Solar cells are in fact large area semiconductor diodes. Due to photovoltaic effect energy of light (energy of photons) converts into electrical current. The term “photovoltaic” comes from the Greek φῶς (phōs) meaning “light”, and from “Volt”, the unit of electro-motive force, the volt, which in turn comes from the last name of the Italian physicist Alessandro Volta, inventor of the battery (electrochemical cell). The term “photo-voltaic” has been in use in English since 1849.

Solar cells produce electricity in three steps;

1. Photons in light hit the solar cells and are absorbed by semiconducting materials, such as silicon.
2. Electrons (negatively charged) are knocked loose from their atoms, causing an electric potential difference. Current starts flowing through the material to cancel the potential and this electricity is captured. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction.
3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.

 

In this lab, we discovered the relationship between a light source and solar cell. In two different experiments, we measured the voltage output of the solar cell. In the first experiment, using a flashlight and solar cell connected to the NXT in order to measure the voltage output, we placed the light source in different distances and measured the voltage output of the solar cell. It was noticeable that the further the light source the lesser the voltage output. In the second experiment, the distance of the light source was kept constant and we changed the light color using colored filters. Therefore, the voltage output varies because of changing the color of the light leads to changing in the energy of the photons according to the following formula:

E= hc/λ

Where E is the energy of the photon, h is Planck constant (6,626·10-34Js), λ is the wavelength, and c is the speed of light.

Experiment (1)

The main point of this experiment is to determine the relationship between the solar cell and the light source in terms of the distance. Basically, if the light source is placed far from the solar cell, the light intensity becomes smaller resulting in smaller voltage output.

Therefore, we can conclude that the voltage output is inversely proportional to the distance of the light source.

Experiment (2):

For this experiment, we had to figure out the relationship between the wavelength of light and its energy of the photons. As stated before by the equation, the energy of the photon (E) is inversely proportional to the wavelength. Therefore, light consisting of high energy photons (such as “blue” light) has a short wavelength. Light consisting of low energy photons (such as “red” light) has a long wavelength.

References

http://www.pvresources.com/introduction/solarcells.aspx

http://en.wikipedia.org/wiki/Solar_cell

http://www.pveducation.org/pvcdrom/properties-of-sunlight/energy-of-photon

our class went on a tour to the Sawyer library. We were introduced to several services at the library such as the circulation and reserve desk and the reference desk, which are very essential for a library to have. The three-floor Sawyer library has numerous study group rooms and the students are provided with computers and printers.The study group rooms can be reserved online 24 hours before the next day . Also, the rooms are limited so if your reservation time is over you need to leave the room immediately or you will be charge late fees for the lateness .

 

Circulation and reserve desk provides students the opportunity to borrow text books for 20 minutes at a time. Reference books can be borrowed and taken out of the library for a period of time. This desk is a huge source for students to get their questions answered regarding their study and search. Our tour guide from the reference desk demonstrated all the possible ways to search using the computers in the library. By entering a title or keyword of a book, report, or journals, we are able to find an enormous amount of information from the list of sources the university supplied. For instance, Library catalog option allows students to view all of Suffolk University library on the screen. Databases by subject is a gate to find any subjects or articles , which the library provides associated with EBSCO Host.

 

we were given robot parts to build according to the instruction in one class, and we had to make it moving backwards and forwards . In the next class, we continued working on the robot we built to perform certain tasks.  Lecture was given on distance, velocity, and acceleration. One of the most important tasks was to connect the robot to the PC and program it in order for it to perform. We measured the circumference of the wheel, which was 0.1760m, to determine how far it can travel in one complete rotation of the turn.  By programing the robot different numbers of power due a constant time, the results of rotation, number of wheel turns, velocity, and distance will change directly proportionally. The following table illustrates the relationship previously described.

 

Time= 1s

Circumference of the wheel= Pi* wheel diameter = 0.1760m

 

With time being constant at 1 second, velocity and distance are always equal according to the famous formula: velocity= distance/time.

