Torrefaction

Co-firing with biomass offers cheap and practical ways of reducing carbon emissions using existing infrastructure.
In general, torrefied bio-coal production is similar to conventional white wood pellet production process. The main difference between them is that torrefaction requires a torrefaction reactor.
Many reactors have been tested in pilot projects, but only a very few large industrial-sized plant projects are being developed in the USA and Europe.

Plugging into the massive potential of biomass.

Wood chips are thermally treated in an oxygen deficient environment, which leads to a dry product. Torrefaction combined with densification leads to an energy-dense fuel carrier in the form of pellets. This product has broadly similar properties to that of coal.
Bio-fuel can be used for conversion to energy in power plants and substitution material for co-firing in coal fired power plants.
Torrefied wood is made up of modified cellulose structures containing approximately 61% carbon, 5% hydrogen, 2% moisture and 65% volatile matter; negligible amounts of chlorine, sulphur and ash can also be found. Starch is used as a binding agent in the pellets.

Plugging into the massive potential of biomass.

Torrefaction is thermal treatment of biomass in an environment with low oxygen content.

Although the process is similar to charcoal production, it takes place in a much lower temperature environment that requires less exotic and less expensive materials, which results in biofuels with more favorable combustion properties, better mechanical and storage properties, and higher energy density.

Torrefied biomass especially after it has been pelletized has similar properties as coal and is the ideal fuel to replace non-renewable coal resources for use in existing coal processing plants and facilities, like power plants without expensive capex upgrades required for white wood pellets. Our CEG Technology can operate across torrefaction and up to pyrolysis temperatures, so a wide range of fuel and other thermally treated biomass products can be processed.

Learn about our technology

Pellet technology proven at 6mm

Extremely grindable

High energy value

Water resistant

Durable pellets with choice of performance

CEG's unique torrefaction process converts biomass into biocoal and biochar products, utilizing our proprietary torrefaction reactor

(Hover over the diagram below to interact)

Wood Moisture 50% (mass in biomass source)

Wood when harvested is about 50% moisture by mass and requires that energy be expended to evaporate this water either in a dryer or in a combustion furnace. This 50% moisture also constitutes mass that must be transported. Moisture also obscures accurate pricing when quoted on a per tonne basis. The mass of water reduces the net calorific value as a function of mass such that 50% wet wood has half the energy value of dry wood.

Ash 1% mass, (0% GJ)

Ash is typically 1% of wood mass, is non combustable and therefore must be disposed of when wood is combusted. When wet wood is dried, the apparent ash content increases as moisture is evaporated. Similarly there is an apparent increase in ash content with torrefaction but this is simply because the ash stays when oxygen is removed from the wood. Smaller concentrations of compounds such as chlorine are actually liberated with the oxygen and their concentration can be reduced in the torrefaction process.

Carbon 50% mass, (84.6% GJ)

Carbon is about 45% of the mass in dry wood and contributes about 85% of the energy. When combusted to CO2 no water is created. Torrefied material has higher carbon mass which results in higher energy content as well as higher adiabatic combustion temperature.

Hydrogen 6% mass, (15% GJ)

Hydrogen mass in wood is only 2 to 4 percent by mass but 15% of the higher heating value energy comes from the hydrogen. Some of this energy is contained in steam created when the hydrogen in the fuel reacts with oxygen in the combustion air. In a conventional boiler with a 200C stack temperature this 2% steam energy is lost up the stack such that only about 13% is useful. In a condensing system the entire 15% can be utilized. The amount of hydrogen in a fuel determines the difference between HHV and LHV. Torrefied wood has lower hydrogen content by mass and therefore has a smaller difference between HHV (gross calorific value) and LHV (net calorific value).

Oxygen 43% mass, (0% GJ)

Drying (energy needed for drying wood)

Oxygen makes up about 50% of the mass of dry wood but contributes no energy content. During torrefaction, heating under anoxic conditions results in partial oxidation of hydrogen and carbon in the form of CO and CO2. Because oxygen molecules weigh more than carbon and hydrogen the relative mass of oxygen decreases and the energy density of the material increases.

Energy Lost Evaporating H20 Before energy can be extracted from wood the water must be evaporated and this reduces the amount of energy available for beneficial use. While the theoretical energy required is about 640 kWh per tonne of water, the actual value can be 2x higher depending upon dryer or boiler efficiency. This energy loss is not reflected in laboratory analyses as it is affected by the appliance the water is evaporated in. For dry wood this can be as little as 8% (boiler) and as much as 30% (dryer) of energy lost to remove the water. At about 85% moisture content, the energy required to evaporate water is about 1 kWh but the energy in the remaining 20% wood is also only 1 MWh so no net energy can be obtained despite lab analyses that would show the net calorific value as 1 MWh/tonne.

21Gj Light Torrefaction Line In light torrefaction the amount of energy liberated regardless of technology is sufficient to drive the torrefaction reaction and may also be sufficient to completely remove the moisture from 30% wet feedstock. The increase in energy density results from the greater loss of mass (20%) relative to energy (10%). At this level the material is a medium brown.

24Gj CEG Torrefaction Line At about 24 Gj, enough energy is liberated to torrefy the material and evaporate all of the moisture from 50% wet wood. At this energy level the material is a very dark brown bordering on black and is very brittle.

30Gj Charcoal Yield Line

As you remove most of the oxygen the amount of volatiles in the wood is diminished, the material becomes jet black and more of the carbon is present as fixed carbon. Energy density is maximized and adiabatic flame temperature is highest. In theory all hydrogen and oxygen could be completely removed but this is only necessary for very specific end use applications

What is Torrefaction?

Plugging into the massive potential of biomass.

Co-firing

So, what is Biomass?

Plugging into the massive potential of biomass.

What is Torrefaction?

Plugging into the massive potential of biomass.

Key Pellet Information

How torrefaction works

CEG's unique torrefaction process converts biomass into biocoal and biochar products, utilizing our proprietary torrefaction reactor