We fully recognize from countless examples that you cannot get into the Greenpeace School of Magical Thermodynamics if you can multiply, add and subtract, but let's pretend for a moment that a graduate of this august school of magical thinking could do these things. Let's
calculate how reasonable the claim that the shit from 120 million cows, ignoring for a moment that most all of the cows (beaucoup barrels) are dependent on petroleum for their existence.
According to this link, 127 million cows in Canada produce 137 teragrams (137 million metric tons) of cow manure each year, releasing almost one million tons of methane into the atmosphere in the process:
http://res2.agr.gc.ca/publications/ha/2d1c_e.htm (But we will ignore the environmental cost of producing cow shit, because anything proposed by a Greenhouse, whoops I mean Greenpeace, twit is to be assumed to be without environmental cost on the grounds that a Greenpeace twit has proposed it.)
Let's be generous for the benefit of the stupid and suppose that only 70% of the mass of cow shit is water. This means that 30% is biomass, or doing the (gasp) multiplication 0.3*137,000,000 MT = 41,000,000 MT tons of dried cow shit biomass produced annually. Let us also assume, again in complete defiance of reality (because the grasp of solar only Greenpeace twits on reality is so tenuous) that a lump of cow shit
magically is processed so that none of the energy is lost in processing (in other words, at 100% efficiency.) Finally, let us assume that dried cow shit has the same energy density as coal, roughly 30,000 kilojoules/kg. It is easy to calculate the energy in the cow shit in the magical case where it is equivalent to coal in energy content: It is 30,000,000*41,000,000,000 kg = 1.23 X 10^18 joules, or 1.23 exajoules.
If the average American home consumes 30 kilowatt hours of electricity a day, and there are 125,000,000 such homes in the US. We have 125,000,000 * 30,000 watts-hours/day * 3600 seconds/hour * 365.24 days/year = 4.93 X 10^18 or 4.93 exajoules per year, electric.
The efficiency of most thermodynamic heat engines, including those that burn cow shit for the magical thinkers in the remedial thermodynamics drinking class at Greenpeace, is roughly 30%. This means that the energy requirement for producing 4.81 exajoules of electrical energy (delivered) is 4.93/0.3 = 16.4 exajoules.
This means that the output of cow shit from 127 million (Canadian) cows is sufficient to provide (again in the magical case where the energy content of cow shit is the same as that of coal) 1.23 X 10^18/16.4 X 10^18*100 = 7.5% of the energy required to produce the yearly electrical energy requirement for 125,000,000 homes.
As for the absurd claim that human feces can make up the missing percentage, I suggest that someone contemplate the volume of shit in one's own toilet bowl and compare it to the volume of a gallon of gasoline. Then contemplate that shit is mostly water.
Here's a problem though: The magical little machine referenced in this thread does not operate at 100% efficiency. Here's another little tiny insignificant problem: It costs energy to collect, transport and process 127,000,000 metric tons of cow shit. Then there is the matter of the fact that cowshit doesn't really contain 30,000 kJ/kg of energy content. Then there's the matter of collecting and transporting the grain used to feed the cow. Then there's the matter of the energy cost of purifying the water polluted in the digestor...
It goes on and on...
Now we know if you belong to Greenpeace, you are required to have contempt for the poor, and so it fine, I suppose, to imagine thousands of third world vilified central American immigrants shoveling cow shit into trucks in order to fuel the magical middle class homes inhabited by magical Greenpeace twits. We will also assume that the cows continually are forced to reside in filthy cruel feeding lots where they are fed petroleum produced grain, so that our central American workers will not have to wander the range while they collect the cow shit from
grass fed cows. Believe it or not, the shovelers require
food to operate, and they require food to drag their asses to little anaerobic digesters while they slave in the fields collecting cow shit for twit Americans. Now what is required to transport the cow shit to the magic anaerobic cow shit machine? Fuel? And what goes into the digester as a matrix? Water. And where does water come from? Well, in the Greenpeace magic world, it all rains from the sky whenever we need it, but in the real world, at least where most of our cows grow, it is pumped, sometimes from fossil water sources like the Ogalla aquifer (which is being depleted to make cows) expending energy.
Nobody is saying that possible supplies energy provided by processing cow shit should be discarded. As a person who doesn't eat cows in part on the grounds that I am an environmentalist, I certainly would love to have some of the enormous environmental cost of the cattle industry diverted to ameliorate whatever tiny fraction of the global warming crisis that it can relieve
in reality, just as I would approve of technologies to raise the efficiency of the retarded Repuke Governor of California's Hummer. This doesn't mean, however, that I think more efficient Hummers are the answer to the crisis occurring
now.
Further I do understand that you cannot get into Greenpeace Hogwarts School of Magical Thinking if you can do arithmetic or understand basic science. But let's get real folks. We are in a crisis. Burying our faces in a pile of cow shit and pretending that this is a solution to the very real problem of global climate change is pathetic, pathetic, pathetic. The fucking amount of methane released by cow shit alone (methane being an extremely potent greenhouse gas) should disabuse one immediately of the desirability of this program. If you buy this shit (literally) you will get what you deserve: Poverty and the destruction of the future.
This claim about shit is shit. Pathetic, even for shit, but shit all the same.