[Fwd: DIG-L: energy conversion]

[cbocch <cbocch@ozemail.com.au>]

 

cbocch wrote:

oops forgot to mention that its one cubic meter

Rules of thumb are just that: rules of thumb:

One Cubic Meter of Methane has a calorific value of 36 Mj @ STP
biogas @ 58% methane has a calorific value of 20.88 Mj @ STP
Full heat value is: 20.88 / 3.6 = 5.8 Kilowatts of heat
an engine of 28% efficiency will convert this to: 1.624 Kw
taking into account 10% loss in plant efficiencies then the final value is: 1.462Kw Nett

Heat loss around the digester reactor vessel is a function of its surface area and the depth of insulation and the operating temperature and the temperature of the effluent and the frequency of the injection of the 'cooler' effluent into the digester and the rate of heat removal via the gas produced.
This is more complex!

Hoping this helps

Carmine Bocchino
http://www.bocchtech.com
Australian Biomass

"R.Edwards" wrote:

Could anyone confirm these figures that I obtained from calculation: A digester produces 76,285 m^3 of biogas per year to fuel a CHP unit. Now, British Biogen state that 1m^3 of biogas produces 1.7 kWh of electricity, and 2kWh of thermal energy. Therefore the CHP unit should produce 76,285 x 1.7 = 129685 kWh electricity AND                                                 76, 285 x 2 =152570 kWh of thermal energy BUT, It is stated that half the thermal energy generated has to be used to keep the digester running at temperatures of 35 - 40 dgs. Therefore 76285 kWh of thermal energy is still available as heat. Is this right? This figure seems very high. Any help on this would be , as always, greatly appreciated R.Edwards

begin:vcard 
n:Bocchino;Carmine 
tel;cell:+61 (0) 41 0501 452
tel;fax:+61 (0) 7 54 961 955
tel;home:+61 (0) 7 54 428 493
tel;work:+61 (0) 41 0501 452
x-mozilla-html:FALSE
url:http://www.bocchtech.com
org:Bocchino Technologies
adr:;;P.O. Box 5650;West End;Queensland;4101;Australia
version:2.1
email;internet:cbocch@bocchtech.com
note;quoted-printable:=0D=0A=0D=0A=0D=0APhone Free:5126139=0D=0A=0D=0A=0D=0ATIME ANYWHERE=0D=0Ahttp://www.timeanddate.com/=0D=0A
x-mozilla-cpt:;-30400
fn:Carmine Bocchino
end:vcard

Digestion List Archives:
http://www.crest.org/discussion/digestion/200202/

Digestion List Moderator:
Paul Harris, paul.harris@adelaide.edu.au
http://www.roseworthy.adelaide.edu.au/~pharris
List-Post: <mailto:digestion@crest.org>
List-Help: <mailto:digestion-help@crest.org>
List-Unsubscribe: <mailto:digestion-unsubscribe@crest.org>
List-Subscribe: <mailto:digestion-subscribe@crest.org>

Other Digestion Events and Information:
http://www.bioenergy2002.org
http://crest.org/discussiongroups/resources/biomass/biogas/BIOGASMK.pdf
http://www.crest.org/articles/static/1/1010424940_7.html

Beginners Tour of Biogas
http://WWW.roseworthy.adelaide.edu.au/~pharris/biogas/beginners