BLACK PELLETS WITH A LIGNIN LINING

How Steam Explosion broke the biofuel code to release a powerful polymer.

Article Summary

Power Wood's innovative steam treatment process will revolutionize the biomass industry by transforming wildfire-damaged hardwood into highly efficient Canadian biofuel wood pellets. By redistributing lignin—a naturally occurring polymer—these advanced pellets will achieve exceptional bulk density, durability and will possess an entirely waterproof coating. As a high-quality drop-in replacement for coal, these energy-dense black pellets for power plants eliminate the need for costly infrastructure upgrades while providing a reliable, low-emission solution for sustainable energy generation.

Written by: Jonathan Stones

Published by: Power Wood Green Energy Holdings Ltd.

Published on: 29th May, 2026

Last updated on: 3rd November, 2026

WHITE wood pellets had limitations that drew doubts from some over the viability of biomass as a utility-scale energy source.

Generating stations needed multi-million dollar mega-conversions to burn them. New loading, storage, conveyance and furnace infrastructure couldn’t though change their poor energy output.

Torrefied pellets, prepared in batches, had inconsistent heating values. Baked in kilns, they were too brittle and friable around furnace infrastructure. But the innovative application of steam explosion has produced biofuel pellets that meet the energy and processing needs of large utilities companies.

Energy-dense, durable and waterproof advanced black pellets made by steam explosion are spurring multinational energy providers to re-write biofuel into their energy mixes. They have all of the positive properties of coal without its catastrophic carbon footprint or local pollution.

Homogenous and highly transportable, in all weathers, advanced black pellets burn easily in place of coal – with comparable energy release and without expensive station upgrades and downtime.

Their impressive profile is achieved with two fundamental bio-structural changes made to biomass, during steam explosion.

Steam explosion reduces the presence of lower calorie hemicellulose to immediately enhance the energy-density of its end pellet product. [1]

Then it redistributes lignin, a naturally-occurring polymer, from inside cell walls to the surface of each microscopic biofuel granule produced by the process. [2]

This second bio-structural change – from organic, energy-dense polymer keeping plant life rigid and waterproof to structural biofuel component – gives Power Wood Energy’s steam-treated black pellets their water resistant coatings, greater bulk density and high mechanical strength.

At 190°C, steam explosion caused by rapid depressurization ruptures plant cell walls and draws molten lignin throughout the biofuel.

Pelletized under 180MPa pressure, the viscous, carbon-rich grain is bound tightly into homogenous biofuel pellets with energy-dense payloads.

Close-up laboratory shot of glass test tubes set in a wire rack, containing vibrant green liquid solutions and rolled green leaves, illustrating plant biology and lignin research.

Lignin is an organic polymer that occurs naturally in plants to keep them rigid and waterproof. High in carbon, Power Wood reallocates lignin to produce waterproof, resilient, energy-dense black biofuel pellets.

THE STEAM EXPLOSION PROCESS

Steam explosion disintegrates lignocellulosic structure.

Sudden pressure withdrawal during autohydrolysis causes the flashing of water into steam to rupture biomass at cellular level.

At the right temperature, lignin softens just enough to bead on the surface of tiny, exploded organic granules – before lignin droplets merge and migrate as a natural water resistant binder.

This redistribution of lignin is why steam-treated advanced black pellets boast unprecedented bulk density, mechanical strength and impact resistance.

Lignin, repolymerizing on the surfaces of Power Wood Energy’s pellets, briquettes and bales, gives them a thick natural hydrophobic coating.

And lignin's higher carbon and hydrogen, and lower oxygen, content than other elemetns of the wood feedstock lost in the process raises the energy value of each biofuel pellet unit.

Power Wood Energy’s lignin-rich, steam-treated black pellets offer up to 23MJ/k of energy. And they can be stockpiled outdoors in existing coal yards and in all weathers.

The steam treatment they undergo ensures they achieve superior results in many test categories promulgated by the pellet industry’s institutional standards boards.

Low-angle industrial interior view of an advanced biomass steam explosion processing facility, showing a dense, complex network of insulated silver piping, manifold ductwork, and structural steel beams. JPG

Source Credit: Valmet - Steam explosion ruptures the lignocellulosic structure of biomass so softened lignin coats the grain produced for pelletizing. The outcome is an energy-dense, durable, water resistant biofuel pellet for use in power stations and the energy transition.

