Uncategorized – Jennifer Straka

Pandora’s Promise

Pandora’s Promise is a documentary covering the debate over nuclear power. It presents the aspects of both sides, pro and anti-nuclear and many of the pro-nuclear interviewees were at one time anti-nuclear. This provides an interesting perspective on how some very enthusiastic environmentalists publicly condemning nuclear power can now be very much so in support of nuclear power.

Overall the documentary presents a position in support of nuclear power and does so by “debunking” many of the myths associated with nuclear power. These myths mostly center around the danger nuclear power presents such as the history of nuclear accidents- Three Mile Island, Fukushima, Chernobyl… They addressed the fact that the death toll is thought to be very high, with some extremists (as shown in the documentary) when that is actually not the case at all. Nuclear power has one of the lowest amount of deaths in regards to energy types, an even lower position than solar energy.

I was not aware of the varying levels of background radiation that exists everywhere in varying quantities. Radiation is a naturally produced substance and it is different when one goes to different locations, such as being higher in high altitudes. Chernobyl had a lower amount of radiation than many other locations, so what does this mean? Many people who lived in the area before the accident have returned and, as far as they are aware, no one has suffered any deaths related to the radiation.

One of the most interesting parts of the documentary in my option was when the fine print of an anti-nuclear add was read and it turned out to be sponsored by the oil and gas industry. It is true that solar and wind energy at this point are not capable of making up for the energy production fossil fuels contribute, at least not today and maybe not ever.

The fact is that the world’s energy needs are continuing to grow, especially as third world countries develop. Electricity brings a higher quality of life to people and the people of developing countries are making strides in gaining access to electricity. As this energy demand grows, so does the strain on the environment as we use resources (fossil fuels) that produce emissions. Nuclear is a very clean producer of energy and it can reuse its fuel! The dangerous products that nuclear energy produces are very minimal and can safely be stored. New models of reactors can even use this stored material as fuel.

While I was in support of nuclear energy before this documentary, it did a clear and concise job of explaining many of the key issues people, including myself, associate with nuclear power- weapons, toxic material, safety… I feel it is very informative and addresses the issues in ways that the general public can understand. There are many misconceptions when it comes to nuclear energy and it is an interesting take having people who used to believe in those misconceptions take part in the explanation of why they are inaccurate.

Iceland’s Use of Geothermal Energy

Blog about Iceland’s use of geothermal energy for generating heat and electricity.

Iceland is largely made of porous basalt at the crack in Earth’s crust where the North American and Eurasian plates are pulling apart. There are enormous underground reservoirs of water that are continually renewed by levels of annual precipitation that range as high as 177 inches over Iceland’s glaciers, and shallow patches of magma that heat the deepest reaches of these reservoirs to temperatures in excess of 750 degrees Fahrenheit. The image below details Iceland’s use of their geothermal energy resources. The largest portion goes to space heating and the second largest percentage goes to electricity generation.

Generating Heat: There is no national grid in Iceland – harnessing the energy comes via the remarkably simple method of sticking a drill in the ground near one of the country’s 600 hot spring areas, and using the steam that is released to turn the turbines and pump up water that is then piped to nearby settlements. Geothermal water is used to heat around 90% of Iceland’s homes, and keeps pavements and car parks snow-free in the winter. Hot water from the springs is cooled and pumped from boreholes that vary between 200 and 2,000m straight into the taps of nearby homes, negating the need for hot water heating. It’s also purified and cooled to provide cold drinking water.

Geothermal Electricity: Geothermal power facilities currently generate 25% of the country’s total electricity production. There are three basic designs for geothermal power plants, all of which pull hot water and steam from the ground, use it, and then return it as warm water to prolong the life of the heat source. In the simplest design, known as dry steam, the steam goes directly through the turbine, then into a condenser where the steam is condensed into water. In a second approach, very hot water is depressurized or “flashed” into steam which can then be used to drive the turbine. In the third approach, called a binary cycle system, the hot water is passed through a heat exchanger, where it heats a second liquid—such as isobutane—in a closed loop. Isobutane boils at a lower temperature than water, so it is more easily converted into steam to run the turbine. These three systems are shown in the diagrams below.

