Material and Energy Balance of Biogas Plant

FEEDSTOCK PARAMETERS Units Cow Manure Feedstock Total Notes

Dry Matter (DM) of cow manure % 11% 11%
Organic Dry Matter (ODM) of cow manure % 87% 87%
CH4 content biogas % 50% 50%
Biochemical Methane Production (BMP) m3CH4.tonneODM-1 190 190
Specific Gravity kg.m-3 1.03 1.03
Manure Production per head per day kg.hd-1./day 60 -
Animals No. 1,222 -
Mass tonne./day 73.3 73.3
Volume m3./day 71.2 71.2 = mass / SG.
Mass tonne.yr-1 26,762 26,762
Dry matter tonne./day 8.1 8.1 = mass x %DM
Organic Dry Matter tonne./day 7.0 7.0 = DM x %ODM
Methane Production m3./day 1,333 1,333 = ODM x BMP
Biogas Production m3./day 2,666 2,666 = CH4 / %CH4
 DIGESTER CAPACITY CALCULATION
Mass of Feedstock tonne./day - 73.3
Volume of Feedstock m3./day - 71.2
Organic Dry Matter tonne./day - 7.0
Digester Capacity m 3
- 3,000
Hydraulic Retention Time d - 40.9 = Digester Capacity / Feedstock Volume
Organic Loading Rate kg.mR-3./day - 2.3 = Organic Dry Matter * 1000/ Digester Capaci
ENERGY BALANCE
Methane Production m3./day 1,333 1,333
Energy Value of Biogas MJ./day 47,594 47,594 = CH4 * 35.7
Energy Value of Biogas kWh./day 13,221 13,221 = MJ / 3600
Energy Value of Biogas kW 551 551 = kWh / 24
Biogas for Boiler % - 5%
Biogas for Combined Heat and Power (CHP) partnership % - 90%
Biogas Flared % - 5%
Heat Efficiency of Boiler % - 85%
Electrical Efficiency of Combined Heat and Power (CHP) partnership % - 30%
Heat Efficiency of Combined Heat and Power (CHP) partnership % - 55% = 85% - Electrical Efficiency
 Energy Production
Heat Production from Boiler kW - 23 = Energy Value * Boiler% * Boiler Efficiency
Heat Production from Combined Heat and Power (CHP) partnership kW - 273 = Energy Value * CHP% * CHP Heat Efficiency
Total Heat Production kW - 296
Total Heat Production kWh./day - 7,106 = kW * 24
Electricity Production kW - 149 = Energy Value * CHP% * CHP Electrical Efficien
Electricity Production kWh./day - 3,570
Digester Heat Input
Temperature of Feedstock o
C 20 20
Temperature of Digester o
C - 40
Heat Input to Feedstock MJ./day 6,144 6,144 = Mass * Delta T * 4.19
Heat Input to Feedstock kW 71 71 = MJ * 1000 / 3600 /24
Digester Surface Area m2 - 1,151 Assumes Height = Diameter
Thermal Conductivity W.m-2.oC-1 - 0.35 Assumes 100mm of Mineral Wool
Outside Air Temperature o
C - 4
Digester Heat Loss kW - 15 = Tank Area x Delta T x Conductivity / 1000
Digester Heat Loss MJ./day - 1,254 = MJ * 1000 / 3600 /24
Total Digester Heat Input MJ./day - 7,398 = Heat to Feedstock + Heat Loss
Total Digester Heat Input kW - 86 = MJ * 1000 / 3600 /24
Digester Heat : Available Heat % - 29%
 Energy Balance
Electricity Production kW - 149
Digester Electricity Consumption kWh./day - 50
Digester Electricity Consumption kW - 2 = kWh /24
Digester Electricity : Output % - 1%
Heat Production kW - 296
Total Digester Heat Input MJ./day - 7,398
Total Digester Heat Input kW - 86 = MJ * 1000 / 3600 /24
Digester Heat : Available Heat % - 29%
MASS BALANCE
Mass of Feedstock tonne.yr-1 26,762 26,762
Volume of CH4 m .yr
3 -1
486,610 486,610
Volume of CO2 m .yr
3 -1
486,610 486,610 = Biogas - Methane
Mass of CH4 tonne.yr -1
345 345 = CH4 * 0.71 / 1000
Mass of CO2 tonne.yr -1
954 954 = CO2 * 1.96 / 1000
Mass of Biogas tonne.yr-1 1,299 1,299
Mass of Digestate tonne.yr-1 25,463 25,463 = Feedstock Mass - Biogas Mass
Mass Reduction tonne.yr -1
1,299 1,299
% Mass Reduction % 5% 5%

0.5 0.6 m3/kwh from biogas kwh production

nt

473.684

M
M
MP
4
dstock Volume
Digester Capacity

7
0

fficiency
 Boiler Efficiency
HP Heat Efficiency

Electrical Efficiency

* 4.19
00 /24
Diameter
ineral Wool

ductivity / 1000
00 /24
Heat Loss
00 /24
00 /24

hane
1000
1000

ogas Mass