The article below is from the magazine Popular Science, the March 1922 issue, with some additional comments by yours truly.
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SEWAGE that costs large cities tremendous sums each year can be turned into a source of power equivalent to thousands of tons of coal! The waste now dumped into rivers or shipped to sea may be used to run factories or to light buildings!
That conversion of sewage into power is possible has been proved conclusively by the city of Birmingham, England. There a suction gas engine of 20 brake horsepower has been successfully driven by the gases given off by sewage sludge.
On the basis of the Birmingham experiments, an American city that must now pay for the disposal of 400,000 tons of sewage sludge a year might produce 320,000,000 cubic feet of gas suitable for heat and power, or, in terms of energy, 16,000,000 horsepower hours at 20 cubic feet per brake horsepower.
The apparatus for producing gas from sewage consists of two sludge digestion tanks in which the sewage is allowed to ferment. The gases given off are composed of from 25 to 75 per cent of methane, or marsh gas.
A gas engine of the usual type will run on sewage gas without adjustment of the valves. Sewage gas has a higher calorific value than some illuminating gas, averaging about 650 thermal units to the cubic foot, as against 550.
The Birmingham engine runs about six hours a day and is used to operate a centrifugal sludge pump that moves the wet sludge from the gas-generating tank to the drying grounds. In this process a small proportion of the waste material produces enough power to run the pumps of the sewage disposal plant. If all the material were used, there would probably be enough gas available to light the city.
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What has taken us that long and we still have not got any sewage gas powered electricity generating plants in operation proper. We are, however, flaring off tons and tons of methane gas, what sewage gas, after all is, off from sewage works day in, day out.
Not far from where I live this is happening all the time and it is a shame to see the waste of a perfectly good gas that, though volatile when handled incorrectly, could produce energy and reuse the effect of this gar, if it at all is a contributor, as claimed, with regards to “climate change”, the new word for what was once called “global warming”.
Then there are the landfill sites, the refuse dumps, that are vented to get rid off the methane gas that is produced in them. Further contribution of greenhouse gases?
Why then, though, are we looking to grow grains from which to produce bio-fuel, and other crops, while, at the same time, we are being told that agriculture cannot grow enough food for a growing world population. Somewhere there is more than one paradox here, methinks. Maybe it is time we all sat down and thought about what we are being told and then began wondering what the truth is behind the claims and then why we are not doing the things that were already being successfully toyed with in the beginning of the last century.
Michael Smith (Veshengro), March 2008
Gas from Sewage Waste Runs City Power Plant
