[Rod_Cloutier]

I saw an advertisement in the newspaper recently about a engineer promoting anaerobic digesters, biopower and kinetic turbines. Through all the articles on this page none of these technologies are mentioned:

Webpage Title

Can any professionals out there enlighten me on these technologies and their viability as oil alternatives??

[MonteQuest]

I have built small digestors for demonstration purposes utilizing sewage sludge from a treatment plant. Here's a good link with lots more.

Biogas is generated when bacteria degrade biological material in the absence of oxygen, in a process known as anaerobic digestion. Since biogas is a mixture of methane (also known as marsh gas or natural gas) and carbon dioxide it is a renewable fuel produced from waste treatment. Anaerobic digestion is basically a simple process carried out in a number of steps that can use almost any organic material as a substrate - it occurs in digestive systems, marshes, rubbish dumps, septic tanks and the Arctic Tundra.

http://www.ees.adelaide.edu.au/pharris/ ... nners.html

[0mar]

Methanogens are Archea and Baceterial groups of microorganisms. They are quite diverse in their metabolism, but share a common feature; taking CO2 and reducing it into CH4 (methane). They are strictly anaerobic and require almost no free O2 in the environment. The slight whiff or breeze of oxygen is enough to kill them.

They are usually mutualistically involved with other groups of bacteria/archea (the acetogens come to mind right now). Acetogens provide the CO2 and help move the methanogenic reactions into favorability.

As for their viability. I'm not sure of any successful work in making methanogens in a reactor. Getting a totally anaerobic environment is very difficult and lots of their biochemistry isn't known. And symbiosis relationships are very difficult to setup in a controlled setting. Too litte and the methanogens can't grow at a reasonable rate, too many and the methanogens die due to competetion and unfavorable reaction conditions.

Biofuels are usually of some sort of plant derivatives, usually soybean or rapeseed. The plant itself produces oils that are extractable or are readily refinable into something usable. While they show some promise, they also require a ridculous amount of investment and arable land to suitably sustain transportation needs.

Of kinetics/biopower, I haven't studied/heard much but I think they are talking about using the heat produced by organisms to power machines. I have absolutely no basis in making this claim so someone please prove me wrong.

[MonteQuest]

As for their viability. I'm not sure of any successful work in making methanogens in a reactor. .

Are you kidding? What do you think a sewage treatment plant is? Biogas digestors are a proven technology and are used worldwide quite successfully. Do a google search on Biogas, you will be reading for days!

MQ

[0mar]

I meant from the ground up by feeding it raw materials from the environment. Eating our waste up isn't a viable solution unless we become a sustainable society in that the energy from wastes makes enough energy to supply the reactor with enough waste to continue the cycle.

I think the hang-up was on different intrepations of success

[MonteQuest]

I meant from the ground up by feeding it raw materials from the environment. Eating our waste up isn't a viable solution unless we become a sustainable society in that the energy from wastes makes enough energy to supply the reactor with enough waste to continue the cycle.

I think the hang-up was on different intrepations of success

On the contrary, Biogas is a clean and efficient fuel, generated from cow-dung, human waste or any kind of biological materials derived through anaerobic fermentation process. The Biogas consists of 60% methane and rest carbon-di-oxide mainly. Biogas plants provide safe fuel for cooking and light. The by-product , a solid residue is a high grade manure. The Biogas plants are the cheap sources of energy in rural areas all over India. The enormous potential of biogas, estimated at 17,000 MW, is derived principally from estimated agricultural residues and dung from India's 300 million cattle.

Here is an impressive link on biogas with drawings of various types of digestors in use and a lot of info.. These have evolved in India over the last forty years.

http://www.ganesha.co.uk/Articles/Bioga ... #Table%201

[MonteQuest]

Here's a "success"story by anyone's standard:

Biogas plant dissemination: success story of Sirsi, India

Dissemination of alternative energy technologies such as biogas in various parts of the world has rarely led to a success rate of 90%. This study in Sirsi block, Karnataka, south India, revealed that 43% of rural households (HH) had dung resources to operate biogas plants and 65% of them had already built biogas plants. 100% of the plants built were functioning satisfactorily and 85%of HH with biogas plants met all their cooking energy needs with biogas, improving the quality of life of women. The presence of multiple agencies in the dissemination network, participation of entrepreneurs competing to assist households in all aspects of biogas plant construction, commissioning, procuring subsidy, guaranteed performance and free servicing contributed to the high rate
of success (of 100% of biogas plants being functional). Most biogas plants built had excess plant capacity, with cost implications. An observed shift in the design choice from mild steel floating drum design to fibre reinforced plastic-based floating drum design and then to a less expensive fixed dome model shows that rural households respond quickly to technological developments. The paper discusses the roles of various factors and their implications for future dissemination programmes.

http://www.ieiglobal.org/ESDVol5No1/bio ... nation.pdf

[0mar]

whoa I guess I was wrong.

That is some intriguing reading there. Thanks Monte!

[Laurasia]

Montequest: You mentioned you had built small bio-digesters as experiments, etc. - did you find them dangerous? When I first heard about Peak Oil I was absolutely fascinated by the idea of turning waste into fuel for cooking and heating, but I am not a practical person and I could visualize me blowing up the suburb where I live!!

Regards,

L.

[fastbike]

Monte,

I followed up the links you provided. Maybe the less developed countries will not find peak oil/gas to be such a big deal if they are already using bio gas for domestic cooking etc.

Another thing, all the feedstock for the digesters appears to be animal dung. Is vegetative matter, eg straw, wood chips, grass etc suitable or can the bacteria not convert the cellulose ?

[MonteQuest]

Montequest: You mentioned you had built small bio-digesters as experiments, etc. - did you find them dangerous? When I first heard about Peak Oil I was absolutely fascinated by the idea of turning waste into fuel for cooking and heating, but I am not a practical person and I could visualize me blowing up the suburb where I live!!

Regards,

L.

Dangerous? No, quite to the contrary, biogas digestors are quite safe. The first one I built was from a glass 5gal drining water bottle like you find at water coolers. I used an inner tube for the capture and expansion of the gas. My feed stock was sewage sludge from the Phoenix sewage treatment plant. To heat the digestor I placed it in a glass-topped, solar heated insulated box.

[MonteQuest]

Monte,

I followed up the links you provided. Maybe the less developed countries will not find peak oil/gas to be such a big deal if they are already using bio gas for domestic cooking etc.

Another thing, all the feedstock for the digesters appears to be animal dung. Is vegetative matter, eg straw, wood chips, grass etc suitable or can the bacteria not convert the cellulose ?

fastbike,

Generally speaking, any organic matter can be converted to biogas. The physical and chemical state of a material feedstock used for anaerobic digestion is initially determined by its source. The feedstock may be a clear liquid, a suspension of solids in a liquid, or a "solid" - a material with less than 70 - 80% water content. The best biogas feedstocks are animal (including human) wastes, and while other constituents may be added, for example crop residues, these will usually affect the C/N balance of the mix to its detriment. Various digester systems have been designed to treat these physically different forms of feedstock. Sometimes physical and chemical problems may be solved by modifying the feed. These modifications may allow the original type of digester to be used, or they may be such that a different type is needed.

Small-scale biogas plants as typified by rural India and China offer a renewable energy source and a “total solutionâ€

[Permanently_Baffled]

I saw a program on the use of bio gas in China. The farmers not only get gas off there human/animal/plant waste they also get a nice liquid fertilizer to put back on crops!

PB

[johnmarkos]

I get my milk from Straus Family Creamery: they're using a methane digester to produce electricity.

http://www.strausmilk.com/feature/press.html