October 2015 – Jennifer Straka

Self-Study of Nuclear Energy

The details of how nuclear energy works has been discussed in previous posts, but as a refresher, the following paragraph is a summary.

A nuclear reactor produces electricity in much the same way other power plants do. Some form of energy creates heat, which turns water into steam. The pressure of the steam turns a generator, which produces electricity. The difference is in how the heat is created. Power plants that run on fossil fuels burn coal, oil or natural gas to generate heat. In a nuclear energy facility, heat is produced from splitting atoms – a process called nuclear fission. Enriched uranium is the fuel for nuclear reactors. Uranium is an abundant, naturally radioactive element found in most rocks. As uranium breaks down or decays, it produces heat inside the Earth’s crust. A similar process generates heat inside a nuclear reactor. The image below is a graphic representation of the production of nuclear energy.

Globally, there have been at least 99 (civilian and military) recorded nuclear power plant accidents from 1952 to 2009 (defined as incidents that either resulted in the loss of human life or more than $50,000 of property damage, the amount the US federal government uses to define nuclear energy accidents that must be reported), totaling $20.5 billion in property damages. Property damage costs include destruction of property, emergency response, environmental remediation, evacuation, lost product, fines, and court claims. Because nuclear power plants are large and complex, accidents on site tend to be relatively expensive. The International Atomic Energy Authority ranks them using an International Nuclear Events Scale (INES) – ranging from ‘anomaly’ to ‘major accident’, numbered from 1 to 7. Some of the worst accidents include:

>Chernobyl, Ukraine- INES Level 7, 1986

>3 Mile Island, Pennsylvania- INES Level 5, 1979

>Fukushima, Japan- INES Level 7, 2011

References:

1. ENEC

http://www.enec.gov.ae/learn-about-nuclear-energy/how-does-nuclear-energy-work/#nuclear-fission

2. The Guardian

http://www.theguardian.com/news/datablog/2011/mar/14/nuclear-power-plant-accidents-list-rank

3. Wikipedia- List of Nuclear Power Accidents By Country

https://en.wikipedia.org/wiki/List_of_nuclear_power_accidents_by_country#cite_note-bksaccident-7

4. Take Part

http://www.takepart.com/photos/11-worst-nuclear-accidents/windscale-pile-great-britain-ines-level-5-1957

Fukushima Daiichi Nuclear Disaster

The Fukushima Daiichi Nuclear Disaster- What happened? The Great East Japan Earthquake (magnitude 9.0) occurred on March 11, 2011 at 2.46 pm and did considerable damage in the region. The large tsunami it created caused significant damage as well. Fukushima Daiichi was one four nuclear power plants with eleven reactors between them in the region operating at the time and all shut down automatically when the quake hit. The reactors held up to the seismic activity of the earthquake, but were vulnerable to the tsunami. Power, from grid or backup generators, was available to run the Residual Heat Removal (RHR) system cooling pumps at eight of the eleven units, and despite some problems they achieved ‘cold shutdown’ within about four days. The other three, at Fukushima Daiichi, lost power at 3.42 pm, almost an hour after the quake, when the entire site was flooded by the 15-metre tsunami. This disabled 12 of 13 back-up generators on site and also the heat exchangers for dumping reactor waste heat and decay heat to the sea. The three units lost the ability to maintain proper reactor cooling and water circulation functions. It took weeks to stabilize the reactors.

Evacuation and Radiation: The government issued an evacuation instruction for residents within 3km radius in the beginning. Eventually it was expanded to within 20km, and the residents of a range of 20km -30km were instructed to stay indoors. There have been no deaths or cases of radiation sickness from the nuclear accident, but over 100,000 people were evacuated from their homes to ensure this. Government nervousness delays the return of many. As of July 2012, all nuclear energy efforts are suspended. The image below is a map depicting ground radioactive iodine levels based on US aircraft monitoring data.

Japan’s New Energy Strategy: Japan has limited domestic energy resources that have met less than 9% of the country’s total primary energy use since 2012, compared with about 20% before the removal of nuclear power following the Fukushima plant accident.t is the third largest oil consumer and net importer in the world behind the United States and China. Furthermore, it ranks as the world’s largest importer of liquefied natural gas and second-largest importer of coal behind China. The image below is a graphic representation of Japan’s energy consumption.

References:

1. Fukushima on the Globe

http://fukushimaontheglobe.com/the-earthquake-and-the-nuclear-accident/whats-happened

2. World Nuclear Association

http://www.world-nuclear.org/info/safety-and-security/safety-of-plants/fukushima-accident/

3. EIA

http://www.eia.gov/beta/international/analysis.cfm?iso=JPN

President’s Climate Action Plan

The President’s Climate Action Plan was published in June 2013. In his Second Inaugural Address, given January 2013, President Obama stated, “The path towards sustainable energy sources will be long and sometimes difficult. But America cannot resist this transition, we must lead it.” The Climate Action Plan is part of how President Obama will achieve the pledge he made in 2009 that by 2020, America would reduce its greenhouse gas emissions in the range of 17 percent below 2005 levels. His plan can be divided into three pillars-

1. Cut Carbon Pollution in America

2. Prepare the United States for the Impacts of Climate Change

3. Lead International Efforts to Combat Global Climate Change and Prepare for its Impacts

This blog will discuss one initiative from each of the three pillars.

