Monday, November 10, 2008

Torrefaction of Biomass: Useful Bio-energy Densification Strategy Growing Slow and Sure

Torrefied biomass:

* has a much higher energy density than raw biomass
* it allows for a dramatic increase in the distance over which the biomass can be transported to the plant (some studies show distances can be squared)
* because torrefied biomass is hydrophobic, it can be stored in the open, for long times, in the same infrastructures as those used for coal
* it requires less energy to crush, grind or pulverise torrefied biomass than it takes to crush coal, and the same tools can be used
* given its excellent combustion properties, the fuel can be readily co-fired with coal
Torrefaction of biomass takes place at temperatures of 200 to 300 degrees C, with little or no oxygen. 90% of the energy is retained, while eliminating roughly 20% of mass, including moisture. Torrefied biomass can be co-fired with coal in unmodified coal plants.

At this time only one biomass torrefaction plant is active on the planet Earth. A new plant is on the boards for North Carolina, with 10 other US torrefaction plants at various stages of planning.
During torrefaction the molecular structure of the wood is altered, enhancing some of the wood’s physical properties. Torrefaction liberates water and releases volatile organic compounds (VOC) through the devolitization of primarily the hemicelluloses and extractants. The lignins are loosened and have limited devolitization while the cellulose is nearly unimpacted at these temperatures. As the hemicellulose, which binds the cellulose, is burned away, the wood is unbound making it more brittle. This increases the grindability of torrefied wood and makes its handling properties more like coal. This unbinding also releases the last of the water not stored at the cell level, leaving the wood hydrophobic. During the torrefaction process most of the energy value of the wood is preserved with the product losing 20-30% of its mass while retaining 90% of its energy. The calorific value of the wood increases to 9,500-11,500 Btu per pound.

So far, there is only one commercial torrefaction plant operating in the world, located in the Netherlands. It supplies torrefied biomass pellets to large coal-fired power plants, who get a green credit for each ton of biomass they burn. Integro Earthfuels is now planning to open a similar plant in Roxboro County, North Carolina. The $12 million plant will have an initial capacity to produce up to 84,000 tons of torrefied biomass annually:

Currently, Integro is finalizing off-take agreements with local utilities and Universities with their own heat and power plants to provide them with a majority of the supply beginning in 2009. Integro will build 10 additional facilities over the next 6 years to meet the demand from coal-fired electricity producers.
The logic behind biomass torrefaction is quite sound. If the moronic Democratic Party controlled congress along with an eternally posturing Obama administration could get over their distaste for large-scale energy, perhaps they would drop the carbon hysteria that they have allowed to paralyse US energy production. The best thing for the fatuous morons would be to simply GET OUT OF THE WAY!

Oynklent Green is keeping tabs.



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