Geothermal Energy is a renewable energy source that has been used for thousands of years.  Geothermal energy derives from harvesting Earth’s natural internal heat.  This heat is collected beneath Earth’s crust anywhere from shallow ground to miles beneath the surface.  This is a very clean source of energy since no fuel is burned.  Geothermal energy has become a popular source of energy in Iceland, as well as other renewable energies.

In Iceland, renewable energy accounts for roughly 85% of Iceland’s energy consumption and 66% of that being geothermal energy.  Iceland has unique geology has made it very easy and cheap to acquire renewable sources of energy.  Since Iceland is located on the Mid-Atlantic Ridge, which is one of the most tectonically active locations in the world, geothermal energy is quite abundant and easy to access.  In fact, there are over 600 hot springs and over 200 volcanoes located in Iceland.  The country became very involved in renewable energy after the second world war and it has ultimately changed the country and its economy as a whole.  The primary use of geothermal energy is keeping Iceland’s buildings and homes warm.  Geothermal energy is used to heat and cool 9 out of 10 buildings/homes.  Geothermal heat pump systems located in building/homes are used to moderate temperature.  The pump only penetrates the crust about 10 feet and is able to harness the constant temperature offered by the Earth’s surface and distribute the heat into buildings.  The pump can also work in reverse and extract heat from the building and transfer it into the ground during summer months.  Heat pumps are also commonly found in greenhouses allowing Iceland to grow crops when it’s too cold.

Geothermal energy is also used to generate electricity.  In order to produce electricity with geothermal energy, a well a mile deep or more is drilled into the ground.  These wells are drilled to access heat sources, like steam and very hot water, that will provide enough heat energy to spin turbines that are connected to electricity generators.  There are three different kinds of geothermal power plants which include; dry steam, flash, and binary.  Dry steam is the oldest geothermal technology and simply uses steam acquired from fractures in the ground and uses it to spin a turbine resulting in electrical generation.  Flash plants are slightly different.  These plants harvest the very hot water from underground reservoirs and mix the high-pressure hot water with low-pressure cooler water to create steam which then spins a turbine.  The latest technology is found in binary plants.  Binary plants acquire hot water, like flash plants, and pass it by a secondary fluid with a much lower boiling point that water, causing the secondary fluid to turn to vapor which is then used to spin a turbine.  Binary plants are the most modern and are most likely to be found recently established plants and plants that are to be built in the near future.    

Geothermal energy offers numerous advantages when compared to other common sources of energy.  For example, geothermal energy can be extracted without the burning of fossil fuels.  Binary plants are nearly 100% emission free, making geothermal energy an extremely ‘clean’ energy source.  Also, when looking at other renewable energy sources geothermal energy is available all day every day of the year, unlike wind and sunlight where the amount of free energy is limited.  Lastly, geothermal energy is relatively inexpensive.  Iceland has made itself a role model for other countries to look up to when it comes to efficiency and a cleaner future.

The Stirling Heat Engine was invented by Robert Stirling in 1816.  The Stirling Engine was gained a lot of popularity because it was much safer than the steam engine and had endless applications.  This engine is very basic and has the potential for very high efficiency when compared to the internal combustion engine.  These engines are also known for being very quiet.  Today, this engine is still used but in few modern day applications where a quiet engine is important.  For example, they are often used for powering submarines and yachts.

The Stirling engine uses a Stirling cycle to generate power, a unique approach that is different from other engines.  These engines uses external sources of heat to create power.  The interesting thing about these engines is that the heat source can by any resource that provides enough heat to change the temperatures of the gases contained in the cylinders, meaning gas could be used to power the engine or even sun light.   There are four components to the Stirling cycle.  First, heat is used to changes the pressure in the ‘heated’ cylinder.  When the pressure gets high enough this forces the piston down.  Second, the left piston, located in the ‘cooled’ cylinder, moves up while the right piston moves down, pushing the hot gas into the cooled cylinder cooling the hot gas and ultimately lower the pressure back down.  Third, the piston in the cooled cylinder compresses the gas.  The right piston moves up with the left moves down.  This forces the gas into the heated cylinder where it quickly heats up and and builds pressure and the cycle is repeated.    The gases contained in the engine never leave and this engine does not have exhaust valves.  Since the Stirling Heat Engine is very quiet, can run on almost any heat source, and is very efficient innovators are attempting to re-apply this engine to the modern world where efficiency is becoming an important topic.

