Making fuel ethanol leaves behind a protein-rich residue (distillers’ grain) that can be fed to livestock, and exposes the maker to three separate hazards: methanol, which is poisonous and not a problem for engines but is for anyone who drinks the product; ethanol’s easily ignited, nearly invisible flame and vapour; and carbon dioxide, which collects in low closed spaces. Plan the feed use and the hazard controls before the first batch, not after.
Part of Ethanol Fuel Production
The byproducts of ethanol production (spent grain, gas, heat) and the main hazards of brewing and distilling it as fuel.
What Comes Out Besides Fuel
- Distillers’ grain: the solids and liquid left in the still after the ethanol is boiled off. Most of the grain’s starch has gone, but its protein, fibre and oil remain, which is why it is worth feeding (Distiller’s Grain).
- Carbon dioxide: about 0.42 m³ for every litre of ethanol made (Fermentation).
- Heat: most of the energy cost of the whole process (Yield per Hectare Comparison); a plant that can use it, for drying grain or heating water, wastes less.
Three Hazards, Three Different Controls
| Hazard | Who it harms | Control |
|---|---|---|
| Methanol | anyone who drinks or handles the early distillate | label fuel as poison; keep it away from drink; ventilate; wear gloves and eye protection (Methanol Hazards) |
| Ethanol fire and vapour | the maker and bystanders | no flame near vapour; sealed joints; ventilation; extinguishing plan (Fire Safety) |
| Carbon dioxide | anyone in a closed room, cellar or pit | ferment outdoors or ventilated; never enter a fermenter space unaired (Fermentation Vessel Design) |
One Rule Over All Of Them
Fuel alcohol is made to burn, not to drink. Keep every container labelled, store it apart from food and drink and out of reach of children, and never decant it into a drinking bottle. A bottle of clear liquid that looks like water but is ethanol with methanol in it is the realistic way people are hurt.
Never drink fuel ethanol
Methanol is present throughout a distillation run, not only the early fraction, and it absorbs through skin and vapour as well as the mouth and can cause permanent blindness. Discarding the early fraction is a flavour step; no discard rule used at home makes a distillate safe to drink. Label all fuel as poison.
What’s Next
- Learn next: Methanol Hazards, on where methanol goes in a run and why fuel makers can ignore it for the engine but not for the people
- Combine with: Distiller’s Grain, the food-side payback