With rising heating costs, many homeowners are looking for affordable and sustainable ways to heat their homes.
Two popular options are wood chips and wood pellets. As an experienced writer covering green energy topics, readers often ask me about the differences between wood chips and pellets, these two wood fuels.
In this blog post, I’ll explain what wood chips and pellets are, how they’re made, their heating properties, costs, and their pros and cons.
I’ll also offer tips on deciding which may better fit your needs. When choosing a renewable fuel source, there’s a lot to consider, so read on for an in-depth look at wood chips vs. pellets!
What Are Wood Chips And Wood Pellets?
With rising home heating costs, many homeowners are turning to renewable biofuels like wood to warm their houses. Two popular options are wood chips and wood pellets. But what exactly are wood chips and pellets, and how are they different?
What are Wood Chips?
Wood chips are made by chipping, crushing, or shredding waste wood material into small wood chunks. Sources for wood chips include tree branches, logging residue, wood pallets, untreated demolition wood, and more.
Wood chips have an uneven, varied shape and size. Their moisture content can range from 15-60%.
What are Wood Pellets?
On the other hand, wood pellets are made by compressing dried, pulverized wood material, like sawdust shavings of wood extruded, into uniform cylindrical shapes.
The pellets are typically 6-8 millimeters in diameter and 10-30 mm long. They have a moisture content of around 8-10%. Pellets are more refined and consistent than wood chips.
The production process gives wood pellets a higher energy density per volume compared to wood chips. So, pellets require less storage space. But chips are cheaper to produce.
In terms of heating, wood chip furnaces are suited for whole-home central heating. Pellet stoves and fireplace inserts let you heat single rooms.
What Are The Differences Between Wood Pellets and Wood Chips?
1. Manufacturing Process
Wood pellets are made by compressed sawdust and wood shavings into uniform cylinder shapes under high pressure. This compression process removes moisture and increases the density of the pellets, resulting in high energy content per volume.
Wood chips are wood waste materials like branches and logs chipped or shredded into irregularly shaped chunks. Wood chips are not as processed as wood pellets, so they have higher moisture content and lower density.
2. Moisture Content
The moisture content of wood pellets is less than 10%, whereas wood chips typically have a moisture content of 20-30%.
The lower moisture content of pellets enables more complete combustion, increasing their heat output compared to wood chips containing more moisture.
3. Energy Density
Wood pellets have a higher energy density than chips due to their dense, uniform shape and low moisture content. Wood Pellet boilers and stoves can burn pellets more efficiently than less dense, irregular wood chips.
4. Cost
Wood pellets require more processing, making them more expensive than wood chips per weight. However, pellets generate more heat energy, offsetting their higher cost.
5. Applications
pellets are better suited for small-scale heating like pellet stoves. Chips work better for large industrial-scale energy production. The difference comes down to handling and burning the two types efficiently.
In summary, pellets are a more processed, higher energy-density fuel. At the same time, wood chips provide a cheaper but less consistent option.
Wood Chips: Advantages And Disadvantages
Advantages of Wood Chips
Wood chips can be used as an energy source due to their cost-effectiveness and high moisture content, which offer various benefits of wood chip.
1. Cost Savings
Wood chips are cheaper to produce than pellets because they require less processing. Simple chipping or shredding of low-grade wood materials like sawmill residues, tree trimmings, and forestry byproducts creates wood chips.
This is less expensive than drying, pulverizing, and densifying wood particles into uniform pellets. The lower cost of chips makes them attractive for large-scale industrial energy applications.
2. High Moisture Content
Wood chips typically have a fresh moisture content between 20-30%. While high moisture content reduces the net energy output when burning chips, it also prevents dust explosions.
The high moisture content improves safety for industrial systems equipped to handle excess water.
3. Utilization of Wood Waste
Wood chips allow mills and forestry operations to generate value from low-grade wood waste. Rather than pay for disposal, wood wastes can be chipped to create a fuel product. This supports sustainability and the diversion of wood residuals away from landfills.
Disadvantages of Wood Chips
Despite their cost advantages, chips have some inherent drawbacks as a biomass heating fuel.
1. Lower Energy Density
Wood chips’ irregular shape and size result in a lower energy density than dense, uniform wood pellets. More volume is required to produce the same heat output.
2. Combustion Inefficiency
High moisture content and variable particle size lead to incomplete combustion and more residual ash when burning chips.
3. Material Handling Challenges
Handling chips requires conveying systems and pneumatic equipment for irregular, chunky material. Pellets are better adapted to screw-fed stoves and boilers.
4. Storage Concerns
Wood chips can decompose or spontaneously combust if not stored properly. Pellets are more stable.
In summary, chips can provide a cost-effective but lower-performance biomass fuel suitable for large industrial applications equipped to handle their moisture and irregularity.
Wood Pellets: Advantages And Disadvantages
Advantages of Wood Pellets
Wood pellets offer several benefits that make them a top choice of wood for residential and commercial biomass heating:
1. High Energy Density
The densification process creates pellets with consistent pellet shape, size, and density. This allows pellets to reach an energy density of 8,000-10,000 BTU/lb versus chips at 4,000-8,000 BTU/lb. More energy can be generated per unit volume.
2. Low Moisture Content
Wood pellets typically contain less than 10% moisture content. This aids efficient combustion. Chips have moisture levels of 20-30% or more.
3. Ease of Handling
The uniform shape and small size of pellets allow automated feeding using screw augers or vacuum suction. No special material handling equipment is required.
4. Reduced Emissions
Low moisture and consistent composition enable more complete combustion with fewer particulates or harmful emissions.
