Too good to be true? 2

[KENAT]

Howdy all, there have been numerous threads on alternative energy sources etc.

I saw this article in the magazine earlier this year and it the time thought it almost sounded too good to be true so, what says the eng-tips community.

Can we get massive amounts of 'clean' energy from our rubbish/trash without some unforseen unpleasent side effect?

http://www.popsci.com/popsci/science/873aae7bf86c0110vgnvcm1000004eecbccdrcrd.html

http://www.geoplasma.com/

Try and keep it vaguely on topic, although I realize it will almost certainly descend into "global warmings real/no it's not/there's no link to human activity..."

KENAT, probably the least qualified checker you'll ever meet...

 

[GregLocock]

Well in principle there isn't much wrong with it. The usual problem with these things is capital cost and payback time. A 10 year payback just doesn't fly. As an electricity generator it'll be base load, so won't be getting much for the electrical power.

There's also a longer term point of view that says it is silly to turn old plastic bags into carbon dioxide for two reasons (a) it creates two fairly bad greenhouse gases (grin) and (b) plastic is basically an oil resource, so if we are running out of easy oil it may be unwise to burn it very inefficienctly for energy. On the other hand, that may be the case, but we aren't doing anything very sensible with plastic waste to date.

Another objection is that sequestration of rubbish tip methane, and then burning it in diesel engines for power generation, is a much cheaper alternative that makes more efficient use of the gas.

Still, given the popularity of landfill, it might be a goer.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[dcasto]

An energy balance is even hinted about. How much electricity is used to generate the plasma?

A thermo oxidizer operating at 1500 F can do almost the same thing.

 

[TheTick]

If it produces worthwhile amounts of surplus energy, capital should be no problem. Generate power, rake in cash, build more cash-generating plasma doohickeys.

 

[BJC]

Tray doing a mass-ballance. There probably isn't enough energy in the garbage to fule the trucks that brought it to town ( as packaging, fihished goods etc.) and the trucks that haul it out( as garbage)

 

[Ashereng]

The carbon equivalents for garbage (which would also be carbon based I would think) would probably make it not so "clean".

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[melone]

Isn't there more to this than just the energy portion of the discussion? Landfills take up space, and we are running out of places to put them. Does it makes sense to reduce the amount of trash that we bury, and if we get some energy back in the process, isn't that a good thing? Obviously, they will never be able to obtain more energy out of a system than what the put into it.

 

[EOIT]

This really seems like it could be a great idea, basically a garbage incenerator on steroids without all the emissions. Looks like there is probably still a concern for the solid waste on the back end which is always going to be a problem. There isn't anything out there that can make EVERY environmental group happy but this one sounds close. Perhaps if the "obsidian" like solid waste can be effectively dealt with or negated this would be a viable alternative. Of course the power supply isn't nearly enough for all of a city/state/country's needs but it would help out and kill a few birds with one stone.

The trucking issues are without merit since the product is already being trucked somewhere for a cost anyway as addressed in the write-up. It is a matter of what happens to the garbage when it gets to where it is going.

Overall this could be helpful for cities with the infrastructure inplace for the collecting and disposing of garbage and tranmitting of power across distribution lines. With the gas "polisher" on the backside of the operation it sounds like the biggest killjoy would be the solid waste, kinda like nukes.

My two cents,

EOIT

 

[GregLocock]

The solid waste would be some mixture of ash and glass, (it says obsidian which is glassy)- sounds ideal for foundations or roadbeds.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[electricpete]

Um, if this thing is anywhere close to competitive to the cost of normal landfilles, than from the sounds of it, it would be aa panacea (sp?) for chemical/biological/toxic waste disposal.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[Gymmeh]

I guess in the big picture, this is not that unreasonable.

I am sure they will never replace land fills but if they were used with land fills to destroy solid waste that does not decompose well, it seems reasonable to diversify our methods of waste disposal.

 

[mjl2023]

I hope some technology like this could be developed However, FROM THE LAST PAGE: "the technology, still unproven on a large scale, has its skeptics. “That obsidian-like slag contains toxic heavy metals and breaks down when exposed to water,” claims Brad Van Guilder, a scientist at the Ecology Center in Ann Arbor, Michigan, which advocates for clean air and water. “Dump it in a landfill, and it could one day contaminate local groundwater.” Others wonder about the cleanliness of the syngas. “In the cool-down phases, the components in the syngas could re-form into toxins,” warns Monica Wilson, the international coordinator for the Global Alliance for Incinerator Alternatives, in Berkeley, California."

 

[ivymike]

“Dump it in a landfill, and it could one day contaminate local groundwater.”

yeah, and was he planning to do something else with those compounds? Sounds like the choices were "dump it in a landfill" or "burn it, then dump it in a landfill."

 

[Gymmeh]

Mike, LOL, I love common sense. At lest if they burn some of it, less space will be wasted!

