Month: March 2016

Introduction

Our last class, we visited the Museum of Science to learn about alternative energy beyond the classroom.  We visited four exhibits, all linked to energy production and consumption. We learned the technical and statistical aspects of wind and solar production, and got a better idea of their contribution in the grid. We also compared these renewables with all sources of energy. Finally we looked at efficient energy consumption, and what it looks like on a household level. These four exhibits each helped to expand our perspective on energy production and consumption in a different manner.

Catching the Wind

This exhibit was about the efficient harnessing of the wind to generate electric power. Using a visual representation, the exhibit illustrates the mechanics of transforming wind motion into energy. The diagram disassembles the standard wind turbine so the inner workings can be observed, and each parts function is explained. Some interesting parts that I was not aware of are things like the yaw

motors, which turn the blades of the turbine towards the directions of the wind in order to maximize efficiency.  This exhibit also shows the different designs of wind turbines, and classifies them with respect to their output efficiency. The most efficient design of course is the commonly observed straight bladed turbine called “Proven 6”. Other designs however include the skystream, the AVX1000, and windspire, which all vary greatly in their design.

Energized!

Energized is an exhibit focused on the problem of limited resources of fossil fuels. These resources will eventually run out, so this exhibit aims to educate people on the pros and cons of alternative energy sources. The exhibit also goes in depth in the renewables such as solar energy, and the science of energy storage. We looked at an interactive part of the exhibit that let us shine light at different angles on a solar panel. The exhibit recorded

the output, and it showed us that a direct angle is the most efficient angle for solar panels. Another interesting part of the exhibit was the magnetic flywheel. This device is one attempting to solve a very big problem with renewable energy production, and that is energy storage. The energy storage device is produced by Beacon Power Corporation in Massachusetts. This device can compensate for fluctuations in energy demand by receiving excess electricity to convert it into mechanical energy. This is why the vessel has a large spinning wheel component. When demand is high, the spinning wheel can act as a generator and provide the additional output.

Conserve At Home

This part of the museum was about how to reduce energy demand per household by making reasonably easy measures in your lifestyle. The most interesting and interactive part of this exhibit was the light-bulb comparison. The exhibit allowed visitors to try to power three different lightbulbs using a hand crank generator.  The first light, LED, is an 8 watt, and it can light up its surroundings with a few easy cranks of the wheel. The incandescent on the other hand is listed as a 40 watt, and this lightbulb barely glows no matter how fast you try to crank the generator. This stark difference gives everyone a common perspective on how much energy certain lightbulbs can conserve, making this a very good part of the exhibit. The exhibit included other informative sections on domestic conservation, such as how to reduce the amount of trash we produce by simply recycling. The exhibit stated that without recycling, we produce and average of 4.4 lbs of trash per person per day. After recycling, we produce 2.9 lbs of trash per person per day. This is a very solid difference to show people the value of separating their recyclables.

Investigate!

This exhibit allows for the visitors to act as scientists themselves. There are several experiments that are set up to demonstrate laws of motion. I used the motion tracker. The motion tracker shows your position versus time on a graph. As you walk along the pad, sensors track your position, and records it. On the graph, the actual slope of the line tells the visitor his speed of motion at different times. The other experiment we observed was one concerning the acceleration due to gravity, or g. It is known that on all objects, g is constant regardless of mass. The only thing that impedes g is air resistance. So, our experiment dropped a ball with a larger mass and a ball with a smaller mass from the same height, at the exact same time.  We expected them to hit the bottom at the exact same time, but in fact the larger ball hit an instant before the lighter ball. This proved that in our atmosphere, air resistance is a factor and can not be negligible in an object’s acceleration due to gravity.

Conclusion

I think these exhibits are a good review and a good addition to what we have covered in class. There is a large kid demographic for the museum, so having interactive exhibits are a great idea for teaching the next generation about the importance of alternative energy, and energy efficiency. As for students and adults, the exhibits still provide very informative data. I am glad the museum brings attention to the issues of energy research and efficiency.

