Generating electricity from grabage?
 

I know this isn't a car-free topic, but I think it fits with a lot of the same intentions behind many people's car-free lifestyles.

http://www.usatoday.com/news/nation/...ty-trash_x.htm

A town is going to start a power plant that will vaporize garbage with plasma-arcs to create electricity. They have some pretty wild/crazy claims, so I have some questions for everyone.

1. Is it true that the vaporization will have zero emissions?
2. Will the emissions from powering the plasma-arcs really be less than that of natural gas (they're using synthetic gas)?

"No emissions are released during the closed-loop gasification, Geoplasma says.
The only emissions will come from the synthetic gas-powered turbines that
create electricity. Even that will be cleaner than burning coal or natural gas,
experts say."

3. Can they really create as much energy as they're claiming?

Energy/product creation claims:

Synthetic, combustible gas produced in the process will be used to run turbines to create about 120 megawatts of electricity that will be sold back to the grid. The facility will operate on about a third of the power it generates, free from outside electricity.

About 80,000 pounds of steam per day will be sold to a neighboring Tropicana Products Inc. facility to power the juice plant's turbines.

Sludge from the county's wastewater treatment plant will be vaporized, and a material created from melted organic matter — up to 600 tons a day — will be hardened into slag, and sold for use in road and construction projects.

Hmmmmm........this sound a little to energy intensive to me. I knew that
methane could be captured from garbage dumps to burn for electricity
generation but this??? I'm not so sure.

Matter can't be created or destroyed (except to some degree in nuclear reactions) so they have to have some kind of residue or emissions. Old school incinerators are very dirty, so people have been very reluctant to believe these new generation incinerators are as clean as claimed. Are they for real or just hype? I don't know.

Here's more background info: http://www.cpeo.org/techtree/ttdescript/plarctech.htm

I can't say it's impossible, but it sounds a little like Star Trek or something. Garbage has plenty of carbon in it, so you can easily syntheisize methane or other hydrocarbons. It would be a pretty slick trick if all you got was methane and a bunch of insoluble solids in a fully contained system. That doesn't make it cleaner than a natural gas generator (natural gas is almost 100% methane, and methane is the cleanest hydrocarbon fuel), unless you get a lot of heat off the synthesis process directly, or unless you generate hydrogen to burn, which seems unlikely.

em

One more comment: "Volatile metals and products of incomplete combustion (PIC) can be generated and may need to be removed by an appropriate scrubber. If required, disposal of the scrubbing water would add additional cost. "
http://www.oztoxics.org/research/300...ck/plasma.html
In other words, there's an unresolved issue of how much waste is actually left over and needs to be disposed of through other means and/or may escape into the environement.

What comes out of the process is likely something called syngas, which is mostly hydrogen and carbon monoxide. Syngas can be burned. It's the same stuff you get from coal gasification.

Carbon dioxide is toxic, and does not burn.
Coal is 100% carbon, so it's impossible to get hydrogen from coal (without a nuclear reaction). 19th century coal gas plants generated a gas that included various hydrocarbons, including with carbon monoxide. That stuff was toxic, as were the other byproduts of the process. Those plants were abandoned beginning in the 1950's when the large interstate pipoelines were built. The old gasification sites are now being cleaned up at the cost of billions of dollars. Modern coal gasification plants produce mostly methane.

em