Power	Rotation 1	Rotation 2	# Of wheel turns	Distance	Velocity
75	558	567	1.55	0.2728 m	0.2728 m/s
50	348	353	0.967	0.1701 m	0.1701 m/s
25	145	147	0.4026	0.0709 m	0.0709 m/s

 

 

 

All in all, although it was more of entertaining activity, it was very informative and encouraging in way that connects my preference in doing physical work with physics.Also, we got to know how to program the robot using some programing languages .

In class, Tom Vales introduced us to some amazing devices. Some of these devices were invented in the 18th century. The purpose behind some of them was mainly to generate electricity. It is really interesting for me to see how the development of making generators has become from the past up until the present. It is very crucial for every electrical engineering student to have knowledge about these various electrical inventions. 

A Tesla coil is an electrical resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high-voltage, low-current, high frequency alternating-current electricity. His invention of the alternating current motor set the stage for the power and lighting systems now used every day around the world.

here is a link that explain how it is works

https://www.youtube.com/results?search_query=tesla+coil+how+it+works

The propose of this lab was to explore Newton’s 2^nd Law , The law of conservation of energy, Velocity and acceleration and Power. We had to use the Lego Mindstorm motor in order to  lift weights with a pulley. Also, we used the below VI for this experiment .

 

 

First , we Explored Newton second law by keeping the power level fixed and changing the mass . Then we kept the mass fixed and change the power level.

When we kept the power level fixed and changed the mass we found that power level and acceleration are in direct relationship

power level	acceleration
75	28.352045
85	30.978509
95	33.274113
105	41.293876
115	47.209877

 

 

^After that when we kept the mass fixed and change the power level ,we found out that mass and acceleration are in inverse relationship

MASS	acceleration
0.25	28.352045
0.2	30.978509
0.18	33.274113
0.14	41.293876
0.12	47.209877

 

 

 

second , by Computing  we explored the law of Conservation of energy. By making the power fixed we plotted the battery discharge and the energy as a function of mass

potential	battery
0.59584	111
0.65856	120
0.784	125
0.72128	139

 

From that, we can see that the greater the masses , the greater is the battery discharge .

 

Finally , by using the formula

We calculated the average power used by the motor. Then , we plotted the power used as a function of the power level of the motor .

battery dis	power(mgh/t)
83	0.285922684
97	0.297646166
111	0.013516775
125	0.264884319
139	0.243911111

 

 

 

 

The MIT Nuclear Reactor Laboratory (MIT-NRL) is an interdepartmental center that operates a high performance 6 MW research reactors known as the MITR-II. It is the second largest university research reactor in the U.S. and the only one located on the campus of a major research university.

A nuclear reactor is a system that contains and controls sustained nuclear chain reactions. Reactors are used for generating electricity, moving aircraft carriers and submarines, producing medical isotopes for imaging and cancer treatment, and for conducting research.

What Are The Components of a Nuclear Reactor ?

1. Core  It’s the focal point of the reactor, where fuel is contained and nuclear fission reactions take place.
2. Fuel – Generally, fuel is made of small-enriched uranium oxide rods, stacked so as to form cylinders, approx. 4 meters long and with a diameter of about one centimetre. These rods are wrapped in metal sheathes (steel or zirconium alloy), which allow heat to pass through while blocking the radioactive elements produced by fission.
3. Moderator – This is a material placed in the reactor to slow down the neutrons produced by fission, in order to reach the most suitable speed allowing the chain reaction to continue.
   Depending on the various reactor models, the moderator may consist of graphite, water or heavy water
4. Heat-transfer fluid (or coolant) – This fluid cools the core and carries outside the heat that is produced there. The most commonly used fluid is water, but some types of reactors use different fluids .
5. Control rods – These are rods used in specific materials to control fission inside the core. Since they absorb neutrons, they are capable of controlling the chain reaction which – depending on how deep down the rods are inserted into the core – can be accelerated, slowed down or even stopped, thus changing the capacity of the reactor. Indeed, if necessary, the reactor can be immediately stopped when they are fully inserted.
6. Vessel – The large steel recipient containing the core, the control rods and the heat-transfer fluid.

