I like to read the fun scientific journal Energy and Fuels from time to time. If you must know, it's sort of a guilty pleasure, because so much of this journal is devoted to the chemistry of dangerous natural gas, dangerous oil, and dangerous coal, three fuels whose use I oppose and wish to see phased out.
I am almost completely alone in this desire, or feel I am so, even though one can find people who give a lot of lip service to this cause, while not understanding a damn single thing about what such a cause would involve, technically or economically.
Still, if one were interested in technical approaches to abandoning these fuels - none of these will be adopted, but rather we will choke our planet to death burning the last gram of fossil fuels all the while broadcasting cute and useless pictures of wind farms around on our portable electronics - one should "know the enemy," and, just as there are useful things to learn about refractory systems from the failed thermal solar industry's research, there are interesting things to learn from reading about the chemistry of fossil fuels.
I am ambivalent, and by ambivalent I mean "not totally hostile to" three forms of so called "renewable energy," one of which is hydroelectricity, the second of which is geothermal energy, and the last of which is biofuels. I don't think that biofuels are actually a viable solution to addressing anything but a tiny fraction of human energy requirements, but they can - under limited circumstances - be a useful tool to recover carbon dioxide from the atmosphere, albeit not under the conditions under which they are currently industrailly practiced. However, Energy and Fuels does cover regularly the means under which they might make a contribution, which is thermal gasification. The paper I will cite in this brief diary comes from the current issue of Energy and Fuels and is entitled Behavior of Phosphorus and Other Inorganics during the Gasification of Sewage Sludge and it is published by a group of French scientists.
Right now, I'm reading a fabulous and wonderful book called "The Big Necessity" by an insightful, fine young woman named Rose George, which is all about sewage practices around the world. She has traveled the entire planet to talk and walk shit - yes, she has crawled through the sewer systems of London and New York, visited latrines, talked to world experts on toilet technology. Because she asks the questions that no one thinks about, she's a real asset to this planet of lotus eaters.
She reports that about 2 billion people out of the 7 billion people now living here have no access to even the most basic sanitary facilities, and that deaths from improper sanitation easily exceed worldwide deaths from malaria and AIDS combined, but the problem is especially intractable because, um, people are uncomfortable discussing, well, shit, even though shit is one of the world's largest health and environmental issues.
So let me talk shit. (I'm good at that in any case.) Shit matters.
I have always been amused by the "Eureka!!!!!" kind of comments that one sees on various blogs talking about the manifestation of "biogas from poop" miracles du jour. Whenever I hear this sort of thing, I'm inclined to ask - and sometimes do ask - whatever biogas cheerleader happens to be leading the cheer at that moment, to compare the size of his or her poops with the size of his or her gas tank.
Sometimes, regrettably not always, this kind of image can stop this particular brand of "renewables will save us" wishful thinking dead in its tracks.
There is not enough human shit, cow shit, pig shit, horseshit or chicken shit on the entire planet to save the American car CULTure lifestyle. Period.
But clearly there is shit, lots of it.
How much shit is there?
The Energy and Fuels paper suggests an answer for Europe, but first this excerpt from the paper:
This research deals with biomass thermochemical conversion by gasification to produce fuel synthetic gas or “syngas”. The type of biomass that was selected for this study is the dried sewage sludge. The high organic content of sludge (5070 wt % of the total dry solids) constitutes a potentially valuable renewable energy resource without any impact on food cultures. Moreover, sewage sludge gasification is a technical challenge,1 as a result of the particularly high mineral content of the biomass (i.e., 30-50% of the dry solids).
And now the question that need answering, the "how much" question:
Finally, from an environmental viewpoint, gasification may provide a solution for the waste volume reduction of sludge with a high yield of energy production (i.e., electricity and/or fuel). In Europe, for instance, the year round production of sludge is estimated at 10 million tons of dry solids (or 42 TWh).
How much energy is 42 TWh? It translates into 0.15 exajoules of energy for the entire continent of Europe. For contrast, Germany, which is Europe's largest user of coal energy, produces about 3.31 exajoules (3.15 Quads) of coal energy.
(Neighboring France, by the way, uses only 14% as much coal as Germany, although as Europe's second largest user of energy, it uses almost 80% as much energy as Germany does. Almost all of the coal used in France is used for the purpose of making steel, whereas the Germans burn coal and dump the coal waste into the planetary atmosphere, a practice that is about to get much worse in that august country.)
The rest of the paper goes into some interesting chemistry concerning phosphorous, and its recovery (or lack of recovery) from sewage.
Phosphorous is yet another problem you really don't want to know about. Eat, drink and be merry.
Have a nice day tomorrow.