[gozur88]

>Nice thing about wood power is that as long as you have a sustainable source of wood, you're 100% solar-powered and carbon neutral. That is to say, it's a source of energy that is (can be) non-fossil, nor derived from any fossil sources, and which recycles it's own CO2 emissions.

As long as you're happy pouring carcinogens into the air, sure. Also, compared to oil or coal there's not much energy in wood, so it doesn't scale very well.

[xyzzyz]

There's a lot of energy in wood compared to coal. Wood has around 2/3 of the energy of coal by mass. What do you think coal is made from?

[QAPereo]

Charcoal is made by burning wood in a low oxygen environment, driving off water and organics, while carbonizing lignin, cellulose, etc. Coal is a petrochemical mass formed underground from organic matter over long timescales.

[aidenn0]

Isn't most of the mass of wood water?

[Yetanfou]

Fresh wood contains ~50% water (up to 70% for certain species), 'dry' wood lies around 15% water. Depending on the type of gasifier you can feed it anything between fresh from the tree to kiln-dried wood. Starting a gasifier requires dry wood or charcoal but once it is going it will do a lot of the drying itself. The reduction process in the lower part of the hearth - where the gas production goes on, reducing CO2 to CO - can also reduce H2O to H2. The end product of a wetter wood will be gas with a higher H2 content next to the CO which forms the main combustible component in wood gas. Yes, wood gas is mainly carbon monoxide and as such highly poisonous, you do not want to start a gasifier in an enclosed environment nor open an unvented gasfier in such.

[sitharus]

Dried wood suitable for burning is around 20% water at most, else it won't burn with much heat. It can go down to around 6% IIRC for kiln-dried wood suitable for construction.

[jjoonathan]

Boiling water costs a helluva lot of energy. Do these engines recover that energy?

[jabl]

How would they work if they didn't?

[jjoonathan]

At low efficiency.

[DrScump]

You can get power out of wood/cellulose without combustion byproducts.