How the Stirling Heat Engine Works

The Peltier Device can be used for either heating and cooling applications and is classified as a thermoelectric generator.  This device was invented through two important discoveries.  In 1821, a scientist named J. T. Seebeck discovered that dissimilar metals that are connected at two different locations, known as junctions, will generate a small voltage if the two junctions are held at two different temperatures.  This set up is called a thermocouple and the greater the difference in temperatures the greater the charge that is generated.  This is known as the ‘Seebeck Effect’.  About a decade later, another scientist, Peltier, discovered the inverse of the Seebeck effect and called it the ‘Peltier Effect’.  Peltier discovered that if you put a voltage across a thermocouple it will cause a temperature difference at each of the junctions.  Peltier’s discovery allowed for the development of small heating and cooling systems.  This device is often found in water coolers and air conditioning units.Home Video Experiment: Peltier Device

In this experiment my partners and I explored Faraday’s Law.  This law states that changing magnetic fluxes through coiled wires generates electricity.  In order to change change the magnetic flux, a magnet has to pass through the coiled wire.  This law also states the greater the change in magnetic flux, the greater the current and voltage that is generated.

During this trial we used a tube attached to a reader that was hooked up to the computer.  The tube, shaped like a small flashlight, contained coiled wire and a magnet.  When you tilted the tube upright or downward, a magnet would fall through the coiled wire.  We connected the tube to a reader that was able to record the magnetic flux and electricity generated, but we had to count how many times we shook the tube manually.      

In this lab we shook a tube, which had a magnet in it that traveled back and forth through coiled wire, in five different trials to generate varying amounts of current and voltage.  In each trial we had a 30 second time frame to shake the tube.  In each trial we shook the tube more times.  After looking at all the data provided from the trials, we came to the conclusion that the more times we shook the tube, and the more times the magnet passed through the coiled wires, the more electricity we generated.

# of Shakes    Sum of Square of Voltage

45                158.86

60                179.22

86                198.72

107                238.1

114                399.89

The idea of electric cars has been around since cars became a popular form of transportation.  Modern versions of electric vehicles are growing in popularity due to their environmental impact.  Growing concerns around global warming and greenhouse gas emissions has influenced the transportation sector to rethink energy efficiency.  The standard car is run by an internal combustion engine which at best is roughly 30% efficient.  In other words, 30% of the energy stored in gasoline is used to move the car.  New technology that is incorporated into the latest electric cars, like the Tesla Roadster, is almost 90% efficient and produces nearly zero emissions.

 

The Tesla Roadster is powered by an electric motor.  The reason why this motor is so efficient is because the motor also acts as a generator when the the car is not being accelerated, turning mechanical power into electricity.  The Roadster uses a three-phase Alternating Current (AC) Induction motor, a very reliable, simplistic, and efficient motor.  The motor has two primary components, a rotor and a stator.  The rotor is a steel shaft with copper bars running through it, it rotates and turns the wheels.  The stator surrounds the rotor but doesn’t physically touch it.  The stator creates a rotating magnetic field, creating a current in the rotor.  The current in the rotor ‘chases’ the rotating stator and produces torque which moves the wheels.  This motor operates very quickly allowing the vehicle to accelerate faster than sports cars.  Since the Tesla Roadster is an electric vehicle it needs to be charged when the battery is low.

Tesla offers 520 charging stations called ‘supercharger stations’ that are spread out all throughout the United States.  These supercharger stations are able to fully recharge the car in only a few hours and are very easy to use.  The chargers deliver up to 120 kW of direct current (DC) directly to the battery, which can power the battery for a range of 170 miles in 30 minutes.  Charging your car is as easy as charging your phone, all you have to do is plug the adapter into the vehicle.  Tesla plans on building more charging stations in the near future.

Personal vehicles account for over half of the transportation sector’s emissions, and the transportation sector accounts for about 27% of the our total greenhouse gas emissions.  There are over one billion vehicles on the world’s roads today heavily contributing to global warming.  In order to become more energy efficient and to lower the amount of C02, more people should invest in the very energy efficient electric cars.

 

Source 1: http://my.teslamotors.com/roadster/technology/motor

 

Source 2: http://www.teslamotors.com/supercharger

 

Source 3: http://www3.epa.gov/climatechange/ghgemissions/sources/transportation.html

The purpose of the pulley experiment was was to explore Newton’s second law, the conservation of energy, velocity, acceleration, and power.  Newton’s second law states that the acceleration of an object is dependent on the net force acting upon an object and the mass of an object.  In 1842, Julius Robert Mayer discovered the Law of Conservation of Energy.  This law states that energy is never created nor destroyed.  This means that in any scenario energy is never ‘lost’, but simply transferred to another form of energy.  In this experiment we used a Lego Mindstorm motor and a pulley to lift weights to measure power and acceleration.  Through the application that we used on the computer, we were able to change the power of the motor and also calculate the acceleration that the weights ascended.

 

The apparatus that was used for the experiment was a pulley, a motor, and weights that measured up to 250 grams.  The motor was attached to the base of the pulley system.  A rod held the pulley about 12” above the motor, and a string was attached to the motor ran over the pulley and was connected to the series of small weights.  The apparatus is shown below.  

 

During the first half of the experiment we were testing Newton’s second law.  We did five separate trials to measure the acceleration of the weights.  We kept the power at a constant of 50 and did five trials with different weights varying between 0 grams and 250 grams.  Because the how the computer application was set up we had to consistently convert grams to kilograms to get accurate results.  By looking at the data we collected from the five different trails, we can see that we have confirmed Newton’s second law.  As we increased the mass and kept the power constant, it can be seen that the acceleration of the mass diminished as the weight increases.

