Environmental Test #2

What do we currently do with spent fuel?

-put them in pools -creates nuclear waste

New Designs/Improvements for Nuclear Energy

-use solar energy to heat homes -carbon tax -smaller homes, super insulated homes, live closer to jobs, cars with better mpg -mass produce these reactors to lower the cost

Describe the current practices for dealing with spent fuel rods

. Spent fuel rods are placed in storage pools to decay in an environment that dissipates the continuing heat from the rods and prevents the escape of radiation. These rods are left in dry seals to be left to decay.

Advantages and Disadvantages of Nuclear Energy

c. Advantages i. Small amounts of fuel run reactors ii. Little carbon footprint iii. No other pollution other than radioactive waste 1) Burning coal produces 100 times more radiation iv. Base Load 1) Nuclear power can run 24/7 We never drop below a certain minimum amount of energy use

Discuss changes in nuclear power that might brighten its future

-framework for licensing and monitoring reactors must be streamlined, waste dilemma with the Yucca Mountains must be resolved, industry's manufacturing philosophy will have to change to favor standard designs and factory production of the smaller reactors

Control Rods

-rods of neuron-absorbing material that controls the chain reaction in the reactor core -withdraw and insert control rods to start and control the chain reaction

Fuel Rods

-to achieve the geometric pattern necessary for fission, the enriched uranium dioxede is made into pellets that are loaded into long metal tubes (fuel rods) -placed close together to form a reactor core inside a strong reactor vessel that holds the water

Describe two concentrated solar power systems, how they work, and their potential for providing power

. Solar Trough: collectors are long, trough-shaped reflectors tilted towards the sun, all the sunlight hitting the collector is reflected onto a pipe running down the center of the system, usually oil circulates through the pipe and is heated to high temperatures, this oil is passed through a heat exchanger to boil water and produce steam that is put into a generator. This has great potential because it can store thermal energy at night. Power Tower: ann array of sun-tracking mirrors that focus the sunlight onto a receiver mounted on a tower in the center of the area, the receiver transfers the heat collected to a liquid and is flowed to a heat exchanger, and then stored.

Indirect Solar

1) Hydroelectric a) The sun shines on the land, water and plants and plants give off oxygen as they grow b) Use water pressure from dam that is connected to a generator c) Advantages i) Lasts a long time so it is relatively inexpensive d) Disadvantages i) When you create a large dam you destruct the ecosystem One. Microhydro small and less harmful has begun to be more popular e) Big dams around the world i) China - 3 Gorges Dam ii) Many in south America iii) Largest one in the Congo 2) Wind Power - electricity a) Solar power makes air rise, creating more wind b) Power = xy(velocity)^3 therefore small increases in wind velocity can make a huge increase in amount of power produced c) 25 MW of peak power per tower d) Around 800 homes (32% utilization factor) e) $.03-.05 kW/hr f) Iowa produces 33% of its electricity g) Can get smaller personal ones but they are not economic because they don't last long h) Inside the wind turbine is a gear box and generator that produces electricity 3) Biomass - fuels, chemicals, plastics a) Animal and plant material = biomass b) Plants grow because of the sun's energy, plants take carbon dioxide out of the atmosphere c) If we added up all resources of biomass in USA we could produce 21% of US energy d) Carbon neutral because it uses the sun's energy to grow and take in the earth's carbon dioxide e) Biological Conversions i) Definition: Using biology or creatures to makes biomass into energy ii) Types One. Digestion: biomass is put and sealed in a closed building, bacteria uses all types of oxygen, there are other types of bacteria that do not need oxygen to live (anaerobic) that produce methane Two. Fermentation: sugar -> yeast -> about 10% ethanol (industrial plants call this beer) if you distill this you get 95% ethanol Three. Corn -> sugar -> ethanol Four. Cellulose (fiber -> sugar -> ethanol f) Thermochemical Conversion i) Using heat to convert biomass ii) Combustion (100% O2) iii) Pyrolysis (0% O2) iv) Gasification (30% O2) One. Smolder biomass and use smoke to create energy/chemicals Two. Uses: plastics, liquid fuels and chemicals g) Dedicated crops i) Quantity per acre One. Mescanthis grass: 10 ft tall, lots of diversity Two. Seed production to create ethanol Three. Oil crops: sunflowers -> you can turn oil into biodiesel Four. A lot of possibility to grow different crops to produce energy h) Vegetable Oil -> biodiesel

