Heating Systems

Section 4: Fuel Sources

There are many considerations when deciding upon a fuel source. These include availability, cost, price volatility, pollution regulations, storage requirements, equipment requirements, boiler requirements, and maintenance requirements.

When determining fuel cost, all costs of using a given fuel must be considered. This includes handling and storage equipment required as well as maintenance costs. Additionally, different fuels contain different amounts of energy. Therefore, when evaluating the cost of the fuel, the cost per Btu (or per 1,000,000 Btu for example) should per determined and not the cost per weight or volume of the fuel. This will allow a more direct comparison of cost among fuels.

Common Fuel Sources Used for Heating Greenhouses and Their Characteristics
Fuel Source	Characteristics
Natural Gas	Usually low cost but prices fluctuate; clean burning; no storage tanks required; simple inexpensive system with generally low maintenance costs. Commonly used in greenhouse.
Propane and Butane	Similar to natural gas but more expensive; price can be volatile and storage tanks are usually required. Often used for greenhouse where natural gas is unavailable.
Oil (grade No.2 or lower)	More expensive than natural gas; requires more boiler maintenance because it does not burn as clean as natural gas or propane; storage tanks required.
Coal	Generally low in cost if readily available; generates significant pollution; large storage area needed; moving and loading equipment required; significant boiler cleaning and maintenance required.
Wood chips	Often low cost if available; need secure source; need large storage area, handling and loading equipment; significant boiler maintenance and cleaning required.
Logs	Similar to wood chips but require different handling systems.
Electric	Expensive; limited to small or hobby greenhouses.

Estimates of BTU Output Expected From Different Fuel Sources (corrected for efficiency)
Anthracite Coal	8,300 Btu/lb
No. 1 Fuel Oil	93,000 - 96,000 Btu/gallon
No. 2 Fuel Oil	95,000 - 99,000 Btu/gallon
No. 4 Fuel Oil	95,000 - 104,000 Btu/gallon
Natural Gas	750 Btu/ft³
Propane	1,900 Btu/ft³
Dried Wood Chips	5,000 Btu/ft³