Subject:- Renewable Energy Sources

Topic:- Wind Energy

Difficulty:- High

Following observations were recorded from biogas system.

No. of cows=9 , Dry matter consumed/cow/day=2.2 kg , retention time=20 days , temperature of fermentation=300c , Biogas yield=$0.22 m^3/kg$ , Burner efficiency=85% , methane production in biogas=0.68 , c.v. of methane =$28mJ/m^3=28000KJ/m^3$.

Density of matter in fluid (slurry) in digester=50kg/m3.

a) Volume of Biogas Digester.

b) Power available from biogas plant in kw.

Mo = 2.2 Kg/Day/Cow.

∴ Total dry mass input, Md= Mo x No. of cows

= 2.2 x 9=19.8Kg/day Density of dry mass $Pm= 50Kg/m^3$

∴ Fluid Volume $VF=MD/Pm= 19.8/50= 0.396 m^3/day$

Find

1) Digester volume

Vd=Vf x tr

= 0.396x20

=$7.92m^3$. (Where tr is retention period).

2)Energy Available, E in KW.

Methane production biogas:-

∴ Volume of biogas produced Cb=0.22m3/Kg

Vb=Cb x Mass of dry input

= 0.22 x 19.8

$= 3.96 m^3/day.$

E = "η" .∆Hm.fm x Vb

= 0.85 x 28000 x 0.68 x 3.96= 64088.6 KJ/day

= 64088.6/24 KJ/hr

= 64088.6 /(24 x 3600) KJ/S or KW

= 0.7418KW