Biogas Stoves: How do they work?

This image of a biogas stove was provided by http://news.co.cr/a-well-grounded-young-tico-marcos-vinicio-lopez/3237/. 

To begin explaining biogas stoves, it is probably useful to first think about what "biogas" is? Biogas is essentially another word for a gas mixture that is predominantly made up of methane (CH4) and carbon dioxide (CO2). It is created as a byproduct when organic material decomposes in anaerobic conditions.  When the decomposition process occurs in an enclosed environment it can be captured and used as a natural fuel source. Biogas production for any scale requires a digester and a gas storage tank (depicted below). The digester holds the organic waste and water mixture, called slurry, that slowly decomposes to form biogas. The biogas rises into the storage tank and stays there until is needed.

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This image of a biogas digester and fuel unit was provided by http://puxinbiogas.en.alibaba.com/product/320459746-214346657/New_style_biogas_digester_plant.html.

Biogas has not been successful marketed on a large scale yet, but there have been many accounts of successful biogas usage in smaller projects. Several grassroots and nonprofit organizations (such as Heifer International and it's partners), have in recent years started biogas fueled stove projects to allow people in impoverished communities to have a sustainable way to cook their food and heat their homes. For people in these communities, biogas is a much cleaner alternative fuel source. It burns with minimal CO2 output and uses products that are readily available. Many of these communities use wood as a fuel source for their homes, but the demand for wood is often higher than the supply which causes deforestation in those areas. Wood smoke in homes has also been known to cause health problems for the inhabitants and anyway to eliminate health complications in countries where health care is not necessarily available is beneficial.

There are a host of possibilities that biogas fuel could offer the world as a renewable energy source. Biogas could become a fuel alternative in homes around the world. People could work to make it more feasible to produce biogas on a large scale and provide it as an energy source if people are not interested in installing the systems in their homes. If it spreads far and wide enough it could significantly reduce deforestation and all of the environmental problems that come with it. It is interesting to contemplate, even if it might not be entirely feasible.

Sources and Links:

1) Brief Overview of Biogas Production: http://www.wisegeek.com/what-is-biogas-production.htm

2) Heifer International: http://www.heifer.org/blog/tag/biogas

**I give my sincerest apologize for my two month hiatus, but as of this post, I hope to begin weekly posts once again.

Soil: A Brief Overview

This image was provided by http://www.cityfarmer.info/category/soil/.

Have you ever scooped up a handful of dirt from your backyard and wondered how it got there? If you said yes, this is the blurb for you. That dirt in your backyard is likely some variation on your region's local soil. Soil is the material at the surface of our planet that helps give nutrition to many types of biota (e.g. plants, insects, microbes, and animals).

Many of you may now be asking yourselves: What is soil really? The technical definition of soil is porous material created at the land surface by weathering processes derived from biological, geological, and hydrological phenomena (e.g. precipitation, erosion, decay, etc). The term soil does not refer to weathered rock, but specifically refers to material that shows vertical stratification (or the layers of buildup that occurs as soil forms) and has been produced by the continual influence of percolating water and living organisms.

One of your next questions might be what is in soil? This is a deceptively simple question. First it is important to know that soil is composed of three types of sediments: 1) sands, 2) silts, and 3) clays. The main physical difference between each of these types of sediments is the size of the grains. According to the Wentworth grain size chart, sands have the largest grains with a range of  2.0 mm  to .074 mm in diameter. Silts are the second largest in terms of its grain size and they range between .074 mm to .004 mm in diameter. Clays have the smallest grain sizes and they range from .004 mm to .001 mm. The individual grains of silts and clays can be so small that they are hard to see with the naked eye.  The second thing you need to know is that the composition of soil varies depending upon the parent material (or the type of rock that the sediments in the soil came from). Different parent material results in different types of soil. Rocks that are rich in clay rich minerals create clay rich soil. Rocks that are rich in sand sediments create sand rich soil, and on it goes. It is one of the reasons that different areas of our country are better suited for different types of plant life and agriculture techniques.

The last really essential thing you need to know about soil is how it varies with depth. Soil types differ with depth in the same way that different types of ocean life vary with depth. This variation with depth is referred to in different layers which most people refer to as horizons. Each horizon has a slightly different composition and is the location for different types of water and soil interactions. I have included a soil horizon diagram below to help you get a sense of how soil horizons change with depth.

This image was provided by http://pdsblogs.org/2011pdsapes8/2011/02/15/soil-and-agriculture/.

Sources and Links:

1.  WENTWORTH CHART: http://woodshole.er.usgs.gov/pubs/of2007-1191/html/fig11.html

**Much of my studies in college revolved around the study of sediments. This particular topic is one of great interest to me, so I hope you enjoy.

Lightening Part 2: Man-Made Lightening

I recently came back from a trip to Boston where I had the wonderful fortune to stumble upon the Museum of Science and it's indoor Lightening show. If your ever in the Boston area, it is definitely worth checking out.



