Power Supply Plan: 2014‐2017 Power Generation/Market Power Biomass/Gasification Hydroelectric Landfill Gas Solar PV Wind Geothermal Energy Efficiency & Energy Optimization Grants Overview $1.8 million – Wind/WIRES 2 $3.8 million Energy Efficiency & Conservation Block Grant (EECBG) $315k Better Buildings $100k LED street light conversion Continue to solicit grants for various projects Wyandotte receives many grants because we are a Municipal Utility and have the means to get things done on a timely basis and derive greater benefit for our community US Electricity Generation by Fuel Solar, 0.029 Wind, 2.2864 Geothermal, Other unkown/ 0.3689 purchased fuel, 0.1162 Coal Oil Gas Nuclear, 19.5589 Coal, 44.7748 Hydro, 6.173 Other fossil Biomass Hydro Nuclear Gas, 23.9686 Wind Biomass, Other fossil, 1.3571 0.3498 Oil, 1.0174 Source: U.S. EPA, eGRID, year 2010 data Natural Gas y Natural gas is a fossil fuel formed when layers of buried plants and animals are exposed to intense heat and pressure over thousands of years. The energy that the plants and animals originally obtained from the sun is stored in the form of carbon in natural gas. Natural gas is combusted to generate electricity, enabling this stored energy to be transformed into usable power. Natural gas is a nonrenewable resource because it cannot be replenished on a human time frame. y The natural gas power production process begins with the extraction of natural gas, continues with its treatment and transport to the power plants, and ends with its combustion in boilers and turbines to generate electricity. Natural Gas y Initially, wells are drilled into the ground to remove the natural gas. After the natural gas is extracted, it is treated at gas plants to remove impurities such as hydrogen sulfide, helium, carbon dioxide, hydrocarbons, and moisture. Pipelines then transport the natural gas from the gas plants to power plants. y Power plants use several methods to convert gas to electricity. One method is to burn the gas in a boiler to produce steam, which is then used by a steam turbine to generate electricity. A more common approach is to burn the gas in a combustion turbine to generate electricity. y Another technology, that is growing in popularity is to burn the natural gas in a combustion turbine and use the hot combustion turbine exhaust to make steam to drive a steam turbine. This technology is called "combined cycle" and achieves a higher efficiency by using the same fuel source twice. Coal Nine out of every 10 tons of coal mined in the United States today is used to generate electricity, and more than half of the electricity used in this country is coal‐generated electricity. How is coal converted into electricity? Electricity from coal is the electric power made from the energy stored in coal. Carbon, made from ancient plant material, gives coal most of its energy. This energy is released when coal is burned. Coal Releasing Coal's Energy The process of converting coal into electricity has multiple steps and is similar to the process used to convert oil and natural gas into electricity: A machine called a pulverizer grinds the coal into a fine powder. The coal powder mixes with hot air, which helps the coal burn more efficiently, and the mixture moves to the furnace. The burning coal heats water in a boiler, creating steam. Steam released from the boiler powers an engine called a turbine, transforming heat energy from burning coal into mechanical energy that spins the turbine engine. The spinning turbine is used to power a generator, a machine that turns mechanical energy into electric energy. This happens when magnets inside a copper coil in the generator spin. A condenser cools the steam moving through the turbine. As the steam is condensed, it turns back into water. The water returns to the boiler, and the cycle begins again. Coal As A Fuel Coal Other processes of using coal to make electricity include the following: Fluidized bed combustion (FBC), in which coal is inserted into a bed of particles suspended in air that react with the coal to heat the boiler and make steam. Integrated Gasification Combined‐cycle systems, in which (1) gas produced by heating coal operates a combustion turbine connected to a generator and (2) the exhaust gases from this turbine heat water, which in turn operates a steam‐powered generator. (Natural Gas can also utilize this technology) The Department of Energy is working with the coal and electrical generation industries to find ways to utilize coal more cleanly and efficiently. Types Of Coal Coal is classified into four main types, or ranks (anthracite, bituminous, subbituminous, and lignite), depending on the amounts and types of carbon it contains and on the amount of heat energy it can produce. The higher ranks of coal contain more heat‐producing energy; due to availability, bituminous and subbituminous are the most common coal types used in power generation. • Bituminous coal contains 45‐86% carbon. It was formed under high heat and pressure over time. Bituminous coal in the United States is between 100 to 300 million years old. It is the most abundant rank of coal found in the United States, accounting for