2013年10月28日 星期一

Post 5 : Biomass Energy

Biomass Energy

1. Definition of biomass

      According to a website, biomass is "organic matter (such as wood, crops, and waste) that is used as a fuel souce."(#1) For instance, burning wood for cooking is a way to use biomass. Nowadays, there are many ways to take advantage of biomass, and these methods can be classified into three groups.  They are biofuel, biopower and bioproduct. I will give you each group an example in the third section of this article.

2. The advantage of using biomass energy

        We might be confused that why people call biomass as a kind of green energy while burning biomass (such as wood) dose cause the emission of carbon dioxide. In fact, we won't increase the amount of CO2 in the air by using biomass as a source of energy! You can get this idea from the picture below.



 

 

3. Example of applications of biomass

1. biofuel : "Right now, the most common biofuel is ethanol and most ethanol is made from corn grain or sugar cane. But ethanol also can be made from the cellulose, plant stalks, grass, poplar trees, willow trees, corn cobs, and other woody plant parts."(#2)
 
 
2. biopower : This video will explain how biopower is transfered into electricity.
 
 
3. bioproduct : "Bio logs consists of 100% coir Fiber webs cross lapped or air layed , followed by needle punching or stitch bonding. The substrate is rolled into desired dimensions. Bio logs promote plant growth and microbial activity." (#3)
 


 
 reference:
                     

 

 

 



2013年10月23日 星期三

Post 4: Geothermal energy

Geothermal energy

1. Iceland

     Before we move onto our topic, geothermal energy, I would like to introduce a country depending a lot on this kind of energy, Iceland. We can find out that some 66 percent of energy of Iceland comes from geothermal energy! People on Iceland make good use of this underground energy. Geothermal energy is not only used to generate electricity, it is also the resource of hot springs, a gift given by God for people on Iceland. Interestingly, there is a restaurant on Iceland where food is cooked by the steam generated by the underground heat.
 
 
                                                                              pic. 1

                                                                       pic. 2

A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapour phase (steam).   #1


2. Geothermal power plant

     The picture below shows how geothermal power plant functions simply. Although geothermal power plants produce little amount of greenhouse gas, it dosen't mean that it is completely friendly to earth. The steam is composed of hot water vapor, carbon dioxide, hydrogen and hydrogen sulfide(toxic). Separating hydrogen sulfide from the steam can be a costly procedure.You can take a look at how people on Iceland are trying to deal with this problem in the video.
 


                      pic. 2:  http://en.wikipedia.org/wiki/Geyser
                           #1: http://en.wikipedia.org/wiki/Geyser
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

















2013年10月14日 星期一

Post 3 : Wind power

Wind power

1. Windmill

     I guess that we are all familiar with windmills. You might make yourself a toy windmill in your kindergarden art class, or watched it on a very famous cartoon, "Teletubbies(天線寶寶)" . However, windmills are essential tools for whole human race now. They now transfer wind power into electricity we need! In my opinion, windmills are such beautiful tools because of their simple design . What's more, every time I think of windmills rotating elegantly in the winds, I wish that I can be one of them.
        


                            pic.1
                                                                                         pic.2
 
 

 
 

 
video 1

 

 
 

2. Wind power

     According to a data, "in 2011/9 electricity generated by wind power plants aroud the world reached 200 million kW!!!! Besides, wind power are now growing at an incredible pace. If it keeps growing, there will be 12% of electrity provided by wind power in 2020."(#1) Let's take a look at some factors making wind power grow so fast recently. 
(1) It's cheap
 
(2) It can not be used up, or say it's sustainable.
 
(3) It is accessible in many regions.
 
    We now konw that wind power plants transfer the energy of wind into electricity, but a question may flash into our mind immediately, 'How dose it work?' Let me explain it briefly for you. There are two kinds of forces that make windmills rotate, drag force(阻力) and lift force(升力). In pic.3 the drag force acting on wing A is bigger than that of wing B, so the windmills will rotate clockwise. In pic.4 there are two winds flow through the wing, the speed of A is higher than the speed of B. By Bernoulli's principle(白努力定律) the pressure below the wing is bigger than the pressure beneath the wing. Thus, a lift force is generated by this difference of pressure, and its direction is up. Finally this lift force makes the windmill rotate clockwise.

 
pic. 3

    pic.4
     
     
     
     
     
     
     
     
     
     
     
     
     
     



    reference:
    #1 : 瑞昇文化 <用再生能源打造非核家園> p70
     

     
       


       
       
       
       
       
       
       
      

         
     

