Purdue Makes Trash To Electricity Generator

musicon writes "A group of scientists at Purdue University have created a portable refinery that efficiently converts food, paper, and plastic trash into electricity. The machine, designed for the U.S. military, would allow soldiers in the field to convert waste into power. It could also have widespread civilian applications in the future. Researchers tested the first tactical biorefinery prototype in November and found that it produced approximately 90 percent more energy than it consumed."

Re:In this house we obey the laws of thermodynamic

[teletype]

OK, now I did read the article, and it simply says:

Researchers tested the first tactical biorefinery prototype in November and found that it produced approximately 90 percent more energy than it consumed, said Jerry Warner, founder of Defense Life Sciences LLC, a private company working with Purdue researchers on the project. He said the results were better than expected.

So, as we've all been commenting, this makes no sense. They simply must mean that it takes a certain amount of energy to power the thing. And that this energy (is it electric?) plus the mass being 'converted', will produce 90% more energy than it took to power the contraption.

Maybe I'm just rationalising outrageous claims or something, but I simply can't think of another way that this could make any sense.

Re:In this house we obey the laws of thermodynamic

[Guybrush_T]

Actually, they combine trash with ethanol to run a diesel engine ... The electricity produced is 90% higher than it would be with only ethanol. ... is what I understood :)

Re:How does it stack up?

[Animats]

This is described as energy returned on energy invested, or EROEI, of 1.9, which is not all that great. Ethanol from corn has a value of about 1.25, and that number is from its proponents. Anything below 1.0 is a lose.

US oil production has a value of about 3. That number declines over time; it was as high as 100 in the early days of oil production. (Look up "Spindletop") Saudi oil production has a value of about 10. Wind energy has a value of around 5. Solar power values depend on how long the equipment lasts; energy breakeven on solar cells happens some time around 5 years.

Re:Incredible

[dangitman]

So this takes WASTE and turns it into USABLE ELECTRICITY!!?!?! If true, this shit could save the planet a lot of pain.

Not on a large scale, I think. This is likely to be a very polluting energy source. Hence it being described as "tactical." Good for emergency use - or for a desperately poor village that doesn't have any electricity to meet basic needs. But not to power your Plasma TV or Playstation.

Re:Perhaps this could reduce a lot of waste issues

[teletype]

Many landfills already do produce power from garbage.

The local landfill where I live, the Johnston landfill [rirrc.org], here in Rhode Island, operates a methane recovery plant. This methane gas then flow through eleven twelve-cylinder turbocharged engines, to power a bank of generators.

This produces 15.3 megawatts of power. 1.3 megawatts is used to power the plant and landfill site. The remaining 14 megawatts is sold back to the grid, and provides power for 21,000 homes.

It's not quite 1.21 gigawatts, but it's still pretty cool.

Re:In this house we obey the laws of thermodynamic

[BlackTachyon29]

RTFA they say the generator has to run off diesel oil for several hours to power the bioreactor/reformer. Once the components have had time to break the waste material down into ethanol, methane, and propane that gets funneled back into the generator that the net result is 90% additional output. If it was to take 10 liters of diesel to start the process, after using those 10 liters, and also burning the resultant fuels from the bioreactor/reformer it would be approximatly equal in electric output to having only used a plain old generator with 19 liters of diesel. In addition it reduces the trash input to aproximatly 1/30th of the volume in ash. It is bascially a mobile trash incenerator/generator that can be jumped started with diesel. Electrical plants that burn trash to produce electricty has been around for a long time. This sounds only slightly more efficent/environmentally friendly in that they use a bioreactor to produce ethonal from the biowastes, and use gasification techniques on the other types of trash instead of just plain burning all the trash together with a steam generator.

No matter is 'converted' to energy, it is only a chemical process to rearrange the the energy in the chemical bonds of the existant trash into a more useful form of energy(ie. electricity). Same as burning coal or any other fuel, the energy is released in the form of heat to provide work.

That's because you're misreading it

[benhocking]

Easy enough to do. What the article means is that for every joule the energy consumes it generates 1.9 joules. The joules it is consuming are not from the trash itself. It might be converting the trash at an efficiency of only 5% (making that number up, of course). It's just saying that it does, in fact, actually generate a net positive amount of energy while consuming the trash.

Somehow I suspect I haven't made this any clearer.

Consider the "Mr. Fusion" reference. We've created fusion generators that actually produce energy through fusion. However, so far, they've all produced less energy than it has actually required to run them, thus resulting in a net negative. All that 90% figure means is that this is a net positive.

Re:Incredible

[Sj0]

Not all materials are metals which can be relatively inexpensively melted back down and used with no negative effects in the next recycled generation. Paper recycling, for example, might be a cure worse than the disease.

The harsh chemicals used to remove the many and varied dyes from paper to be recycled are pretty terrible to begin with (And unlike bleaching regular pulp, you don't know what's going to be there, so you can't reformulate all that well), then you end up throwing the recovered pulp right back into the pulper anyway, so while there are likely some gains in energy, it's not necessarily friendly to the environment. Making matters worse, recycled paper seems to have less strength than original pulp.

In the end, you're making more use of toxic chemicals for a product of lower quality. I'm sure there are other similar materials where the friendly concept meets unfriendly process control reality.

Re:Incredible

[OnlineAlias]

2 stroke engines are far more polluting than either 4 stroke gas or diesel engines. They must mix their oil with their fuel, creating an exhaust that cannot be cleaned up (well) with catalytic converters or urea injection. This is why they have been all but banned in advanced industrialized nations.

