A vehicle on wood gas has about 40-60% of its petrol power, a top speed 60-70% as high, a 20-30 minute start and daily cleaning, and wood fuel that costs land, cutting and drying even though it needs no money. It is worth running for local and farm work where a vehicle is wanted for hours at moderate speed, and not for fast, long or urgent trips.
Part of Wood Gas Vehicles
What a vehicle running on producer gas can and cannot do compared with petrol: power, speed, hills, start-up, range, upkeep and fuel.
The Carrier’s Comparison
| Parameter | Petrol | Wood gas |
|---|---|---|
| Power output | 100% | 40-60% |
| Top speed | 100% | 60-70% |
| Hill climbing | Normal | Significantly reduced |
| Start-up | Seconds | 20-30 minutes |
| Range per “tank” | 400-600 km | 60-100 km per hopper |
| Fuel cost | Petrol price | Free (wood) |
| Maintenance | Low | High, daily cleaning |
Each line needs a reading, not just a number.
- Power and speed. The 40-60% is the engine’s power loss, explained from the energy in the gas in Power Output Derating. The top speed loses less because the power to drive a car rises as the cube of speed at the high end; see Speed & Power Reduction.
- Hills. Climbing needs power in proportion to weight and speed, and the gasifier adds 175-315 kg. A truck on a long climb is the case that suffers most.
- Start-up. 20-30 minutes, and never in a shed (Startup Sequence (20-30 Minutes)).
- Range. 60-100 km per hopper does not agree with the carrier’s own consumption table, which gives longer range for a car; the arithmetic is in Range & Fuel Consumption.
- Fuel cost. “Free” means no money changes hands. Wood has to be grown, cut, split, dried for months and carried, and the land that grows it is not growing food or anything else.
- Engine life. The carrier’s history records engine life cut by about 30-50% by abrasive particles in imperfectly filtered gas, so filtering is a running cost.
When It Is Worth It
- The vehicle is used locally and for hours, so the long start is paid once.
- The route has few steep or long hills, or the vehicle can be dual-fuelled and switched to petrol for them.
- Dry wood is cheap and plentiful, and there is somewhere to stack and dry it.
- Someone can spend time every day on cleaning.
It is the wrong choice for an emergency, a long fast trip, or a heavily loaded vehicle on mountain roads. The liquid-fuel alternatives are in the second carrier’s comparison: Biodiesel Production for diesels and Ethanol Fuel Production for petrol engines.
Common Mistakes
- Expecting petrol performance. The vehicle is slower and weaker.
- Counting only the fuel and not the labour. Preparing it is the work.
- Starting a trip without a plan for the start-up time. Twenty to thirty minutes disappears before the first kilometre.
Safety
The limitations include a fire and a poison that travel with you
Producer gas is about 18-22% carbon monoxide by volume, odourless and colourless, and the hot unit holds a fire and combustible gas. Never run, light, warm up or park the vehicle with the gasifier lit in a garage, shed, lean-to or enclosed yard, and never sleep in or near it. See Carbon Monoxide Risks.
What’s Next
- Learn next: Range & Fuel Consumption — how far a hopper really goes
- Combine with: Speed & Power Reduction — what the lost power does on the road