Page 69 - Biomass Gasification, Pyrolysis And Torrefaction Practical Design and Theory

48 Biomass Gasification, Pyrolysis and Torrefaction

living and recently dead biological species that can be used as fuel or in
chemical production. Biomass does not include organic materials that over
many millions of years have been transformed by geological processes into
fossil fuels such as coal or petroleum. Common sources of biomass are:

Agricultural: food grain, bagasse (crushed sugarcane), corn stalks, straw,
seed hulls, nutshells, and manure from cattle, poultry, and hogs.
Forest: trees, wood waste, wood or bark, sawdust (SW), timber slash, and
mill scrap.
Municipal: sewage sludge, refuse-derived fuel (RDF), food waste, waste
paper, and yard clippings.
Energy Crops: poplars, willows, switchgrass, alfalfa, prairie bluestem,
corn, and soybean, canola, and other plant oils.
Biological: animal waste, aquatic species, and biological waste.

3.2.1 Biomass Formation

Botanical biomass is formed through conversion of carbon dioxide (CO 2 )in
the atmosphere into carbohydrate by the sun’s energy in the presence of chloro-
phyll and water. Biological species grow by consuming botanical or other bio-
logical species. Plants absorb solar energy by a process called photosynthesis
(Figure 3.1). In the presence of sunlight of particular wavelengths, green plants
break down water to obtain electrons and protons and use them to turn CO 2

Oxygen
Carbon Dioxide

Chlorophyll

Water
FIGURE 3.1 Biomass grows by absorbing solar energy, carbon dioxide, and water through
photosynthesis.