The effects of Air Humidity on Gasification

We here Pacific Northwest wetside are appreciative of all of the good wishes and prayers for the rains now stopping our destructive, smokes generating wild fires. Our seasonal October rains did come early. Be 7 inches of rain in 7 days by day ending today. Just right for wildfire suppression. Just enough that any woods outside not undercover will never be truly dry again until after mid-July next year.

For us here this means an 8 day sudden transition from 8-10% 80-90F humidity air; to 90-100% humidity 50-60’s F. air.

I am now using outside under cover paper grocery sacks to strip-timed burn document the combustions effects of our air humidity.
For years I have seen and experienced this in woodstoving.
In driven vehicle engines.
Then later in wood gasifier performances.

Air humidity effects are real, and significant.
Number 3 performance factor behind the base wood fuel moisture level. And gasifier hearth core section; heat bleeding out losses effects.

More later if there is an interest.
Steve Unruh


That sounds like wildfire weather around here. Does it happen up there?

15 Washington State wildfires so far this year at ~300,000 acres.
30+ Oregon State wildfires so far this year at 1.2 million acres.
Idaho too.

Yes. Happens here every year. And has happened every year here for as far back as records, and photos go.


We have now swung back after three overlapping Pacific storms and a cumulative 11 inches of various raining in 8 day to warm-hot low humidity continental air flow now.

My paper rate burn test for air effects humidity have evolve to this:
strips cut from the brown craft type paper grocery bags.
4 inch (100mm) by 14 inch (230 mm).
90 degree fold crease these down their center for stiffness.
Cloths pin these horizontal to a metal fixture.
Wooden match or butane lite them across the whole end.
Time the burn to a 12 inch (200mm) line.

I am seeing a timed difference depending on the papers air absorbed humidity.

This is for me and my works.
NOT directly comparable to others climates and conditions.
You’d have to do your own tests.

That is the real problem with scientific method. Standardizing all test conditions for world wide repeatability then “discovered” relationships that can only then be directly applied to those standardized conditions. Ideals. The miles-per-gallons never real. The oil change intervals too soon for some. Destructive too long for others. Big difference between taxicab/long commuter and granny/grandpa’s miles and drive time for the engine oils life!!
Real world applications are always a sum of the many factors local conditions.
Conditions that operators learn to make-work-with to achieve results. Practical achievable ranges then.

'Nother 2-3 hours and I will go out and wheelbarrow into the woodshed the last two cord of winter heating fire wood.
AFTER the 50F night dew-down wettening sun evaporates off. The air drops from 100% over night humidity down to 40%.
Having late afternoon September “Goldilocks” best weather in the world, yesterday, today, that will be ~20% R.H. full sunny and “dry”.
Wood be sun warmed and dryed down just a bit more.
Do my wood-sweating for real. Best combo aerobics and resistance conditioning possible.
Wood sweat’ers, live longer and happier.
The Wisdom of woods.
Steve Unruh


GOOD to see the fires subside in your area, the smoke was definitely blocking the sun here. here in ALBERTA Canada have bedn spaired the fires with copious amounts of rain for in June and July…
Farmers are struggling with crazy weather variations here in the north…
Our power grid went down for 12 hrs in june and I ran my 15000 gasifier for the duration of the outage , I was popular with the nieghbours…


Hey there you go TomL.
Be the hero of your neighborhood.
Ha! Put those neighbor responsible young’ens to wood-chunk fuel making to pay for their electricity says I.
Steve Unruh