BENEFITS OF USING LIGNIN-RICH, STEAM-TREATED PELLETS

Lignin, abundant in the trunks of fast-growing hardwood tree species like Canada’s Trembling Aspens and Balsam Poplars, constitutes approximately 30 percent of the dry mass of wood.

Power Wood Energy uses dead hardwood lumber left by Canada’s wildfires to manufacture its multi-faceted black biofuel pellets.

High lignin levels in its feedstock support pellets with much greater bulk density, more durability and a higher heating value than all other pellets used for utility-scale energy production.

For these reasons, steam explosion black pellets with re-allocated lignin are the only true low-emission ‘drop in’ replacement for coal:

Greater Bulk Density

Higher lignin content results in pellets with greater density and therefore energy payloads. Denser fuels possess more energy and are more cost-effective to process. Greater bulk density raises heating value, alleviates transportation costs, and makes handling and storage easier.

Better Durability

Steam explosion advanced black pellets score much more highly on the Pellet Durability Index than both previous generations of biofuel wood pellets.

The softening and redistribution of lignin during explosion, binds granular biomass firmly during densification and creates a compact structure capable of resisting knocks and abrasions.

Greater Hydrophobicity

Steam explosion advanced black pellets can be stored and handled under the same conditions, and in the same storage yards, as coal – without any detrimental impact on their functionality.

Lignin, remaining in its natural state, forms a waterproof barrier around each pellet, eliminating the expense of humidity-controlled dry silo storage containers. [4]

Studio product photograph of dark, glossy steam-exploded black biofuel pellets spilling outward from a clear plastic jar onto a seamless white surface.

Steam explosion advanced black pellets have qualities more akin to coal than previous generations of biofuel pellet. But they don’t leave coal’s deadly carbon footprint and local pollution.

Higher Energy Content

Steam treatement increases the overall calorific value of biomass by partially hydrolyzing hemicellulose to a monomer, while retaining energy-rich cellulose and redistributing high-carbon lignin. [5]

Extreme pressure and the presence of the glue-like polymer lignin allow a denser biofuel pellet with enhanced calorific value to be produced. Power Wood Energy’s biofuel will burn with up to 23MJ/k.

Improved Grindability

Power Wood Energy’s steam treated black pellets will grind easily into a homogenous fine, granular biofuel powder, which has uniform energy release. They will be able to be processed with most existing power plant milling facilities. [3]

Their consistent grain supports close and accurate control of furnace temperatures and station efficiency, while it is Power Wood energy's aim that they also extend the lifespan and value of national coal-fired energy infrastructure.

Lower Ash and Particulate Content

Lignin redistribution and hemicellulose degradation modifies biomass structure. Resulting dense and robust hydrophobic pellets have fewer impurities and don’t break down into fine particles or dust.

The transportation, storage and combustion of steam-exploded biofuel reduces the production of sulphur dioxide, nitrogen dioxide, nitric oxide, particulate matter and ash compared to coal.

Consistent Fuel Quality

Power Wood Energy’s biofuel products – whether pellet, briquette or bale – are homogenous in the density of their physical form and their heating value, allowing for more consistent energy production.

The company’s uniform product size and quality allows for efficient transportation, handling, temperature control and power generation.

References & Citations

[1] MDPI. (2022, October 26) Chao Ma, Liying Ni, Zebin Guo, Hongliang Zeng, Maoyu Wu, Ming Zhang. Baodong Zheng. Principle and Application of Steam Explosion Technology in Modification of Food Fiber. Fujian Agriculture and Forestry University. https://www.mdpi.com/2304-8158/11/21/3370

[2] Valmet. Pretreatment BioTrac, Heat and Chemical Recovery. https://www.valmet.com/industries/bio/bio-coal/feeding-technology/

[3] Valmet. A replacement for fossil coal in heat and power plants: steam treated black pellets. https://www.valmet.com/insights/articles/biofuels-and-biomaterials/black-pellets---a-replacement-for-fossil-coal-in-power-plants/

[4] International Energy Agency. 92018, September). Biomass pretreatment for bioenergy. https://www.ieabioenergy.com/wp-content/uploads/2018/10/CS4-Steam-explosion.pdf

[5] Frontiers. (2021, November 11) Steam Explosion Pretreatment of Lignocellulosic Biomass: A Mini-Review of Theorical and Experimental Approaches. Isabelle Ziegler-Devin, Laurent Chrusciel, Nicolas Brosse. https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2021.705358/full