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Practivistas renewable energy 2014/Literature Review

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Literature Review[edit]

This is a a review of the literature pertinent to the La Yuca renewable energy 2014 project, and the Ghetto2Garden renewable energy 2014 project.

Location[edit]

La Yuca del Naco, Santo Domingo, Dominican Republic
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Weather[edit]

Santo Domingo, which is located on the southeast side of the Dominican Republic, possesses tropical climate characteristics. These include long hours of sunlight, high average temperatures, frequent calm winds, and rain. [1] The average annual temperature for Santo Domingo is approximately 79 degrees farenheit with the warmest months ranging from June through October and the cooler months are from November to May. These high temperatures are a result of the long hours of sunlight this region receives each day, the average annual sunlight hours per day is around 6 hours and 30 minutes. The longest sunlight hours is in March with about 7 hours and 30 minutes per day, while the least amount of sunlight hours is in December with around 6 hours per day. Santo Domingo receives an average annual of 2,320 hours of sunshine per year. Despite these warm temperatures and sunshine, Santo Domingo receives an average of 57 inches of rain per year.[2] The rainiest months are from May to October and the lowest amount of precipitation is from November to April. When considering renewable energy ideas to implement, climate characteristics will heavily influence appropriate installations.

Alternative energy[edit]

"There are several alternative ways of energy production that have found different kinds of application areas. Renewable sources like wind and solar energy have become prominent in this regard among the different alternatives due to the huge energy potential of wind and solar power...the main disadvantage of these technologies is the direct relation of their electric power production with the meteorological conditions like wind speed, solar radiation, and temperature. These conditions may change from season to season, and even from one moment to another, providing the need to balance the load demand variation and variable renewable power production. This issue can be overcome by employing some form of backup unit that can provide deficit power when the renewable sources are not sufficient to meet the load demands and accept and store excess power production when the renewable power production is greater than the load power. This integration of renewable sources with backup units provides a hybrid system to ensure the supply of the load in all of the possible conditions." [3]

Solar power[edit]

How Solar Works[edit]

In order for solar panels to work, energy from the sun in the form of electromagnetic radiation must reach the solar cells. Most of the energy from the sun is either absorbed by the earth, allowed to bounce back into the atmosphere, or it can become visible light. The amount of energy that the earth receives can also be dependent on the weather. Solar panels and their ability to collect the suns energy are directly affected by these factors. These solar panels are made up of solar cells which consist of two thin layers of silicon known as the n-type (first) and p-type (second) layers . As the suns energy reaches these solar cells, the electrons from the electromagnetic radiation hit the silicon atoms within the first layer and force the existing atoms out of the way. The displaced atoms transfer across the gap between the two layers of silicon which in turn produces an electrical current. This however is the process of a single cell where most of the suns energy is either lost through heat, or through the fact that only a small range of light wavelengths can be picked up through the solar cells. Thus, it is necessary to wire together large amounts of these solar cells together to create the solar panels that have the capacity to produce a usable amount of energy. [4]

Installation[edit]

A general template for configuring a solar photovoltaic system includes 5 major components. The first and most essential component is the solar PV array, otherwise known as the actual solar panel. After the suns energy has been converted into electricity, it travels to the system control interface. This component is responsible for the collection of the energy and the direction of the energy to either the load that is being supported or to the battery bank. The system control interface is also responsible for transmitting signals to the user to determine the operations of the system and for general information about necessary maintenance. From here the energy travels to a transfer switch which, depending on the system can send the electrical current to different components. The two most common components that receive the signal are the critical loads, which is the machine or system that is being powered, and the battery which receives any excess electricity that isn’t being utilized by the systems being powered. [5]

Theft Prevention Techniques[edit]

"Strategies for reducing theft of equipment, especially solar panels include:

