Search This Blog

Wednesday, May 4, 2011

Self - Evaluation #3

After completing the third evaluation period for this blog project I feel that my performance has improved.  For the first time I feel that I have covered a wide range of topics within the waste to energy field, in a more interesting way.  I tried to tie together technologies in the waste to energy field with everyday experiences that people may have.  Including beer!  The one area I feel that my blog has suffered is in the publicizing area.  I have had minimal comments, especially from those other than the Prof. Schneider.  I do realize that most students have just enough time to write their own posts, let alone read others and comment.  I feel that I could have improved my blog by letting others know of my blog who are not in the class.  I have produced 15 posts this period and feel that a wide range of topics were covered in different ways.  I have slacked on commenting on others blogs, but have done well responding to comments I get on my blog.  The use of different media formats have been effective throughout my blog.

Overall I feel that this blog project has been effective in changing/improving my communication abilities.  I feel that I have made the transition from producing bland deficit model posts to more interesting and practical posts.  Although I would have never decided to create a blog on my own, I feel that this has made me a better communicator and I have enjoyed the experience.

Goodbye to school, this class, and this blog

If there are any avid readers out there that have followed my blog, you will know that this blog was done as an assignment for my Science Communication class.  If you do fall into the category presented by the first sentence of this post, then why haven't you posted any comments.  Have you agreed with everything that I have said, or is the content so boring that you couldn't even make up a question to ask, or at least a good job or way to go! Anyways...  Although I would have never decided to create a blog on my own I have enjoyed the experience.  If this is the first post you have read on my blog, then I will give a quick recap of what the purpose of my blog was throughout the semester.

From the title of the blog it is clear that the blog has focussed on waste to energy technologies.  I have covered anaerobic digestion, gasification, and algae to energy as my main three technologies to focus on.  I have also mentioned some off the wall ideas that show that there are others who share my interest in the waste to energy field (capturing energy from falling waste water in drain pipes, using dog poop to light a park, etc.).  My main goal of this blog was to introduce the major technologies that currently exist.  If the public understands that wastes can used to create energy then popularity of these facilities might grow here in the United States as they have done in Europe.  Any energy source is a good source in my book.  While I feel that fossil fuel energy is one of the most important energy sources, especially domestic fossil fuels, any energy will help.  A lot of the time these waste to energy technologies can even be incorporated into the fossil fuel industry to make their process more efficient.

Another goal of this blog was to show that you don't have to be an engineer or scientist, or be able to have access to large amounts of money to be able to understand and build a waste to energy process.  In particularly, anaerobic digestion has been used all over the world in high poverty area to create a cheap energy source for locals.  Often times these digesters are even sized for individual households, where family member operate their own personal digester.  I have covered issues that arise when certain processes are being implemented, and even covered what to do with the wastes of the waste to energy processes.  YouTube has been a great source foe information on this blog and if you are interested in building just about anything, dealing with waste to energy or not, check out YouTube for helpful do-it-yourself videos.  If anyone does come to my blog and like something they read or have comments or questions don't hesitate to leave a comment, I will get an email notifying me!

New Belgium Brewery and there waste treatment

Although the partnership between New Belgium Brewing and Solix Biofuels did not work out in the end, New Belgium is still committed to reducing their wastes as much as possible.  And if they can make some energy out of their wastes then they will surely do it.  The video below gives an overview of the breweries waste water treatment plant that utilized anaerobic digestion.  The biogas they produce during this process is then used to power their combined heat and power unit.  Their combined heat and power unit does just what the name implies.  The biogas is combusted in an internal combustion engine that then powers an electrical generator.  The heat that is produced by the combustion of the biogas is also used to heat certain processes throughout the brewery.  Whats the only thing that is better than waste to energy? Beer!


Tuesday, May 3, 2011

Wastes of the wastes, Part 3

So we have covered several wastes of anaerobic digestion, and one waste of gasification.  How about the other major waste of gasification, fly ash.  Why is it considered fly ash? Because it literally flies away with the gas stream.  Fly ash produced in the gasification process can be harmful to humans if inhaled.  In order to protect the public this fly ash must be collected and used in a productive way.  First after the gasification process has converted nearly all of the solid material to gases, some solids are left over, the fly ash.  Because the fly ash is so light in weight it travels out of the reactor with the gas stream.  In order to separate the ask from the gas stream a cyclone is used.  A cyclone is a device that changes the path of the flowing gas so that is is spun, like the motion of a tornado.  This high velocity path that the gas/fly ash stream takes cause there to be centrifugal forces acting on the heavier object.  Centrifugal force can be though of as the force that holds water in a bucket when the bucket is swung over your head.  The fly ash in this case has the most centrifugal force acting on it and travels to the outside of the cyclone.  Here the fly ash is allowed to exit the cyclone to be collected.

What is there to do with the fly ash once it has been collected?  One typical way of utilizing this fly ash is to use it as a component of concrete.   The fly ash when added to concrete can increase both the strength and durability of the concrete.  This is not just a recent technology either.  The ancient Romans used materials that contained volcanic ash to build a lot of their aqueducts and monuments.  One reason these structures are still standing is due the increased strength and durability added to the concrete by the volcanic ash present.

Waste of the wastes, Part 2

Another waste of anaerobic digestion is hydrogen sulfide gas.  Hydrogen sulfide is also produced as a waste product in all types of gasification, as long as sulfur is present in the feedstocks used in the the process.  Hydrogen sulfide is very toxic and can be deadly in the parts per million range.  In order to produce a safe product from digestion or gasification the hydrogen sulfide must be removed.  Luckily numerous technologies exists to get rid of this harmful gas.  

