Wood Gasification for Emergency Energy

Wood gasification converts solid wood or other biomass into a combustible gas mixture called syngas (or woodgas), which can fuel engines, power generators, and provide heat. Unlike direct wood burning, gasification extracts significantly more energy per unit of fuel and allows wood to power internal combustion engines — including generators. While more complex than other emergency energy options, gasification is one of the few renewable energy pathways available in a long-term, extended infrastructure failure.

How Wood Gasification Works

A wood gasifier heats wood in a low-oxygen environment, producing syngas — primarily carbon monoxide (CO), hydrogen (H2), and methane (CH4) — by incomplete combustion. This gas is then cleaned, cooled, and burned in an engine or for direct heat.

The four zones in a gasifier:

1. Drying zone — moisture is driven off the wood
2. Pyrolysis zone — wood breaks down into volatile gases and charcoal
3. Combustion zone — partial combustion of gases and charcoal provides heat
4. Reduction zone — steam and CO2 are converted to H2 and CO

The output is a combustible gas that can replace diesel or petrol in a modified internal combustion engine.

Types of Gasifiers

Type	Best For	Fuel Requirements
Downdraft (Imbert)	Engine fuel (clean gas)	Dry, uniform chip or chunk wood
Updraft	Heat production	More flexible fuel
TLUD (Top-Lit Updraft)	Small-scale; cooking; charcoal production	Pellets or chips
Commercial gasifier units	Full generator operation	Dry chips or pellets

For emergency power generation, a downdraft gasifier connected to a generator is the most practical large-scale setup.

Practical Energy Output

Configuration	Output
Small TLUD gasifier (cooking)	1–5 kW heat equivalent
Medium gasifier + generator (3–5 kW)	3–5 kW electricity (modified engine)
Large gasifier + generator (10 kW)	~10 kW electricity
Wood fuel consumption (3 kW generator)	~4–8 kg dry wood per hour

A dry hardwood supply of 50 kg would run a 3 kW generator for approximately 6–12 hours.

Fuel Requirements

Gasifiers are highly sensitive to fuel quality:

1. Moisture content must be below 20% (ideally below 15%) — wet wood produces poor quality gas and extinguishes the gasifier
2. Uniform size — chips of 20–50mm or chunks of similar size; irregular sizes cause bridging and uneven combustion
3. Clean wood — avoid wood with paint, preservatives, or contamination that produces toxic tars
4. Hardwoods are preferred over softwoods for energy density and tar production

Drying and preparing fuel adds significant effort to gasification as an emergency energy source.

Generator Modification

Standard petrol generators can be converted to run on woodgas, but modification is required:

1. A gas mixer/carburetor adapter allows woodgas to be injected into the air intake
2. The fuel valve is typically left slightly open or closed — the gasifier provides the fuel
3. Engine timing may need adjustment for optimal woodgas combustion
4. Converted engines typically produce about 20–30% less power on woodgas than on petrol

Pre-modified or "dual-fuel" generators that can run on both petrol and woodgas are available commercially.

⚠️ Carbon monoxide is a primary component of syngas. Gasifiers and gas-powered generators must only be operated outdoors or in very well-ventilated spaces. CO exposure is lethal. Install CO detectors wherever woodgas handling equipment operates.

TLUD Gasifiers for Cooking

A simpler and more immediately accessible gasification device is the TLUD (Top-Lit Updraft) gasifier, used for cooking:

• Burns pellets, chips, or small sticks with very high efficiency
• Produces minimal smoke (most volatiles are combusted in the flame)
• Produces biochar as a residue (useful soil amendment)
• Can be constructed from two nested cans as a DIY project
• Excellent for outdoor cooking and water heating

Is Wood Gasification for You?

Factor	Suitable	Not Suitable
Skill level	Mechanically capable; willing to learn	No mechanical aptitude
Fuel access	Access to dry wood	No wood available
Use case	Long-term extended crisis; rural	Short-term urban outage
Time investment	High — fuel prep, maintenance	Not available
Budget	Moderate — gasifier + conversion	Tight

For most urban households, a generator with stored fuel or a solar + battery system is more practical for short to medium outages. Wood gasification becomes relevant in rural settings or truly extended infrastructure failures where fuel is unavailable but wood is accessible.

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Quick Reference

Aspect	Detail
What it does	Converts wood to combustible gas for engines and heat
Fuel	Dry (<20% moisture) wood chips or chunks
Output	3–10 kW electricity; heat
Wood consumption	~4–8 kg/hr for a 3 kW generator
CO hazard	Always operate outdoors — CO is lethal
Simpler option	TLUD gasifier for cooking — DIY-buildable
Best for	Rural; extended outage; wood available