What Is A Chain Reaction

The neutron-fission chain reaction: a neutron plus a fissionable atom causes a fission resulting in a larger number of neutrons than was consumed in the initial reaction.  Chemical reactions, where a product of a reaction is itself a reactive particle, which can cause more similar reactions. For example, every step of H2 + Cl2 chain reaction consumes one molecule of H2 or Cl2, one free radical H· or Cl· producing one HCl molecule and another free radical. Electron avalanche process: Collisions of free electrons in a strong electric field forming  new electrons to undergo the same process in successive cycles.

 

 

Faraday’s Law states that changing magnetic fluxes through coiled wires generate electricity. Also, The greater is the change in magnetic flux, the greater are the currents and voltages. In the lab that we had on Friday ,we had to prove that the faster we shake the tube, the greater will be the generated voltage. In order to do that, we used magnet that moves back and forth inside a coil of wire (generator), One voltage probe, One NXT adaptor, NXT, Labview VI and Excel sheet.

 

The generator _lab was reviewed by our instructor in order for us to understand how to use it to measure the voltage output of the generator. Our aim was to correlate the number of shakes of the generator, in a thirty second-time interval, with the squares sum of the voltage.

 

First we shake the tube at a particular speed. Then, the number of shakes was counted. Next, the sum of squares of the voltage was calculated by using Excel. After that, the previous steps were repeated five times at five different rates shakes. Finally, the SSQV’s was plotted as a function of the number of shakes and the result was fit to a linear curve.

 

For the first three attempts, the squares sum of the voltage was correlated to the number of shakes (0 , 130 ,95 ) .in the fourth attempt , the number of shakes (60) did not correlate to the squares sum of the voltage , it was bigger than the squares sum of the voltage of  (95) shakes . This unexpected result might happen because of some problems in the NXT adaptor, the voltage probe or the speed of the shake. It is not possible for a human to shake at the same speed for certain time.

0 shakes		130 shakes		95 shakes		60 shakes		42 shakes
0.19059		0.04946		0.20342		0.04946		0.10078
0.20342		0.26757		0.21625		5.91277		-1.10524
0.07512		-5.51876		1.4351		2.19207		0.08795
0.16493		0.07512		6.38748		0.06229		0.11361
0.08795		-5.53159		0.21625		0.06229		0.06229
0.11361		-5.32631		0.17776		-5.54442		0.08795
0.17776		0.07512		-0.4894		-5.53159		0.65247
0.20342		-0.06601		1.12718		3.96261		-5.53159
0.17776		-5.51876		0.06229		0.47285		0.08795
0.19059		0.06229		0.19059		0.12644		0.21625
0.06229		0.07512		0.11361		0.11361		0.07512
0.19059		0.44719		0.21625		0.22908		0.08795
0.21625		0.10078		0.12644		0.13927		0.10078
0.06229		0.13927		0.08795		0.11361		0.20342
0.08795		-0.82298		0.63964		0.17776		0.21625
0.10078		0.20342		6.41314		0.11361		0.1521
0.08795		1.21699		6.36182		0.19059		1.03737
0.07512		0.1521		0.33172		0.11361		0.10078
0.21625		0.21625		0.46002		-0.18148		6.47729
0.20342		0.65247		0.63964		-1.6441		0.08795
0.12644		-5.51876		0.16493		0.11361		0.60115
0.16493		6.38748		0.07512		0.12644		0.06229
0.10078		0.13927		0.20342		6.55427		0.33172
0.16493		6.47729		0.10078		-5.57008		0.19059
0.07512		-5.53159		0.21625		4.50147		0.1521
0.22908		0.0238		0.19059		0.29323		-0.72034
0.08795		0.10078		1.11435		1.96113		0.08795
0.20342		0.07512		0.11361		0.51134		0.20342
0.08795		0.12644		6.42597		0.20342		0.20342
0.11361		-0.33544		0.1521		0.25474		0.17776
0.69078105		266.8802397		170.1389959		218.5607137		4.60149