One simple technique is to pass the sour gas (gas that has hydrogen sulfide in it) over iron shavings.  Iron reacts very quickly with hydrogen sulfide and removes a majority of the hydrogen sulfide from the gas.  The exiting clean gas is then considered sweet gas.  This process is known as a non regenerative process because the iron that reacts with the hydrogen sulfide becomes spent or useless after a certain amount of hydrogen sulfide has come into contact with it.  Other technologies follow this same type of process but use a different scavenger.  The scavenger, iron shavings in this case literally grab the hydrogen sulfide out of the passing gas and convert it into a non toxic form.  Other scavengers include iron oxides, and zinc oxides.  

A regenerative process that is typically used in the natural gas industry is an amine gas treating unit.  This process uses a mixture of water and amines (to be discussed later) to absorb the hydrogen sulfide from the passing sour gas stream.  The sweet gas is allowed to continue upward and on with processing while the water/amine/hydrogen sulfide solution falls and is regenerated.  Regeneration occurs when the temperature is increased and the pressure is dropped.  This can be described with a simple bottle of soda analogy.  When a bottle of soda is allowed to warm up and the cap is suddenly taken off (decreasing the pressure inside the bottle) a bunch of fizz is produced.  This fizz is simple carbon dioxide escaping from the liquid phase to the gas phase.  So back to amines.  Amines are simple compound that resembles ammonia.  Ammonia is a compound that contains one nitrogen atom bonded to three hydrogen atoms.  An amine is produced when at least one of these hydrogens bonded to the nitrogen is replaced with a larger hydrocarbon chain.  Amines have the great property of  being slightly basic.  When the hydrogen sulfide comes into contact with the water a slight acid is produced.  And when a acid and base come into contact they react.  A simple acid base reaction that may ring a bell is heartburn.  Acid from your stomach travels up your esophagus causing irritation.  Once you feel this pain you take some Tums.  Tums make this feeling go away (hopefully), because Tums are made up of basic compounds that react with the acid and neutralize it, or turn it into water.

Wastes of the wastes, Part 1

We have covered several different types of wastes to energy through this blog, but what about the wastes that are produced from these processes.  For anaerobic digestion there are several main waste streams that much be handled correctly in order for the process to have minimal effects on the environment.  As mentioned before, there is a large amount of wet sludge that is left over from anaerobic digestion.  This wet sludge has had all of the volatile (vapor acting) molecules removed, which is the known as the biogas.  Although most of the solids in this process are digested and converted to methane and carbon dioxide there are some left over solids and water that make up the wet sludge.  Typically the wet sludge contains about 6% solids by weight.  Meaning that if the water and solids were to be separated from each other than the weight of the solids would be 6% of the total weight of the wet sludge.  While this wet sludge isn't particularly harmful or polluting it must be disposed of used in a certain way.  Most commonly the wet sludge is give to farmers so that they can apply this digested material to their crop land as fertilizer.  Remember cow manure, the feedstock to the anaerobic digester, is also a reliable and effective fertilizer used by farmers around the world.  There have been studies showing that not only does the application of wet sludge to field not stink as bad as fresh manure but that it is also better for the environment.  This is due to the fact that when fresh manure is applied to the fields the volatile compounds contained within the manure are released to the atmosphere. These compounds being methane, ammonia, and carbon dioxide. 

Another typical way of handling the wet sludge produced from anaerobic digestion is composting.  The wet sludge is dried and allowed to rest while the left over naturally occurring microorganisms continue to degrade the left over solids.  This compost can be used just as any other compost would be used.  The dried solids from the wet sludge have also been recycled and used as bedding for livestock.  The pictures below show the two different ways of applying both fresh manure and wet sludge to crop land.  

Liquid application of left over wet sludge from anaerobic digestion.

Fresh manure application.

Sunday, May 1, 2011

Solix Biofuels Update

My last post was based on a article that was published in 2007, so I wanted to find some updates on the project and see where things were at here in 2011.  After searching both New Belgium's and Solix Biofuel's websites it appears that Solix has decided to implement its technolgy else where.  After reading a post on New Belgium's blog, investors thought that it would be a better investment to implement a demonstration plant near a coal bed methane plant where more carbon dioxide is available and on a more reliable basis.  The demonstational plant is known as the Coyote Gulch Plant and is located in Durango, CO.  The waste water streams from the coal bed methane plant are utilized as well as carbon dioxide from a amine gas scrubbing plant nearby.  The amine gas scrubbing plant cleans raw natural gas streams. Raw natural gas can contain large amount of carbon dioxide and must be removed from the natural gas.  Carbon dioxide is considered an acid gas and when mixed with water can produce carbonic acid.  After the carbon dioxide is absorbed by the amine solution in an amine scrubbing unit the amine solution that is rich in carbon dioxide can be regenerated by both heating and reducing the pressure of the amine solution.  This is analogous to opening a bottle of soda.  Carbon dioxide is used to carbonate the soda and as many of you know that when soda gets hot and you take the lid off large amounts of fizz is produced.  This is because the carbon dioxide in the soda wants to escape and does so when the cap is opened or when the pressure is dropped.  So overall an amine scrubbing plant takes the carbon dioxide from the natural gas stream and moves it to an amine solution stream, and finally the carbon dioxide is released from the amine solution.  Where the carbon dioxide can be utilized, like it is here at the Coyote Gulch Plant,  it is fed into the algae bio reactors and used by the algae to grow and produce oils.