Wood fires are warm, beautiful, emotionally satisfying, and relaxing. We are, perhaps, hard-wired by our cave ancestry to gather round a bright, cozy wood fire on frosty nights.
The problem is that burning wood is harmful to the environment, inconvenient, messy, and comes with storage and transportation issues.
Like many people, if you love wood-fires but have major concerns about using wood, you can choose a more environmentally-friendly alternative – wood pellets.
With increasing interest in renewable energy sources and the production of related products, there is a focus on alternatives that reduce greenhouse gases, toxic emissions and contribute to the country’s socio-economic, healthcare, and environmental goals.
The European Union’s goals too align with these aspects, and there is a concerted effort to identify resource availability and unique energy markets. Many of these countries are heavily dependent on imported biomass materials sourced from responsible regions and manufacturers.
Wood pellets have emerged as an important product that syncs with the new thinking on energy utilization. 2018 statistics show that wood pellet trade across 28 EU countries exceeded 18.2 million tons, with the US positioned as the biggest trading partner.
What Are Wood Pellets?
Pellet fuels are made from compressed organic matter or biomass such as agro-waste, food-waste, energy crops, industrial waste, and virgin lumber. The most common raw materials are sawdust, wood shavings, off-cuts, or freshly-sawn timber. Wood is one of the most common materials used, and wood pellets, the size of a kid’s crayon, are usually made in a pellet machine from compressed sawdust generated by wood-utilizing industries and construction.
Wood pellets are usually available in 6mm diameter pellets in a uniform shape and size, about 10-20mm in length, with a moisture content of less than 8%. The size and shape make for easier transportation and storage. They are easy to feed automatically into burners, and their uniform shape/size/form makes for easy handling.
They are used in place of fuels such as charcoal, oil, firewood, and gas in heating and cooking and boiler and power plants. They are a clean-burning, sustainable energy form, and they leave the lowest ash residue of all wood fuels. Alternatively, they’re also used for animal bedding.
How Wood Pellets Are Made
Generally, they’re manufactured in bulk in industrial pellet factories or mills, but with the greater interest in this sector, many homeowners and small/medium businesses are entering this space.
- It starts with the trucks arriving at the manufacturing plant, carrying the raw material. This may be low-grade Roundwood: thin tree prunings, driftwood, twigs, dead branches, harvesting residual, treetop cuttings, bark, sawdust, and similar wood-based items. The wood is sorted, with Roundwood is delivered to a part of the factory where it is staged for processing. Sawdust, shavings, and other materials can be collected in a wood-chip pile. The bark is stored for use as fuel in the dryer.
- Logs are debarked, chipped into small pieces, and then delivered to the wood-chip pile by conveyor belt.
- Sorting occurs where any unwanted materials such as mud, sand, bones, bark, etc., are processed through a screener, and only the chips are sent to the dryer.
- Drying is done by large industrial dryers that use super-heated steam to reduce the moisture content to less than 12%. These dryers use the bark burning in a drum burner.
- A hammer mill works to convert the dry chips into fine fiber.
- Finally, this fiber is fed into a pellet mill that converts it into compressed wood pellets under intense heat and pressure. The uniform size and shape come from metal die in the mill.
- Pellets are transported to large storage silos, where they are dried and hardened before being shipped out to the buyers.
Home-Made Wood Pellets:
The process is the same for DIY enthusiasts and home-based industries but on a smaller scale.
- Collect the raw materials that you require. You may have to gauge the amount of space you have to store these logs and other materials before starting the collection. These are the right options if you have a large outdoor shed, lumber room, basement, or big yard. You can also build temporary shelters on your terrace.
- For a small batch of pellets for home use, you may need just about 10 buckets of sawdust, or 8-10 mid-sized logs. This can yield between 4-9 kgs of pellets. If you need larger quantities, you can order from a sawmill, but you must pay for transportation.
- Order the materials well in advance so that you can ensure that they are dry and sorted out well.
- Use a wood chipper to convert the material into small chips.
- If you’re using sawdust, you don’t have to go through this stage.
- You will need a hammer mill to grind/chop the chips into smaller particles. Again, if you’re using sawdust, skip this stage.
- Sundry the particles for at least 24 hours till they’re relatively moisture-free and feel dry to the touch.
- You will have to remove contaminants and other non-wood materials with a sieve, especially if you’re working with large quantities of wood.
- Add vegetable oil in the measure of 1 tsp for 1 lb of particles if the amount of wood particles is smaller (lower than 10lbs). Otherwise, you won’t need any binding agent.
- Use a batch-mixer to thoroughly blend the particles. If you’re making the pellets at home, with small quantities of particles, you can use a kitchen stand-mixer and run for about 10 minutes.
- You will have to invest in a flat-die pellet mill that uses heat and pressure. It has die-casts to shape the pellets uniformly. These machines are available in most agricultural machinery or hardware stores and are used for agri-feed. You can also purchase them online.
- Remove the pellets and then sort them according to shape and quality if you plan to sell them. For home use, you don’t have to worry about this.
- Keep the pellets in a cool, dry place to cool down and harden completely.
- Once they’re completely cold, you can store them in bags till they’re transported or used.
Pros and Cons of Wood Pellets
Wood pellets pros:
- Convenient and hassle-free to use
- No mess or hard work in gathering firewood
- No need to stoke the fire as with logs
- Pellet-feeder feeds pellets into the stove at the right rate according to the amount of heating you want
- Stove can be thermostat controlled
- Prevents extreme temperature swings
- More efficient, with better heat and less emissions
- Among the cleanest burning solid wood fuels
- Stoves are easy to clean and install, cheaper, don’t produce much ash or cause creosote buildup
- Can be installed in smaller spaces and regions where air-quality controls are strict
- Pellets are easily available, convenient to store and transport
On the flip side:
- Stoves may require electricity for heating, making it difficult during power outages unless you have generators or battery back-up
- Manufacturing wood pellets is a laborious process
- Pellets may be more expensive than traditional firewood, especially if you live in a forested area or estate
Interesting Related Article: “Gas vs. Wood-Fired Ovens: Which is Best for You?“