Direct Solar

1) Passive heating of our homes a) Key Features i) Super insulate houses - 12'' thick walls One. Lots of insulation in the attic Two. Get better windows Three. Build a house that is tight-no cracks in construction ii) Building orientation One. Put most of the windows on the south side of the house First. In the winter these windows allow sun for heating Second. In the summer the sun is positioned so that barely any sun gets into these windows Two. Overhang on windows iii) Thermal mass One. Have brick, concrete, or stone that takes the sun a while to soak up Two. Prevents house from getting too hot Three. These substances store solar energy throughout the day to heat the house at night iv) Insulated shades for windows One. Traps heat in the house v) Landscaping can help shade the house form the sun in the summer b) Save 40-60% on yearly energy costs by just facing the windows in a house to the south i) If you super insulate your house as well, you save up to 90% less energy 2) Heat water with sun 3) Produce electricity with photovoltaic panels

Storage of Renewable Energy

1. Batteries: many new types a. Cars and utilities (Tesla) b. Prices are going down 2. Thermal storage -> store heat a. Residential i. Store in the ground through geothermal heat pumps 3. Biomass has built in storage a. Can be converted to liquid fuels 4. Compressed air - old mine shafts a. Limited by geography 5. Pumped hydro a. Store water up on a mountain 6. Hydrogen a. Works best with electricity b. Produce hydrogen from water with extra electricity c. Store water d. Use it in a fuel cell 7. Ammonia a. Produce ammonia with extra electricity b. Can burn it in our cars

Why is it important for renewable energy sources to replace fossil fuels? What are the prospects for getting it done?

1. The most prominent reason is global climate change, because fossil fuels have loaded the atmosphere with greenhouse gas carbon dioxide. Sea levels and temperatures continue to rise. Other reasons include that oil and gas reserves may not last for more than a couple of decades and the problem of pollution. This will happen through wind farms, solar power, electric cars, and the RPS in states.

Hydrogen/ammonia economy

6. Hydrogen a. Works best with electricity b. Produce hydrogen from water with extra electricity c. Store water d. Use it in a fuel cell 7. Ammonia a. Produce ammonia with extra electricity Can burn it in our cars

Describe how energy is produced in a nuclear reaction. Distinguish between fission and fusion.

A nuclear reaction results from the splitting and controls of atoms from Uranium. There are two processes that this can look like which is fusion and fission. Fission: nuclear energy is released when the splitting of certain large atoms into smaller atom Fusion: nuclear energy is released frim the fusing together of small atoms to form a larger atom In both cases, some of the mass of the starting atom or atoms is converted to energy.

What is the potential for developing more hydroelectric power in North America versus developing countries, and what are the impacts of such developments?

About 6.6% of the electrical power used in the USA comes from large hydroelectric dams, and worldwide the average is about 18%. In the USA there are about 87,000 dams that are six feet high or more and an estimated 2 million smaller structures. Only 2% of rivers remain free flowing. It is hard for developing countries to build dams because of the ecological and sociological trade-offs.

How do active and passive solar water heaters work?

Active: the heated water is moved by mean of a pump, Passive: the system is mounted so that the collector is lower than the tank, and the heated water from the collector rises by natural convection into the tank, while cooler water from the tank descends into the collector

What features might make nuclear power plants safer?

Advanced boiling-water reactors in the event of a loss of coolant accident, two separate passive systems would allow water to drain by gravity to the vessel Generation 5 plants: pebble-bed modular reactor will fed spherical carbon coated uranium through the reactor vessel and will be cooled with fluidized helium

Benefits of Renewable Energy

Advantages of Solar/Renewables: 1. Energy is free once the infrastructure is built 2. Pollution free 3. Domestic - not depending on politically unstable countries 4. Sustainable - fossil fuels will run short 5. Cheaper - most of the time

What makes economic sense now with renewable energy and what may be coming in the future?

