Should add

Traditional Historic Fuel, Coal - Range 11,000 to 14,000 BTU/lb

N&W typical 13,500
UP typical about 10,000 or so, depending on the source.

A bit closer to 9,250 BTU/lb.

What about ash content and its effect?

I'd say M Austin's figures have more to do with firing rate. Boiler HP reflects the evaporation rate and steam quality.

Biocoal with 9,250 BTU per pound? Not too bad, I seem to recall that awful Rosebud lignite the Northern Pacific used was in the 7,000 BTU/pound range. That road had some good-sized modern power, too, even if that lousy coal required the biggest grate areas you ever saw, and was infamous for being almost impossible to fire cleanly.

My own take on this is that oil is too valuable, too volatile, and too short in supply between depletion and increasing world demand to continue using it the way we have. Having said that, I'm also going to say this is not a final or ultimate solution. There is no silver bullet for that. Rather, it's going to take a shotgun of "silver pellets," including electrification, better town design, less driving, more trains in general, and--maybe--modern steam power to have a good life in a post-oil world.

I gather that the torrefaction industry is in its infancy, and that no commercial production facilities have yet been designed or built.

In the CSR website on modern steam locomotives, they say that torrefied wood firing will be more costly than coal, but cheaper than oil. Has that been proven accurate, or is it just an estimate?

It would be interesting to learn the BTUs per acre, per year of feedstock production.

Those brain cells got tickled again, in this case thinking about some of the problems with traditional coal.

One of them is ash; some coals don't have much, others you think half the content of the coal must be ash. Sometimes that !!@#$%^!!! ash includes fusible elements, giving us those wonderful things called clinkers.

Among the advantages I could see for this, if it is economically viable, is that we would be dealing with a "manufactured" fuel that would be more consistent than what comes out of the ground. Very likely the ash content will be a lot less, and that ash likely won't have the nasty stuff coal ash can have in it.

Again, not a silver bullet, but maybe something for special jobs, stationary and maybe mobile, too.

Thanks for the breakdown of the numbers Matt. I will say that the fuel looks interesting from the standpoint of a tourist operation with a locomotive having excess grate capasity for the current service.

Has anything been said about the storage of the torrified wood pucks? If they can be stored outside uncovered like coal I'd be really interested. If they need to be kept dry that would be an issue.

The pellets are compressed to the point where they will not absorb water, so they need not be protected from rain, snow, or other sources of moisture.

Good question, Ron. Please research that and report back to the Board.

Coal can also self-ignite if stacked too deep and not wetted. They figured out how to deal with it with coal; they'll have to figure out a way to deal with it with this fuel.

Why are the CO2 emissions a problem? That's the whole point of burning biomass. Plants live, die and rot and give off CO2, or they're processed into fuel and burned and give off CO2, or they're processed into fuel and apparently give off CO2 in storage. No net gain of CO2 to the atmosphere in any of the cases.

Heat content of the fuel has very little to do with nominal 'boiler HP' which is a measure of heating surface. A much more important characteristic is the rate of energy release.

Highly unlikely that any full-scale locomotive will be burning pelletized fuel, either the densified-wood or torrefied 'biocoal'. Too much complication getting the fuel to stay on the grates, either with draft pulling it up or gravity pulling it down through the holes or bars. Likewise, it is unlikely that any sort of pulverized feeding would be used, ESPECIALLY in pre-pulverized form (as used on the coal Eldorado, for example) on locomotives. Look a few days down in the blog that was cited in the original post for a hint as to why, if one is needed...

The torrefied fuel that will be used for something like 3463 is likely to be about the form factor of the washed and graded lump coal that was being advocated for least-expense road service in the early 1950s -- but on the other hand, when densified, it is going to have more the combustion characteristics of anthracite than bituminous. Yes, it's water-resistant. I also expect it to be relatively slow-igniting and slow-burning as a normal fuel, which goes a fair way toward explaining where the GPCS comes in. One problem the design team will have to watch for is that 'normal' forcing of the boiler is probably going to result in more-steeply-falling-than-usual efficiency, and at the point that forcing becomes desirable or necessary they may need to revise the fuel composition in some way that improves the speed of heat release even if that reduces nominal energy density of the fuel.

A nice thing is that the ash content is likely to be lignite-type, which has some of the innate characteristics of dolomite additive, for example. I'd expect that it would not be difficult to tinker a bit with additives, if needed, to make the ash characteristics 'right' -- indeed, to tune them optimally over a variety of expected firing rates. (My own preference would be to use solvent extraction on the torrefied product, but that's not relevant here.)

Even if we assume the existing firebox configuration is preserved on 3463, there's scarcely an inadequacy of available 'grate area' that could be inserted in place of the pan and burner. If you look at the mass flow required for high speed, which is one of the missing metrics in the 'analysis' above -- say, at about 40% cutoff in the stock cylinders at 520rpm -- you'll get a better sense of what the heat-release rate would have to be at achievable boiler efficiency. All the additional helps that the Rankine cycle provides (such as feedwater heat, air preheat, exhaust-steam injection or recompression) only improve the situation from there.

