THE PRECURSOR TO BLACK BIOFUEL PELLETS

The lauded benefits of burning white wood pellets in generating stations instead of coal have come under increasing scrutiny in recent years, and for good reason.

A primitive biofuel – in essence highly compressed sawdust and wood shavings – white pellets were once seen as a suitable replacement for the fossil fuel.

First brought into the global energy mix two decades ago, after climate policies incentivized switching from coal, they were regarded as a renewable source of energy because the trees felled to produce them could be replaced.

White pellets appeared to cut some carbon emissions from large utility-scale power plants, but their greater service was to clean up the image of many energy companies operating them.

But as the white pellet industry expanded and more generating stations underwent extensive modifications to burn them, questions about their viability began to arise.

White pellets presented environmental, technical, logistical and economic problems at multiple points of their supply chain.

Then, more recently, they were succeeded by steam explosion advanced black pellets – an economically viable and logistics-friendly biofuel which behaves more like coal and emits much less carbon dioxide than white pellets do.

Combined, these emerging challenges inevitably led to the closure of many white wood pellet plants. The most recent to end production was Williams Lake plant in British Columbia, Canada, shut down in November 2025.

The end of a generation of biofuel, which led to the development of advanced black pellets, is near if not at hand.

So, in this article, we take a look at the five core reasons why white pellets were never destined to be a sustainable long-term alternative to coal.

1. Their Diminutive Energy Density

As a fossil fuel, coal is a highly concentrated form of ancient energy. Its matter has been compressed over millions of years. And, as a result, it provides an average 27 megajoules of energy per kilo. Raw wood feedstock is much less energy dense than coal, producing just 16 megajoules of energy per kilo.

This means that energy companies must burn, ship and source much greater volumes of white pellets to achieve the same megawatt outputs at their generating stations.

Steam explosion advanced black pellets have much more bulk density than white pellets. They have undergone their own compression and release up to 23 megajoules of energy per kilo.

This is a key reason why steam explosion advanced black pellets have succeeded white pellets in the marketplace as the preferred choice of energy companies switching from coal.

2. Their Hydrophilic Vulnerability

Coal is recognisably resilient. Piled in yards around the world, it can be exposed to the elements indefinitely. Rain nor snow will permeate it. The sun does not parch it. Wind cannot diminish it.

White wood pellets are highly absorbent. They soak up moisture from humid environments and disintegrate when immersed in water. Once dry again, they create dust explosion safety risks. This inherent drawback necessitates expensive, airtight, climate-controlled storage silos as well as sophisticated dust-suppression and spark-detection systems in generating stations.

Advanced black pellets are wholly water-resistant, due to natural lignin dispersed throughout them. In the same way as coal, they can be exposed to all weathers without deterioration or concern.

The emergence of more practical green alternatives to coal is another reason why white pellets have become obsolete in the marketplace.

Coal-fired generating stations aren’t configured to burn wood and must undergo expensive upgrades to boiler furnaces to avoid corrosion from alkali metal slagging released by white wood pellets.

3. Boiler Fouling and Slagging

Coal-fired boilers in generating stations and steel mills are specialized appliances, calibrated for the chemical signature of coal. Their combustion chamber membranes are made from high-grade carbon steel tubes.

Virgin wood has a different ash chemistry to coal because it contains high amounts of alkali metals like potassium, magnesium and sodium. When burned in furnaces these elements vaporize and deposit onto boiler tubes as a sticky, glass-like substance known as foul or slag.

This build-up causes pitting and corrosion of the metal and reduces heat transfer. Boilers designed for burning coal can see their lifespan halved or their maintenance costs tripled when run on white wood pellets without a full, expensive redesign.

Steam-exploded black pellets contain no harmful elements or particulates. They produce negligible ash or slag, and can be burned in coal-fired boilers without any costly modifications or maintenance.

4. The Carbon Dioxide Challenge

Coal is correctly castigated for emitting high quantities of carbon, as well as other toxic gases, that have been locked in fossil form for millennia. Burning it greatly increases the amount of greenhouse gases in our atmosphere.

Virgin wood is considered renewable because trees can be replaced, and they draw down atmospheric carbon as they grow. But wood burns with an inherently higher carbon output per unit of energy than coal – producing between 20 and 150 percent more CO 2 depending on efficiency.

And because white wood pellets are less energy-dense and often wet, more of them must be burned to create equal heat.

Advanced black pellets made by steam explosion release up to 94 percent less CO2 than coal, and therefore are the only truly green direct drop in replacement for the fossil fuel burning in generating stations.

5. The CapEx Cost

Retrofitting a coal-fired generating station to burn white wood pellets is an extensive and expensive engineering operation. It typically comes at a significant cost of several hundred million dollars.

Power plants that switch from burning coal to white wood pellets must integrate a dedicated weatherproof unloading depot. This sealed reception area for handling the biofuel, alongside several airtight, climate-controlled storage silos and new air-driven conveyor belts constitute approximately half of the capital expenditure needed.

Elsewhere the generating station’s grinding mills require new pulverizers and motors and its furnaces need upgraded burners. In addition, the entire transfer chain must mitigate explosion and fire risks with dust suppression and spark detection equipment.

Burning advanced black pellets made by steam explosion doesn’t incur any of these costs. They require minimal modifications to plant infrastructure because they possess many physical similarities to coal. While white wood pellets proved an unsuitable replacement for coal, they did pave the way for later generations of biofuel pellet that are a viable alternative.

To learn more about PowerWood Canada Corp’s advanced black pellets, please use the contact details available on this website.