about half of U.S. coal production. • Subbituminous coal has a lower heating value than bituminous coal. Subbituminous coal typically contains 35‐45% carbon. Most subbituminous coal in the United States is at least 100 million years old. About 46% of the coal produced in the United States is subbituminous. PRB Coal Powder River Basin (PRB) coal is classified as "subbituminous" and contains an average of approximately 8,500 btu/lb, with low SO2. Contrast this with bituminous coal containing an average of 12,500 btu/lb and high SO2. PRB coal was essentially worthless until air pollution emissions from power plants became a concern. A coal‐fired plant designed to burn bituminous coal must be modified to remove SO2 at a lower cost per ton of SO2 removal by switching to burn PRB coal, or install scrubbers to continue burning the existing coal at a much higher cost per ton of SO2 removal. The majority of the coal mined in the Powder River Basin is part of the Fort Union Formation (Paleocene), with the lowest sulfur and ash content of the coal in the region, making it very desirable. Coal supplies about half of the United States' electricity supplies, with the Powder River Basin mines supplying around 40 percent of the coal that fuels those stations for generating electricity. PRB Coal Many utilities, independent power producers, and large industrial generators have switched from bituminous coals to PRB coal for reasons of cost alone. Others have turned to the fuel because its use reduces emissions of SO2—without the need to install costly scrubbers—and of NOx. An Example: A local power plant in Monroe, MI, one of the largest and most efficient power plants in the U.S., fires a blend of PRB, mid‐sulfur (MID) and low‐ sulfur (LSS) eastern coals, the plant burned over eight million tons of fuel last year. The main reason the plant began using blends was to meet Clean Air Act (CAA) standards for sulfur dioxide (SO2). To meet the more‐stringent standards, there were two choices: put in scrubbers or blend in PRB coal to reduce emissions. By taking the latter approach, the plant was able to meet the new CAA limits without resorting to scrubbers, a more costly alternative. Lower coal costs were another factor. The delivered price of PRB coal is considerably cheaper than central Appalachian coal. The plant now burns blends with as much as 75% PRB coal. Tire‐Derived Fuel (TDF) Scrap tires are used as fuel because of their high heating value. Using scrap tires is not recycling, but is considered a beneficial use — it is better to recover the energy from a tire rather than landfill it. In 2003, 130 million scrap tires were used as fuel (about 45% of all generated). Tires can be used as fuel either in shredded form ‐ known as tire‐derived fuel (TDF) ‐ or whole, depending on the type of combustion device. There are several advantages to using tires as fuel: Tires produce 25% more energy than coal; The ash residues from TDF may contain a lower heavy metals content than some coals; Results in lower NOx emissions when compared to many US coals, particularly high‐sulfur coals. Based on over 15 years of experience with more than 80 individual facilities, EPA recognizes that the use of tire‐derived fuels is a viable alternative to the use of fossil fuels. EPA testing shows that TDF has a higher BTU value than coal. Wood Biomass Biomass is any biological material that can be used as fuel. Biomass fuel is burned or converted in systems that produce heat, electricity, or both heat and power. Woodchips, wood pellets, and other low‐grade wood wastes are the major type of biomass fuel. Other common biomass fuel sources are agricultural crop residues and farm animal wastes. Low fuel cost is the main attraction of heating with woodchips. Unlike fuel oil, propane, and natural gas, biomass has a history of stable prices that are unaffected by global economics and political events. Burning wood for energy has a positive impact in moderating global climate change. Carbon dioxide (CO2) buildup in the atmosphere is a significant cause of global climate change. Fossil fuel combustion takes carbon that was locked away underground (as crude oil and gas) and transfers it to the atmosphere as CO2. When wood is burned, however, it recycles carbon that was already in the natural carbon cycle. Downsides: High dust potential, breakdown prior to reaching boilers, unavailability of local biomass resources and cost of transportation to site. Biomass Gasification Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures (>700°C), without combustion, with a controlled amount of oxygen and/or steam. The resulting gas mixture is called syngas (from synthesis gas or synthetic gas) or producer gas and is itself a fuel. A wide variety of feedstocks can be gasified: wood pellets and chips, waste wood, plastics and aluminum, Municipal Solid Waste (MSW), Refuse‐derived fuel (RDF), agricultural and industrial wastes, sewage sludge, switch grass, discarded seed corn, corn stover and other crop residues. The advantage of gasification is that using the syngas is potentially more efficient than direct combustion of the original fuel because it can be combusted at higher