BIOMASS ENERGY CONTENT

The energy content of biomass is obviously a very important parameter from the standpoint

of conversion of biomass to energy and synfuels. The different components in biomass would

be expected to have different heats of combustion because of the different chemical structures

and carbon content.

Energy content equations:

Bain/Graboski (1979):

HHV [Btu/lb] = 85,65 +137,04 C + 217,55 H + 62,56 N 107,73 S + 8,04 O - 12,94 Ash

Dulong-Petit (Perry, 1997)

HHV [kJ/kg] = 337 C + 1428 (H - O/8) + 95 S

Dulong-Petit (Tillman)

HHV [Btu/lb] = 14490 C + 61000 H + 5550 S

HHV [Btu/lb] = 14440 C + 61020 H + 5550 S - 6590 O - (39 O)^2

Boie (Standard and modified for MSW respectively)

HHV [kJ/kg] = 351,7 C + 1162,4 H + 104,6 S - 110,9 O + 62,8 N - 439,6

HHV [kJ/kg] = 227,9 C + 1162,4 H + 104,6 S + 58,2 O + 62,8 N - 439,6

Vondracek

HHV [kcal/kg] = 85 C + 270 H +25 S - 27 O

HHV [kcal/kg] = (89,1 - 0,067 C) + 270 H + 25 S - 27 O

IGT/Graboski

HHV(kJ/g) = 0.341 C+ 1.322 H + 0.0686 S - 0.120 (O+N) - 0.0153 Ash

Atlas of Thermal Data (NREL/TP-433-7965)

HHV(kJ/g) = 0.3491 C + 1.1783 H + 0.1005 S -0.1034 O -0.0151 N - 0.0211 Ash

Channiwala

HHV [kJ/kg] = 349,1 C + 1178,3 H - 103,4 O + 100,5 S - 15,1 N - 21,1 Ash

Dr. Demirbas, published in the journal Fuel in 1997:

HHV = 0.312(FC) + 0.1534(VM).

Dr. Demirbas, published in the journal Fuel in 1997:

HHV = 0.196(FC) + 14.119.

Dr. Demirbas

The HHV(kJ g−1) of the biomass fuel as a function of lignin content (L, wt%) was calculated

using the following equations:

The HHV is calculated from the ash, C, and H content by (Sheng and Azevedo, 2005):

HHV (MJ/kg) = -1.3675 + 0.3137C + 0.7009H + 0.0318 O*

Where O* = the sum of the contents of oxygen and other elements (including S, N, Cl, etc.)

in the organic matter, i.e. O*=100%-C-H-Ash.

Milne’s formula

HHV(MJ/kg) = 338.2 x C + 1442.8 x (H-O/8)

Grummel and Davis

HHV, Btu/lb = [654.3 H/(100-A) + 424.62] [C/3 + H – O/8 + S/8}

Mott and Spooner

HHV, Btu/lb = 144.54 C + 610.2 H + 40.5 S – 62.46 O O < 15%

HHV, Btu/lb = 144.54 C + 610.2 H + 40.5 S – [65.88 – 30.96 O/(100-Ash) (O)] O > 15%

Francis and Lloyd

HHV, kJ/kg = 357.8 C + 1135.6 H + 54.9 N + 119.5 S – 85.4 O -974

Shafizadeh and Degroot

HHV, kJ/kg = 173.89 Ce + 266.29 L + 321.87 E

  Pine

Giant Brown Kelp

Water Hyacinth

Livestock waste RDF

Carbon, % 0.518 0.277 0.411 0.351 0.412Hydrogen, % 0.063 0.037 0.053 0.053 0.055Oxygen, % 0.413 0.282 0.288 0.332 0.387Nitrogen, % 0.001 0.012 0.020 0.025 0.005Sulfur, % 0.000 0.003 0.004 0.004 0.002Ash, % 0.005 0.389 0.224 0.235 0.139

  Pine

Giant Brown Kelp

Water Hyacinth

Livestock waste RDF

Bain/Graboski (1979),kJ/kg 388.305 290.716 345.618 328.478 348.630Dulong-Petit (Perry, 1997) 190.810 96.502 162.958 135.089 148.495Dulong-Petit (Tillman) 186.551 96.399 160.064 133.471 146.198Boie 209.673 110.495 175.716 150.224 166.437Vondracek 208.536 108.911 173.611 147.475 164.989Atlas 208.046 101.069 168.052 142.878 162.475IGT 210.168 102.623 169.979 143.596 164.173Milne’s formula 191.599 96.542 163.311 135.300 148.897Grummel and Davis 314.914 152.597 266.170 209.072 237.875Francis and Lloyd 221.668 118.317 184.066 159.272 177.335