  • Proper installation of a solar system is one effective strategy to reduce theft.
  • Theft-proof hardware such as bolts that require special wrenches can help prevent theft of solar panels.
  • Solar panels, without special secure mounts, are frequently stolen. Tamper free mounting systems can complicate removal of the system.
  • Positioning of the solar panel - pole mounting and roof top installation - could also serve as a tamper/theft prevention measure.
  • Timely maintenance of solar systems is also an important deterrent to theft.
  • Community involvement is crucial for theft prevention.
  • Hiring a guard to protect the equipment has been an effective technique utilized in USAID-supported solar hospital electrification programs in sub-Saharan Africa.
  • Training solar panel operators and maintenance staff on theft prevention measures and strategies is also essential." [6]

Silicon solar cells[edit]

There are three main types of solar cells that are commonly used for non-commericial use, among these three are, mono-crystalline silicon, poly or multi-crystalline silicon, and amorphous silicon cells. Each of these three silicon cells have pros and cons. Budget, location and amount of desired energy output all need to be taken into consideration before deciding on which one to install.

Mono-Crystalline cells use one endless silicon grid, designed to eliminate the chance of any deformities. This type of cell is the most difficult of the three to construct and therefore has the highest price cost. On the other hand, it the most efficient when it comes to powering appliances, efficiency is recorded around 15%.

Poly and or Multi crystalline cells are another popular silicon cell. These cells are much easier for companies to assemble because the process uses liquefied silicon which is put into molds and left to sit until crystals form in the molds. The mold size varies based upon the company. This process is relatively inexpensive compared to the prices of mono-crystalline which makes them desirable to public consumers who wish to spend less money but are looking for similar efficiency. On average these systems run around 12% efficient.

Amorphous silicon cells differ from the other two because they are constructed from narrow layers of silicon atoms. This type of construction process results in a less efficient energy output, but costs significantly less money to build and is therefore the least expensive of the three products. Amorphous silicon cells can be beneficial to consumers who wish to power small appliances, such as garden lights.[7]

Solar irradiance[edit]

Global Horizontal Irradiance is defined as the amount, in units of area that radiant energy from the sun is taken in by a level surface. These values are mainly used in photovoltaic systems. Both direct and diffuse radiation are accounted for in the final amount. Direct radiant energy is defined as light that comes from the sun without interference and diffuse energy is harnessed from all directions, indirect or direct. Santo Domingo has an annual global horizontal irradiance of approximately 27 W/m^2.

Direct Normal Irradiance is defined as the amount, in units of area that radiant energy from the sun is harnessed by level surface which is always in exact viewpoint of the sun. These values are mainly used in concentrating solar installations.

Diffuse Horizontal Irradiance is defined as the amount, in units of are that diffuse radiant energy is harnessed by a level surface. This type of irradiance does not take into consideration shade, nor does it depend on a fixed angle from the sun. Santo Domingo has an annual mean diffuse horizontal irradiance value of approximately 85 W/m^2. [8]

Solar Efficiency[edit]

"The crystalline silicon solar cell was the first practical solar cell invented in 1954. The efficiency of such solar cells as mass produced is 14–20%, which is still the highest in single-junction solar cells." [9]
“The efficiency of a solar cell is determined as the fraction of incident power which is converted to electricity and is defined as:

Pmax = Voc*Isc*FF
η = Voc*Isc*FF/Pin

Where:
Voc is the open-circuit voltage;
Isc is the short-circuit current; and
FF is the fill factor
η is the efficiency.” [10]

Batteries[edit]

