"Smokeless Heat"

By beginning our tomato crop in October, you may wonder how we are able to heat the space (and I do mean space....12,000 plus square feet of area enclosed by a two thin layers of plastic).  We are burning woodchips in a “wood gasification boiler” which is also know as an "automated wood waste combustion unit".  

With mostly our own funds, and a little cost share assistance from Tobacco Communities Reinvestment Fund through RAFI we were able to purchase and put our boiler into operation in the 2010/2011 season.

Ours is a “Goliath 300” and was purchased from “New Horizons Corporation”.   The wood burns inside the firebox at approximately 2,000 degrees.   The woodchips are automatically fed into the firebox by a controller when heat is needed.  The Goliath unit will heat water to about 190 degrees.  This hot water is then pumped into the greenhouse into four 200,000 Btu heat exchangers.  The heat exchangers act similar to radiators by re-circulating the water from the boiler to the greenhouse.  Fans blow the greenhouse air across the hot coils inside the heat exchangers to extract the heat out of the water.  This system keeps the greenhouse space an average of 65 degrees. 

This one million Btu, woodchip burning boiler, with automatic feed, when combined with the proper water storage,  is capable of heating groups of houses, agricultural greenhouses, tobacco barns, chicken houses, workshops, etc.   For us, this heater is large enough for future greenhouse expansion.  For fuel, we are using ground-up wood waste (woodchips) from Elkin Sawmill, a central NC lumber yard.  The woodchips are a waste product from wood processing.

Research done by Dr. Mike Boyette of North Carolina State University has proven that this technology can heat greenhouses, chicken houses, and tobacco barns using woodchips. According to Dr. Boyette’s research, converting to wood boilers requires upfront capital costs, but this initial investment is quickly offset by the cost of wood energy.  Estimates are that the simple payback period of the wood boiler system is in the range of 4 to 5 years.  Our analysis reveals that we can recover the capital costs of converting to a wood energy system in about 3 years.  This is based on today’s price of woodchips relative to LP gas. 

I know this all sounds technical, scientific, and like way too much information, but our operation is now so much more cost effective by using wood waste instead of traditional fuel.   It's a great feeling not having to write out a check for LP gas at the end of the season.

FIRE! 
Not your typical flames, it's roaring sideways from the other box.  Within this box, the water in the pipe system is heated and then the heated water is pumped into the greenhouse heat exchangers.

Within 30 seconds of the picture of the fire, here's what the exhaust looks like.
That's how much smoke we get with a full burn. 
The boiler burns the wood and exhaust gases so HOT and thoroughly that we RARELY see smoke.

The clean, woodchip pile also serves as a great play area for our 3 yr. old grandson.