 

MASS(KG)                       POWER                     ACCELERATION(RPM/S)

0.25                                       50                                   10

0.09                                       50                                    21.74

0.13                                       50                                    20.8

0.15                                       50                                    18.75

0.19                                       50                                    14.25

 

During the second half of the experiment, we ran the trails nearly opposite.  We kept the mass constant while we increased the power level and examined the acceleration.  As we increased the power of the motor, the acceleration of the mass continued to increase which would make sense when comparing the data to the first half of the experiment.

 

MASS(KG)                       POWER                     ACCELERATION(RPM/S)

0.25                                       45                                   6.58

0.25                                       55                                  13.93

0.25                                       60                                  19.42

0.25                                       70                                   32.85

0.25                                       85                                   57.67

Electricity is the primary energy source used in our everyday lives.  It is used to light our homes, keep us cool/warm, and it powers endless technology that is used on a day to day basis.  The Energy Grid in the United States is primarily powered by coal, natural gas, and nuclear reaction.  In 2014, 39% of the electricity generated was through using coal, natural gas was used for roughly 27%, nuclear reaction 19%, and hydropower and other renewable sources was used for the remaining percentage.  But just how ‘clean’ are these methods of producing electricity?

Coal is the most used fuel to create energy around the world.  This organic sedimentary rock is made of decomposed plants from millions of years ago and can be found in underground deposits gloabally.  These deposits are easily accessible making coal cheaper than other methods of electric generation.  Converting coal into electricity is a multistep process and is performed by coal plants.  The first step is crushing the coal into a fine powder.  They then use the powder as fuel in a furnace.  The furnace heats a boiler, which holds water, to create steam.  The steam turns a turbine engine which powers a generator, creating electricity.  Although this resource is easily accessible and is used globally, coal plants are among the top sources of carbon dioxide emissions.  Burning coal produces nitrogen oxides, sulfur dioxide, and carbon dioxide.  A typical coal plant in the United States generates 3.5 million tons of carbon dioxide per year.  Coal may be the cheapest resource of generating electricity, but it is the dirtiest.

Throughout the years, there has been an increased use of natural gas to generate electricity.  Steam generation units can also be used with natural gas, just like with coal.  Although, basic steam generation units are usually not that efficient.  According to reports, only about 33-35% of the thermal energy used to generate the steam is converted into electricity.  Electric generation can also be achieved through the use of a gas turbine fueled by natural gas.  This system uses hot gases released by the burning of natural gases to turn a turbine to generate electricity.  Combined-cycle plants recycle the waste heat from the gas turbine and used to generate steam to increase natural resource efficiency.  These plants can achieve thermal efficiency of 50-60% making them much more efficient that coal plants.  Like coal, natural gas emits both nitrogen oxides and carbon dioxide but at lower rates, nearly half the C02 emissions of coal.

There are nearly 100 nuclear facilities in 30 different states in the U.S. that are responsible for almost 20% of the energy grids electric generation.  Nuclear reactors are powered by uranium.  Reactors produce and control energy that is acquired through the splitting of uranium atoms.  This harnessed energy is then used in the same manner as coal plants and combined-cycle plants; water is boiled to make steam which drives turbine generators.  This process is a much cleaner and efficient way of producing electricity.  Greenhouse gases are not a byproduct of nuclear reaction.  According to reports in 2014 nuclear energy facilities prevented 595 million metric tons of C02 emissions, 1 million short tons of sulfur dioxide, and 0.48 million short tons of nitrogen oxide which would have been polluted the atmosphere if electric generation was done by coal plants and combined-cycle plants.  Although nuclear reaction might seem like the most efficient way of producing electricity, there are numerous risks associated with the process.  For example, if a serious accident were to occur at a nuclear power plant dangerous amounts of radiation would enter the environment and would result in disastrous damages.  There is also an increased risk of cancer for those individuals exposed to the radiation.  Radioactive waste is the byproduct of nuclear reaction.  This waste is often kept at the nuclear facilities for a certain period of time while the level of radiation decays until it is safe to be buried deep in the ground.

In order for the nation to become more efficient and produce less C02 emissions, the use of coal plants must be replaced by cleaner and more efficient methods of generating electricity.  Even transforming the current coal plants into combined-cycle plants would prove very effective in the short run considering natural gas produces half the emission of coal.

 

Source 1: http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3

 

Source 2: http://www.peabodyenergy.com/content/178/coal-fueled-electricity

 

Source 3: http://www3.epa.gov/climatechange/ghgemissions/sources/electricity.html

 

Source 4: http://naturalgas.org/overview/uses-electrical/

 

Source 5: http://www.nei.org/Master-Document-Folder/Backgrounders/Fact-Sheets/Quick-Facts-Nuclear-Energy-in-America