 

The mechanism of producing power used to be by burning something,but in nuclear energy was a new source of energy and a new way of generating heat. One bound of uranium which equivalent to the size of a finger, if they can release all the energy it has it will be equivalent to the energy of 5000 barrels of oil.
The problem with nuclear power is that  was used in the first place to make an atomic bomb, and that’s what gives it a negative image. There is a huge gap between fossil fuel and renewable energy. The problem with renewable energy like wind and solar power is that it is not always sunny or windy. So they must have natural gas as a backup. What we end up with renewable energy is the expansion of natural gas. In order to get the most from renewable energy like solar power, we need 3000 feet altitude, flat island and 360 of sun light. That  what makes these kind of energy sources limited.

In this blog, I would like to contribute something instead of writing a review about  Pandora’s Promise. I will be comparing the nuclear power and wind power from an economical side.

As  a general rule, the bigger the nuclear power reactor is, the more efficient it is and the more efficient any generator is, the cheaper electricity it produces. Nuclear reactors scale up very well, but because of efficiency and over head issues they do not easy scales down. Newer nuclear design helped with this problem. On another hand, nuclear will never be economical for small scale generations which make it more suitable for large areas that have large populations. The international agency estimated that the nuclear power  is leveled  generation cot are between 3 cents and 4.8 cents per kilowatt an hour. As compared to  3cents to 5 cents for wind. However, the contraction  cost for nuclear plants are about 90000 per kilowatt of capacity as compared to 15000 for coal and just 1000 for wind.In fact between 50 and 75 % of the generation  cost of nuclear plants are paying back the initial investment. The cost for nuclear plant is very front-loaded, most of the costs occur in the contraction that most occur before any single watt is being produced. This makes nuclear plants a riskier economic investment than coal or natural gas, but once the plant is  finished and producing electricity, nuclear has much less risk than it is for fossil  fuel and wind counter apart,because it is much less sensitive to rise in cost fuel and the threat of carbon.
Operation and maintenance are high for nuclear plants than wind at an annual 63 dollar per kilowatt of capacity as compared to 27 dollar per kilowatt for wind. If wind power is much cheaper than nuclear, in construction, cost, operation cost and fuel cost, why we don’t go with the wind instead of nuclear? Wind by it is nature is an intermit generator, the turbines will only generate power when the wind is blowing, and the blades are spinning. In USA, which has some of the best wind potential, wind turbines capacity factor only averaged in 33%. That  means if you have a generator that was rated at 300 watt and ran it for an hour in an ideal world you would produce 300 watt in hour of energy. This mean that the actual energy generated is 100% of the maximum capacity of generation. On average, a wind turbine rated at 300 watts only generate 100 watt hour of energy per hour. This is much lower than the capacity of nuclear capacity factor, which average over 90% in USA. This means in order to get the same amount of energy in the same amount of time, you need to install two to three times as wind capacity as would nuclear. That’s cancels  out the cost advantage that wind has over nuclear.  The nature of wind leads to another problem we can not control. When the wind is blowing, and we can not control when electricity demand will rise and fall. This leads to the issue when  the electricity generated by wind and can not immediately  used. So the extra electricity is just wasted. When there is more demand at  a given can be met by current wind speed there is no way to pick up this lack of electricity. The solution to this problem would be to store the generated energy and keep it  stored until the time of higher demand. There is no actual way to store large amount of energy yet. Also, large scale energy storage is too expensive and unconvinced to be an option for now.