 

[moltenmetal]

ivymike: depending on the process and which metals we're talking about in the source garbage, this process could either stabilize and encapsulate the toxic metals rendering them immobile and safe, OR it could take a non-leachate toxic garbage stream and turn it into a smaller quantity of leachate-toxic material: ie. converting 100 tonnes of non-hazardous landfill waste and turning it into 30 tonnes of HAZARDOUS landfill waste. The latter would KILL this thing, and is often the dirty little secret of other municipal waste incinerators out there. Sure the mass and volume of material to dispose of after incineration are significantly smaller, but the waste remaining is NOT suitable for use in building materials due to its leachate toxicity and hence becomes an expensive hazardous waste.

We have the desire to permanently remove carbon from the atmosphere to deal with greenhouse gas emissions, to the point of wanting to put CO2 absorption/desorption systems and the like on fossil fuel power plants. Given the tendency of a dry landfill to slow decomposition to a near-standstill such that you can mine out 100-year old newspapers and still be able to READ them, I don't know why we'd be in a panic to generate energy by gasifying landfill waste. The waste itself, denuded of recyclables and compostables, represents nearly permanently sequestered CO2, without having to waste ANY energy in the sequestration process! The CO2 you make when burning the syngas from gasification will take yet more energy to sequester, and soon this plasma thing is greenhouse gas positive and energy neutral at best- why do it at all then?

In Europe where there's limited land available and incineration is already in widespread use, perhaps- but North America is far from running out of suitable space and geology to build secure landfills. Rather, what we're suffering from here is a severe case of NIMBYism- nobody wants a landfill in their own back yard, but everybody still generates trash and expects someone (else) to deal with it.

There's a similar company here in Ontario, the name of which has long ago fallen out of my head, which has a demo facility running in Ottawa if I'm not mistaken. But when you read the fine print, their unit is only energy positive or self-sustaining if they blend the feed regular municipal garbage with another (unidentified) stream which is higher in heat value. I suspect the stream they're admixing is "biosolids", ie. dried sewage sludge. That's another material which is tough to get rid of presently and which contains a hell of a lot of energy of biological origin (ie. CO2 neutral)- but which can be safely burned without wasting the energy to generate an electric plasma arc first.

 

[KENAT]

First off an appology, the article is mainly about Startech Environmental Corporation

http://www.startech.net/

not geoplasma. I'd read it a while back and got confused, sorry:-(.

The 10 years was using average land fill prices ($35/ton) and not taking into account selling any excess electricity or the syngas/syngas product. Elsewhere it says that some places pay twice that and NY pays $90/ton. So the payback time might be less than 5 years if you get nearer $90/ton and sell the electricity & syngas. (Yes I'm believing their figures which is probably an error).

As to the energy/mass balance, sure if we could get away from disposable packaging, re-use more stuff recycle what we can't re-use, waste less... then it's far less efficient/benefficial than the ideal. However, if you look at it as pretty much dropping it in instead of direct land fill, possibly closer to where the waste is generated than many current land fill sites it's got to look pretty good.

The solid waste does sound like a potential issue. I was originally thinking along the same lines as Ivymike though molten may have some points. If it can be used for construction though without leaching then great. Seems like no one knows for sure yet if it's a problem and given the range of different things that get into waste I suspect its almost impossibly to be sure it's safe all the time. I was wondering if it could be refined to remove some metals etc, though this would of course take energy.

The article does talk about using it to get rid of hazardous waste/chemicals be it military or commercial. In fact the US military apparantly has one for just that at Aberdeen and there's one in Japan too.

Well Molten, thanks for peeing on my parade;-).

Serously though, not everyone is onboard with the CO2 reduction issue. If you want to cut down on fossil fuels for energy independance issues, then isn't this possibly a good thing?

As to the energy out, I'd think like some others that this will depend what you put in. If you put in a lot of organics I'd suspect it would generate quite a bit of energy & syngas but if you put in mainly rubble of some kind (or similar) will it generate even enough to keep it going?

So in summary, in an ideal world, it's probably not the best solution. But as a pragmatic solution in an imperfect world, sounds pretty good to me.

KENAT, probably the least qualified checker you'll ever meet...

 

[GregLocock]

Possibly, but as the saying goes, a quarter of a billion here, a quarter of a billion there, soon you are talking real money.

Isn't there a better use for that money?

Maybe not, admittedly, depending on your goals.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[owg]

The Canadian waste/plasma company is Plasco. See

http://www.plascoenergygroup.com/

HAZOP at

http://www.curryhydrocarbons.ca

 

[rbcoulter]

These things usually suffer from the NIMBY syndrome.

 

[JStephen]

I recall a number of years back, some of the local cement plants were coal-fired, and also were incinerating waste of various kinds. The theory was that the 3000 degree coal burning operation was able to take care of just about anything you put in it. And of course, the neighbors all complained because it was in their backyard.

This to me sounds like a very similar operation when it's all said and done. Hard to imagine that it wouldn't have any drawbacks either on the ash disposal or the emissions end of it.