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Solid Waste-to-Ethanol Process Offers Lower Life Cycle Energy Use than Corn- or Cellulosic-Ethanol Production

3 December 2006

Researchers from the University of Toronto and Michigan State University have concluded that ethanol derived from municipal solid waste (MSW) can deliver a life cycle total energy use per vehicle less than that of corn-ethanol and cellulosic-ethanol (derived from energy crops).

The team modeled a municipal solid waste (MSW)-to-ethanol facility that employs dilute acid hydrolysis and gravity pressure vessel technology and estimated the life cycle energy use and air emissions. The researchers also assumed the ethanol was used in an E85 blend.

Compared to extant life cycle assessments of gasoline, corn-ethanol, and energy crop-cellulosic-ethanol fueled E85 vehicles, the team found that the life cycle total energy use per vehicle mile traveled for MSW-ethanol is less than that of corn-ethanol and cellulosic-ethanol. Energy use from petroleum sources for MSW-ethanol was also lower than for the other fuels.

MSW-ethanol use in vehicles reduces net greenhouse gas (GHG) emissions by 65% compared to gasoline, and by 58% when compared to corn-ethanol. Relative GHG performance with respect to cellulosic ethanol depends on whether MSW classification is included or not.

In an evaluation of waste management alternatives, the team found that MSW-ethanol production will result in net fossil energy savings of 397-1,830 MJ/MT MSW compared to net fossil energy consumption of 177-577 MJ/MT MSW for landfilling. However, landfilling with landfill gas (LFG) recovery either for flaring or for electricity production results in greater reductions in GHG emissions compared to MSW-to-ethanol conversion.

The research appears online in Environmental Science & Technology.

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December 3, 2006 in Biomass, Ethanol, LFG | Permalink | Comments (16) | TrackBack (0)

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I presume that the considerable energy that goes into garbage collection is regarded as a freebie. Of course no community can live on its waste products due to the Second Law but fuel from MSW is a form of energy recovery. Probably getting quite effective since atmospheric methane has stabilised.

Like Al Gore said on Saturday Night Live..
"..since I insisted that cars run on garbage, gasoline is now 50 cents a gallon.." :-))

I'd imagine with all the agricultural and forestry waste, Canada could meet Kyoto by moving 25% of energy needs to biomass residues. They can also conduct thinning+controled burns of parts of their forests, with environmental audits by various accredited NGOs (Greenpeace), schools and firms. That would but down on forest fires, and create another source of biomass.
_In the US, something similar can happen. Companies can be hired, and minimum security level prison inmates (Enron scum and the like) be deployed to thin the brush and overgrowth (not mature trees). After most of the biomass is removed, controlled prescribed burns can finish the job, and germinate heat dependent seeds.

This is about municipal solid waste. Agricultural and forest waste is another story and would require a separate energy analysis.

If you are already using municipal waste for energy then it might be an opportuinty to increase the amount of metals recycled.

I've often wondered if there is enough "good" stuff in old landfills to justify a mining operation to recover materials that were not previously recycled.

Landfills are already being used as energy sources, exploiting the methane produced by anaerobic decomposition of organic matter. This could be accelerated by properly control of moisture content, and I believe some operators are doing this now.

Garbage dumps are quite ridiculous to me, we toss our uneaten materials, and packaging, then the waste is pushed into vast domains or cavities that hold the material under ground where the temperature is a modest 55°F at its highest year round. The bacteria that produce the gas we will use work efficiently at 100°F for maximum Mesophillic and Thermophillic productivity. So how on earth do you expect great numbers of gas production from a refrigeration unit lying under ground?

Startech makes syngas from garbage and other things using an O2 deprived plasma environment. You can Membrane for H2 or use a FT gas to liquid process for ethanol Syndiesel. In Toms River,NJ they will plasma 700ton/week of old tires into 1,000,000 gallons of ethanol/week. Landfills are enourmous assets that generations have donated to. It's resources in the bank.

www.startech.net

Sorry that was Ethanol or Syndiesel. Anyways Startech is cool. Checkout their H2 powered Ford ICE pickup. It's powered by plasma derived H2.

The last sentence states: "However, landfilling with landfill gas (LFG) recovery either for flaring or for electricity production results in greater reductions in GHG emissions compared to MSW-to-ethanol conversion."
I'm taking that to mean that this process isn't as good as what is already being done in some places, and would have a larger up front cost as well.

I only wonder why bother with ethanol? Dilute Acid Hydrolysis is not established technology, and the fermentation that follows can only use certain sugars. A gasification/Fisher-Tropsch process would be able to convert all forms of organic carbon, and yield a liquid fuel identical to what we already use (no need to convert to flex-fuel vehicles, or to convert existing fuel distribution infrastructure to make it ethanol-compatible).

And if this technology is worse than flaring, heck, why bother?

I presume that the considerable energy that goes into garbage collection is regarded as a freebie.
More likely it is regarded as a given, since we are always going to have garbage collection, no matter what we do.

Of course no community can live on its waste products due to the Second Law but fuel from MSW is a form of energy recovery.
Why not? We are getting more than enough energy from an external source (the sun), so the Second Law does not apply to the system (where system = earth). It is up to us to get our conversion efficiencies high enough and/or our energy consumption low enough to make it work.

There are developments in DME in China:
DME is an LPG-like synthetic fuel can be produced through gasification of Biomass. The synthetic gas is then catalyzed to produce DME. A gas under normal pressure and temperature, DME can be compressed into a liquid and used as an alternative to diesel. Its low emissions make it relatively environmentally friendly. In fact, Shandong University completed Pilot plant in Jinan and will be sharing their experience at upcoming North Asia DME / Methanol conference in Beijing, 27-28 June 2007, St Regis Hotel. The conference covers key areas which include:


DME productivity can be much higher especially if
country energy policies makes an effort comparable to
that invested in increasing supply.
By:
National Development Reform Commission NDRC
Ministry of Energy for Mongolia

Production of DME/ Methanol through biomass
gasification could potentially be commercialized
By:
Shandong University completed Pilot plant in Jinan and
will be sharing their experience.

Advances in conversion technologies are readily
available and offer exciting potential of DME as a
chemical feedstock
By: Kogas, Lurgi and Haldor Topsoe

Available project finance supports the investments
that DME/ Methanol can play a large energy supply role
By: International Finance Corporation

For more information: www.iceorganiser.com

thanks

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