Resources:

1. Orkustofnun

http://www.nea.is/geothermal/direct-utilization/nr/91

2. Scientific American

http://www.scientificamerican.com/article/iceland-geothermal-power/

3. The Guardian

http://www.theguardian.com/environment/2008/apr/22/renewableenergy.alternativeenergy

The Stirling Heat Engine & Peltier Device

What is the Stirling Heat Engine? The Stirling engine was invented by Robert Stirling in 1816. There hasn’t been a successful mass-market application for the Stirling engine. The gasses used inside a Stirling engine never leave the engine. There are no exhaust valves that vent high-pressure gasses, as in a gasoline or diesel engine, and there are no explosions taking place making Stirling engines very quiet. The Stirling cycle uses an external heat source, which could be anything from gasoline to solar energy to the heat produced by decaying plants. No combustion takes place inside the cylinders of the engine.

Modern Day Applications? Stirling engines are used only in some very specialized applications, like in submarines or auxiliary power generators for yachts, where quiet operation is important.

What is the Peltier Device? Peltier devices, otherwise known as thermoelectric coolers, are solid-state heat pumps that operate according to the Peltier effect: a theory that claims a heating or cooling effect occurs when electric current passes through two conductors. A voltage applied to the free ends of two dissimilar materials creates a temperature difference. With this temperature difference, Peltier cooling will cause heat to move from one end to the other. The Peltier Effect was discovered by Jean Peltier in 1834.

A typical thermoelectric cooler will consist of p- and n- type semiconductor elements that act as the two dissimilar conductors. It is possible to shift the balance of electrons and holes in a silicon crystal lattice by “doping” it with other atoms. Atoms with one more valence electron than silicon are used to produce “n-type” semiconductor material. Atoms with one less valence electron result in “p-type” material.

The array of elements is soldered between two ceramic plates, electrically in series and thermally in parallel. As a DC current passes through one or more pairs of elements from n- to p-, there is a decrease in temperature at the junction (“cold side”), resulting in the absorption of heat from the environment. The heat is carried through the cooler by electron transport and released on the opposite (“hot”) side as the electrons move from a high- to low-energy state. The heat-pumping capacity of a cooler is proportional to the current and the number of pairs of n- and p- type elements (or couples).

Modern day applications? Peltier elements are commonly used in consumer products including camping products, portable coolers, cooling electronic components and small instruments. The cooling effect of Peltier heat pumps can also be used to extract water from the air in dehumidifiers. Climate-controlled jackets are beginning to use Peltier elements. Thermoelectric coolers are used to replace heat sinks for microprocessors. They are also used for wine coolers.

References:

1. How Stuff Works

http://auto.howstuffworks.com/stirling-engine.htm

2. II-VI Marlow

http://www.marlow.com/resources/general-faq/6-how-do-thermoelectric-coolers-tecs-work.html

3. PV Education

http://www.pveducation.org/pvcdrom/pn-junction/doping

Tesla Electric Car

How does the Tesla electric car work? The Tesla uses a three-phase Alternating Current (AC) Induction motor. The motor has two primary components: a rotor and a stator. The rotor is a shaft of steel with copper bars running through it. It rotates and, in doing so, turns the wheels. The stationary stator surrounds, but does not touch, the rotor. The stator has two functions: it creates a rotating magnetic field and it induces a current in the rotor. The current creates a second magnetic field in the rotor that chases the rotating stator field. The end result is torque. The magnetic field is created completely from electricity. The stator is assembled by winding coils of copper wire through a stack of thin steel plates called laminations. The copper wire conducts the electricity fed into the motor from the Power Electronics Module. There are three sets of wires – each wire conducts one of the three phases of electricity. The three phases are offset from each other such that combing the rises and falls of each phase creates a smooth supply of current—and therefore power. The flow of alternating current into the copper windings creates a magnetic field. This is electromagnetism. And just as the current in each phase constantly rises and falls, the magnetic field also varies between “North” and “South”. -Tesla

Use of technology- Nikola Tesla emigrated to America from Croatia to work for Thomas Edison. The partnership did not last long and soon after he ended up going out on his own and launched a small company and development laboratory in 1886 in New York. In 1887 Tesla files his first patents for a two-phase AC system with four electric power lines, which consists of a generator, a transmission system and a multi-phase motor. The image below is a picture of one of many patents he filed for.

George Westinghouse licensed his AC induction motor and transformer and Tesla also worked for a short time as a consultant for Westinghouse. Tesla also made many other discoveries in fields such as lighting and radio technology. Below is a picture of Tesla around 1890.

