# Biomasses used as Fuel - Energy Content

## Some biom fuels and their energy content

Approximately energy content in different biomasses, used as fuels (not prosessed material):

See also Heat of combustion

Bio Fuel | Energy content (MJ/kg) Load Calculator! Load Calculator! |
---|---|

Alfalfa straw | 18.5 |

Charcoal | 30 |

Coal | 28 |

Coconut husks | 10 |

Coconut shells | 18 |

Coffee husks | 16 |

Commercial wastes | 16 |

Cotton hulls | 19.5 |

Cotton stalks | 17.5 |

Domestic refuse | 9 |

Dung, dried | 16 |

Grass, fresh | 4 |

Groundnut shells | 20 |

Maize cobs | 19 |

Maize stalks | 18 |

Methane from biogas | 55 |

Paper, newspaper | 17 |

Peat | 14.5 |

Petroleum Oil | 42 |

Rice hulls | 15.5 |

Rice straw | 15 |

Soybean stalks | 19 |

Straw, harvested, baled | 15 |

Sorghum bagasse | 19 |

Sugar cane residues | 17 |

Wheat straw | 19 |

Wood, green with 60% moisture | 6 |

Wood, air-dried to 20% moisture | 15 |

Wood, oven-dried to 0% moisture | 18 |

*1 MJ/kg**= 0.28 kWh/kg*= 430 Btu/lb_{m}

### Wood required to Boil a Litre of Water

The energy to heat one litre of water (*1 kg)* with specific heat *4.2 kJ/kg ^{o}C* from

*20*to boiling

^{o}C*100*can be calculated with the heating equation

^{o}C

q = m c_{p}dt (1)

where

q = heat (J, Btu)m = mass of water (kg, lb)

c_{p}= specific heat of water (J/kg^{o}C, Btu/lb^{o}F)

dt = temperature change (^{o}C,)^{o}F

Inserting the values

*q = (1 kg) (4.2 kJ/kg^{o}C) (1000 J/kJ) ((100 ^{o}C) - (20 ^{o}C)) *

* = 336000 J*

* = 336 kJ (kW/s)*

* = (336 kW/s) / (3600 s/h)*

* = 0.093 kWh*

With energy content of air dryed wood *15 MJ/kg (15000 kJ/kg)* and combustion efficiency *0.25 (25%)* - the amount of wood to heat the water can be calculated as

*m _{w} = q / μ h_{w} (2)*

*where *

*m _{w} = mass of wood (kg)*

*μ = combustion efficiency *

*h _{w} = energy content wood (kJ/kg)*

Inserting the values

*m _{w} = (336 kJ) / 0.25 (15000 kJ/kg)*

* = 0.09 kg*