temperatures. Syngas may be burned directly in gas engines, used to produce methanol and hydrogen, or converted via the Fischer‐Tropsch process into synthetic fuel. Gasification can also begin with material which would otherwise have been disposed of such as biodegradable waste. In addition, the high‐temperature process refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels. Gasification of fossil fuels is currently widely used on industrial scales to generate electricity. Hydroelectricity Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. • It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. • Worldwide, an installed capacity of 1,010 GW supplied hydroelectricity in 2010. • Approximately 16% of the world's electricity is renewable, with hydroelectricity account for 21% of renewable sources and 3.4% of total energy sources. Hydroelectric Projects Hydroelectric Projects Project Participation Agreements with American Municipal Power (AMP) Meldahl Hydroelectric Project Greenup Hydroelectric Project Landfill Gas Projects Landfill Gas Projects Large municipal or industrial landfills produce gas that can be tapped to generate electricity. Microorganisms that live in organic materials such as food wastes, paper or yard clippings cause these materials to decompose. This produces landfill gas, typically comprised of roughly 60 percent methane and 40 percent carbon dioxide (or "CO2"). The US Environmental Protection Agency (EPA) requires all large landfills to install collection systems at landfill sites to minimize the release of methane, a major contributor to global climate change. Though not a renewable resource, landfill gas will be in great supply absent major innovations in solid waste management systems and could supply up to 1 percent of the nation's energy demand. Landfill gas generators produce nitrogen oxides emissions that vary widely from one site to another, depending on the type of generator and the extent to which steps have been taken to minimize such emissions. Combustion of landfill gas can also result in the release of organic compounds and trace amounts of toxic materials, including mercury and dioxins, although such releases are at levels lower than if the landfill gas is flared. Landfill Gas Projects Landfill gas is collected from landfills by drilling "wells" into the landfills, and collecting the gases through pipes. Once the landfill gas is processed, it can be combined with natural gas to fuel conventional combustion turbines or used to fuel small combustion or combined cycle turbines. Landfill gas may also be used in fuel cell technologies, which use chemical reactions to create electricity, and are much more efficient than combustion turbines. A landfill gas power plant burns a waste ‐ methane ‐‐‐ that would otherwise be released into the atmosphere or burned off in a flaring process. Methane is a highly potent agent of global climate change, having about 23 times the negative impact on a pound‐by‐pound basis as CO2. Landfill gas combustion produces some CO2, but the impact of these emissions on global climate change is offset many times over by the methane emission reductions. Landfill Gas Projects Project Participation Agreements with Michigan Public Power Agency (MPPA) Granger Project North American Natural Resources Photovoltaic (PV) panels convert sunlight to electricity that can be used to supplement or replace the electricity supplied by the utility grid. PV panels are most commonly installed on rooftops, and are most effective with a southerly exposure that provides full sun. Other possible installations include a ground mount, a pole mount, and atop a porch, carport, or other shaded area. PV energy systems are eligible for federal tax credits and state incentives. Solar thermal energy, or solar hot water, uses flat collector plates to harness the sun’s energy to heat water for use in businesses, homes, and pools. The installation and appearance are much like those of the PV panel, and the collectors are best installed facing south, under unobstructed sunlight. Unlike PV panels, solar thermal collectors do not convert sunlight to electricity, but transfer the energy directly to the water. Solar thermal systems displace the electricity or natural gas that would otherwise be required to heat water. Federal tax credits are available for most solar hot water systems, but cannot be used for systems that heat swimming pools or hot tubs How Solar Cells Work Solar Photovoltaic Cells – Converting Photons to Electrons – The Basic Process: y Photo meaning "light" and voltaic meaning "electricity" y Converts sunlight directly into electricity. Module: y group of cells connected electrically and packaged into a frame, solar panel panels grouped into larger solar arrays Photovoltaic cells: y made of special materials called semiconductors, such as silicon; currently most commonly used. How Solar Cells Work How it works y Light strikes the cell, a portion is absorbed. y Energy of the absorbed light is transferred to the semiconductor. y The energy knocks electrons loose, allowing them to flow freely. y Electric field acts to force electrons freed by light absorption to flow in a certain