One of my theses involved the conversion of Honest-to-Goodness Solid Waste (HGSW) to energy. The process made sense then- and makes even more sense now. (Believe it or not, there’s only one company examining this process on a large scale, some 4 decades later.) But, we also need to treat our liquid wastes (sewage)- because we want to keep our rivers and streams (which is where we discharged those treated waters) safe. Amazingly, we employ about 2% of our energy supply to treat this waste stream.
Dr. Orianna Bretschger (J. Craig Venter Institute, San Diego) and a team of researchers developed a microbial fuel cell (MFC) to convert some of the energy harbored in the organic compounds of the wastewater into useful electricity that can be used to treat that same wastewater. Conventional fuel cells directly convert fuel (typically hydrogen) to energy; when hydrogen is used, the byproduct to the energy produced is water. A biological or microbial fuel cell is different in that organic matter (in this case, waste) is the fuel and the microbes decompose this matter, which produces electrons (notice the similarity of the word to electricity- the flow of electrons that generates power) which are then employed to complete an electrical circuit.
This MFC is a sealed chamber where the microbes grow on membranes that surround electrodes. The electrodes serve as “sinks” for the electrons released from the decomposition of the organic matter. Protons (positively charged subatomic particles) pass through a membrane to another chamber, which contains other microbes atop different membrane-encompassed electrodes, thereby combining oxygen with the protons and forming water or hydrogen peroxide.
Presenting her team’s results to the 243th American Chemical Society meeting in March, Dr. Bretschger described the 380L (100 gal) MFC test apparatus. This was the next stage in her research, which previously was based upon a 75L (20 gal) fuel cell that only recovered about 2% of the available energy. This larger device yielded a 13% conversion rate. However, only 97% of the waste was degraded (which is an insufficient level to afford its discharge).
Other improvements in the scaled-up device included the replacement of expensive titanium components with PVC and graphite electrodes. This reduced the costs of the device from close to $300 per gallon down to $ 150 (which means it ran about $15K).
More work is still needed, however, for this device to be used in real applications. The improvements include genetically modifying the microbes so they can better deliver the electrons from the waste products to the collecting electrodes; this should afford a 30 to 40% conversion of waste to energy. The costs for the device need to drop below $ 20 per gallon, to make it cost competitive with existing treatment technologies. And, the degradation of waste has to approach about 99.9% or higher.
I know cattle ranches have been working on using manure for many different areas of running the ranch. And I know it can produce heat so in my head it doesn’t take much to make the leap of using waste water to produce energy.
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Manure is generally used for fertilizer, with an occasional conversion to methane. Waste water is not as concentrated as manure (one is 99% fluid the other is 40% fluid…), so it’s a little different, though.
Thanks for that mention, Shawn…
Roy
You know this is a kind of plan that makes sense to me. Not just human waste, but our garbage in general, everyone puts it out, why aren’t we putting it to a good use. And I know people who are an endless supply 😉 No more energy worries ever!
I have never understood why we have not converted our garbage via pyrolysis to energy or via anaerobic digestion to methane. Why fill up all these lands?
Thanks, Lisa.
This was an interesting post – thanks for the education (as always)….
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Thanks for your comments, Tor!
I agree with Lisa, we should invest in the technology to recycle and reuse our waste products. I am glad there are scientists working on this and I hope our large cities will try to implement these new techniques in the coming years.
My ex-husband worked as an operator in a wastewater treatment plant for many years. He always wore a brown jacket with the word “WASTEWATER” written on the back. I heard many stories about things that went on there.
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We certainly needs methods that cost us less money and provide better results, Janette.
I’m not certain this process will get us there, but we’ll see…
Roy
Waste is waste and if we can convert it then we would not have waste. One of the reasons I love Science fiction is that many writers eliminate the waste or burn the waste – in Back to the Future, or Soylent Green (Harry Harrison Make Room Make Room)
We seem to think that we can pollute and destroy for the sake of the future but…the future is being polluted and destroyed by our avarice and stupidity. I hope that research like this will eventually get the proper support that it deserves
Roberta Budvietas, recently posted..How to simplify numbers in business.
I’m with you, Roberta!
Doesn’t the process of entropy create heat? Bodily waste, garbage waste all disintegrate. Why let it build up when it can be recycled? Come to think of it, aren’t fossil fuels the result of entropy? We really have been missing the bet not using our own discards to create more fuel. Truly disgusting topic, Roy, but I liked it.
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Hmm. So, you like disgusting topics, Ann?
Actually, though, dealing with our waste is an issue that must be resolved. If we can do so and generate energy simultaneously, thne, we ought to rush in– now!
Yes, I like disgusting topics. I watch murder and mayhem on TV. That’s pretty disgusting on many levels and even sometimes in a landfill besides. The only thing is that I don’t want to have to actually go there.
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Amazing how scientists find things like this out that can better our world. But where is the people to back it? I don’t hear to much about this, so how do you get people made aware and on board to back this?
Always appreciate your knowledge Roy. Thank you for sharing and hopefully by us sharing your post, others will gain awareness.
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Lynn..
A lot of these technologies need to be backed by our government, since the major applications will be municipalities. But, given the current political climate, I fear this sort of research may starve before the political scene changes.
Sounds great ! sewage as an energy source. Yes we can convert sewage water to useful water by using it to generate energy and produce light for human resources. There are various regions where sewage water is used for making their application to work out like in agricultural fields.
You are absolutely correct! Too many of us wrinkle our noses and won’t consider it… At the very least, providing the power we need to purify the waste is more than a worthwhile endeavor…