[Digestion] Biogas conversation rates

Franssen, Loe (Alumni) LLC.Franssen at alumni.maastrichtuniversity.nl
Sun Jan 16 06:34:06 CST 2011


Hey Duncan (and the others),

thanks for your elaborate answer ! I'm sorry for being unspecific. Let me be a bit more specific and take the kerosene conversion rate because the information on this one is the most inconsistent.

Assumptions
Consumption rate simple wick kerosene lamp; 0,01 liter kerosene per hour
                         Biogas lamp; 70 liters of gas per hour (specifications of the lamp that will be supplied: http://kingoni.en.ec21.com/Biogas_Lamp--3003470_3352352.html)
Lumen output of a simple wick kerosene lamp 7,8 lumen
                           biogas lamp; 50 lumen (not sure on this number as there is a large range for it right?!)
Calculation
so 1 liter of kerosene is equivalent to 7000 liter gas. After correcting for lumen output, 1 liter of kerosene is equal to 1,077 liter of gas

If i use calorific values i get the following result

1kilo kerosene = 46 mj/kg with a density of 0,95 kg/l so

1 liter kerosene = 43,7 mj/l

1m3 biogas is 22.5mJ

1 liter biogas = 0,0225 mJ



1L kerosene = (43.7/0.0225) = 1942,22L biogas


Quite a difference hm probably because of the lumen i took for the biogas lamp and the consumption rates?! do you have recommendations on these numbers?

Then another small question.. for anthracite charcoal i found a calorific value of 27mJ/kg, for lignite charcoal 15 mj/kg. I'm talking about charcoal that these rural african farmers simply make in their backyard. i assume i should take 15 mj/kg then right?! or even less?

Thanks again!

________________________________
Van: digestion-bounces at lists.bioenergylists.org [digestion-bounces at lists.bioenergylists.org] namens Duncan Martin [duncanjmartin at gmail.com]
Verzonden: zaterdag 15 januari 2011 10:51
Aan: For Discussion of Anaerobic Digestion
Onderwerp: Re: [Digestion] Biogas conversation rates

Hi Loe

A few quick comments:

1. You can check equivalences yourself by looking up the calorific values (heating values) of the three reference fuels. Go back to the raw data, rather than relying on the interpretations of others - who may well be biased. The data is readily available and it needs no more specialized knowledge to calculate equivalences than it does to calculate a currency conversion - which I am sure you could do in your sleep! *

2. Some of these fuels (eg biogas, firewood) are q variable so all equivalences would be best expressed as ranges. That might be one reason for the inconsistencies you mention. Make sure your source isn't based on biomethane - ie purified biogas.

3. Rating biogas per so many hours of cooking is meaningless unless better defined - are you assuming an open gas ring, an enclosed oven or what**? Just one burning at a time? What kind of food is being cooked - because some foods need long, slow cooking? (Maybe a better yardstick would be a typical daily household consumption.)

4. Rating biogas per so many hours of lighting is equally meaningless. How many lights? What output? A reasonable assumption for this application might be a single ~40W-equivalent to light a single room  - but state it.

* If that sounds unhelpful, it comes from long experience of university teaching - and exposure to a lot of "I am a student and I need someone to do my assignment for me" requests! You'll learn more if you learn how to work it out for yourself.

** A well known problem here is that the poorest people often (though not always) use the least efficient cooking methods - eg an open fire. A common site in urban Zimbabwe a few years ago was a pot suspended above an electric fire laid on its back!!!

Duncan Martin
Cloughjordan Ecovillage
Ireland

On 12 January 2011 13:52, Franssen, Loe (Alumni) <LLC.Franssen at alumni.maastrichtuniversity.nl<mailto:LLC.Franssen at alumni.maastrichtuniversity.nl>> wrote:
Dear biogas experts,
I am a 22 year old student from the Maastricht University where I am doing a bachelor in International Business. I am currently doing an internship for a Dutch biogas company that is planning to sell systems in East Africa. I am developing a huge mathematical model that calculates - among other things - how big (m³) a digester should be for those households. I want to determine this on the basis of the kilo’s of charcoal and firewood and liters of kerosene they already use and also on the basis of cooking time and lighting hours. After studying several articles from GTZ, SNV, and master or Phd. students’ reports I came to the following conversion rates and I was hoping you guys could give your opinion on it.


Source

Charcoal (kg) >> Gas (l)

500

GTZ article Biogas digest volume 1<http://www.gtz.de/de/dokumente/en-biogas-volume1.pdf>
GTZ article Biogas digest volume 1

firewood (kg) >> Gas (l)

200

Kerosene (l) >> Gas (l)

1600

   link 1<http://www.shvoong.com/humanities/1957301-biogas-making-technique-simplified/>

link 2<http://www.inseda.org/Presentation/Biogas-the%20future%20Sustainable%20Energy-Fr%20Mathew.pdf>

link 3<http://www.eplantscience.com/index_files/biotechnology/Biotechnology%20and%20environment/Biomass%20Energy%20(Bio-energy)/biotech_bio-energy_gaseous_fuels.php>


Cooking (hrs) >> Gas (l)

300

Lighting (hrs) >> Gas (l)

70

SNVworld.org link4<http://www.snvworld.org/en/Documents/Biogas_stoves_and_lamps_test_report_2009.pdf>



I am particularly concerned about the conversion rate from liters of kerosene to liters of biogas. The results I found online don’t seem to be very constant. I tried to do some calculations myself but I have no idea how to calculate this (my background is (micro-) finance) so I was hoping you could shed some lights on these numbers!!
Kind regards,
Loe Franssen Maastricht University student


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