5. Pellet Stove Compatibility
Wood pellet stoves are designed to automatically feed the uniform pellets into the burn chamber. Pellet stoves provide clean, convenient heating.
Disadvantages of Wood Pellets
Despite the advantages, pellets also come with a few drawbacks:
1. Higher Cost
Wood pellets are more expensive to manufacture than chips due to the extra processing involved. The higher energy density helps offset the increased price.
2. Dust Production
Handling and transport of wood pellets produces fine dust that requires safety precautions.
3. Storage Space
The bulk volume of pellets requires more storage room than fuel oils or natural gas. Proper moisture-proof storage is needed.
4. Regional Availability
The ready availability of pellets depends on the distance from manufacturing facilities. Delivery costs can be high in some locations.
In summary, wood pellets represent a premium biomass fuel that carries a higher price balanced by higher burning efficiency, cleaner operation, and ease of handling.
Which Is Better, Wood Chips Or Wood Pellets?
Wood pellets are generally considered superior to chips for residential and commercial biomass heating applications. The main advantages of pellets include:
1. The higher energy density per volume results from the densification process. This allows more energy to be produced from less storage space.
2. Lower moisture content below 10% enables nearly complete combustion and higher efficiency. Chips have moisture levels of 20-30% or more.
3. Consistent size and shape allow automated feeding with augers or vacuum systems. No special material handling equipment is needed.
4. Wood pellet stoves are designed for this uniform fuel source. Pellet stoves provide clean and convenient heating.
5. Reduced emissions from more efficient burning give wood pellets environmental benefits.
The main tradeoff is pellets have a higher manufacturing cost from additional processing steps. They also produce more dust, requiring safety measures.
Chips offer a less expensive but lower-performance option. Their irregular shape and high moisture are better suited for large industrial energy systems, not small residential applications.
Which requires less frequent refueling, wood chips or pellets?
Wood pellets require less frequent refueling than chips in biomass heating systems. The main reasons are:
1. Wood pellets have a higher energy density per volume than chips due to the pellets’ consistent size, shape, and compactness. More energy can be produced from an equivalent volume of wood pellets.
2. With lower moisture content below 10%, pellets undergo more complete combustion. This extracts more potential energy in the wood fiber versus chips with higher moisture levels.
3. The uniform shape and small size of pellets allow highly efficient automated fuel feeding into the combustion chamber. This optimizes the burning process.
4. Pellet stoves and boilers are designed to utilize wood pellets as fuel sources. The equipment is engineered for maximum efficiency with pellets.
5. Wood chips require more specialized handling equipment to move their irregular shapes. This can result in feeding inconsistencies and lowered efficiency.
In summary, pellets offer a higher energy density fuel that burns more efficiently in biomass heating systems designed for their uniformity.
Less frequent refueling is a notable advantage of pellets compared to chips for residential and commercial heating applications. The convenience of pellets outweighs their higher costs for most users.
Best Tips To Improve Performance Wood Chips And Wood Pellets?
For wood chips, the main tips for improving performance:
1. Reduce moisture content to 30% or less for cleaner, more efficient combustion. Store chips under cover to keep them dry.
2. Use screened chips with a uniform size range for more consistent feeding and burning. Avoid fines and oversized pieces of wood.
3. Invest in specialized handling equipment like conveyors, augers, and pneumatic systems to feed irregular wood chips smoothly.
4. Use combustion equipment designed for chips – large industrial boilers with fire tubes or burners to accommodate variability.
For wood pellets, key tips include:
1. Ensure airtight storage and minimal temperature fluctuations to avoid pellet breakdown.
2. Use pellet heating appliances specifically engineered for pellets, like pellet stoves or boilers.
3. Follow manufacturer guidelines on equipment settings like feed rate, burn temperature, and airflow.
4. Vacuum out ashes regularly for clean, efficient combustion.
5. Have pellets delivered when storage is down to 20% to maintain supply and prevent jams.
6. Keep pellet feed mechanisms and burner components clean.
Following these best practices allows both wood chip and pellet systems to maximize performance and heating value efficiency based on the inherent characteristics of each fuel type.
Conclusion
After extensive research and analysis, pellets perform superior to chips for most biomass heating applications.
The additional manufacturing steps required to create dense, uniform pellets result in a fuel with higher energy density, lower moisture, more complete combustion, and easier handling.
Despite their higher cost, these advantages make pellets the preferred choice for small residential and commercial systems.
Wood chips work best for large industrial systems equipped to handle their moisture, size, and shape variability.
For the average consumer seeking a renewable heating solution, the benefits of wood pellets in terms of efficiency, heat output, emissions, and convenience outweigh their higher price point.
Pellet stoves and boilers optimize the performance advantages of pellets. While chips have a place for some large operations, I recommend pellets for small-scale biomass boiler systems.
FAQs
Wood pellets are generally more expensive than chips on a per-ton basis. The additional processing required to dry, grind, and densify wood material into uniform pellets results in a higher manufacturing cost than simply chipping or shredding waste wood into chips.
Chips are less dusty to handle compared to pellets. The granular nature of pellets results in more dust generation during transportation and conveying. Wood chips have larger, irregular shapes that produce minimal dust when handled properly. Taking steps to reduce and contain pellet dust is recommended.
Wood pellets are better suited for short burning times compared to chips. The consistent size and high density of wood pellets allow them to be efficiently burned in small batches. Wood chips require longer, sustained burns in larger furnaces to fully utilize their irregular shapes and higher moisture content.
Wood pellets burn hotter than chips. Pellets’ dense, uniform structure and low moisture content enable them to combust thoroughly and efficiently. Chips have lower density, higher moisture, and irregular shapes, leading to lower heat output when burned than pellets.
