---
title: "Hog fuel"
description: "Hog fuel is the coarse, mixed wood-residue stream — bark, chips, sawdust, screen rejects, urban-arisings green waste — burned in pulp-mill bark boilers and biomass side boilers. The name comes from the \"hog\" mill that shreds raw wood waste into a burnable consistency."
canonical_url: "https://sylio.co/glossary/hog-fuel"
last_updated: "2026-06-28T02:29:41.400Z"
---

**Hog fuel** is the coarse, mixed wood-residue stream — bark, chips, sawdust, screen rejects, urban-arisings green waste — burned in pulp-mill bark boilers and biomass side boilers. The name comes from the "hog" mill that shreds raw wood waste into a burnable consistency.

## Composition and variability

Hog fuel composition is even more variable than [wood pellets](/glossary/wood-pellet) because no densification or sorting standardises it. Moisture content swings from 30% (kiln-dried sawmill residues) to 60% (fresh winter bark). Ash content and alkali loading vary with bark fraction (high alkali) versus wood fraction (lower).

## Where it burns

- [Hog-fuel boilers / bark boilers](/glossary/hog-fuel-boiler-bark-boiler) at pulp mills
- Standalone biomass boilers at sawmills and forest-products operations
- Smaller WtE / biomass cogeneration plants
- Co-fired with [coal](/glossary/pc-boiler) or wood pellets

## Fouling

Hog-fuel ash slags moderately on the radiant section and fouls the convective pass. [Sonic horns](/glossary/sonic-horn) on the convective pass and [air-heater](/glossary/air-heater) cold end are standard cleaning equipment.

## Related terms

- [Hog-fuel boiler / bark boiler](/glossary/hog-fuel-boiler-bark-boiler)
- [Recovery boiler](/glossary/recovery-boiler)
- [Alkali metals in ash](/glossary/alkali-metals-in-ash)