Advantages of Solar/Renewables: 1. Energy is free once the infrastructure is built 2. Pollution free 3. Domestic - not depending on politically unstable countries 4. Sustainable - fossil fuels will run short 5. Cheaper - most of the time Disadvantages 1. Cheaper for long term but expensive at first 2. New unknown 3. Some forms are inconsistent -> need storage 4. Biomass is bulky and takes up space 5. Some more expensive -> carbon tax would help 6. Aesthetics (especially wind turbines)

How does a PV system work, and what are some present applications of such cells?

Each cells consists of two thin layers of semiconductor material separated by a junction layer. The lower layer has atoms with single electrons in their outer orbital that are easily lost. The upper layer has atoms lacking electrons in their outer orbital and easily gain electrons. When light strikes the two layer "sandwich" it dislodges electrons from the lower layer that creates a current. This current travels to the upper layer through the means of an electrical device. These are used in pocket calculators, watches, toys, and

How can hydrogen gas be produced via the use of solar energy? How might hydrogen be collected and stored to meet the need for fuel for transportation in the future?

Employ a catalyst to do what the photosynthetic pathways do through a collector that converts photons into electrical energy and an electrolyzer that uses the electron energy to split water into hydrogen and oxygen. Another strategy is employing a water-oxidizing electrolyzer catalyst made from cobalt and heavy metal alloy. The process uses light energy captured by silicon solar cell and generates oxygen in either a wired or wireless cell. For transportation, it would start by building arrays of solar-trough or photovoltaic gernating facilities in the deserts of the southwestern US. The electrical power produced by these methods would then be used to produce hydrogen gas by electrolysis.

Which biofuels are used for transportation, and what is the potential for increasing biofuels in the USA?

Ethanol and Biodiesel. USA must make federal tax credits to make biofuels more competitive. A renewable fuel standard requires a minimum volume of renewable fuel in gasoline. Maybe algae used to induce and produce oils and complex oils.

How can a building best be designed to become a passive solar collector for heat?

First, windows, walls, and floors should be designed to collect, store, and distribute solar energy. It is important to take in to consideration the climate of where this building is to be planted. Windows should be planted on the south side of the house, and less windows in the north.

What is geothermal energy, and what are two ways it is being harnessed?

Geothermal energy uses such naturally heated water or steam to heat buildings or drive turbogenerators. Two ways it is harnessed is through heat pumps and dry steam plants.

How do fuel cells work, and what is being done to adapt them to power vehicles?

Hydrogen or some other fuel is chemically combined with oxygen in a manner that produces an electrical potential rather than imitating burning. To power a vehicle, hundreds of fuel cells are combined into a fuel-cell stack. The vehicle must also include a hydrogen storage device to force oxygen into the fuel cells and a cooling system. We would need many fueling stations for hydrogen.

How do nuclear reactors and nuclear power plants generate electrical power?

Nuclear Power Plants: use the fission of uranium-235, fission reactions give off several more neutrons and releases a great deal of energy, if theses neutrons are slowed down and then strike another U-235 atom they cause fission to reoccur Nuclear Reactor: designed to sustain a continuous chain reaction by enriching the uranium-235 to 3-5% which prevents a nuclear explosion, one third of the energy of a nuclear reactor is from plutonium fission

What are some ways of converting biomass to useful energy, and what is the potential environmental impact of each?

Pellet Stove: a device that burns compressed wood pellets made from wood wastes, pellets are loaded into a hopper and feeds fuel when it is needed. a. Emits greenhouse gases, produces a lot of smoke Underground brick masonry fermentation chamber with a fixed dome on top for string gas Agricultural wastes are put into the chamber and diluted with water, the anaerobic digestion of the wastes produces biogas which is used for electricity.

How are radioactive wasted produced, and what are the associated hazards?