To go back over to the 'preservation' aspect of this fuel: I suspect there will need to be some admixture of 'biocoal' with other materials to produce something that will act as expected for a bituminous-coal replacement in normal restored-locomotive firing. Likeliest co-material will likely be coal itself (you will note how many of the torrefaction companies hint at this firing mode in their descriptions, without actually revealing what materials they would use to optimize that, and can you blame them?). It would also be possible to add volatiles back in, if desired (for example, less-refined 'biodiesel' stock) to give easier lightoff or shorten combustion reaction time even as the fuel pieces burn down. Perhaps needless to say, the densification process would produce larger pieces; someone has already mentioned the intentional inclusion of surface roughness for better heat absorption up to transition temperature, and then lightoff, for newly-stoked pieces.

One other point: I would not expect the primary source of this fuel biomass to be trees, particularly old-growth forest trees. Some logical sources are, in no particular order:

Waste wood from sawmills, lumber, other industrial production facilities that make or produce wood products. (The lumber, or whatever is produced, serving neatly as a sequestration mechanism for the fixed CO2 as long as it remains intact).

Branches, bark, windfall timber, etc that is recovered separate from logging

Farmed biomass involving 'wood' -- short coppice rotation, eucalyptus/corymbia and the like.

Farmed or incidental biomass such as switchgrass or bagasse

Residuals from other processes, such as spent mash from ethanol production or press cake from biodiesel.

I would also assume that solar or process pre-drying would be used wherever practical to reduce the dewatering requirement...

Don't think anyone is pretending, or expecting, the use of renewable 'coal replacement' to cut into the existing economics of fossil-coal production and usage, or even to bring the rate of acceleration of coal usage to a steady rate, at this point. On the other hand, every bit helps. And, in particular, the prospect of a renewable, politically-acceptable, low-polluting fuel that makes steam-locomotive operation 'clean' ought to be a worthwhile goal that most of us could get behind...

Sorry if this causes too much MEGO syndrome.

The gist of this is that torrefaction does not arrest natural cellulose decomposition. The puck will have a shelf life.

Oh, Please.

Finely-divided uranium... that's pyrophoric. Has to do with reactivity, and with the rate of reaction. On the other hand, it would be a very long stretch to term torrefied fuel 'pyrophoric' in the quoted sense. Hugh has already pointed out that bunkered bituminous coal is more "pyrophoric" by the given definition ... and that adequate safety procedures and countermeasures were determined, long ago, for those storage situations where common sense didn't already prevail.

So what if carbon that has a large internal area turns out to liberate higher amounts of CO2... what we care about is the heat rise, relative to the heat loss from the piece to its environment. What needs to be seen is not the absolute evolution in CO2 in ppm or whatever, it's the relative rate of generation of CO2 over time from a given mass, and in a given configuration... i.e., to determine if you're getting thermal gain that will result in going over transition temperature and starting spontaneous combustion rather than just oxidation.

If you actually READ the cause of the 'danger' from the higher production of CO2, it was unintentional asphyxiation. The blogger conveniently forgot to mention, probably because he already knew it to be obvious, that CO2 is a much heavier gas than the main constituents of the atmosphere -- and therefore it sinks into low enclosed spaces, like ship's holds, displacing the air more effectively than gas exchange or turbulent mixing can keep it there. Yes, that's an important thing to watch out for, and yes, microstructured torrefied fuel that evolves CO2 at a nominally higher rate is more likely to produce asphyxiant blanketing if allowed to sit in an enclosed space, and someone is dumb enough to walk down into that space without breathing air. But that is CERTAINLY not a demonstration of pyrophoricity, any more than it is a reason to shout that there is inherent and inevitable fire danger from torrefied fuel (vs. more conventional pelletized fuel, or high-carbon fossil equivalent fuel).

The sky is not falling, yet.


RME

Here is a very informative site that describes bio coal and related biomass feedstock production:

http://www.viaspacegreenenergy.com/docs ... 1-2011.pdf

It provides a lot of information, but nothing I see that directly relates to the amount of energy yield per acre of biomass when converted to torrefied pellets. That statistic would shed light on the number of acres required to sustainably supply biomass to produce enough energy to power a town, for instance. It addresses the question of land use.

Generally, it seems like it would take a very complex analysis to break out the cost and other statistics of biomass energy production. It would have to account for land use, seed stock, planting, fertilization, perhaps spraying, transportation to the plant, the full manufacturing process (harvesting, chopping, drying, torrefaction, and compression), transportation and distribution to the market, and capital cost for combustion.

The website does indeed give the cost of pellet energy production compared to coal and oil. But with all the details making up the cost of fuels, I wonder if they have fully accounted for all of those details.

Generally, since torrefied biomass pellets are not yet in full production, I also wonder if the costs stated are really known, or just estimates.

Also, the feedstock production would be highly variable, so the flatly stated cost of bio coal compared to oil would have to apparently be based on an average of the feedstock production, lacking any other explanation.