Bioenergy & Gasification Glossary
Biomass gasification comes with its own vocabulary. This glossary defines the terms used throughout this resource in plain language. For fuller explanations, follow the links back to the topic pages.
Core terms
- Biomass
- Organic material — wood, crop residues, agricultural and forestry waste — used as a renewable fuel. See feedstocks.
- Gasification
- The thermochemical conversion of solid biomass into a combustible gas under controlled, oxygen-limited conditions. See what is gasification.
- Producer gas
- The combustible gas from air-blown gasification, containing carbon monoxide, hydrogen and methane diluted with nitrogen. Also called wood gas. See producer gas.
- Syngas
- Synthesis gas — a broader term for hydrogen-and-carbon-monoxide gas mixtures; producer gas is a nitrogen-diluted form.
- Pyrolysis
- Thermal decomposition of biomass in the absence of oxygen, producing volatile gases, tar and char; one of the four stages inside a gasifier.
Process and engineering terms
- Sub-stoichiometric
- Operating with less oxygen than needed for complete combustion — the condition that makes gasification rather than burning occur.
- Downdraft gasifier
- A fixed-bed reactor in which gas flows down through the fuel and the hot zone, cracking tar to yield relatively clean, engine-grade gas. See gasifier technology.
- Tar
- Condensable organic compounds carried in raw producer gas; must be reduced (typically below ~15 ppm) for reliable engine use.
- Char
- Carbon-rich solid residue from pyrolysis; a saleable by-product and, as biochar, a soil amendment.
- Thermic fluid heater
- Equipment that heats a circulating oil to carry process heat indirectly; readily fired by producer gas. See thermal applications.
- Calorific value
- The energy released per unit of fuel or gas burned; clean producer gas is around 1,100–1,200 kcal/Nm³.
- Nm³ (normal cubic metre)
- A standard volume of gas measured at defined reference temperature and pressure, used to compare gas quantities fairly.
Application and performance terms
- Dual-fuel mode
- Running a diesel engine on producer gas plus a small pilot of liquid fuel, typically displacing 75–80% of the diesel. See power generation.
- Plant load factor (PLF)
- The fraction of maximum possible output a plant actually delivers over time; biomass gasifiers can achieve a high PLF because they run on demand.
- Briquette
- Loose, powdery residue (rice husk, saw dust, groundnut shell) compressed into a dense fuel suitable for fixed-bed gasifiers.
- Feedstock
- The biomass fuel fed into a gasifier; its moisture, size and ash content largely determine performance.
- Village electrification
- Supplying decentralized electricity to rural communities, often via mini-grids. See village electrification.