Municipal Solid Waste (unrecyclable trash) has a negative fuel cost. We have to pay to have trash hauled away and landfilled, so why not try gasifying trash?
Besides cost, the advantage of trash vs wood, is that wood has to be chipped or pelletized for efficient gasification, requiring “jaw type” heavy shredder and high pressure pelletizer, because wood has little resin that works as the adhesive in pellets.
Trash is generally much softer than wood, much easier to shred into little pieces, and pelletize under much lower pressure, because trash has thermoplastics that bonds particles together when heated and pressed.
A truck could easily carry a “blade type” trash shredder and pelletizer, both quite small size, to feed trash pellets into gasifier.
Lets say that it can be done, easy…
However… look at the basics for good gasification and what is needed for making clean gas…
Clean gas is ,in my humble experience, free of toxins or having health endangering issues…
A good gasifier breaks down the molecules chained until there is “pure” CO, H2, CH4 and so on…
The reality with waste is that heavy metals and chlorines spoil the fun and high temperatures needed.
Lets say, i am there and i am doing that…
Once you understand the power of glowing carbon, being able to manage and control that hot layer, then you will notice how important wood or biomass becomes in a gasifier…
Control the endothermic reactions with the exothermic ones, et voila, you have a good gasifier…
Understand the differences between conductive, radiant and convection heat, also the importance of each of those in the function of a gasifier and you will be on the path of adding your waste in the fuel…
Try to understand how much waste you make, how you could turn that into use and then calculate cost / benefit / fun to do it yourself for yourself…
For government and big dollar company’s ? they look to the profit and how they can maximise that.
Hint: at the end its YOU that pays for it… and they pocket the money…
Yes, it has been tried many times, and just as many spectacular failures. Several elements common in human waste streams will lead to pollution at the tail pipe. Some of these elements are heavy metals: lead (Pb), Arsenic (As), Mercury (Hg), Cadmium (Cd), and halogens: Fluorine (F), Chlorine (Cl). Typically a large scale waste gasification systems will be rendered an economic and environmental disaster if only five old car batteries go through it per year. Ancient swamps, now become coal seams, acted as charcoal filters and trapped most of these elements. Separation of such materials from a large scale waste stream has proven to be very difficult, and expensive so far.
What’s nice about wood, and other biomass, is that plants act as filters by only taking up very small amounts of these materials.
Rindert
I guess the trash materials that are easily shredded don’t have heavy metal?
Pb is in old car batteries which won’t pass a blade type shredder,
As, Hg – mostly banned from consumer products?
Cd – still exists in NiCd batteries, will Cd remain solid, or will it become an aerosol and feed into the engine?
F – only in Freon, and Freon is in recyclable trash ACs/fridges
Cl – I guess the worst is vinyl plastic, still widely used for wires and other stuff. Vinyl is recyclable, but might still make its way into unrecyclable trash.
KVL and Rindert you have both addressed the very real problems of using Municipal Solid Wastes as an energy fuel stock very well.
I will address this from another direction.
Wood-for-Energies scales very well easily for an Individual, and/or family/small group.
MSW can only, even be marginally done on Big Scale Systems. So . . . . that means money lender “investors” deholdings; or Gov’mint HogTroughs to finace these Big-Systems.
And once up and running always the real fear of running shy of the once cheap “free” MSW input stocks.
So . . . 3R’s (REDUCE the primary use/bi-products making - REUSE again and again the primary and all by-products - finally only then RECYCLING the remains), programs and ethics are discouraged.
Declared as Foolish, Unnecessary. Even declared as “counter productive”, “anti-social”.
Puts the watstes making consumers into a dumbed-down: use more - don’t worry - WE will take care of your problems. Just keep elections voting and pocket book voting for us.
Us being the Solution’eer Priests.-of-Tech.
Not me; or my cuppa’ tea, moreass to choose to feed. Thank you.
Steve Unruh
Picking through the dead tree wood is less sorting too probley, maybe card board wood be worth it if could get enough too supply your needs in pellot fuel.??
To give you an example: plastics as in beer crates might contain heavy metals as CD for color stabilizing as it was with the yellow heineken crates.
If you brake down every plastics or material around in trash, to it smallest molecular component, then you would end up with a lot of nasty stuff that probably should not be set free in the environment.
Gasification is one step further than pyrolysing… As in any process, if done right no problem, but the problem is that it’s not always done right…
There is nothing wrong with the process, but with the operators and the moneymakers…
Political ? They are not interested in an easy solution, they are seeking for a solution that brings them profit…
No problem ? “we just stockpile waste untill someone let us make some big profit and we make damn sure nobody else can touch it”
Yup, and that why I said I heard it can be done… I remember working outside while one of my early systems was running. A guy pulls up, we start talking and he looks at the genset running and says “hey, that’s a gasification system running”. I replied yes. “How’d you make it so small?” He had worked on a large scale systems using hospital waste and the like. I just smiled and told him no one told me I couldn’t. And of course I had lots of help.
I have tried a lot of schemes. Came to the conclusion that wood fuel makes your life so much easier. Figure out how to grow more trees and use waste trees/wood.