Solar EROEI

[mdsolar]

One aspect of large scale solar fabrication is that heat management is easier. One only has to get silicon up to temperature but you don't have to keep it there with more energy in, so the 5 year figure you give is coming down dramatically. EROEI should end up near 40 on a single fabrication cycle, and potentially much higher depending on how recycling of the cells is handled during subsequent fabrication cycles. If the dopant gradiant is preserved through a cell-by-cell reannealing process to repair cosmic ray damage, then the energy requirements for recycling solar cells could be quite low compared to the initial fabrication requirements and thus boost the final EROEI over many recovery cycles. If not, one still saves on initial purification costs. Since we are considering a 40 year cycle, it is possible that silicon will be displaced by something more efficient, and it will become a nitch application, in which case determining the recycled EROEI will depend on how much silicon is retained in the energy generation sector.
--
Happy days are here again: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]

Re:Dreaming in technicolor

[GerTheDwarf]

Did you even read the article?

The reason everyone isn't doing it is because it isn't economic.

The point of the work was to make it economical. There hasn't been any work, until now, on _small_ scale waste management that _directly_ produces electricity. Before, the inventions required the business to perform some technical/dangerous/expensive task, mainly storing the gas, or installing a permanent structure.

AFAICT, they are using the same process as everyone else. Ergo, they should have the same results as everyone else.

No, not ergo, because the "results" are not based only on the fuel production process. What they were measuring was the ratio between diesel fuel consumed and electricity produced. They are probably using a highly efficient, highly modified engine, as well as other more advanced parts.

The guys at Purdue didn't mention how nasty the waste product from their process might be.

From the article:

The machine produces a very small amount of its own waste, Warner said, mostly in the form of ash that the Environmental Protection Agency has designated as "benign," or non-hazardous.

Back to the Anonymous Coward:

I don't expect to see one of these behind my local restaurant any time soon.

True, but I don't expect you would even look.

"tactical"

[AKabral]

I think you mis-understood the use of the term "tactical". Since the point of the generator was military, i think "tactical" referred to that it is portable and flexible relative to other waste-disposal means and/or energy-generating means. And on what basis do you say "likely to be a very polluting energy source"? The article linked said that the reduction of materials was a 30-1 ratio and that the EPA designated all the output materials (ash) "benign". So where do you get the conjecture "very" from? So it won't power my playstation, but it might power my block.

Re:Incredible

[WATYF]

Not on a large scale, I think. This is likely to be a very polluting energy source. Hence it being described as "tactical." Good for emergency use - or for a desperately poor village that doesn't have any electricity to meet basic needs. But not to power your Plasma TV or Playstation.

Did you RTFA? What leads you to believe that this will be a "very polluting energy source"?

From TFA:

"Much of the fuel the system combusts is carbon-neutral... Carbon-neutral fuels like ethanol do not cause an appreciable net increase in atmospheric levels of the greenhouse gas carbon dioxide. This is because the fuel releases carbon that has only recently been taken up by plants during photosynthesis, the process by which plants convert carbon dioxide to oxygen and sugars...

The machine produces a very small amount of its own waste, Warner said, mostly in the form of ash that the Environmental Protection Agency has designated as "benign," or non-hazardous. Any leftover materials from the bioreactor are put into the gasifier, which has to be emptied every two to three days.

"It's about enough to fill a regular sized trash bag, and it represents about a 30-to-1 volume reduction," Warner said."


So it burns clean AND it reduces the garbage that you put into it by a 30:1 ratio. Sounds pretty non-polluting to me. My only question is... why can't I have one of these things powering my house? I could dump my garbage into it every day and lower/eliminate my electric bill. Or maybe that's not practical. Maybe it requires an inordinately large amount of waste to run it. But still, they could build a bunch of these right next to a garbage dump and just start powering the city off of all our old garbage.

WATYF

Re:In this house we obey the laws of thermodynamic

[Orne]

Good analysis. Normally, you have two types of generators that are built on a landfill: a landfill gas (LFG) powered generator, or a municipal solid waste (MSW)(aka incinerator) generator. The LFG extracts vapor from the decomposition of organic waste and uses it to power an on-site generator, however, most LFG generators are built with the ability to also burn natural gas, since that can be a more reliable source. An MSW generator will incinerate the waste as fuel to power the boiler, which is then used to generate electricity, and then they just bury the ash again. This process can actually create an income stream for the landfill, as they will buy waste from other sites, burn the fuel, and sell the energy on the wholesale electricity spot market.

• 5 Years of Biomass Fuel Energy Production [doe.gov] for the USA
  
• Landfill Gas [doe.gov]
  
• Municipal Solid Waste [doe.gov]
  

This product sounds like the best of all worlds: Start with waste biomatter, force decomposition using power from fuel oil, incinerate the rest, and eventually use the synthetic oil to power the generator. Would be extremely beneficial in a disaster area, such as after a huricaine, where you have plenty of building waste (wood) and an immediate need for local generation.

Re:Yawn...

[deadphoenix]

Ah well you see, at the beginning of the film it's the Twin Pines Mall (as you see when marty skates in front of the sign). But then when he goes to the past he runs over one of Old Man Peabody's pine trees, the spot where the mall will be constructed. Upon returning to the future at the end, you can see it's now called the Lone Pine Mall. God i know too much about that film!