In regards to the first pillar (Cut Carbon Pollution in America), the plan includes deploying clean energy by cutting carbon pollution from power plants as power plants, “are the largest concentrated source of emissions in the United States, together accounting for roughly one-third of all domestic greenhouse gas emissions.” As of the plan being written, there were no federal standards in place to reduce carbon pollution from power plants, although some changes were being made at the state level. Carbon pollution standards for both new and existing power plants are being created by the Environmental Protection Agency.

In regards to the second pillar (Prepare the United States for the Impacts of Climate Change), the plan includes protecting our economy and natural resources in many ways including promoting resilience in the health sector, conserving land and water resources, and identifying vulnerabilities of key sectors to climate change. Promoting resilience in the health sector means providing guidance on affordable measures to ensure that our medical system is resilient to climate impacts, collaboration with partner agencies to share best practices among federal health facilities, and training public-health professionals and community leaders to prepare their communities for the health consequences of climate change.

In regards to the third pillar (Lead International Efforts to Combat Global Climate Change and Prepare for its Impacts), the plan mainly attempts to work with other countries to take action to address climate change. This is accomplished in numerous ways including expanding clean energy use and cutting energy waste by:

-Financing and regulatory support for renewable and clean energy projects

-Actions to promote fuel switching from oil and coal to natural gas or renewables

-Support for the safe and secure use of nuclear power

-Cooperation on clean coal technologies

-Programs to improve and disseminate energy efficient technologies

References:

1. The President’s Climate Action Plan

https://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf

2.The White House

https://www.whitehouse.gov/climate-change

3. Environment and Energy Study Institute

http://www.eesi.org/papers/view/fact-sheet-timeline-progress-of-president-obama-climate-action-plan

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

Museum of Science

Catching the Wind:

How do wind turbines generate electricity? Wind turbines catch the energy of the wind and change it into a form we can use. As the wind turns a turbine’s blades, the machinery inside the machine coverts the energy into electricity.

What factors need to be considered when selecting and siting them? The decision to install a wind turbine is generally based on a location’s wind speed and duration over the course of a year. Other factors include how much energy a wind turbine is capable of generating, efficiency, cost, the time it will take for the turbine to return a profit, how wildlife will be affected, and acceptance by the community.

What are the tradeoffs?

Renewable:

Wind- Wind is only available at certain times and in certain parts of the country, often times in areas far from large amounts of energy consumption. Also, an efficient method of storing excess energy produced by windmills has not been invented.

Solar- Solar energy is only available for half of the day and can be lessened with weather conditions. Also, the technology for solar panels is expensive.

Hydropower- Dams can negatively affect the ecosystems in the water and can also potentially contribute to the pollution of the surrounding water.

Biomass- The tradeoffs for biomass include that it is expensive, it is not as efficient as fossil fuels, and it creates methane gas when burned which is harmful to the environment.

Non-renewable:

Coal- Burning coal emits harmful waste such as carbon dioxide, sulphur dioxide, nitrogen oxides, sulphuric acids, arsenic and ash into the air, acid rain, mining can negatively affect the ecosystem, miners and employees can suffer from coal related health issues, and there is a limited amount of coal to be used.

Nuclear Power- Radioactive wastes are produced and either have to be recycled or disposed of safely, safety of nuclear power and weapons use, limited amount of uranium, and nuclear accidents are tradeoffs to consider.

Natural Gas- Natural gas use produces greenhouse gas emissions, it is toxic and flammable, not as efficient as gasoline for transportation, and its supply is also limited.

Conserve @ Home:

Changes to make to energy “budget”-

>buying a car that gets 30.7 mpg vs 20 = 13.5% savings

>carpool to work = 4.2% savings

>install more efficient furnace = 2.9% savings

>lower winter thermostat = 2.8%

>replace single pane windows with more efficient ones = 2.8%

>lower highway speed from 70 mph to 60 mph = 2.4% savings

>buy low rolling resistance tires = 1.5% savings

>reduce washing machine temp. = 1.2% savings

>line dry clothing for 5 months of year = 1.1% savings

What’s a watt? The hair dryer used considerable more energy (1000 watts) versus the mixer (250 watts).

Energized: I went through all the interactive exhibits and found the solar energy ones to be intriguing. It was interesting to see the reading on the solar panel change depending on where you put it representing different times of day.

Investigate!: This exhibit went over the four steps of an at-home investigation- Ask a question. Make a guess. Check it out. Investigate further.

References:

1. Conserve Energy Future

http://www.conserve-energy-future.com/Advantages_Disadvantages_BiomassEnergy.php

2. Fossil Fuel

http://fossil-fuel.co.uk/coal/the-disadvantages-of-coal

3. Museum of Science

http://www.mos.org/

Generator Activity

My partner and I did the generator lab demonstrating Faraday’s Law that states that changing magnetic fluxes through coiled wires generate electricity. The greater the change in magnetic flux, the greater the currents and voltages. We used a flashlight shake generator to demonstrate this and are results were in accordance with Faraday’s Law.

To conduct the experiment my partner shook the tube for thirty seconds at a constant rate. She counted the the number of times she shook it and I recorded the number. Using excel, we took the sum of the square of the voltages and recorded that number. We repeated this four more times at different rates of shakes. Below are our results and a graph with a trend line representing what we learned from Faraday’s Law. The more shakes, the higher the sum of the square of the voltages.

Labs

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