Introduction 

Throughout the world’s use of nuclear power, here have been several very significant accidents regarding radiation leakage. These disasters associate fear with the entire nuclear industry, and combined with the history of nuclear weapons destruction, can easily ruin the demand for nuclear energy  expansion. The two relatively largest nuclear disasters to ever occur were in Chernobyl, Ukraine in 1986, and Fukushima, Japan in 2011. Both disasters called for immediate evacuation of the surrounding area due to extreme levels of radioactivity. By learning about what caused these accidents, we can be sure that mistakes are never repeated, and nuclear power does not harm any more people.

Chernobyl

The disaster at Chernobyl was undoubtedly the result of gross negligence in safety design and operation. The plant consisted of four light water reactors, with no external radiation containment structure. This design flaw is critical, because radiation can be contained well with the proper design. The accident was caused by a poorly designed control rod in the reactor. Operators had disabled the shut down function of the reactor the day before the accident, so when the power surge in the fuel rod occurred,  resulting steam pressure caused the entire core to overload, and explode. This was followed by a second explosion, which scattered half of the reactor along with its graphite control rods, and highly radioactive fission fragments.

Two people were killed by these explosions, and 28 people were killed due to radiation exposure during emergency response actions. Those killed had been

exposed to levels up to 20,000 millisieverts (mSv). The natural dose of radiation for a person is about 2,5 mSv per year. These extreme dosages were caused by the fission fragments that were around the close proximity of the explosion site. However, lighter radioactive particles were released into the atmosphere and carried by wind. The closest town to Chernobyl, Pripyat, had to be immediately evacuated, and residents still received doses of 50 to 100 mSv. Ultimately, the accident created a 4,300 square kilometer zone unfit for residence, due to levels of radiation that would exceed the normal 2,5 mSv per year.

Fukushima

The Fukushima disaster introduces a whole new threat to nuclear energy: natural disasters. Exactly 5 years ago, on March 11th, 2011, a tsunami caused by an earthquake in Japan damaged the cooling process and power supply of the

Fukushima nuclear plant. The result was an overheating that caused 3 nuclear reactors to meltdown. Throughout several days there were a number of failures causing this meltdown, and a hydrogen explosion. This leaked radioactive fission fragments into the surrounding water, as well as dispersed lighter fragments into the air.

What is more unnerving about Fukushima is that it was not caused by design or operator negligence. The plant was designed to withstand earthquakes and even significant tsunamis, but the Fukushima tsunami still put the nuclear plants 5 meters below sea level, causing in the meltdowns and explosion. Not only did the tsunami disable the reactors, but it also disabled people’s ability to respond effectively. Radiation monitoring could no longer be used, so the plumes of radioactive clouds could not be tracked to notify locals to evacuate. This is why in the course of days the prime minister’s evacuation order from the proximity expanded from an initial 2km to 20 km.  Nobody was killed due to radiation exposure, but some workers have been exposed to as much as 250 mSv during the disaster, and have to be closely monitored. Still today the area of Fukushima is under reconstruction, and many people are still living in government subsidized housing. Hopefully, an unnerving situation such as this never causes us to lose control of our nuclear reactors, because if natural disasters remain a threat to nuclear reactors, nuclear reactor will be considered a threat to health and safety.

Works Cited

“Chernobyl Accident 1986.” Chernobyl. World Nuclear Association, n.d. Web. 11 Mar. 2016.

“What Happened?” Fukushima on the Globe. N.p., n.d. Web. 11 Mar.2016

Introduction

I think this movie is an excellent production to enlighten today’s citizens on the realities of nuclear power. It is designed to dispel the shadow left by the generation of anti-nuclear activism, and put the benefits of nuclear power into perspective. They make the argument even stronger by having previous anti-nuclear environmentalists preach this message, and admit to their faults in opposing nuclear power. Their argument is strong because they systematically address the concerns of anti-nuclear advocates, and then clearly explain why their concerns are either no longer legitimate, or are extremely outweighed by the benefits of nuclear power. These concerns could be categorized into three topics: Operation safety, radiation, and environmental damage.

