the true cost of biomass - tappithen this is the cost of your biomass energy $0 $2 $4 $6 $8 $10 $12...

The True Cost of Biomass

T. J. Paskach

Getting at the true cost of biomass feedstock energy– Need to account for all the costs of biomass in

a project• Moisture effects• Ash effects• Density effects• Scarcity effects (procurement risk)

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Properly correcting for moisture

• Impacts of moisture content for thermochemical processes (e.g. combustion)– Boiler capacity and efficiency effects– Increased material handling costs– Increased storage volume requirements– Stability issues– Decreased heating value



Effect of Moisture on Real Fuel Value

• Each lb of liquid moisture in the feedstock typically ends up as roughly 300-400˚F steam at 1 atm

• This translates into a loss of 1178Btu/lb of water in the feed



Example

• HHV (bone dry basis) = 8378

• HHV (as received) = 7300• 8378x(1-0.1286) = 7300• Ref. temp is 68˚F



Definition of Higher Heating Value

• Determined by ASTM D2015, heat released by combusting a known mass of fuel in a bomb calorimeter, completely to CO2, SO2, nitrogen and liquid water. (aka gross calorific value)



Definition of Lower Heating Value

• Heat produced by combustion of one unit of a substance, at atmospheric pressure under conditions such that all water in the products remains in the form of vapor. (ASTM D407)

• LHV = HHV – 1030*MC 1

1 Steam, its Generation and Use, 41st Ed., John Kitto and Steven Stultz, Babcock & Wilcox Co., 2005.



Introduction of energy based moisture correction concept

• Simple Formula

• The usual LHV formula uses 1030 Btu/lb– Assumes water vapor at 68˚F

• Use 1178 for water vapor at 350˚ F:

• (Heat of melting water is another 144Btu/lb: in the winter, use 1322 Btu/lb!)

( ) ( )MCMCHHVLHV dryAR 10301 −−=



( ) ( )MCMCHHVLHV dryAR 11781' −−=

Example LHV’AR



Moisture Content (as‐received)

HHV (as‐received)

LHV(as‐received)

LHV'(as‐received)

Real Feedstock Value (wet basis)

cost of available energy

(wet basis)wt% Btu/lb wet Btu/lb wet Btu/lb wet $/wet ton $/MMBtu0% 8500 8037 8037 $47.27 $3.1110% 7650 7130 7115 $41.85 $3.5120% 6800 6223 6194 $36.43 $4.0430% 5950 5317 5272 $31.01 $4.7440% 5100 4410 4351 $25.59 $5.7550% 4250 3503 3429 $20.17 $7.2960% 3400 2597 2508 $14.75 $9.9770% 2550 1690 1586 $9.33 $15.7680% 1700 783 665 $3.91 $37.60

* Feedstock at $50/ton (dry basis), with a dry‐basis heating value of 8500 Btu/lb and 5% H

Example LHV’AR

$‐

$10.00

$20.00

$30.00

$40.00

$50.00

$60.00

0% 20% 40% 60% 80% 100%

Moisture‐Co

rrected Va

lue of Biomass, $/w

et ton

Moisture Content

Effect of Moisture Correction Formula on Dollar Value of Feedstock

Overvaluation at 50% moisture is $4.83 per wet ton, or $9.66 per dry ton

This is nearly a 20% difference

If this is how you correct for moisture….

• $/ton wet = $/ton dry*(1-MC)• Example:

– $50/ton (agreed on dry-basis price)– 40% moisture incoming– $50 * (1-40%) = $30 per wet ton paid

Then this is the cost of your biomass energy

$0

$2

$4

$6

$8

$10

$12

$14

$16

$18

$20

0% 10% 20% 30% 40% 50% 60% 70% 80%

True

Cost o

fBiomass En

ergy, $/M

MBtu (LHV')

Moisture Content

True Cost of Biomass Energy with Fixed Dry Basis HHV Pricing

Basis:$50/ton dry basis8500 Btu/lb HHV dry

Ash is not “free”

• Cost of handling– CAPEX of ash handling equipment– Footprint/site costs

• Handling• Storage

– Liability/hazards• Flammability, dust, etc.



Ash is not “free”• Problematic ash constituents

– K (potash)– Na (soda ash)– P(phosphorus)– Si(silica)– Cl (Chloride)

• Fast-growing biomass sources contain higher amounts of these

Problematic ash constituents

• Alkali: – Increased boiler fouling– With silica and chloride, forms low-melting phases

(slagging) – Forms ultra-fine PM – PM emissions– SCR catalyst poisoning

• Chlorides– In low-sulfur environment, cause boiler corrosion

– S/Cl ratio < 2 = certain problems– S/Cl ratio > 4 = not a problem



Ash is not “free”

– The true cost of these equipment impact issues is much harder to quantify. – Use experience, frequency of sootblowing,

tube failures, cost of outages, maintenance, depreciation/replacement frequency, other factors

Density Effects• Use “Dry Basis Density” for energy

• Bulk density changes• PSD effects• Cost of storage, transportation, and material

handling– Generally scale with volume or 1/density

• Geographic density (harvest density)– Energy crops harvested each year– Wood can be harvested 6+ year rotation

( )MCwetdry −= 1ρρ

Biomass demand may increase the value of “easy” biomass

• Potential demand for electricity (State RPS’s)• Potential demand for liquid biofuels (RFS2)• Value of biomass depends as much on the

downstream use as it does on the cost of production/storage and transportation

• What’s “Easy Biomass”– Low moisture– Low ash– High density (dry basis)– Availability per acre



Biomass Demand for BioPower

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2010 2015 2020 2025

Biom

ass D

eman

d, millions of ton

s per year

Gen

eration from

biomass, billions of k

Wh pe

r year

Biomass Electric Power Generation

Biomass Demand

Power Generation from Biomass

Source: EIA Energy Outlook 2011



Biomass Demand for Biofuels• One 50 mmgpy advanced biofuels plant

running on wood will consume about 700,000 dry tons/year.

• RFS2 mandates 36 billion gallons by 2022• 500 million dry tons/year of biomass



Thank you!

Frontline BioEnergy, LLC1421 S Bell Ave Ste 105

Ames, IA 50010515-292-1200

www.frontlinebioenergy.com

the true cost of biomass - tappithen this is the cost of your biomass energy $0 $2 $4 $6 $8 $10 $12...

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