direction. y Flow of electrons is a current y Placing metal contacts on the top and bottom of the PV cell draws that current off for external use y This current, together with the cell's voltage (a result of its built‐in electric field/s), defines the power (wattage) that the solar cell can produce. A Closer Look: The Single‐Crystal Silicon Cell How Silicon Makes a Solar Cell y Silicon has some special chemical properties, especially in crystalline form. y An atom of silicon has 14 electrons, arranged in three different shells. y The first two shells are completely full. y The outer shell, however, is only half full y A silicon atom will always look for ways to fill up its last shell, to do this, it will share electrons with nearby atoms. y This forms the crystalline structure, and that structure turns out to be important. y The only problem is that pure crystalline silicon is a poor conductor of electricity ‐ none of its electrons are free to move about y To address this, impurities are added to the silicon A Closer Look: The Single‐Crystal Silicon Cell How Silicon Makes a Solar Cell y Less energy is needed to knock loose the electrons in impure silicon. y As a result, most of these electrons do break free, and we have a lot more free carriers y The process of adding impurities is called doping; when doped with phosphorous, the resulting silicon is called N‐type (for neg), due to the prevalence of free electrons. y The other part of a typical solar cell is doped with the element boron, to become P‐type silicon. Instead of having free electrons, P‐type (for positive) has free openings and carries the opposite (positive) charge. A Closer Look At What Happens When These Two Substances Start To Interact. Anatomy of a Solar Cell y Before now, our 2 separate pieces of silicon were electrically neutral; the interesting part begins when you put them together ‐ without an electric field, the cell wouldn't work; the field forms when the N‐type and P‐type silicon come into contact. y free electrons on the N side see all the openings on the P side, and rush to fill them; Eventually, equilibrium is reached and we have an electric field separating the two sides. A Closer Look At What Happens When These Two Substances Start To Interact This electric field acts as a diode, allowing (and even pushing) electrons to flow from the P side to the N side. A Closer Look At What Happens When These Two Substances Start To Interact y When light, in the form of photons, hits our solar cell, its energy breaks apart electron‐hole pairs. y Each photon with enough energy will normally free exactly one electron, resulting in a free hole as well. y This causes disruption of electrical neutrality, y Provided with an external current path, electrons will flow through the path to the P side to unite with holes that the electric field sent there. y Electron flow provides the current, and the cell's electric field causes a voltage. With both current and voltage, we have power, which is the product of the two. y Current x Voltage = Power Other Components Needed To Complete A Solar Panel y Antireflective coating ‐ to avoid losses due to photons bouncing off silicon, a shiny material. y Protective barrier – often a glass cover plate to protect against elements y Sturdy mounting frames with positive/negative terminals. Example of a Residential PV System y This simple schematic shows how a residential PV system will often take shape. y Once installed, a PV system requires very little maintenance and will provide electricity cleanly and quietly for 20 years or more. Wind Power DOE Grant – 1.8 million Brownfields to Greenfields Re‐scoped grant to expand project capabilities ‐ evaluating midsize/micro turbines Wind Power y It's hard sometimes to imagine air as a fluid. It just seems so ... invisible. But air is a fluid like any other except that its particles are in gas form instead of liquid. And when air moves quickly, in the form of wind, those particles are moving quickly. Motion means kinetic energy, which can be captured, just like the energy in moving water can be captured by the turbine in a hydroelectric dam. In the case of a wind‐electric turbine, the turbine blades are designed to capture the kinetic energy in wind. y The rest is nearly identical to a hydroelectric setup: When the turbine blades capture wind energy and start moving, they spin a shaft that leads from the hub of the rotor to a generator. The generator turns that rotational energy into electricity. At its essence, generating electricity from the wind is all about transferring energy from one medium to another. Wind Power y Wind power all starts with the sun. When the sun heats up a certain area of land, the air around that land mass absorbs some of that heat. At a certain temperature, that hotter air begins to rise very quickly because a given volume of hot air is lighter than an equal volume of cooler air. Faster‐moving (hotter) air particles exert more pressure than slower‐ moving particles, so it takes fewer of them to maintain the normal air pressure at a given elevation. When that lighter hot air suddenly rises, cooler air flows quickly in to fill the gap the hot air leaves