October 24, 2005

More Gasifier & IGCC Information

I ran across these links to presentations on gasifiers and IGCC, which I hadn't seen before and found them informative.  Eventually some of the info will be incorporated into a revision of the "About Gasifier" and "About IGCC" posts, but for now you will have to peruse them by yourself if you have any interest.  They were all found on a search for "Rocketdyne Gasifier" although they have much more information.  They are all quite recent, so all the better.

An outline of the content of each presentation follows:

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April 16, 2005

Technical Note: Sequestration

Sequestration, the capture and storage of carbon dioxide, CO2, and other greenhouse gases, is necessary to control the concentrations of greenhouse gases, that unless controlled will, according to most engineers and scientists, lead to global warming.  CO2 constitutes 81% of green house gases, followed with methane which represents another 9%.  When any fossil fuel is burned this results in production of CO2.  Since 86% of our energy comes from fossil fuels they release such large quantities of CO2 without imposition of controls, that global warming is inevitable. The concentration of CO2 in our atmosphere has increased dramatically since the start of the industrial revolution, increasing its concentration to 380 ppm in 2004, accompanied by a corresponding increase in the temperature of the atmosphere. By 2020 our energy requirements are forecast to increase by 40% and 86% of the energy will still come from fossil fuels, increasing CO2 concentration to even more dangerous levels.    The exact point at which global warming will become excessive is not known, but it according to one report, when the atmospheric temperature is increased by another 2oC (3.6oF) and the CO2 level reaches 400 ppm we will have reached conditions of unacceptable global warming.

About 40% of our energy comes from coal, oil and gas each supply 24% and the other 12% is split between nuclear and renewables.  Electrical generation contributes 39% of the CO2, transportation 32% and other sectors 30%. 

Carbon can be reduced by using more renewable and nuclear energy, improvements in efficiency or by sequestration.  Sequestration can be accomplished by storing CO2 in underground reservoirs, in trees, plants or algae, converting it to soil materials or dissolved it in deep oceans.

The above items are further elaborated in a presentation  by the National Energy Technological Laboratory (NETL)

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April 06, 2005

Technical Note: Gasification

Gasifiers convert carbonaceous feedstock (coal, wood, cornstalks, most any biomass) into gaseous products.  The process usually takes place at high temperatures and pressures and with a carefully controlled amount of oxygen.  The oxygen can come from air, pure oxygen or from steam. At operating conditions a chemical reaction occurs that converts the feedstock into a synthesis gas or "syngas".   The syngas is a mixture of predominately carbon monoxide (CO) and hydrogen (H2).  The amount of heat that can be recovered from burning syngas can be as much as 50% higher than direct combustion of the feedstock.

Gasifiers can divided into three general catagories:

  1. Moving Bed Gasifiers (dry ash)
  2. Fluidized Bed Gasifiers and
  3. Entrained Bed Gasifiers

Descriptions of several specific types and subtypes can be found at this NETL site.

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April 05, 2005

Technical Note: Fischer-Tropsch Process

The Fischer-Tropsch process often comes up in the discussion of new technologies for producing liquid fuels from solids or gases.  The Fischer-Tropsch process produces high value, clean-burning fuels.  FT fuels can be used in conventional engines with no modification and have improved combustion which reduces emissions, but may have a lower fuel economy.  The resulting fuels are colorless, odorless and low in toxicity.   FT fuels have less sulfur, nitrogen oxide, carbon monoxide and particulate matter emissions than petroleum fuels. 

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