In order to store excess energy produced by solar photovoltaic systems, batteries can be wired together to create battery banks. These systems, which may consist of 2, 6, or 12 volt batteries are then wired in a parallel circuit to create a system that is capable of producing high amounts of energy and storing it for an extended amount of time. While many types of batteries exist to harness excess energy produced by solar photovoltaic (SP) systems, two of the more popular types of batteries that are currently available are lead-acid batteries and lithium nickel metal hydride batteries. Lithium and nickel hydride batteries are known for being utilized in common everyday items like laptops and cellphones. These batteries are most compatible with these types of devices because they tend to retain a lot of energy despite their capacity to be very small. However, due to their capabilities, they tend to be more expensive and are not recommended for SP systems on any level. Deep-discharge lead-acid batteries however, are designed specifically for SP systems and have been the standard for most residential solar systems for years. Lead acid batteries are most commonly found in cars, but are also used for maintaining critical electrical systems when conventional power grids fail or go temporarily offline. [11] The advantages that come with batteries are that they can provide energy during periods of time when the sun isn’t out, and they can provide a constant and stable energy output, especially during times of peak energy demands. Some disadvantages to batteries in SP systems are that they can be costly, and they increase the general complexity and over need for maintenance of the system. [12] [13]

Price[edit]

According to an article focusing on renewable energy in the region of Central America the price for domestic Photovoltaic systems of 75Wp decreased approximately 29% between and years of 1997 and 2000. The table below describes the estimate cost in Central America of different Photovoltaic systems in 2002.

Type of System Capacity (W) Range of Cost (US $)
Individual CD 50-100 600-2,000
Individual CA 75-500 W 1,030 - 5,000
Isolated System 0.3 - 10 kW 3,560 - 50,000
Off-Grid system 10 kW - 1 MW 75,000 - 750,000

[14]

Wind power[edit]

"Wind turbines convert the kinetic energy in wind into mechanical power that runs a generator to produce clean electricity...The wind turns the blades, which spin a shaft connected to a generator that makes electricity." [15]

"The rated power of small wind turbines falls in the range of 1,000 to 100,000 watts... [and] do not produce their rated power all of the time, only when they're running at their rated wind speed... [Disadvantages] include wind's variability, bird mortality, aesthetics, property values and unwanted sound... To avoid costly mistakes, installers recomend that wind machines be mounted so that the complete rotor (the hub and the blades) of the wind generator is at least 30 feet (9 meters) above the closest obstacle within 500 feet..., or a treeline in the area, whichever is higher." [16]

Equation for power output:[16]

P = 1/2d * A * V3

where:

P = power available in the wind

d = density of the air

A = area of the circle that the blades create when spinning

V = wind speed

Ghetto2Garden[edit]

"Ghetto2Garden takes care of cats and dogs with reduced potential for adoption; that are deformed, blind, unwanted, elderly, and/or are terminally ill." [17]

"A group of individuals... known as Colectivo Revark, have created a colorful sustainable shelter for... unfortunate animals, who have previously suffered from either abuse or neglect. And they've built it from salvaged plywood, tires, shipping pallets, and plastic drums." [18]

"Empty plastic cube tanks are upcycled into cozy rooms for each of the animals, which are arranged on multi-level floors, accessible by ramps...Colectivo Revark...plans to keep the shelter as green as possible, installing...a small wind turbine on the roof, [and] a solar generator... The center will not only help mistreated animals, but it will also provide a blueprint for sustainable architecture in the Dominican Republic." [19]

La Yuca schoolroom renovation[edit]

"In 2011 a renewable energy system used to power lights was installed on a roof near the school. In 2013 the system no longer worked, because the wire was cut, the battery was dead, and there was corrosion in some of the wires. To solve this issue, the panel was moved to the roof of the school, closer to the schoolroom, where it is visible to nearby neighbors and where theft is less likely. Two new batteries were installed, and the system was simplified, since the wind turbine was no longer being used. The shunt and relay installed previously were taken out, and now the batteries, the panel, and the lights are connected directly to the charge controller with fuses near the battery and the light switch."[20]

References[edit]