behind. That air rushing in to fill the gap is wind. y If you place an object like a rotor blade in the path of that wind, the wind will push on it, transferring some of its own energy of motion to the blade. This is how a wind turbine captures energy from the wind. Wind Power Parts of a Wind Turbine y The simplest possible wind‐energy turbine consists of three crucial parts: y Rotor blades ‐ The blades are basically the sails of the system; in their simplest form, they act as barriers to the wind (more modern blade designs go beyond the barrier method). When the wind forces the blades to move, it has transferred some of its energy to the rotor. y Shaft ‐ The wind‐turbine shaft is connected to the center of the rotor. When the rotor spins, the shaft spins as well. In this way, the rotor transfers its mechanical, rotational energy to the shaft, which enters an electrical generator on the other end. Wind Power Parts of a Wind Turbine y Generator ‐ At its most basic, a generator is a pretty simple device. It uses the properties of electromagnetic induction to produce electrical voltage ‐ a difference in electrical charge. Voltage is essentially electrical pressure ‐ it is the force that moves electricity, or electrical current, from one point to another. So generating voltage is in effect generating current. y A simple generator consists of magnets and a conductor. The conductor is typically a coiled wire. Inside the generator, the shaft connects to an assembly of permanent magnets that surrounds the coil of wire. In electromagnetic induction, if you have a conductor surrounded by magnets, and one of those parts is rotating relative to the other, it induces voltage in the conductor. When the rotor spins the shaft, the shaft spins the assembly of magnets, generating voltage in the coil of wire. That voltage drives electrical current (typically alternating current, or AC power) out through power lines for distribution. Wind Power Modern wind turbines ‐ two primary designs: horizontal‐axis wind turbines (HAWT) and Vertical‐axis wind turbines (VAWT) y In a VAWT, the shaft is mounted on a vertical axis, perpendicular to the ground. VAWTs are always aligned with the wind, unlike their horizontal‐ axis counterparts, so there's no adjustment necessary when the wind direction changes; but a VAWT can't start moving all by itself ‐‐ it needs a boost from its electrical system to get started. y Instead of a tower, it typically uses guy wires for support, so the rotor elevation is lower. Lower elevation means slower wind due to ground interference, so VAWTs are generally less efficient than HAWTs. On the upside, all equipment is at ground level for easy installation and servicing; but that means a larger footprint for the turbine, which is a big negative in farming areas. Wind Power Wind Power y As implied by the name, the HAWT shaft is mounted horizontally, parallel to the ground. HAWTs need to constantly align themselves with the wind using a yaw‐adjustment mechanism. The yaw system typically consists of electric motors and gearboxes that move the entire rotor left or right in small increments. The turbine's electronic controller reads the position of a wind vane device (either mechanical or electronic) and adjusts the position of the rotor to capture the most wind energy available. y HAWTs use a tower to lift the turbine components to an optimum elevation for wind speed (and so the blades can clear the ground) and take up very little ground space since almost all of the components are up to 260 feet (80 meters) in the air. Wind Power Large HAWT Components: y Rotor blades ‐ capture wind's energy and convert it to rotational energy of shaft y Shaft ‐ transfers rotational energy into generator y Nacelle ‐ casing that holds the gearbox (increases speed of shaft between rotor hub and generator), generator (uses rotational energy of shaft to generate electricity using electro magnetism), electronic control unit (monitors system, shuts down turbine in case of malfunction and controls yaw mechanism), yaw controller (moves rotor to align with direction of wind) and brakes (stop rotation of shaft in case of power overload or system failure). y Tower ‐ supports rotor and nacelle and lifts entire setup to higher elevation where blades can safely clear the ground y Electrical equipment ‐ carries electricity from generator down through tower and controls many safety elements of turbine Wind Power How It Works: y The energy in the wind is converted to rotational motion by the rotor. y When the blades turn, the rotor turns a shaft, which transfers motion into the nacelle. y The slowly rotating shaft enters a gearbox that greatly increases the rotational shaft y y y y y speed. The output shaft is connected to a generator that converts the rotational movement into electricity at medium voltage (hundreds of volts). The electricity flows down heavy electric cables inside the tower to a transformer, which increases the voltage of the electric power to the distribution voltage (thousands of volts). The distribution‐voltage power flows through underground lines to a collection point where the power may be combined with other turbines. The