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Green Forest

Appendix - Additional Resources

D. Biomass Heating Appliance Price Saving Calculation

Nebraska Energy Quarterly, June 30, 2007
By Bruce Hauschild P.E., CEM


Q: We're considering buying a Maxfire Stove that is fueled with corn made by Bixby Energy. The stoves cost approximately $3,400, and I'm estimating a 60-70 percent reduction in gas heating cost once installed. Would this qualify for a Dollar and Energy Saving Loan?


A: Considering the current price of shell corn, I doubt that a project like this would qualify for a Dollar and Energy Saving Loan.

If you would like to submit an application, you would need to complete loan application Form 32, Energy Saving Improvement Analysis, and Form 33 Energy Billing History. Instructions for these application forms are detailed in Steps to Obtain a Low-Interest Loan Using an Energy Saving Improvement Analysis.

You will need to submit either an Annual Fuel Utilization Efficiency, or a Steady State Thermal Efficiency report for the new unit, from a third party qualified to do such tests. The advertised combustion efficiency of 99.7 percent is only a measure of how much of the fuel is turned into heat within the unit and says nothing about the amount of heat being provided to the home. A common fireplace can have a combustion efficiency of near 90 percent while the efficiency of heat transferred to the home may be as low as 15 percent — 85 percent of the heat goes up the chimney.

We see a number of advertisements for these type systems claiming a British thermal unit — Btu — content for corn at 504,000 Btus per bushel. This Btu content is called the higher heating value which is based on a laboratory test for a substance with all moisture removed. Clean corn at 15-15.5 percent moisture will have a Btu content of 380,000 Btu per bushel. Foreign matter, such as dust, pieces of cobs, leaves and stalk commonly found in off-the-farm corn will further reduce the Btu content of corn. You will need to use 380,000 Btu per bushel in your energy analysis.

A typical energy analysis calculation would be as follows:
 

  1. Current annual fuel costs: From copies of your most recent years bill for heating list the dollars you spent on fuel. $__________

  2. The price per unit of fuel: From your heating bills, find the price paid per unit of fuel (such as $1.00 per therm for natural gas, $1.30 per gallon for propane, $0.05 per kWh for electricity, $140 per cord for wood, etc.). $__________

  3. Annual Fuel Use: Divide your current annual fuel costs, line 1, by the price per unit of fuel, line 2, to find your annual units of fuel use (therms for natural gas, gallons for propane, kWh for electricity, cords for wood, etc.). __________

  4. Decimal Efficiency: In decimal form, list the efficiency of your current heating system. Divide percent Steady State Thermal efficiency or percentage AFUE by 100 percent, 80 percent AFUE = 0.80, 96 percent AFUE = 0.96. NOTE: Do NOT use combustion efficiencies! Combustion efficiencies are no measure of the amount of heat delivered to your home. Divide HSPF by 3.412 Btu/watt-hour, 9.0 HSPF = 2.64. NOTE: HSPF takes into account an average for backup heat — No conversion is needed for COP, 4.6 COP = 4.6, etc., use 0.99 for electric strip heat. __________

  5. Fuel units felt as heat: Multiply annual fuel use, line 3, by the decimal efficiency, line 4, to find the amount of heat that actually entered your home from your current heating system. __________

  6. Btu per unit of fuel: List the number of Btus per unit of fuel (100,000 Btus in a therm, 85,000 Btus in a gallon of propane, 3,412 Btus per kWh electricity, 18,000,000 Btus per cord of wood). __________

  7. Btus felt as heat: Multiply fuel units felt as heat, line 5, by Btu per unit of fuel, line 6, to find the amount of heat, in Btus, that entered your home and were felt as heat. __________

  8. Decimal efficiency of new unit: List the decimal efficiency of the stove you intend to purchase (80 percent AFUE = 0.80, 96 percent AFUE = 0.96, etc. NOTE — Do NOT use combustion efficiencies! If using a steady state thermal efficiency for the new unit, and you used AFUE, HSPF, or COP in line 4 above, you must deduct 5 to 10 percentage points from the steady state thermal efficiency of the new unit to get to an AFUE for an equal comparison, 85 percent steady state thermal efficiency would equal 75-80 percent AFUE = 0.75 to 0.80). __________

  9. Btus required by new unit: Divide the Btus felt as heat, line 7, by the decimal efficiency of the new unit, line 8, to find the Btu input that will be required by the new unit for an equal amount of heat in your home. __________

  10. Btu content of corn: Use 380,000 Btu/bushel for clean corn, or 380,000 Btu/bushel for corn with foreign matter, at 15-15.5 percent moisture content. (Do not use 504,000 Btu/bushel. This is a laboratory condition for zero percent moisture and clean corn). __________

  11. Annual bushels of corn required: Divide Btus required of new unit, line 9, by the Btu content of corn, line 10, to find the number of bushels of corn you will use for an equal amount of heat in your home. __________

  12. Price of corn: Obtain a quote for corn delivered to your home and list the price here. Use market price plus $0.20 elevator handling charge, or current market price if you are a producer, or loan value if market price is below loan value and you are a producer. $ __________

  13. Annual cost of heating with corn: Multiply the annual bushels of corn required, line 11, by the price of corn, line 12, to find the cost of heating with corn. $ __________

  14. Comparison: Subtract your annual cost of heating with corn, line 13, from your current annual fuel costs, line 1, to find if changing to corn heat will save you money. Note that if this number is negative, it will actually cost you more for corn heat. $ __________

Dollar and Energy Saving Loans are for replacement equipment. Unless your current heating system consists of pre-approved equipment, ratings for which can be found on loan application Form 3, you would not be able to keep your current heating system for use as a backup. If you can keep your current system as backup, you should only enter a percentage of your current annual fuel costs — nothing greater than 75 percent of current use, in line 1 of the sample calculations above.

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