  1. "Santo Domingo Annual Weather Averages." Weather Averages for Santo Domingo, Dominican Republic. N.p., n.d. Web. 11 June 2014. <http://www.holiday-weather.com/santo_domingo/averages/#chart-temperature>.
  2. "Climate of Santo Domingo, Dominican Republic Average Weather." Climate of Santo Domingo, Dominican Republic Average Weather. N.p., n.d. Web. 13 June 2014. <http://www.santo-domingo.climatemps.com/>.
  3. Osuagwu, O. E., Agbakwuru, A., & Chinedu, P. (2011). SOLAR POWER AS ALTERNATIVE ENERGY TO DRIVE INFORMATION TECHNOLOGY DIFFUSION IN NIGERIA: A COMPARATIVE ANALYSIS OF COST EFFECTIVENESS OF SOLAR OVER THERMAL ENERGY (SOLAR ENERGY & INDUSTRIAL GENERATORS). Journal Of Mathematics & Technology, 2(3), 43-47.
  4. Hantula, Richard, and Voege, Debra M.A (2010). How do Solar Panels Work?, Infobase Publishing, New York.
  5. Macomber, H.L., Ruzek, John B., Costello, Frederick A. (1981). “Photovoltaic Stand-Alone Systems: Preliminary Engineering Design Handbook.” Monegon, LTD, 18(1).
  6. http://www.poweringhealth.org/index.php/topics/management/theft-prevention
  7. Strong, Steven, and David Lloyd-Jones. "Technologies and Integration Concepts." Designing with Solar Power a Sourcebook for Building Integrated Photovoltaics. Victoria, Australia: Images Group, 2005. 23-24. Print.
  8. A. Ochs, X. Fu-Bertaux, M. Konold, S. Makhijani, S. Shrank, and C. Adkins, "Roadmap to a Sustainable Energy System: Harnessing the Dominican Republic’s Wind and Solar Resources"(Washington, DC:Worldwatch Institute, 2011)
  9. C. Julian Chen. Physics of Solar Energy. (2011). <http://www.vtsnis.edu.rs/Predmeti/obnovljivi_disperzivni_izvori_napajanja/fizika_solarne_energije.pdf> (June 8th, 2014)
  10. http://www.pveducation.org/pvcdrom/design/efficiency-and-cost
  11. National Renewable Energy Laboratory: Battery Power for Your Residential Solar Electric System (Washington, DC: U.S Department of Energy, 2002)
  12. Macomber, H.L., Ruzek, John B., Costello, Frederick A. (1981). “Photovoltaic Stand-Alone Systems: Preliminary Engineering Design Handbook.” Monegon, LTD, 46-47.
  13. Weniger, Johannes, and Tjaden, Tjarko, and Quaschning, Volker. (2014). "Sizing of residential PV battery systems.” Energy Procedia., 46, 78-87.
  14. Solar Fotovoltaica: Manual sobre energía renovable Focer(2002), BUN-CA.
  15. U.S Department of Energy. (n.d.). "Small Wind Electirc Systems." Energy Efficency and Renewable Energy, <http://www.windpoweringamerica.gov/pdfs/small_wind/small_wind_guide.pdf> (June 7, 2014).
  16. 16.0 16.1 Chiras, Dan. (2010). "WIND POWER Basics." New Society Publishers, Gabriola Island, BC, Canada, 1-32
  17. Calcano, A., De Aza Carpio, O., Groves, S., McMeekin, W. (2013). "Ghetto2Garden solar power." Appropedia, <http://www.appropedia.org/Ghetto2Garden_solar_power> (June 6, 2014).
  18. Miller, Sarah. (2013). "Pet-loving architects in the Dominican Republic build a beautiful animal shelter out of recycled materials."grist, <http://grist.org/list/pet-loving-architects-in-the-dominican-republic-build-a-beautiful-animal-shelter-out-of-recycled-materials/> (June 6, 2014).
  19. Inhabitat. (2013). "Gallery: Ghetto2Garden is a sustainabl..." Inhabitat,<http://m.inhabitat.com/inhabitat/#!/entry/gallery-ghetto2garden-is-a-sustainabl,513840e9d7fc7b56705ba493/2> (June 6, 2014).
  20. Triola, D., Sanchez, A. (2013). "La Yuca schoolroom renovation." Appropedia, <http://www.appropedia.org/La_Yuca_schoolroom_renovation> (June 6, 2014).