Pick Your Poison… Please!

So I’ve been informed that my biomass  burning heating appliance is bad for the environment, compared with rubbing two stick together, living like a hermit, or moving to a tropical paradise.

Oh, come on, how could something so pretty be so deadly?   Lets find out…

“It emits CO2!”

Its essentially but not completely carbon neutral.  CO2 absorbed by cherry trees, they make pits, I burn the pits, and everyone get pie.   Or more recently, its sawdust from a hardwood flooring mill.   It uses small amount of electricity ( ~200W ) to liberate up to 20,000W, so surely the measly 200W I have to use from the grid is not a problem.

“Oh, well fossil fuels is used to transport the pits from Michigan.”  ( Or whatever you burn! )

So true.   And many people discount the shipping of otherwise renewable fuels.   A good rule of thumb is 0.3725 lbs CO2 per Ton-Mile for truck, 0.2306 lbs CO2 per Ton-Mile via train.   So worst case,  3.5 tons of pits, 850 miles away is 1100 lbs of CO2, which is considerable.

“See, I told ya so!”

And that’s why I’ve abandoned the pits ( in addition, had too many issues using them in this stove ) for a local manufacturer of pellets, which is about 150 miles away.   That reduces the transport “costs” to a mere 200 lbs of CO2.   Now that seems like a lot.  But burning the 3.5 tons of fuel, which is about 40% carbon by weight, will yield 10,000 lbs of carbon cycle neutral CO2 – not dug up from the ground and added to the biosphere – net zero.

So its a matter of using fossil fuels efficiency when you have to use them.   With the cherry pits, 10% of the heating related emissions are indirectly from fossil fuels.   With locally sourced wood pellets, this will be, for me about 1% – which means a net reduction in fossil fuel consumption of 98%.  But 90% is not shabby.  So the best practice is to source the fuel from the nearest, least morally reprehensible manufacturer.

“Well it has to put out smoke and soot.”

Well sure, I’m not saying I want to duct the emissions into my kids bedrooms.   But properly operating modern pellet stoves do not emit visible smoke, and certainly not soot.    They do emit fine particulates. Compared to prior generations of pellet stoves, they are very clean.   In many cases its possible to achieve below 1g / hour of particulate emissions.

How bad is particulate emissions?

Oil heaters are limited by EPA to less than 1.5g particulates per 1M BTU of fuel.   By comparison, modern pellet stoves produce particulates at 15x higher levels.    This is “higher.”   But the difference is that they also produce near 0 net carbon output.   It does, however, underscore one of the next advances in the evolution of this technology: particulate scrubbing.

The other consideration: is there a quantifiable difference in the impact of particulates produced by various combustion methods?   Part of the particulates produced by oil and coal are sulfur compounds, which produce greater harm compared to carbon black.

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