Charging stations- The Tesla can charge wherever there is an outlet, 120v or 240v! The Tesla can be programmed to charge at a certain time of day. The recommended time is between midnight and 6 am when the cost of electricity may be lowest. Tesla also offers high power charging stations for home use that greatly increase the speed at which the car charges. Another option are Superchargers- stations on the road users can rapidly charge their cars at. There are also public charging stations across the country Tesla cars can use with an adapter. The map below shows the Supercharge stations as of January 2015.

References:

1. Tesla

http://my.teslamotors.com/roadster/technology/motor

http://www.teslamotors.com/models-charging#/onthego

2. Explain That Stuff

http://www.explainthatstuff.com/induction-motors.html

3. KIT

https://www.eti.kit.edu/english/1390.php

4. Hybrid Cars

http://www.hybridcars.com/tesla-updates-map-of-supercharger-sites/

Pulley Lab

My partner Jill Swan and I did the pulley lab together. The lab consisted of exploring Newton’s 2^nd Law- the law of conservation of energy, velocity and acceleration, and power. We used the Lego Mindstorm robot to see how acceleration changed when mass changed and power was fixed and when power changed and mass was fixed.

Does the acceleration vary with mass? Yes. When we changed the masses- .05 kg, .1 kg, .15 kg, .2 kg, and .25 kg, with the power level left constant at 75, the acceleration decreased. The first graph is a representation of our results. It shows the trend line angled in a downward slope in regards to acceleration vs. mass.

Does the acceleration vary with power level? Yes. When we changed the power level- 50, 60, 70, 80, and 90, with the mass left constant at .1 kg, the acceleration level increased. The second graph is a representation of our results. It shows the trend line angled in an upward slope in regards to power vs. acceleration.

Is the linear trend line as expected? Yes. The linear trend line reflected what I expected the results to be based on the lecture and understanding the formula F=ma.

17.5 cm- to bottom of pulley

9 cm- height of weights

Electricity Generation

Electricity Generation:

How does a coal power plant work? The process begins when coal is ground to a powder. It is then blown into a boiler where the coal dust is burned, thus creating heat energy. Why grind the coal? Grinding it into a powder creates more surface are which, in turn, allows for faster and hotter burning producing more heat and less waste. The burning of the coal heats water in pipes coiled around the boiler, turning it into steam. Pressure is created by keeping the steam in pipes where it expands and the pressure drives the steam over the blades of a steam turbine. The steam turbine spins and mechanical energy is produced. A shaft connects the steam turbine to the turbine generator, so as the steam turbine spins, the generator does as well. Using an electromagnetic field, the generator converts the mechanical energy into electrical energy. The byproducts are ash and exhaust gas. The ash is collected from the bottom of the boiler and often sold to be used in building materials and the gases enter the exhaust stack. The exhaust stack has filters to remove the dust and ask before the gas is released into the air.How does a natural gas power plant work? The first step at a natural gas power plant is pumping the natural gas into the turbine. There it is mixed with air and burned, creating heat energy. Combustion gas is also created. The heat causes the combustion gas to expand causing a buildup of pressure. The pressure drives the combustion gas over the blades of the gas turbine, causing it to spin, converting some of the heat energy into mechanical energy. A shaft connects the gas turbine to the gas turbine generator so when the turbine spins, the generator spins as well. Using an electromagnetic field, the generator converts the mechanical energy into electrical energy. The combustion gas is then piped to the heat recovery steam generator where it is used to heat pipes of water, turning the water to steam, before leaving through the exhaust stack. The hot steam expands in the pipes and emerges under high pressure. These high-pressure steam jets spin the steam turbine. The steam turbine is connected by a shaft to the steam turbine generator, which converts the turbine’s mechanical energy into electrical energy.

How does a nuclear power plant work? The nuclear power plant begins the process in a reactor vessel- a tough steel capsule that houses the fuel rods, sealed metal cylinders containing pellets of uranium oxide. When a neutron, a neutrally charged subatomic particle, hits a uranium atom, the atom sometimes splits, releasing two or three more neutrons. This process converts the nuclear energy that binds the atom together into heat energy. When atoms in the fuel split, the neutrons they release are likely to hit other atoms and make them split as well creating a chain reaction producing large amounts of heat. Water flows through the reactor vessel, where the chain reaction heats it to around 300°C. The water needs to stay in liquid form for the power station to work, so the pressuriser stops it from boiling. The reactor coolant pump circulates the hot pressurised water from the reactor vessel to the steam generator. Here, the water flows through thousands of looped pipes before circulating back to the reactor vessel. A second stream of water flows through the steam generator, around the outside of the pipes. This water is under much less pressure, so the heat from the pipes boils it into steam. The steam then passes through a series of turbines, causing them to spin, converting the heat energy produced in the reactor into mechanical energy. A shaft connects the turbines to a generator, so when the turbines spin, so does the generator. The generator uses an electromagnetic field to convert this mechanical energy into electrical energy.There are similarities in the three types of power plants. They all use hot water, steam, turbines, and electromagnetic fields in their production process. There are a couple big differences I think are worth mentioning- the ability to control when and how much power is made and environmental impact. While nuclear power plants are in full effect at all times, natural gas and coal production can increase and decrease as needed to meet the demands, a definite benefit. On the note of environmental efficiency, nuclear is the clear winner producing carbon-free electricity as well as being a renewable resource. Natural gas produces less greenhouse gases than coal, about half as much, but the goal should eventually be no gas emissions so natural gas is not a perfect solution. It is abundant and cheap at the moment making it an appealing source of energy for now.

