Efficiency Calculations...
For any given energy related process, the efficicncy
can be calculated as:
Efficiency = Output/Input = Methane actually used / Max. methane produced
For our particular case, the output is the data
reported as gas extraction rate. The input should be
calculated as the maximum amount of gas that can be
recovered for a particular site. However, these is a
function of many factors, including time, waste
composition and climatic conditions. Therefore, the
estimation of the maximum amount of gas that any
particular site can produce is a key factor in the
project.
Methodology...
The group decided to tackle this problem by
use of empirical formulas in order
to claculate the maximum amount of landfill gas generated.
Empirical Method...
The following standards, as recommended by the USA. EPA were used to estimate the maximum amount of methane generated;
• EPA guidance. CAA standard based on MSW source.
• EPA guidance. AP-42 standard based on MSW source.
• EPA document. Gas-to-Energy project opportunities. (Only considers waste in place)
- For CAA and AP 42, the formula is shown below;
LFG = Lo*R*(e-kc-e-kt)
where
Lo = Total LFG yield per kg of municipal solid waste (MSW)
K= Annual rate of LFG generation
R= Waste in place (kg or tons)
c and t are the number of years since the landfill closed and opened.
| Parameter |
CAA Default Value |
| Lo |
170m3/tonne |
| K |
0.05/yr (non-arid region) |
| K |
0.02/yr (arid region) |
| Parameter |
AP-42 Default Value |
| Lo |
100m3/tonne |
| K |
0.04/yr (non-arid region) |
| K |
0.02/yr (arid region) |
- For EPA document, the formula is shown below;
For WIP<907200; 0.05085*(6.95X10-6)*(WIP)*A*B
For WIP >907200; 0.05085 *(8.22+(5.03X10-6)*(WIP))*A*B)
Where A and B are conversion factors: A=365; B=0.0283
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