Wednesday, December 17, 2008

Canadian Bio-Oil from Pyrolysis, Since 1989

Pyrolysis can take biomass and turn it into liquid pyrolysis oil -- bio-oil -- , gas, and biochar. It happens at high temperature in the absence of oxygen. Pyrolysis has been around for a while, but as the cost of procuring petro-oil grows greater, pyrolysis and other bioenergy approaches will become more important. The advantage of pyrolysis over gasification, is that pyrolysis oil can be stored, piped, shipped, and otherwise used at leisure. Gasification products must be used promptly to prevent degradation.
During the production of bio-oil, solid biomass wood is blasted into a tornado of hot sand at the bottom of a conversion unit. In less than two seconds the wood is vaporized. It is then condensed and recovered as a liquid bio-oil.

Seventy-five percent of the solid wood biomass injected into the RTP system is transformed into high yields of espresso-like bio-oil. The liquid wood is not a tar. It is a pourable fluid, which Ensyn treats as its own version of crude oil, and is used as a resource to make other products, such as high value biochemicals, in the same way petroleum crude is used in a variety of applications.

The remaining 25 percent of the biomass is converted into non-condensable gas and charcoal. These byproducts are fed back into a reheater in order to keep the tornado of sand at the required processing temperature. More energy is in the gas and char than required to drive this process, so the reheater has a surplus of energy. Ensyn uses this surplus to dry the wet biomass that arrives at the facility and to supply other industrial heat requirements.

Since 1989, Ensyn’s RTP plants have been making liquid bio-oil from solid wood biomass through a patented fast pyrolysis thermal process. Liquid bio-oil can replace heating fuel, natural gas and coal in a vast array of boiler applications. The company produces renewable energy in the form of a liquid fuel as opposed to a gas or solid fuel, which enables what is known as “decoupling.” With decoupling, production can be separated by time and space from the actual use of the product. _Bioenergy
Pyrolysis will be an important method in the bioenergy industry. Providing sufficient feedstock for bioenergy production will be a challenge that will have to be faced over the next decade or two.

Speaking of bioenergy, the Johnny Walker distillery in Scotland is raising $100 million to add a biomass CHP plant to provide most of its own electricity and steam from the distillery's effluent. The project illustrates a growing trend toward producing useful energy from what was formerly considered bothersome garbage.

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Blogger Engineer-Poet said...

Gasification products do not degrade, they are just too bulky to store and too energy-poor (~300 BTU/ft³ for both H2 and CO) to be worth piping very far.

Bio-oil does degrade over time, by polymerizing.  This increases its viscosity, among other things.

10:03 AM  
Blogger al fin said...

It takes pyrolysis oil a number of months to seriously degrade. It does not store well, but it can be transported.

Hydrogen gas is difficult to contain, and does not pipe nearly as well as hydrocarbon gases without significant leakage. The toxicity of carbon monoxide presents serious hazards for extensive handling.

It is important to give development of these resources the two decades generally called for, to deal with such problems.

1:37 AM  
Blogger Engineer-Poet said...

Leakage and toxicity are not degradation.  I would expect you to be more careful with your terminology.  Also, leakage issues have not prevented ~700 miles of hydrogen pipelines from operating in the USA.  Toxicity hasn't stopped ammonia pipelines, either.

Production of bio-oil loses about 30% of the energy of the original biomass (most of which is required to run the process), and there are additional losses in any further conversions.  Gasification has similar losses but the waste heat can be used for e.g. electrical generation.  The key point is that conversion to bio-oil can be used for "stranded" biomass resources, while gasification cannot.

Torrefaction is between.  It compacts and preserves the biomass while losing only about 10% of the energy.  Torrefaction may be a more useful process if the specific chemical products in bio-oil are not required.

3:19 PM  
Blogger al fin said...

Nexterra in BC has done some work on transporting syngas moderate distances from gasification plants to end users. They think syngas from biomass can replace most of the natural gas used at lime kilns and pulp mills in BC.

I expect most of the problems of safely transporting syngas -- with minimal degradation of materials the syngas contacts -- to be solved within 10 years. But it will take 20 years to gear up biomass production to significant levels, unless the narcissist - elect and his quasi-fascist cohorts get with it.

7:14 PM  

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