 

sources :

http://www.world-nuclear.org/info/Economic-Aspects/Economics-of-Nuclear-Power/

Wind Energy Economics

http://theenergycollective.com/willem-post/310631/more-realistic-cost-wind-energy

 

 

 

Demand response mean that, people have a particular time when consumer are paid to shift or lower energy consumption. In certain time of the day, electricity is very expensive to produce, but at another time of the day it is cheap. So what demand response should do or contribute  is to tell or help people to shift from the expensive hours to the cheap hours. It is a pricing mechanism

How does work ?

To know it works, we need to know about demand response consumers to understand  how it will work. A consumer is anyone who uses electricity. For demand response, a consumer could be factory, a group of businesses like supermarket chain, an office building or a farm that uses irrigation.

Demand response consumers have one thing in common. They basically have some megawatts they can sell or rather they can manage or reduce the power usage for a period of time. Factories can offer demand response by changing their production shingle or by using a standing by generator.A group of supermarkets can do the same by switching their freezers off for an hour a time. Office building can demi light or adjust air conditioning  temperature with no noticeable impact on convert level. Farms can reduce water pressure in the irrigation system.

How consumers get involved in demand response ?

In order for consumers to get involved, they need to meet certain requirements. First, being in the right location .this mean being close the trans power.Second, having building management system which allow to control the demand. Third, being able to reduce the demand for 2-3 hours a day in winter and summer. Fourth, being able to measure and capture the data that are accessed and sent from the trans power. That’s mean to have a fuse  meter. Finally, being able to respond to any power call at any time.

 

sources

http://www.pge.com/en/mybusiness/save/energymanagement/index.page

http://www.pge.com/en/mybusiness/save/energymanagement/whatisdr/index.page

http://energy.gov/oe/technology-development/smart-grid/demand-response

http://science.howstuffworks.com/environmental/green-science/demand-response.htm

EPA , is proposal clean power plan to cut carbon pollution from power plants by 30 % , by the 2030 . If we look across the USA power sector , the proposal will boost the UAS economy , protect heath and environment and fight climate change .The US supply the electricity every day form coal , natural gas , hydropower ,nuclear ,wind and solar .

 

When fossil fuel like coal are burned to produce electricity , they release CO , which lead to trap the heat and this will lead to claimant change . According to EPA the best way to cut down carbon pollution  is to generate more power from the cleanest sources and use the energy  more efficiency . The EPA explained that each part in their system offer huge opportunities  to reduce the pollution that lead to claimant change . Also they expecting to make improvement at power plans , expand renewable energy production ,generate more of clean energy and increase energy efficiency .

 

Some Benefits That are Expected From This Proposal:

For every dollar invested in this plan there will be 7 dollar benefits and by 2030 there will be between 55 – 93 billon dollar of net claimant and heath benefits. The proposal is going to increase energy efficiency and clean energy investment. In fact one study has shown that there could be 274000 new jobs associated with this proposal.

 

EPA mentioned that the most immediate impact of this proposal is going to be improved health for many Americans. it is estimated that in the first year this proposal will prevent 100000 asthma attack because of reduced partial pollution , also it is estimated to reduce 2100 heart attack in it’s first year . They expect that 6600 premature heath will be avoided as a result of this proposal.

 

EPA estimated that in 2030 will be an 8 % decrease in the electricity bills. This is because there will be an increase in energy efficiency and the cost of employing clean energy will go down. EPA explained that one of the reasons that this proposal is so achievable is that it is NOT a top down approach. The proposal plan allowed states to chose what works for them, with the recognition that what works for Ohio may not be the best solution for Taxes and vice verse.

SOURCES

http://blog.epa.gov/epaconnect/2014/06/understanding-state-goals-under-the-clean-power-plan/

https://www.federalregister.gov/articles/2014/06/18/2014-13726/carbon-pollution-emission-guidelines-for-existing-stationary-sources-electric-utility-generating#h-43

http://ecowatch.com/2014/07/29/obama-clean-power-plant-rule/