A Brief Explanation of Terms Used in Biomass Analysis Reports
As received basis
As received basis: sample in the condition as received by the laboratory analyzing the biomass.
Dry Basis
Dry Basis. Dry basis moisture content is described by the percentage equivalent of the ratio of the weight of water to the weight of the dry matter. When a sample loses or gains moisture, the change in the dry basis moisture is linearly related to the weight loss or gain.
Dry Ash-Free Basis
An analysis expressed on the basis of a sample from which the total moisture and the ash have in theory been removed.
Fixed Carbon
Fixed carbon is the solid carbon in the biomass that remains in the char in the pyrolysis process after devolatilization. Fixed carbon is a measure of the amount of non-volatile carbon remaining in a biomass sample. Fixed carbon content gives information of the amount of char formation in the thermochemical conversion process. It is the solid combustible residue that remains after the volatiles matter drive off.
Volatile solids
Volatile solids are a substance that can easily transform from its solid phase to its vapor phase without going through a liquid phase
Volatile matter
Volatile matter is measured as the weight percent of gas (emissions) from a biomass sample that is released during heating to 950 C° in an oxygen-free environment , except for moisture (which will evaporate as water vapor), at a standardized temperature.
Total solids
Total solids are a measure of the suspended and dissolved solids in water.
Moisture content
The moisture content of biomass can either be measured on a wet or dry basis. The wet-basis expresses the ratio of moisture mass to the total mass of the substance whilst the dry basis expresses the ratio of the moisture mass to the mass of dry matter. The moisture data reported here is using the wet-basis.
Ash
Ash is generally considered to be the residue remaining after the material has been incinerated. It therefore has no energy value and, being made up of the inorganic elements in the biomass, is of no direct value in hydrolysis technologies. High ash-contents can cause problems in many thermochemical processes (e.g. pyrolysis, gasification, and combustion). There are several units of measurement.
Calorific value
The gross calorific value or Higher Heating Value (HHV) indicates how much energy can be released during the complete combustion of a given amount of fuel; is independent of moisture content and reliant on the chemical composition of the material. A linear relationship exists between the heat of combustion and the carbon content of the substrate while oxygen, nitrogen and inorganic elements tend to reduce the value.
The Lower Heating Value (LHV) (net calorific value (NCV) or lower calorific value (LCV)) or effective heating value, is perhaps more relevant than the HHV in practical operations. It considers not only the energy required to vaporise the moisture of the biomass but also the energy necessary to vaporise the water generated when the hydrogen and oxygen elements of the biomass combine. Hydrogen content then becomes a reducing factor in the heating value.
Oven-dry woody biomass typically has a calorific value of 18-21 MJ per kg on a dry basis (this is the gross calorific value), whereas heating oil has a value 444 -45 MJ per kg. Most fuels are not oven dry when burnt and the water in the wood must be evaporated, detracting from the extractable energy* (or net calorific value).
* We acknowledges Celignis for much of the above information from their website www.celignis.ie
As received basis
As received basis: sample in the condition as received by the laboratory analyzing the biomass.
Dry Basis
Dry Basis. Dry basis moisture content is described by the percentage equivalent of the ratio of the weight of water to the weight of the dry matter. When a sample loses or gains moisture, the change in the dry basis moisture is linearly related to the weight loss or gain.
Dry Ash-Free Basis
An analysis expressed on the basis of a sample from which the total moisture and the ash have in theory been removed.
Fixed Carbon
Fixed carbon is the solid carbon in the biomass that remains in the char in the pyrolysis process after devolatilization. Fixed carbon is a measure of the amount of non-volatile carbon remaining in a biomass sample. Fixed carbon content gives information of the amount of char formation in the thermochemical conversion process. It is the solid combustible residue that remains after the volatiles matter drive off.
Volatile solids
Volatile solids are a substance that can easily transform from its solid phase to its vapor phase without going through a liquid phase
Volatile matter
Volatile matter is measured as the weight percent of gas (emissions) from a biomass sample that is released during heating to 950 C° in an oxygen-free environment , except for moisture (which will evaporate as water vapor), at a standardized temperature.
Total solids
Total solids are a measure of the suspended and dissolved solids in water.
Moisture content
The moisture content of biomass can either be measured on a wet or dry basis. The wet-basis expresses the ratio of moisture mass to the total mass of the substance whilst the dry basis expresses the ratio of the moisture mass to the mass of dry matter. The moisture data reported here is using the wet-basis.
Ash
Ash is generally considered to be the residue remaining after the material has been incinerated. It therefore has no energy value and, being made up of the inorganic elements in the biomass, is of no direct value in hydrolysis technologies. High ash-contents can cause problems in many thermochemical processes (e.g. pyrolysis, gasification, and combustion). There are several units of measurement.
Calorific value
The gross calorific value or Higher Heating Value (HHV) indicates how much energy can be released during the complete combustion of a given amount of fuel; is independent of moisture content and reliant on the chemical composition of the material. A linear relationship exists between the heat of combustion and the carbon content of the substrate while oxygen, nitrogen and inorganic elements tend to reduce the value.
The Lower Heating Value (LHV) (net calorific value (NCV) or lower calorific value (LCV)) or effective heating value, is perhaps more relevant than the HHV in practical operations. It considers not only the energy required to vaporise the moisture of the biomass but also the energy necessary to vaporise the water generated when the hydrogen and oxygen elements of the biomass combine. Hydrogen content then becomes a reducing factor in the heating value.
Oven-dry woody biomass typically has a calorific value of 18-21 MJ per kg on a dry basis (this is the gross calorific value), whereas heating oil has a value 444 -45 MJ per kg. Most fuels are not oven dry when burnt and the water in the wood must be evaporated, detracting from the extractable energy* (or net calorific value).
* We acknowledges Celignis for much of the above information from their website www.celignis.ie