Thursday, October 14, 2010

Biogas as an example of waste to energy

We throw lots of stuff away in this country. We used to just have it hauled to a dump, but that was smelly and attracted vermin. No one wanted to live or be near one. Eventually the dump morphed into the sanitary landfill, but no one wants to live or be near one of those, either. Landfills produce two kinds of byproduct: biogas and leachate. Biogas, at least, can play a vital role in turning waste to energy

If a landfill is at least 40 feet deep and contains at least a millions tons of waste, it is practical to recover that biogas. It has too little methane and too much carbon dioxide for use as fuel. But it is not difficult to upgrade it to turn this waste to energy for either pipeline distribution or use as a vehicle fuel, just like natural gas.

Even if somehow we could reform our ways and never create any waste at all for landfills (a human impossibility, I'm sure), our bodies will still produce waste as a byproduct of eating. And so will the animals we raise for food. Human wastes get carried by sewers to water treatment plants. Reclamation of the water leaves sludge behind. The treatment plants all have sanitary methods of disposing of the sludge. Manure from hogs and cattle too often winds up in waste lagoons. They probably smell worse and produce more health hazards than the old city dumps ever did.

Again, the biogas produced can power waste to energy projects. Anaerobic microbes, that is, those who do not live on air, produce the biogas. Landfills by design facilitate anaerobic digestion. Producing biogas from sewage sludge, agricultural wastes, food-industry wastes, or other other organic industrial wastes requires construction of special anaerobic digestion plants.

Engineers at Hewlett Packard examined turning waste to energy. They determined that, when converted to biogas, manure from 10,000 dairy cows could power 1,000 servers. Since the average dairy farm has fewer than 1,000 cows, a data center powered by dairy waste is probably impractical. On the other hand, many farms could probably produce enough power for themselves and get off the grid. State and federal grants for installing the waste to energy technology would mean that it would pay for itself in about four years.

If exploited to the fullest, turning biogas from these organic wastes into energy could satisfy a significant portion of natural gas consumption worldwide. For that to happen here, Americans would have to be willing to allow the changes in our tax structure necessary to encourage building and installing all of the necessary digestion plants and distribution centers. Biogas has the potential to transform organic waste from a health hazard to a useful resource and turn natural gas into a partially renewable energy source.

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