References:

1. EDF Energy- Coal

http://www.edfenergy.com/energyfuture/coal-generation

2. EDF Energy- Natural Gas

http://www.edfenergy.com/energyfuture/generation-gas

3. EDF Energy- Nuclear Power

http://www.edfenergy.com/energyfuture/generation-nuclear

4. Oil Price

http://oilprice.com/Alternative-Energy/Nuclear-Power/Natural-Gas-Threatens-U.S.-Nuclear-Future.html

Lego Mindstorm Lab Activity #2

My teammate, Jill Swan, and I experimented with three power settings for the motors, keeping both motors the same. We did three trials per power setting. The results are as follows:

Wheel Diameter= .055 m Circumference= .1728 m

The experiments show that the more power the motors had, the farther the robots went. In order to make a full rotation, the power needs to be over 55, as our experiments show that 55 just slightly not enough for an entire 360 degree rotation. The margin of error varied across all the studies anywhere from less than a percent to 12% error with no definitive link between the variation of results. The experience was helpful to reinforce the concepts of distance, velocity, and dealing with diameter, radius, and circumference from the lecture. It also was beneficial in learning to work with the robots and the computer software associated with them.

Fracking

What is fracking? Fracking, otherwise known as hydraulic fracturing, has been in use since the 1940’s but has recently seen a rise in the United States in part due to the economic benefit it brings to the communities where these resources are located and also because of the desire for energy security. The process of fracking begins with a well drilled vertically or horizontally 1-2+ miles into the Earth. In order to reduce the risk of leakage into the groundwater, the well is encased in steel and/or cement. At the time the vertical well reaches the layer of rock where the oil or natural gas is located, the well curves to about 90 degrees to drill horizontally along the rock layer, extending potentially over a mile. Next, fracking fluid is pumped into the well at pressures high enough to fracture the surrounding rock, creating fissures that allow oil or gas to flow through. This fracking fluid, also called slickwater, while mostly water, contains a range of additives and chemicals as well. Proppants are also pumped into the well and are used to keep the fractures open so the oil or natural gas can flow freely through the fissures. The reservoirs of oil or natural gas are then pumped back to the surface along with flowback liquid containing numerous contaminates. The flowback liquid is eventually injected deep in the ground below groundwater or disposed of at wastewater treatment facilities. The image below provides a graphic representation of how fracking works.

Pros:

>Fracking provides economic benefits such as jobs in the communities where the wells are located. (Reference 2)

>Fracking allows the US to produce their own energy resources, decreasing dependency on imported oil and fossil fuels and the costs associated with that. (Reference 2)

>Fracking can stimulate new production from older wells. (Reference 1)

Cons/Environmental Impact:

>An average of 400 tanker trucks are required to carry water and supplies to and from the site, contributing to air pollution and use of fossil fuels. (Reference 3)

>Millions of gallons of water are used in each fracturing job.

>About 40,000 gallons of chemicals (up to 600 types of chemicals such as lead, uranium, and mercury) are used in a fracturing job.

>Groundwater used by nearby towns for drinking water can be contaminated from leaching of the chemicals during the fracking process sometimes causing health complications.

>Up to 50% of the fracking fluid (not biodegradable) is not recovered and is left in the ground.

>Fracking fluid left to evaporate releases harmful VOC’s into the atmosphere contributing to acid rain, contaminated air, and ground level ozone.

References:

1. What is fracking?

http://www.what-is-fracking.com/what-is-hydraulic-fracturing/

2. Live Science

http://www.livescience.com/34464-what-is-fracking.html

3. Dangers of Fracking

http://www.dangersoffracking.com/