Posted by: schmivian | October 29, 2009

Hooray poop!

I went to a pretty interesting talk the other night about alternative energy in rural China. Turns out the Chinese government has been investing massive amounts of money (though by some counts still not enough) to bring fuel and electricity to rural areas. While most of the audience was there because they were interested in the environmental implications of these projects, it soon became clear that the primary aim of these projects has been social development, with rural economy and environment secondary issues. Basically 2 examples were covered: off-grid electrification (distributed renewable energy systems); and biogas digesters.

China has set specific targets for basically every citizen to be ‘electrified’ meaning they will have access to at least 50 kWh per person per year. Before we get too excited, you probably used over 10,000 kWh last year. “Distributed renewable energy systems” are put in place where the government was unable to extend the grid to a village or move people to already electrified areas.


Shiwei PV/wind streetlamp

This means combination photovoltaic/wind systems like these ones I saw in Shiwei (except for households and not random street lamps) and mini-grids in the villages.  I thought it was pretty cool, but it is not without issues. Definitely a great project for social development, allowing extended hours of light and access to communication, but without any direct environmental benefit as some enviros in the room pointed out since they are not displacing any conventional energy use. Another professor pointed out that most of the intended users could not even afford electrical appliances in order to use the new electricity source, much less turn it into an income source. The current project will last until 2010 and Tibet is really the ‘final frontier’ for electrification given the difficult terrain so that’s where most of the money is going.

The second bit was about the miracle of poop, otherwise known as biogas digesters. 2008 saw 3 billion RMB of government money go to the installation of household biogas digesters in China’s ‘Green Stimulus’ package and the government has set a target, which they are near to reaching, of 40 million of these installed by 2010. While rural families previously spent hours a day collecting wood and coal (very dirty fuels – terrible indoor pollutant = health no no) for cooking, these digesters can provide a clean, reliable source of fuel directly to the kitchen and extremely potent, but not smelly, organic fertilizer to boot!



See the picture if you’re confused, but basically you put organic matter (poop from you, and livestock, and food waste) in the in-tube. Through anaerobic digestion, cow dung bacteria convert the waste to Co2 and methane which goes out the out-tube to the kitchen and a secondary product, collects which is a more effective and longlasting fertilizer than anything Cargill could dream up. Plus, heat released from the digester can keep livestock warm (imagine the squatting man is a pig pen) if the pen is built directly over the digester. Sounds like a win-win eh? Well one hurdle is temperature. For sufficient digestion, the mechanism must be kept above 10 degrees celsius. And maintenance can be a pain because the slurry needs to be stirred regulary. But I say still, hooray poop!

Shaanxi Mothers Biogas Case Study



  1. holy poop that’s awesome.

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