Operations Safety

The movie first described Chernobyl and Three Mile Island, and what exactly went wrong. They admitted to the magnitude of these accidents, but then explained why they would not occur again. Chernobyl was an unsafe, and uncontained reactor, and its meltdown was caused by negligence. Three mile island was caused by operators not following proper procedure. These were both significant accidents, but they argue that our lesson is learned, and technology has now made for much safer operations. Nuclear reactors like the one in Chernobyl are not used, and there is always sufficient containment. In addition, they also prove that we now have fail safe reactors, which automatically shut down if they get too hot, so meltdowns can not be repeated.

Radiation

The movie also addresses people’s deep fear of radiation exposure by having nuclear reactors in operation. They enlighten people on the subject by explaining that just about all things on earth emit small amounts of radiation, and that humans are not harmed by small quantities. They visit various places where people live and measure radiation there, and they show that radiation around a nuclear plant, or contained nuclear waste is the same amount of radiation in a normal US city. Indeed, they even show places where natural radiation is much higher than the normal measure, simply because of their elevation, and closer proximity to cosmic radiation. This shows that normal operations of nuclear plants have absolutely no negative externalities.

Environmental Damage

They also recall how in the 60’s and 70’s, being an environmentalist was synonymous to being anti-nuclear. Activists feared radiation emissions (which has already been adressed) and the problem of nuclear waste. They address the nuclear waste problem by showing that proper storage is completely safe, and that technology is allowing for the use of a breeder reactor instead of a light water reactor. Breeder reactors can recycle and reuse plutonium fuel many times over, significantly reducing the amount of waste produced.

Their second argument is that environmentalists have been unrealistic about the growth of solar ad wind power. It is simply too expensive, and is intermittent power, which would require fossil fuel backups. Greenhouse cas emissions cannot continue, and they bring up the reality that singles out nuclear as the only power that can complete with fossil fuels. Alongside this fact,  it also releases even less CO2 than the production of solar panels. As a success story, they look to france who went nuclear in the 70’s, and now enjoy vast amounts of cheap energy with half the emissions per capita than that of Germany, who strives to go solar. With all these benefits to nuclear, the movie brings to our attention that we already have a solution to clean energy, and all we need to do is unite as a planet and invest in it.

 

 

Introduction

Thermoelectric devices are incredibly useful for modern energy production and heat control. The two most widely used thermoelectric devices are those that transfer heat into a system to produce electricity, and adversely those that use electricity to transfer heat out of a system. Both functions have very practical applications, and I find the science behind their heat control very interesting. I will explore both functions of thermoelectric devices by first discussing thermoelectric materials. Then we will see how its properties allow both the generation of electricity, and the transfer of heat from a system.

Thermoelectric Generation

Thermoelectric materials are usually semiconductors that facilitate the Seebeck Effect. In the Seebeck effect, we essentially have the same process as what happens in the silicon layer of a solar panel. But with these systems we have instead two semiconducors: one heated and one cooled. With an electrical circuit between both heated material and cooled material, electrons tend to transfer into the cool material. So in this system, we create a positive field of holes (the heated side) and a negative field of electrons (cooler field) . This electron transfer is what allows for a magnetic field, and voltage to be produced in the system.

This diagram describes the process well. You can see that heat is the input in one material, and  in effect the negative charge produced by the semicoductors flows through the other material, producing a voltage.

Thermoelectric Heat Pump

The Peltier effect is the inverse of this property. This effect states that, “whenever a circuit of two dissimilar materials passes current, heat is absorbed at one end of the junction and released at the other.” (Power Practical) So, in this system, electricity is an input to create a heat transfer, or heat pump.

This diagram of the Peltier effect describes the inverse. In this system, a voltage is the input in the same set of semiconductors, and is used to create a cooler field and a hotter field.

Applications

If a thermoelectric cooler functions with the heat absorbtion side in an insulated space, the heat within that space will be absorbed into the device, and trasferred to the space outside the system. This is how most fridges or freezers can keep food in constant cool temperatures. Beyond food storage, the ability to remove heat from a space is essential for any heat sensitive materials, such as medicines or biological samples.

