Wood Gasifier Builder--39-s Bible- Transform — Tree Branches Into

Below 20% moisture. How to test? The “crack test.” Hit two pieces together. Dry wood makes a sharp, ringing crack. Wet wood thuds.

From the branch, a flame you cannot see. From that flame, the power to move mountains of stone. And from that power, freedom from the pump.

A gasoline engine expects vaporized liquid fuel. Wood gas is dry and has a different air-to-fuel ratio (about 1.2:1 by volume, compared to gasoline’s 14.7:1). Below 20% moisture

You don’t need an oil well. You don’t need solar panels on a south-facing roof. You need branches. And the ancient, almost-forgotten technology of wood gasification. In the simplest terms, a wood gasifier is a chemical reactor that turns solid wood into a flammable gas. It does this not by burning the wood, but by cooking it in a low-oxygen environment—a process called pyrolysis.

John McGrath’s original “Bible” has now been scanned and shared online. A free PDF version, including dimensional drawings and parts lists for three different gasifier sizes, is available through the Open Gasifier Project. Dry wood makes a sharp, ringing crack

John McGrath, a homesteader in the Appalachian foothills, had spent three days clearing storm-damaged oak from his back forty. The trunk went to the sawmill. The branches—tons of them—went into a smoldering, smoky burn pile. That night, watching the news report on diesel prices hitting $5.50 a gallon, he did the math. He was literally burning energy to get rid of energy.

Don’t modify the carburetor. Instead, build a “mixer” that fits between the air filter and the carb throat. It’s just a pipe with a venturi (a narrowing) and a needle valve to bleed in extra air. From that flame, the power to move mountains of stone

It started with a clogged carburetor and a pile of slash.

Because branches are small, you can solar-kiln dry them in a $50 greenhouse frame. Clear plastic, pallet floor, ridge vent. Six weeks in summer. Three months in shoulder seasons. 2. The Heart of the Beast: The Reduction Zone Every gasifier has a narrowing, a throat, where charcoal glows at 1,800–2,000°F. This is where carbon dioxide turns into carbon monoxide—the actual fuel gas.