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Methane / Biogas Production Plants: The Future of Treating Sewage

Methane, Fertilizer and Clean Drinking Water - Treating Sewage Better

by Richard Boettner

Ever since the 1970s I have been fascinated by Methane / Biogas. Putting what everyone considers waste, urine and fecal matter, in a closed environment and behold, you get methane. Ok, so that is a very simple view, but you really could make it that easy, with a 55 gallon drum, attach a hose to pipe methane into a storage device and you are creating your very own Natural Gas. So, more than ever I am pushing this idea to help; 1) reduce our dependence on a non-renewable Natural Gas from under the ground that adds pollution, and, 2) to reduce our carbon debt and reduces pollution, to help clear the air we all breath. Biogas production closes the carbon loop.

To achieve this, every sewage plant could be converted to a Biogas Generation Plant with the Methane it produces piped through existing Natural Gas lines. Instead of having larger sewage treatment plants, centrally located, small plants spread out would have to be built, so if one goes down the rest would be able to take over. Also, by having several smaller plants, they would be much easier to maintain, which translates into reduced cost for the Methane they would produce. Here is an example of how a plant would work:

• Sewage comes in and water is either added or taken away to create the right consistency. At this point animal waste along with plant and other material can be mixed in.
• This mix flows into a tank where it is churned, moved around and kept warm to create an ideal environment for Methane production. Solar energy would be used to supply heat and electricity to power the plant, thereby reducing the plants energy footprint.
• The Methane produced would now have to be cleaned, as more than Methane is produced. The carbon dioxide would be piped into adjoining greenhouses, rather than releasing it and adding to the greenhouse gas problem, or adding to our carbon debt.
• The Methane would then be distributed via the Natural Gas pipeline already in place for home use.
• The spent waste is now a high quality fertilizer that could in part be used in the adjoining greenhouses, hydroponically or traditionally as a soil amendment, with any remaining solids dried and sold, capturing the water to release it into streams or used as drinking water. Yes, water that clean could be produced with little energy input and using all natural processes.

There is more to it, but I am not hear to give you an engineering or a complicated lesson in hydrology, but rather an overview to help spark an ah-ha.

Converting Sewage plants to Biogas Production Plants would in part provide us with Methane that can be used for cooking and as a backup way to heat water or the home, after all, we should be using the Sun as a primary source of heat and electricity. Aside from Methane, the plant would be a source of clean drinkable water and a local food production site. What more could you want: energy, food, water and jobs, all within a local area, not far from where anyone of us live.

What does Biogas have to do with Health. Everything! As I already mentioned, it can reduce pollution, and reducing pollution improves everyones health. Got it, good.

I've created some rough calculations to give everyone an idea what is possible. All numbers are based on hours of surfing the Internet for information and should not be taken as the last word, as we all do not shit the same (most people are seriously constipated) or produce quality shit which influences the production of Methane. Still, see what is possible:

• Each person produces about 2.75 gallons of sewage waste each day.
  (This does not include all the water used to flush waste and is a conservative amount. If you have a traditional toilet, you can be producing ten times that amount, or more.)
• Take 2.75 gallons times 8.35 pounds per gallon equals 41.3325 pounds of waste, each day.
• About 1.8 cu ft [cubic feet] of Methane could be produced from each pound of waste.
  (This is an average number and is very easily influenced by the quality of the waste.)
• Take 41 pounds of waste each day times 1.8 cu ft of Methane equals 73.8 cu ft of Methane produced each day per person and 1 cu ft of Methane equals about 650 Btu's.
• 73.8 cu ft of Methane equals 47,970 Btu's of energy (73.8 times 650).
  [ 1000 cu ft of Methane equals 1 million Btu's (roughly) ]
• Some ancillary information:
  1 million Btu's equals 100 kW of electricity, with the average household using around 10,000 kW each year which comes to 10,000,000 watts each year.
• There are roughly 4,506,542 people living in Colorado (where I live). They produce about 12,392,990.5 gallons of sewage each day. This converts to 103,481,470.675 Lbs of waste which could produce 186,266,647.215 cu ft of Methane each day.
• Take 186,266,647.215 cu ft of Methane times 650 Btu's which comes to 121,073,320,689.75 Btu's of energy produced each day. Now 121,073,320,689.75 Btu's of energy converts to about 1,210,733.2068975 kW or about 1,210,733,206 watts of energy. And, 1,210,733 kW times 365 days each year comes to around 441,917,620 kW of energy produced each year.
• Taking 441,917,620 kW of energy dividing by 10,000 kW, which each household uses on average each year, comes to 44,191 households that could be provided with energy from human sewage each year.

All that from poop, something we current waste, throwing it out as if it didn't matter. Now take that and multiply by the 300,000,000 plus people currently living in the U.S. and you can see we could easily produce more than 10% of our energy needs from human sewage alone. Now add cows, pigs, chickens, turkeys, horses and other poop from other animals kept on farms or zoos, and we could easily produce more than a third of our energy needs from poop alone. Take a quick look at:

Adding cows:

1 cow produces about 125 lbs of dung each day
125 lbs of dung comes to about 225 cu ft of Methane each day
Cows outnumber humans by at least 2:1 conservatively, Colorado alone has around 9 million cows
9 millions cows times 225 cu ft [cubic feet] of Methane comes to 2,025,000,000 cu ft of Methane each day
2,025,000,000 time 650 Btu's equals 1,316,250,000,000 Btu's which converts to 131,625,000 kW of electricity
131,625,000 kW times 365 days comes to 48,043,125,000 kW each year
48,043,125,000 kW divided by 10,000 kW, average usage per home each year, equals 4,804,312.5 households served each year and with conservation measures, 6.5 to 7.2 Million households could be served by cow manure.
(This is just from cows, so think about how much Biogas / Methane could come from all that poop from humans, cows, chickens, turkeys, horses, other farms animals-like ducks, and zoo animals could produce. It doesn't matter that some eat meat, we do too.

Here are some good estimates of various populations, human and animal. Just think if we were to combine all that human sewage and manure from animals in the U.S. hoe much energy we could be producing ourselves from renewable sources. Here are some population numbers:

300,000,000+ people
600,000,000+ cows (there is actually more, but I am keeping it at 2:1, in relation to human population)
10,000,000,000+ chickens, pigs, horses and turkeys (and we should add all the animals kept in zoo's too) in the U.S
(I don't think anyone has ever done an accurate count as chickens alone is estimated at 9 billion, and so this is based on a best guess estimate and I think this number is actually much higher)

That is a lot of poop produced each day. We could easily produce enough energy to replace what we import from other countries, putting us on the path of total energy independence. We would have to combine human, animal, kitchen and other sources of waste like glycerin from BioDiesel production and with improved efficient Methane production we could easily meet most of our energy requirements, when Solar-for heat and electricity and wind energy are included. We would also have to also require more efficiency in every part of our lives from better built homes and more efficient manufacturing methods, making efficiency the center of any policy would allow us to reduce our energy consumption by 35% to 50% and we would never have to import an energy source ever again. All this could be accomplished and we would not give up a whole lot in our daily lives in return. Europeans are not going without and provide us the best example of what is possible.

The lesson here is, using current technologies right off the shelf, so to speak, we could produce all the energy we need, today and in the future. We have to stop thinking some corporation, only interested in short-term profits, or the government will come to our rescue and we need to start acting on our own. Throw some Solar panels on the roof, to heat and produce electricity, invest in wind energy, insulate, drive less-walk more, and throw in some other conservation methods, and your on your way to creating energy independence. It's not that hard, you just have to get off your ass and do it.

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