ash for every 100 pounds of corn, and empty the ash bucket daily.

So far they are quite pleased with the way the stove is working out. Their next project is to figure out a low cost way to dry the 15 acres of corn they planted this spring so that they won't have to buy in any corn at all. We'll post the details of that project here as soon as we have some information to share.