This one of the exciting machines used during the Museum of Science's Lightening Shows. Image provided by the Museum's Theater of Electricity.

The really neat thing about the Museum of Science's Lightening show was all of the equipment in the Theater of Electricity. There was the Van der Graaff generator, several tesla coils of varying sizes, and a specially modified tesla coil contraption that can change the sound that lightening makes. It was a very well equipped set-up. Perfect for creating a man-made indoor lightening storm.

During the presentation, I learned two pretty interesting factoids about lightening that I did not know before:

1. Rubber Tires Do Not Keep You Safe In A Lightening Storm - Instead, it is the car's metal exterior that keeps passengers safe during a lightening storm. Now I know that seems counter intuitive, but just hear me out. Air like rubber is not a conductive material,but lightening has no trouble breaking through hundreds of yards of air to reach its final destination on the surface of the Earth. Which means that rubber tires are not going to be much protection in the event of a lightening strike. This is were the car's metal exterior comes in. Metal is in contrast to rubber and air, a very good conductor of electricity. In fact it is much more conductive than a human being ever could be. So when given a choice between the two a highly charged lightening bolt is going to want to go through metal rather than the human being. The reason that the lightening does not affect the passengers of a car is that the charge of the lightening passes through the exterior frame of the vehicle which is conductive enough to handle the high voltage of the strike and provides the best pathways to the ground. 
2. The Frequency Of Lightening Can Be Changed To Produce Different Sounds - It sounds kind of out there but the Museum of Science has a machine in their Theater of Electricity that can change the frequency of the sound that lightening makes. This allows the machine to produce a whole range of different sounds that can even be put together into a tune. Don't believe me? Check out the Lightening Show link.

I already had a basic understanding of how lightening storms worked, but it was really interesting to see what scientists had been doing with the information.


Sources and Links:

1.  Museum of Science: http://www.mos.org/exhibits_shows/live_presentations&d=194
2.  Lightening Show: http://www.youtube.com/watch?v=Ou47oQdSKho&feature=related
3.  My Previous Blurb About Lightening: http://blurbsaboutscience.tumblr.com/post/28998696197/lightening-and-thunder-storms

Curiosity Rover: Our Lastest Steps on Mars

The past few months have proved to be a time of enormous scientific accomplishment. Not only have the atomic physicists come to find the fist piece of hard evidence to support the Higgs boson theories, but NASA's planetary scientists have successfully landed another rover onto the surface of Mars.

The image above depicts the Mars Curiosity Rover before it was sent into space nine months previously. Image provided by NASA.

As many of you may already be aware, NASA’s Curiosity Rover, landed on the surface of the planet on August 6th, 2012 after an approximate 8 month journey through space. It landed in Aeolis Palus in Gale Crater on Mars’ surface. The approximate landing site can be seen on the Google Mars website (link provided below). For those of you who are unfamiliar with Google Mars, it is a map program very similar to Google Earth that provides information about the topography and geography of Mars' suface. It was created from satelite imagery accumulated from several past and current Mars missions. It is not yet as complex as Google Earth, but it does give the viewer a pretty good idea of Mars topography.

Like many past Mars missions such as the Mars Pathfinder, Mars Global Surveyor, Phoenix Lander, and several others, the Curiosity Rover was designed to record images of the planet and carry out several important experiments that will allow scientists back home to learn more about the red planet. In particular, Curiosity is tasked to collect rock and soil samples using on board equipment, process and distribute the samples to the appropriate test chambers and/or analytic chamber and use the samples collected to look for evidence of microbial life.

The mission is designed to have a power supply that should allow for a full Mars’ year of exploration (687 Earth days). The Curiosity rover holds the ultimate scientific payload in that it holds several billion dollars worth of scientific equipment which includes such instruments as:

1. Mars Hands Lens Imager- a camera mounted on the arm of the rover that allows for extreme close ups shots of rocks and soil.
2. ChemCam - an instrument that can send laser pulses that vaporize thin layers of material or soil targets. It includes a spectrometer to identify the atoms that are excited by the laser
3. Radiation Assessment Detector - an instrument that will characterize the radiation environment on the surface of Mars.

These are just a few of the many instruments that the rover is equipped with, for more information about the instruments check out the NASA Fact sheet (link below).

 If the Curiosity Rover were to discover microbial life on Mars, it would mean that Mars had at one point in its planetary history sustained life. This could also hold the potential for future life on Mars as well. So far though, no previous Mars missions have found any solid evidence to support the idea that microbial life is currently or once was on Mars. For now though, scientists can only wait and see what the rover will discover in its nearly two year journey on the surface of the red planet.

Sources and Links:

1. Google Mars Link: http://www.google.com/mars/#lat=5.090944&lon=148.359375&q=Gale Crater
2. NASA: http://www.nasa.gov/mission_pages/msl/index.html
3. NASA Fact Sheet: http://www.jpl.nasa.gov/news/fact_sheets/mars-science-laboratory.pdf