electricity may be sent to nearby farms, residences or towns. The electricity may also be sent to a substation where the voltage is increased to transmission‐voltage power (hundreds of thousands of volts) and sent through above‐ ground transmission lines to distant cities and factories. Geothermal GSHP‐ Why? The Geothermal Ground Source Heat Pump (GSHP) is one of the most efficient residential and commercial heating and cooling systems available today, with heating efficiencies 50 to 70% higher than other heating systems and cooling efficiencies 20 to 40% higher than available air conditioners. Source: International Ground Source Heat Pump Association Improves power plant load factor – shaves peaks and helps base load How Geothermal Works During the winter, the fluid collects heat from the earth and carries it through the system and into the building. During the summer, the system reverses itself to cool the building by pulling heat from the building, carrying it through the system and placing it in the ground. Geothermal System Overview Wyandotte Geothermal Goals Encourage Ground Source Heat Pump technology (GSHP) to residents & businesses in Wyandotte Residents and Business owners will own their Geothermal systems Opportunity for homeowners to use tax incentives on entire system Obtain grant funded rebates (as available) Lower energy cost to customers Improves power plant load factor – beneficial to community Expand renewable energy & increase sustainability throughout Wyandotte Energy Efficiency & Conservation National DOE Competitive Grant – Energy Efficiency & Conservation Block Grant (EECBG) Only 20 issued to non‐entitlement communities (Less than 35,000 residents) $3.8M on non‐matching DOE Grant Energy Efficiency “Save A Watt in Wyandotte” Energy Programs: Energy Savings Audit Program Energy Optimization Program • Energy Smart Program CFL Lighting Grant LED Street Lighting Replacements Electric Vehicles Energy Savings Audit Program Program Highlights EECBG funded – over 2000 total audits; Res/Comm Incentives to home and business owners Increased Rebates y Electric rebates y Appliance rebates y Lighting rebates y Commercial equipment rebates 1.99% Financing Current Energy Savings Audit Program Residential: Level 1: Walk through audit by certified auditor/contractor and energy advisor to provide customer education, direct install of CFLs, showerheads, aerators, etc., and appliance recycling referral. Level 2: Streamlined process; eliminated Level 2 Level 3 (Optional to homeowner): Improvements recommended by contractor based on audit findings; can include major measures such as attic, wall, or floor insulation, HVAC, water heaters, appliances, windows, and DIY suggestions. Current Energy Savings Audit Program Commercial/Industrial: Level 1: Walk through audit by certified Energy Advisor to provide customer education and outline measures that may be taken; reserve Energy Smart rebates as necessary. Level 2 (optional): Direct Install Program – LED exit sign retrofit, Vending Miser, Programmable Thermostat, Pre‐Rinse Spray Valves and Energy Star Compliant CFL Bulbs. Level 3 (optional): Business Owner decides to move forward with improvements recommended by contractor based on audit findings. Contractor will help fill out form to reserve Energy Smart rebates, as necessary. Energy Optimization Programs State mandated EO programs required for all Utilities; based on PA 295 Goal 1% energy savings per year EO Plans submitted to PSC for review & approval Energy Smart Rebate Program implemented annually Savings verified by independent organization ‐ KEMA Energy Optimization Programs Residential Programs for 2014 Include: Refrigerator recycling program through JACO y $60/each Residential High‐efficiency HVAC Systems y Up to $150 for a furnace w/ECM fan motor Intelligent Surge Protectors y $15 rebate LED bulbs, Energy Star computers, appliances and more!! Wyandotte LED Streetlights Long Term Project ‐10 years Over 100 Streetlights replaced to date Direct Replacement of fixture • No rewiring required Downtown completed in 2013 Grant awarded ‐ $100,000; facilitated fixture purchases Wyandotte LED Streetlights How They Work y LEDs create light by electroluminescence in a semiconductor material. Electroluminescence is the phenomenon of a material emitting light when electric current or an electric field is passed through it ‐ this happens when electrons are sent through the material and fill electron holes. An electron hole exists where an atom lacks electrons (negatively charged) and therefore has a positive charge. y Semiconductor materials like germanium or silicon can be "doped" to create and control the number of electron holes. Doping is the adding of other elements to the semiconductor material to change its properties. By doping a semiconductor you can make two separate types of semiconductors in the same crystal. The boundary between the two types is called a p‐n junction. The junction only allows current to pass through it one way, this is why they are used as diodes. LEDs are made using p‐n junctions. As electrons pass through one crystal to the other they fill electron holes. They emit photons (light). Thank You