Thermoelectric generators are also very useful for energy conservation. Any significant heat exhaustion is otherwise wasted energy being emitted from a system. So, adding thermoelectric generators to any exothermic system (heat emitters) could improve efficiency with greater electrical output. Even batteries can be replaced by small scale thermoelectric generators that can draw energy from heat in its surroudings. As research continues on these devices, even more uses will arise in the future for these generators.

Sources

“How Do Thermoelectrics Work.” Power Practical. Power Practical, n.d. Web. 03 Mar. 2016.

Alphabet Energy. “How Thermoelectric Generators Work.” Alphabet Energy. N.p., 2009. Web. 3 Mar. 2016.

Rouse, Margaret. “What Is Seebeck Effect? – Definition from WhatIs.com.”SearchNetworking. TechTarget, n.d. Web. 03 Mar. 2016.

Introduction

Iceland has a very unique advantage over other countries in terms of domestic energy supply. The country happens to be located on a geographical sweet spot. Traditionally, we assume this means they are living above a sea of oil or coal, but this is not the case. Iceland is fortunate because they  live on a global hot spot. The heat radiates from the land, littering the country with hot springs and volcanic activity. This is fortunate because the natural heat can be captured to produce geothermal energy, which is  a both clean, and renewable power source. So, where does this natural heat come from, and why does Iceland get all of it?

Why Iceland?

The earth’s crust can be considered as tectonic plates, which constantly interact with the liquid magma mantle that lies below it. The process of subduction and convection keeps the tectonic plates moving above the mantle like an incredibly slow conveyor belt–subduction pushes one plate below another and into the mantle, while convection pulls plates apart, allowing for hot magma to rise and cool to form new land. The atlantic ocean as we know it was created due to this process, and just like the ocean that surrounds it, Iceland is also the product of convection. The mid atlantic ridge splits the country in two, and the convection activity makes the heat from the earth’s mantle very accessible from the surface.

Utilization

Iceland does not take this natural resource for granted, and has done an amazing job utilizing it. Since heat is so accessible, almost half of the heat harnessed is pumped directly from the land into the space heaters of local homes. A total of 40% of the heat harnessed is transformed into electric power. The other majority of the heat is transformed into electricity. This initiative is a success story similar to the thriving solar industry in Germany. With the nurturing finances of the Icelandic government, a whole new market in geothermal utilities was allowed to stabilize, and has all but replaced the demand for fossil fuel energy. Today, between heat and electric output, the heated ground satisfies half the island’s total energy demand. Incredibly, the other 49 percent is drawn from different renewable sources such as hydroelectric dams. This is an amazing accomplishment for a country so riddled with natural sources of clean energy. Yet Icelander’s still look to the future with greater goals, and profits in mind.

Innovation

With the combined effort of geothermal companies and the Icelandic government, research is being conducted in the use of supercritical steam power

for the geothermal plants. The Iceland Deep Drilling Project aims to use the hotter spots deeper in the convection ridge to harness supercritical steam. This method, previously used in nuclear energy, is projected to increase the efficiency of the turbines by a factor between 5 and 10 times its current output.

With an endless source of energy, Iceland is now looking to profit from its geothermal energy bank, by exporting electricity. It has found demand in Britain, who is in need of a constant flow of power to supplement their intermittent wind turbine output. The result is the prospect of a 600 mile long, 1 gigawatt capacity cable running in the sea between the two nations. If accomplished this would be an amazing deal of  for both countries energy interests, as well as an even more efficient utilization of Iceland’s natural geothermal resources.

Sources

“Geothermal.” Orkustofnun. National Energy Authority, n.d. Web. 29 Feb. 2016.

Mims, Christopher. “One Hot Island: Iceland’s Renewable Geothermal Power.” Scientific American. Scientific American, 20 Oct. 2008. Web. 29 Feb. 2016.

E.L. “Power under the Sea.” The Economist. The Economist Newspaper, 20 Jan. 2014. Web. 29 Feb. 2016.

Runyon, Jennifer. “Geothermal Energy in Iceland: Too Much of a Good Thing?” Geothermal Energy in Iceland. Renewable Energy World, 4 Mar. 2013. Web. 29 Feb. 2016.