At our scale, CO2 filtration is ruled our because it requires high inputs of chemicals or energy (which can be justified potentially under large scales), and the benefit it really just space, as the CO2 does not significantly hamper the combustion process. If CO2 filtration were easier, carbon sequestration projects would have gained more traction by now. <br>
<br>Methane is similar to other gases, but yet so different. As the most simple hydrocarbon, it has the most energy per unit of mass, but the least amount of energy per unit of space. Picture one carbon with four hydrogens poking out in all directions, versus a tight string of carbon bonds as found in other hydrocarbons. With methane the hydrogens slightly repel each other, and therefore, methane dose not "like" to be compressed. Even natural gas, mostly methane, is not generally compressed to the degree of say, propane, which is even liquefied. There are obviously LNG projects, but again, scale is the key driver. <br>
<br>Maybe there are new technological options, but at my last look, it required between 2 to 3 units of energy to bottle about 10 units of energy worth of methane at a pressure that would give you any useful volume. That math gets worse with 40% CO2. Scale changes everything, and there are biogas transportation projects. Investing the energy into filtration (high pressure water systems can take out CO2) and compression will still leave you energy positive, and the energy was still originated from waste. So, here I am specifically talking about being discouraged by smaller systems. <br>
<br>When one looks at the properties of biogas, and the conditions of small biogas plants, the lowest entropy solution is low-pressure, on-site use. All options within this range should be exhausted before other options are considered. The caveat to this would be micro biogas grids. Biogas can be transported readily in pipes, and there are simple blowers that can make that happen relatively efficiently. A low pressure simple pipeline being fed by one medium to large plant, or a few smaller plants could also be a reality. The longer pipeline option is less of an option when you have limited buy-in and must cross other people's land or roads in the process. <br>
<br>Saludos,<br><br>Alex <br><br><div class="gmail_quote">On Tue, Nov 23, 2010 at 10:03 AM, Reuben Deumling <span dir="ltr"><<a href="mailto:9watts@gmail.com">9watts@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Can you say a bit more about <br>- why separating out the CO2 is ruled out? and<br>- why if methane 'does not like to be compressed' so many other similar gases are compressed regularly?<br><br>Perhaps I'm missing something. <br>
I do appreciate the transport ideas without compression or a pipeline. <br><font color="#888888"><br>Reuben Deumling</font><div><div></div><div class="h5"><br><br><br><div class="gmail_quote">On Tue, Nov 23, 2010 at 8:58 AM, Alexander Eaton <span dir="ltr"><<a href="mailto:alex@sistemabiobolsa.com" target="_blank">alex@sistemabiobolsa.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">We go around this issue frequently, as end users often come up with the same idea. It is hard to tell them no, so we always take a fresh look under the circumstances. At the end of the day filtration of CO2 i always ruled out, and that means 40% of the volume of gas you are compressing serves no energetic purpose. Add that to the fact that methane does not like to be compressed, and we arrive again at a "no" response. <br>
<br>The one option we always examine is the non-compressed transportation of large gas reservoirs. This we have tried for distances that are too long for a simple gas line, and short enough to be practical by cart. Since we can make durable gas reservoirs of any size and shape, this is not unfeasible. Once transported, the gas is connected and used as usual, while a second reservoir is filling. If you can create value for this use, and the transport logistics to not out-weight the value of the energy provided, you may have an option for success. Others have used large truck inner-tubes in the same way, that are then rolled down the street to the end use. I suspect that in certain locations, systems that considered low-pressure distribution could gain some traction. <br>
<br>Saludos,<br><br>A <br><div><div></div><div><br><div class="gmail_quote">On Tue, Nov 23, 2010 at 6:21 AM, Vianney Tumwesige <span dir="ltr"><<a href="mailto:trustvianney@gmail.com" target="_blank">trustvianney@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Hello Harold,<br><br>I completely agree withYvonne, it will be economically expensive to compress the gas.<br><br>P.S. Yvonne, could you send me a copy of the paper and ppt as well? <br><br>Best regards<br><br><div style="display: inline;">
</div><div class="gmail_quote"><div><div></div><div>
On Tue, Nov 23, 2010 at 1:49 PM, Harold leffertstra <span dir="ltr"><<a href="mailto:haroldleffertstra@yahoo.no" target="_blank">haroldleffertstra@yahoo.no</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<div>hello</div>
<div>Got a question from the owner of a small biogass plant in Tanzania.</div>
<div>He is expanding a small existing biogas plant to be able to digest waste from 200 households and manure from 100 cows. </div>
<div>He is interested in using the biogas for fueling vehicles. In our part of the world we think it will be necessary with cleaning, uppgrading of the gas and compressing.</div>
<div>Do any of you have experience/ideas about whether this is feasible for such a small plant?</div>
<div>1)What is necessary to use the biogas for fueling vehicles and 2) what are the technical and economical consequences?</div>
<div>Thank you</div>
<div>Harold Leffertstra</div>
<div>Senior Advisor</div>
<div>Norwegian Climate and Pollution Agency</div>
<div>Oslo </div></td></tr></tbody></table></div></td></tr></tbody></table><br><br></div></div>_______________________________________________<br>
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<br></blockquote></div><font color="#888888"><br><br clear="all"><br>-- <br>Vianney Tumwesige<br><div style="display: inline;"></div><div style="display: inline;"></div>Director - Green Heat (U) Ltd <img src="" alt="Picture" height="20" width="20"><br>
P.O. Box 10235<br>Kampala-Uganda<br>256 (0) 71 237 9889<br><div style="display: inline;">
</div><br>"The more people are self sufficient in cooking fuel, the more personal and financial freedom they have." - Emma Casson<br><div style="display: inline;"></div><br><a href="http://trustvianney.wordpress.com/" target="_blank"><br>
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for more information about digestion, see<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br></div></div>Alexander Eaton<br>Sistema Biobolsa<br>IRRI-Mexico<br>RedBioLAC<br><br>Mex cel: (55) 11522786<br>US cel: 970 275 4505<br><br><a href="mailto:alex@irrimexico.org" target="_blank">alex@irrimexico.org</a><br>
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for more information about digestion, see<br>
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and the Biogas Wiki <a href="http://biogas.wikispaces.com/" target="_blank">http://biogas.wikispaces.com/</a><br>
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<br></blockquote></div><br>
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<br>
for more information about digestion, see<br>
Beginner's Guide to Biogas<br>
<a href="http://www.adelaide.edu.au/biogas/" target="_blank">http://www.adelaide.edu.au/biogas/</a><br>
and the Biogas Wiki <a href="http://biogas.wikispaces.com/" target="_blank">http://biogas.wikispaces.com/</a><br>
<br>
<br></blockquote></div><br><br clear="all"><br>-- <br>Alexander Eaton<br>Sistema Biobolsa<br>IRRI-Mexico<br>RedBioLAC<br><br>Mex cel: (55) 11522786<br>US cel: 970 275 4505<br><br><a href="mailto:alex@irrimexico.org" target="_blank">alex@irrimexico.org</a><br>
<a href="mailto:alex@sistemabiobolsa.com" target="_blank">alex@sistemabiobolsa.com</a><br><br><a href="http://sistemabiobolsa.com" target="_blank">sistemabiobolsa.com</a><br><a href="http://www.irrimexico.org" target="_blank">www.irrimexico.org</a><br>
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