    2013年10月7日 星期一

    Post2: Wave power

    Wave power and Tidal power

    1. How waves are formed?

         There are many ways to make waves, but I would like to introduced only one of them here. One way is related to the flow of air,or we call it "wind". When wind flows beyond the surface of sea, the upper layer of sea water is moved by the wind, and then the waves spread along the direction at which the wind flows.(picture 1) If these words is too abstract to understand, let me show you a image. Consider a cup of tea on your desk, when you blow your tea to cool it down, you will notice there are some little wimples in the cup. This situation is similar to the form of waves I just mentioned.
        Actually, most of the waves paticipating in wave power generation is constructed through the way I mentioned in the first paragraph.
     (If you want to know how waves actually are formed, then you can take a look at http://library.thinkquest.org/03oct/01428/waves1en.html)
     
                                                     picture 1
     

    2. Wave power plants

         Wave power plants transform the kinectic or the work done by the gravitational force into other forms of energy. Next, the energy will make the generator run and then generates electricity. The pictures below are example of wave power plants. Although they might be different to each other, they all function by a commom princinple.  
     

                                            waves             generator       electricity

     picture 2


     
     
     
     We can find out that this kind of worm-like
     wave power generator is quite big.
     
     
     
     
     
     
                            picture 3
     
     

    picture 4

     Isn't it a cool design which uses waves to set pumps into action?




                                        This video introduces another kind of wave energy plant.




     3. Where does waves power come from?

          The answer to this question is sun. When the atmosphere is heated up by sun, some part of air is hotter than other part of air. Since hot air has a lower density than cool air, air starts to flow. The flow of air is wind, and wind causes waves. Thus, the source of wave power is our mighty sun!!!




    Reference: pic.1    http://www.ne.t.kyoto-u.ac.jp/ja/research/introduction/laboratory/n_energy
                      pic.2    http://environment.nationalgeographic.com/environment/sustainable-earth/11-of-the-fastest-growing-green-jobs
                      pic.3    http://www.windprospect.com/technologies?t=wave_pelamis
                      pic.4    http://www.lamtengchoy.com/main/?item-ppr-wave-energy/show/75/
                      video   Functionality of wave power station developed by Voith Hydro (www.voith.com). Animation produced by Kral GmbH (www.kralgmbh.at).


    

    2013年10月2日 星期三

    post1: What is green power?

    1.  What is green power?
     

    1.      three indispensable features of power

    a.      can be provided constantly

    b.     be harmless to the environment
     
    c.      cheap

         green power is a kind of power which features environmentally-friendly
     
    2.      Green powers are natural energetic processes that can be harnessed with little pollution. Besides, most of these energetic processes come from sun.
                         (picture 1)
     
    you will know how sun provides these natural energetic processes with energy in following topics!!
     
     
     
    3.      economic benefits: the major problem of green power

     
     In the table below, we can easily find out that green energy is much more expensive compared to Fossil-fuel power station. Even though everybody know green energy is harmless to the enviornment, when it comes to the costs of green energy, few people are willing to invest their money in it.

     

                      (picture 2)

     

    2. Why green energy is so important ?

     
          Nowadays, we can hear lots of people talking about green energy and some developed countries are trying to develop green energy. It seems that green energy is getting more and more essential. I think there are two reasons that can explain this phenomenon.
                       
     
         One reason is related to the environment, and the other one comes from power. First of all, since Industrial Evolution, the emission of carbon dioxide has accummulated to an incredible amount. Some climate scientists pointed out we human being might be responsible for the climate changes associated with gloabal warming. One of the most horrible things caused by global warming is the rise of sea level. Around 23% of the worlds’ population lives in the near coastal zone with population densities about three times higher than the global average. The most recent IPCC assessment based on the most gloomy scenario puts predictions of 21st century sea level rise at between 26 and 59cm (10-23 inches). (#1)  Obviously, if we keep using fossil fuel instead of green energy, our lives will be threatened. Here is a vedio about the simulation of some place in the U.S. when sea level rises.
     video 1
     
     
    The other reason is related to energy. Actually, all forms of energy on earth come from sun. In other words, as long as sun keeps burning, we won't run out of energy. Unfortunately, the main fuel we use, fossil fuel, need thousands of years(or even longer) to store energy of sun. Shortly after, we will  exhaust all fossil fuel, and it will absolutely be a crisis. Thus, finding ways to take advantages of renewable energy or green energy is a big task for us. Let this video remind us that we must develop green energy as fast as we can.
         video 2
     
     
     
    Reference
     
    picture 2 :  用再生能源打造非核家園    瑞昇文化  p13
    video 1 : https://www.youtube.com/watch?v=N13oAcUITAM
    video 2 : https://www.youtube.com/watch?v=dI4-t7ujgyg