Radioactive wastes are produced because of nuclear fission. Nuclear fission produces a number of unstable isotopes. They become unstable and radioactive by absorbing neutrons from the fission process. Effects/hazards: radiation exposure from biological tissue, prevent cell division, preventing repair of blood, skin, and other tissues, damage DNA (which can result in birth defects, tumors, or cancer), mental retardation, cataracts, weak immune system, and sometimes death

Nuclear Power Plant Operation

This chain reaction is controlled with "control rods" that absorb neutrons. In the core of nuclear reactors, the fission of uranium atoms releases energy that heats water to about 520 degrees Farenheit. This hot water is then used to spin turbines that are connected to generators, producing electricity.

Describe what went wrong at Three Middle Island, Chernobyl, and Fukushima.

Three Mile Island: partial meltdown due to human and equipment failures and flawed design, the steam generator shut down automatically because of a lack of power it its feedwater pumps, a valve on the top of the generator opened in response and grew in pressure Cheronobyl: while conducting a test of standby diesel generators, engineers disabled the plant's safety systems, withdrew the control rods, shut off the flow of steam to the generators, and decreased the flow of coolant water in the reactor. The reactor began to heat up, a worker poured water on the burning control rods, and this resulted in a steam explosion. Fukushima: an intense earthquake was accompanied by a strong tsunami, there was not protection against the power plant, power was lost and backup diesel generators only had eight hours of batteries to provide power for cooling the reactors, there was not way to provide cooling to spent fuel or vent dangerous gases from containment buildings

Where is wind power being harvested, and what is the future potential for wind farms?

Wind power is being harvested in wind turbine windmill farms. China is the world leader in wind energy. Most windmills are wind-driven propeller blades. This development is growing in popularity. In 1996 the capacity was only 6 GW, while in 2013 the capacity skyrocketed to 318 GW.

Geothermal Heat Pump

a. Moves energy from the ground to heat buildings b. Harvest energy from the ground and bring it indoors c. Wells and coils Great from an energy point of view but can be expensive

The potential for conservation as a means of addressing limited energy resources

a. Use less (about 50% less of energy) i. Smaller homes, super insulated homes, live close to job, cars get better mpg

Know the Basics of the Three Main Nuclear Reactor Accidents

c. Advantages i. Small amounts of fuel run reactors ii. Little carbon footprint iii. No other pollution other than radioactive waste 1) Burning coal produces 100 times more radiation iv. Base Load 1) Nuclear power can run 24/7 We never drop below a certain minimum amount of energy use d. Disadvantages i. Nuclear waste 1) Old fuel rods: uranium that is spent 2) Contaminated material: materials that result from being exposed to Uranium 3) Half life a) Time for 1/2 of a radioactive substance to decay b) Some of the worst have a half life of 10,000-20,000 years - what do you do with this? i) Concern for what America will be like in 10,000-20,000 years ii) All nuclear power plants are on hold, collecting it ii. Safety: accidents 1) 3 primary ones a) 3 mile island i) On east coast ii) Human error and machine error b) Chernobyl i) Ukraine ii) Testing safety equipment and overheated iii) During the test they changed workers and there was poor communication which resulted in a call for more electricity iv) Overheated and made the graphite control rods burn v) Workers dumped water on them and there was a steam explosion vi) Poured concrete just a couple years ago and put a new cap on top c) Japan i) Both a tsunami and an earthquake iii. Limited resource iv. Expensive to build but also to take apart 1) Subsidized (supported by government)

Fusion

combining hydrogen atoms to make helium which has less mass than the original two hydrogens - This is how the sun produces its energy - More powerful than fission - trying to find out how to control this reaction to create energy

Fission

splitting of U^235 into other elements that have a total of less mass

What problems are associated with the long-term containment of nuclear waste? What is the current status of the disposal situation?

the buildup of spent fuel in every nuclear power plant is increasing, where to store this waste is very controversial, safety could be jeopardized by earthquakes, volcanic activity, or changes in geologic time, water from Yucca Mountain could leak in to the repository and corrode the fuel assemblies stored there and then release radioistotopes into groundwater. Current Situation: radioactive waste repository has already been contrustices and is operating to receive defense-related wastes in the Waste Isolation Pilot Plan near Carlsbad, New Mexico.