Thermal Depolymerization
 

Okay, so I was just running some random thoughts through my head, and I realized that I really liked the Doc's idea of using trash to produce energy... Maybe not 1.21 gigawatts from a Mr. Fusion, but you never know.

I was wondering if it would be possible to make a portable thermal depolymerization device that runs off of the waste heat from the car's engine. Even diesels lose a huge amount of energy through thermal waste, and I'm wondering if that waste energy could be used to convert plastics and other trash items into a fuel that could be used to... ta da... run the diesel engine.

It might be a little beyond the abilities of someone trying to put together a home-brew type system, but one never knows... So, what to you guys think? Possible? Even worth trying? There are, literally, tons of fuel just lying around. :eek:

I run my diesel off recycled vegetable oil. The process to make diesel fuel from that requires far less energy input than TDP, and because I have a fuel tank, I can travel 600 miles before refueling. No need to make it portable.

What sorts of "trash" do you think a thermal depolymerization unit can use, and what sort of fuel do you want from it?

But to point out the obvious, there is a strictly limited supply of waste vegetable oil. Used to be that restaurants had to pay to have it hauled off. Now they sell it to biodiesel companies, and people get arrested for stealing it: Cooking-Oil Theft: 2 Men Charged In Arlington Waste-Oil Scheme

Well, here are a few points:

It doesn't HAVE to be portable; however, it does require a huge amount of thermal energy. ICE are very inefficient, and most of that inefficiency is lost in thermal energy. Recouping even a moderate percentage of that energy in the form of fuel could be a good thing.

In terms of trash, why not plastics? They seem to be the most readily available, filling up landfills everywhere, taking forever to break down, etc.

As for fuel type, it could be heating oil, or fuel to run the vehicle that is processing it.

And the biodiesel is a good tangent. Just as jamesqf said, previously, companies were having to pay people to haul it off... Now they can't help getting rid of it. Maybe the same will be true of these plastics that are choking up the environment?

Mine does not seem to be particularly limited, it's been free and more than enough for almost 10 years. But you are correct in the larger perspective.

I was just trying to get some specifics, if you had some in mind. Typically TDP will give combustible oils, and most people don't drive vehicles that can use them. By burdening a vehicle with a portable unit, you lose a lot of load capacity for not much gain.

I'd be all for recycling plastics in other ways, but that carbon came from fossil sources, and I don't think we should be burning it, even in a clean way. That carbon, if not re-used as plastic, should go back into the ground and get re-sequestered.

Also I'd imagine you'd need a pretty consistent standard of recycled plastic and it would need to be melted into pellets that could be fed from a hopper. You're talking about 'cracking' the long organic chains into liquid fuel, preferably in one heat-driven step, yes?

Might work on a large vehicle like a artic (semi) where weight isn't so much of an overhead and there's lots of heat to play with.

How about gasifying the waste (from pellets) then using the product gas and adding this to the intake (a bit like a wood-gas generator, but with a denser fuel-stock). What reaction would occur if the plastic was reacted in a stream of superheated steam?

It would be real easy to run natural gas or bio gas intake fumigation on a diesel.
So easy its already being done.

That only works as a fuel supplement. You still need the source of ignition to be a diesel oil.

Being done in a large scale already:
Waste-to-Biofuels Facility :: City of Edmonton

There is a waste incinerator/generator in Brooks Oregon that disposes of large quantities of household waste and produces energy in the process.

Up to 90% to 95% of a diesels fuel can come from natural gas or bio gas.

Or you can do a natural gas conversion. I have seen 5.9L cummins converted to run on natural gas for sale on the government surplus web sites.

100% biodiesel is easier, cheaper and renewable. Also can be produced with TDP. For a conversion to gas, one needs an ignition system in addition to a large heavy fuel system. Much more feasible starting with a gasoline engine.

Liquid fuels make a whole lot of sense.

Yes liquid fuels are so much easier to handle.

I have been trying on and off for years to get into CNG but the tanks and fill station have always been cost prohibitive.

Where as with WVO, setup and running costs are effectively $0.

In warm New Mexico that'll work, but not in colder climates where you'll need WVO heaters to be able to use it as a fuel.
But still, the cost would be far less than for CNG.

They're probably simply burning the waste and making steam + electricity.

Waste incinerators here have trouble with the low caloric value of our waste.
They need to get to high temps to avoid dioxine formation, but with paper and plastics mostly gone due to recycling efforts, the caloric value has dropped significantly.
They've resorted to adding fuel again - scrap wood, paper (though sorted and collected separately).

Sorry but as long as we are burning ANYTHING (coal, natural gas, fuel oil, ect.) to make electricity it doesn't make sense to put a fuel source that is already riding around in a truck, back into the ground just so we can try to forget about it. Reduce consumption. Sequester emissions. Don't waste fuel to sequester fuel.

Even here it gets cold enough in the winter for WVO to gell.

I would burn up to 25% WVO if I could even collect that much in the summer back in virginia.
During the winter time I would run 5% or less most of the time.

Burning WVO would push my diesel only fuel milage well into the 30s, over all WVO+diesel consumption stayed about the same in the 20s.

It was 22 here this morning, I think they called for a low of 31. The low being 10 degrees lower than forcasted is pretty normal.
I am in clovis how about you?
Last year we had a 10 day stretch of -10'F or lower for a week, this year we had a few mornings where is was right around 0'F.

I basically agree with that. I do my best to reduce my plastic consumption, but when it comes to recycling, I'm not that committed where plastics are concerned. I'm ok with letting them get put into landfills, as that carbon represents carbon not going into the air. That's what would happen if we used plastics as fuel via TPD or direct incineration.

Socorro, last year hit -13, lowest ever recorded here. Did you have gas and electric problems during that cold snap last year? We just had low natural gas pressure, but some friends in Las Cruces lost power and gas for several hours.

One of the guys in the off road club got ahold of a 2.5 ton truck that he was planning on running on waste oil, he wasn't planning on running it much in the winter, even then he was planning on blending it in the winter to prevent gelling. I havent seen it in his yard recently so I think he got rid of it.

It hit -16, they warned of possible power outages, which would have been bad since the POS trailer I was renting athe the time had electric spaces heaters and a fire place.

I wouldn't be surprized if we had low gas pressure for the people who had natural gas (I have natural gas now).