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ME 417 Quiz 5 Notes
| Question | Answer |
|---|---|
| photons are ______ | energy |
| list the types of electromagnetic radiation in order of shortest to longest wavelength | gamma rays, x-ray, UV, visible, infrared, radio |
| list the types of electromagnetic radiation in order of lowest to highest frequency | radio, infrared, visible, UV, X-ray, gamma |
| the sun bathes the earth in _________ all day every day | photons |
| where is solar energy potential the highest | the sun belt |
| who discovered solar PV ---> photons into electricty | Alexandre Edmond Becquerel |
| what is the discovery of solar PV ---> photons into electricity | the photovoltaic effect |
| when and where were the first solar panels installed? and by who | 1884, NY rooftop, Charles Fritts |
| 95% of solar modules are made from ________ | silicon |
| what are three types of silicon solar cell materials? | thin film, monocrystalline, polycrystalline |
| silicon is not a metal (conductor, not an insulator - its a ________ | semiconductor |
| semiconductors have a medium sized _______ gap | energy |
| when E(photon) > E(gap) what happens? | light can be absorbed by a material and converted into electricity by a semiconductor device |
| what type of power does solar energy provide? | DC power |
| what does the operation of a solar panel look like? | the sun hits a layer of transparent electrode --> the next layer is semiconductor with protons ---> next layer is with electrons --> bottom layer is black electrode |
| what type of cell? light hits the solar cell, only photons with just the right energy work well | single-junction cell |
| what type of cell? multiple layers, each layer is designed for a different energy level of light | multijunction cell |
| multijunction cells are more efficient because they use multiple ___________ to capture different parts of the solar spectrum, reducing E losses | bandgaps |
| what is a perovskite? | type of crystalline structure (ABX3) that's highly efficient at absorbing light |
| what are the components of a solar panel? | batteries DC-DC convertor, DC-AC power conditioner and invertor, AC-DC rectifier |
| what is a centralized PV plant? | on grid, suitable for PV sys of any size, no need for expensive backup batteries |
| For residential PV systems what is the driving cost and what are other significant costs? | driven by hardware cost, significant soft costs |
| for utility scale what is their major cost and how is it comparable to residental? | hardware, lower cost than residential |
| for PV the user benefits are ________ __________ than the manufacturer profits | 100x greater |
| what are the four types of solar energy? | solar PV, concentrating solar, solar water heaters, passive solar heating |
| what does concentrating solar do? | turns the suns energy into heat, it mirrors direct sunlight to a place where the sunlight boils a fluid |
| what do solar water heaters do? | use the suns energy to heat water directly or through a H.T. fluid that warms a homes water supply |
| what do passive solar heating systems do? | uses building design (windows) to naturally capture store and distribute heat from the sun inside a building |
| the average price of solar PV panels has _______ over the years | decreased, a LOT |
| uses multiple high efficiency semiconductor layers to capture different wavelengths of light for max efficiency: | III-V Multijunction cells |
| a high efficiency solar cell made from gallium arsenide using a single energy bandgap: | Single-Junction GaAs |
| traditional silicon solar cells made form single or multiple crystals, widely used due to reliability and cost: | Crystalline Si cells |
| use very thin layers of materials (CIGS or CdTe) to create lightweight and lower cost solar cells | Thin-Film |
| new and developing solar technologies (perovskites, quantum dots) aiming for higher efficiency and lower cost | emerging PV |
| combine two different materials to improve overall solar cell efficiency | hybrid tandems |
| what are three animals that have adapted to use the suns energy to their benefit? | sea slug, spotted salamander, oriental hornet |
| in the solar PV power equation what is W(dot) | power produced |
| in the solar PV power equation what is n(pv) | cell efficiency |
| in the solar PV power equation what is A(col) | collector area |
| in the solar PV power equation what is G"(solar) | solar irradiance (radiation flux, W/m^2) |
| in the cell efficiency equation what is n(0) | reference efficiecy (ideal conditions) |
| in the cell efficiency equation what is beta(PV) | cell coefiicent |
| in the cell efficiency equation what is T(0) | reference temperature |
| in the cell efficiency equation T(c) | cell temperature |
| what does NOCT mean? | nominal operating cell temperature |
| what is the equation for optimum tilt angle? | optimum tilt angle = latitude - declination (both are angles) |
| in the C(f) equation what is s(m) | optimum tilt |
| in the C(f) equation what is s | actual tilt |
| in the C(f) equation what is C(f) | tilt correction |
| what is K(t) in these solar equations | clearness index |
| what is the simplified LCOE equation? | LCOE = total lifetime cost / total lifetime energy |
| what is radiation H.T.? | energy exchange due to electromagnetic energy propagation |
| what's going on in the earths core? | convection currents |
| where is peak geothermal energy in the U.S.? | western states |
| as you do down in km in the ground the temperatures __________ | increase |
| what is hydrothermal? | use the hot water that reaches close to earths surface |
| what is direct use of hydrothermal? | use of the thermal E as a source of heat for dwelling/business heating |
| what is power generation for hydrothermal? | use of the thermal E from hydrothermal as a source of heat for turbines to make electricity |
| what are enhanced geothermal systems? | drilling into the earth to access thermal reservoirs |
| what are binary power plants? | use geothermal brine as heat source in an organic Rankine cycle |
| what are flash/dry steam? | use geothermal brine as heat source in a traditional water-based Rankine cycle |
| what can geothermal energy be used for? | WIDE range: low temperature uses like heating, high temperature uses like electricity and hydrogen production |
| power generation requires ______ temperatures and _________ wells | higher, deeper |
| direct use - heating applications at ________ tempertaures | lower |
| what do ground heat exchangers do? | transfer heat between the ground and building using different systems |
| what is the first step in EGS | establish a temperature profile |
| what is the next step in EGS | drill a production scale well (>$1 million to drill) |
| what is the next step in EGS | set up valves and controls |
| when and where was the first use of geothermal electricity | Italy, 1904 |
| where is the worlds largest single source of geothermal power? | the geysers in northern CA |
| what are the two wells in a geothermal system? | production well, injection well |
| what is the process of a geothermal system? | high pressure hot water from ground enters production well --> goes to the generator --> pressure drops water becomes steam and powers turbine --> to cooling tower --> cooled water goes into the injection well |
| what does a flash steam plant do? | uses hot water reservoirs (T>180 C) as pressure drops, some water flashes to steam |
| what is the process of a flash steam system? | hot water from ground --> flash tank --> turns to steam --> turbine --> generator to produce electricity --. condensed steam (water) back to ground |
| what does a binary cycle plant do? | uses another working fluid |
| the binary cycle follows the same process as flash but: | the hot water goes through a heat exchanger that contains a binary fluid like butane |
| organic Rankine cycle uses what | low boiling point fluids instead of water so they can generate power from lower temperature heat sources |
| what is the top country for geothermal energy? | U.S. |
| can geo. E be depleted? | over long times --> NO over short periods, locally, with extreme demand --> YES |
Created by:
mccurdyo