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Properties of Feedstocks for Ethanol Production
Each feedstock has unique properties. This page would give you a clear idea about the properties of a few feedstock.
1. Energy Content of Various Feedstock:
|
Bioenergy Feedstocks |
Heating Value / Energy Content (Gross, unless specified; GJ/T) |
|
Corn Stover |
17.6 |
|
Sweet Sorghum |
15.4 |
|
Sugarcane Bagasse |
18.1 |
|
Sugarcane Leaves |
17.4 |
|
Hardwood |
20.5 |
|
Softwood |
19.6 |
|
Hybrid Poplar |
19 |
|
Bamboo |
18.5-19.4 |
|
Switchgrass |
18.3 |
|
Miscanthus |
17.1-19.4 |
|
Arundo donax |
17.1 |
The above values are for the energy content of the cellulosic biomass. The cellulosic ethanol energy content values are provided below.
2. Cellulosic Ethanol Energy Content
|
Fuel |
Lower Heating Value |
Higher Heating Value |
|
Ethanol |
75,700 Btu/gallon = 21.1 MJ/liter |
84,000 Btu/gallon = 23.4 MJ/liter |
|
Gasoline |
115,000 Btu/gallon = 32 MJ/liter |
125,000 Btu/gallon = 35 MJ/liter |
Source: Oak Ridge National Laboratory, USA
From the above table, it can be seen that the energy content of ethanol is only about 65% that of gasoline.
3. Composition of Cellulosic Ethanol Feedstocks
|
Bioenergy Feedstocks |
Cellulose (%) |
Hemi-cellulose (%) |
Lignin (%) |
|
Corn Stover |
35 |
28 |
16-21 |
|
Sweet Sorghum |
27 |
25 |
11 |
|
Sugarcane Bagasse |
32-48 |
19-24 |
23-32 |
|
Hardwood |
45 |
30 |
20 |
|
Softwood |
42 |
21 |
26 |
|
Hybrid Poplar |
42-56 |
18-25 |
21-23 |
|
Bamboo |
41-49 |
24-28 |
24-26 |
|
Switchgrass |
44-51 |
42-50 |
13-20 |
|
Miscanthus |
44 |
24 |
17 |
|
Arundo Donax |
31 |
30 |
21 |
Source: http://bioenergy.ornl.gov/papers/misc/biochar_factsheet.html
Cellulose is crystalline, strong, and resistant to hydrolysis. Hemicellulose, on the other hand, has a random, amorphous structure with little strength. Hemicellulose is easily hydrolyzed by dilute acid or base, as well as by myriad hemicellulase enzymes.
Lignin is a complex polymer and is the binding structure that holds the cellulose fibers together. One can observe that the lignin composition for each of the above cellulosic feedstocks is significant, with the minimum being 11%.
In starch-based feedstocks, on the other hand, the lignin component is low. In sugar beet pulp for instance, the lignin content is less than 2% by weight.
4. Inorganic Content in Cellulosic Feedstock
The inorganic content in biomass feedstocks do not contribute to the fuel or energy product derived from the feedstock. Inorganic contents constitute anywhere between 0.5 and 6% of the total weight in a cellulosic feedstock. Among inorganic contents, ash is the one of the largest constituents. Ash typically comprises calcium, potassium, magnesium, manganese and sodium oxides, and lesser amounts of other oxides of iron, aluminum, etc.
Ash, sulphur and potassium content for sample cellulosic feedstock are provided below.
Ash, Sulphur and Potassium Content for Sample Cellulosic Feedstock
|
Cellulosic Feedstock |
Ash (%) |
Sulphur (%) |
Potassium (%) |
|
Sugarcane Bagasse |
3.2-5.5 |
0.10-0.15 |
0.73-0.97 |
|
Hardwood |
0.45 |
0.009 |
0.04 |
|
Hybrid Poplar |
0.5-1.5 |
0.03 |
0.3 |
|
Bamboo |
0.8-2.5 |
0.03-0.05 |
0.15-0.50 |
|
Switchgrass |
4.5-5.8 |
0.12 |
|
|
Miscanthus |
1.5-4.5 |
0.1 |
0.37-1.12 |
5. Length of Cellulose Fibers
The length of cellulose fibers varies depending on the feedstocks. Here are some sample lengths.
|
Feedstock |
Cellulose Fiber Length (mm) |
|
Corn Stover |
1.5 |
|
Sugarcane Bagasse |
1.7 |
|
Hybrid Poplar |
1-1.4 |
|
Bamboo |
1.5-3.0 |
6. Density of Cellulosic Feedstock
Owing to the wide variety of cellulosic feedstocks available, the density of feedstocks also assumes a wide variety. While densities of feedstock such as hardwood could be about 500-600 Kg/m3 in their unprocessed stages, densities of feedstocks such as sugarcane bagasse (50-75 Kg/m3), hybrid poplar (150 Kg/m3), Switchgrass (110 Kg/m3 approx) and Miscanthus (75-100 Kg/m3) are on the lower end.
Related Links:
- Ethanol as Biofuels
- What are feedstocks?
- Properties of Feedstocks for ethanol production
- Yield of Biomass for Various Feedstocks
- Feedstocks used by Various Companies
- Why Cellulosic Ethanol?
- Cellulosic Ethanol Production
- Cellulosic Ethanol Production Value Chain
- Ethanol production methods
- Latest Discoveries and Breakthroughs
- R & D Roadmap in Cellulosic Ethanol
- Future projections
- Companies Involved in Producing Cellulosic Ethanol
- Investments & Funding
- Challenges & Barriers in the commercialization process
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