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2.0 Background
The electric infrastructure consists of an assortment of parts such as the power station, the substations, the utility poles, the transformers, the power lines and the electricity meters.
2.2 Elements of the Electric Infrastructure
2.2.1 Power Stations
There are a wide variety of power stations that are used, but are still the source of all the electricity that powers the electric infrastructure. Power stations can be categorized by two main elements: fuel, and method of power generation. The types of fuel are: nuclear, fossil fuel (including coal and natural gas), geothermal, waste heat, solar thermal and renewable energy. The methods of power generation are: steam turbine, gas turbine, combined cycle, and internal combustion engines.
2.2.2 Power Substations
A substation is used to either step up the voltage of the electricity or to step down the voltage of the electricity. To do so the substation uses transformers which will be discussed later.
2.2.3 Transformers
Transformers are the actual mechanism by which any changes in voltages are enacted. The equation that governs the relationship between the primary voltage (VP), the secondary voltage (VS), the number of primary turns (NP) and the number of secondary turns (NS) is:
Equation 1 Transformer Equation[3]
A picture of an idealized transformer circuit can be seen below; however, in a real transformer both the primary and secondary windings are on top of each other in order to minimize leakage flux[4].
2.2.4 Utility Pole
One of the connections on a utility pole is for the electric lines which carry electricity. In general, poles are about 35 feet tall and are buried 6 feet into the ground; however, the poles can range in height from 20 feet to 100 feet tall. Utility poles can be made out of concrete, steel, fiberglass, or wood, but wood remains the most common and popular type of material[7].
2.2.5 Power Lines
Power lines carry the electricity from the power station to the substation to the transformer to the meter to your house. They are usually made out of aluminum or an alloy of aluminum although in some cases copper is used.
2.2.6 Meter
Most electricity meters are electromechanical in nature. They utilize an induction motor which is connected to a wheel that is attached to a gear that will turn the dial on your meter. The speed at which the induction motor turns is directly proportional to the voltage and current of the electricity that enters your house[9]. However, more recently smart meters have begun to penetrate the markets. Smart meters have several more features and functions compared to traditional meters in addition to simply monitoring electricity usage. Smart meters will theoretically have the ability to monitor electricity usage by time so that peak hour usage can be determined and by appliance assuming the appliances have the capability to be connected to the network. Furthermore, smart meters will have the ability to turn off electricity to the house during peak hours for example, lowering the cost of electricity[10]. While smart meters are part of the smart grid, they are not the whole of the smart grid.
2.3 History of the Grid
The power grid had very humble beginnings. In 1882, when electricity was first starting to enter households and businesses, it was provided by small generators that were always close by to where the power used and was always transmitted by DC, or direct current. By 1886 AC, alternating current, generators were starting to appear and in 1888 the universal system was developed. This system used transformers to up the voltage as it was put into the power lines and then drop it back down as it entered homes and buildings. The increased voltage allowed the electricity to travel much longer distances in the power lines without being depleted by the time it got to its destination. This ability to transmit electricity over long distances lowered costs and for generation plants to produce enough energy to power far larger areas than ever before.
As with most things, technology improved over time and the grid was made more efficient. Although the basic concept of the grid has changed very little since the inception of the universal system, now the nation is broken down into three main grids; The Western Interconnect; The Eastern Interconnect and the Electric Reliability Council of Texas. The way these grids function allows for a generator plant in one area of the grid to go down and have the other plants within that grid to, for the most part, cover the area in which the downed plant no longer can. This also allows power lines to break and have something similar happen, although the power in the immediate area around the downed line will be temporarily out of service.
2.3.1 Public Service Utility of New Mexico (PNM)
PNM is the current supplier of electricity to Santa Fe. Two of PNM’s coal-firing plants near Farmington, NM provide 62 percent of Santa Fe’s electricity while a Nuclear power plant near Phoenix provides another 19 percent. Natural gas, wind, solar, and third party providers supply the rest of Santa Fean’s energy. By 2020, PNM must meet a state mandate of providing 20% of its energy from renewable resources. With their current renewable energy plan PNM provides 6% of its energy from solar power, and pays 26 cents per kWhr for solar energy sourced from customer sites.
One of the benefits of a municipal-owned power infrastructure is the ability to keep electricity costs down for residents. Profit margin is no longer a concern when the infrastructure owns the power lines. The city can install solar farms if the citizens decide to pursue renewable energy. Although initial costs would be high, the energy independence would help sustain Santa Fe. The county of Los Alamos currently supplies electricity on its municipality-owned power lines to 9,000 customers who pay a little more than the PNM rate, but they pay one service charge and no surcharge that PNM customers do pay.
The control of the power infrastructure has been a topic of debate in recent events. In November 2009, PNM complained to the New Mexico’s Public Regulation Commission about Santa Fe’s intent to contract Mayland-Based SunEdison to install solar arrays on government buildings to reduce municipal energy consumption. The electricity would be purchased from SunEdison, not PNM, and tax credits would also be given to SunEdison. PNM declared that all power in Santa Fe should be regulated by PNM itself.
2.4 Alternative Renewable Energy Resources
The team will be exploring the feasibility of using renewable energy sources to help power the city of Santa Fe. Using renewable energy could potentially allow the city to generate part or all of their energy needs for cheaper. The carbon dioxide emissions are another area of concern that renewable resources could help to reduce.
2.4.1 Solar Power
One of the most feasible forms of renewable energy production in Santa Fe is solar power due to the geographical location of the city. Solar power captures energy from the Sun using Photovoltaic Cells and turns it into usable electricity.
The basic components involved in the production, storage, and usage of electricity from solar power is outlined in the Figure below. The solar panel is composed of an array of a number of solar cells that combine to generate energy from sunlight. Through the photovoltaic effect, solar cells work by using semiconducting materials to absorb photons from sunlight, causing the electrons in the material to flow, thus creating electricity that can be used. Depending on how much power you want to generate, creating a large array of solar cells that can produce the desired amount of energy.[13] The electricity produced by the solar panel is then sent through a charge controller that can send some of the energy directly to DC devices because the electricity produced is in DC(direct current). The rest of the energy is sent to batteries for storage, and then before it can be used the same way as any other power source for the home, it must first go through a power inverter to make it AC(alternating current).
The biggest factor that needs that will make or break using solar power in a certain location is the amount of sunlight that will hit the solar panel because without sunlight no energy being produced. The South Western United States has both long days and direct sunlight for most of the year. The Ideal location for solar panels is usually in a desert due to the strength of the sunlight in those locations. The higher the altitude the solar panel is at also allows more energy to reach the panel because less energy is lost as the Sunlight passes through the atmosphere. The City of Santa Fe is in a desert, as well as the highest capital city in the United States. Due to both of these attributes, Santa Fe meets many of the ideal conditions for producing large amounts of energy from the Sun. The Solar Resource map below shows us the potential the Southwestern US has for producing Solar power.
Figure 7 - Solar Levels Map of U.S.
Most modern solar panels that are in development today have an efficiency rate of approximately 20%. For example, The SunPowerTM 315 Solar Panel has an efficiency of 19.3% and a peak production of 18 Watts per square foot.[14] As production costs and efficiencies continue to improve, the ability of the world to make the switch to renewable resources an ever-growing reality.
By creating large solar plants similar to the one shown above in Nevada, Santa Fe may be able to achieve their goal of reaching lower carbon dioxide emission levels[16].
2.4.2 Geothermal
As the name suggests, geothermal energy comes from heat that is stored in the Earth and is used as a source of heat for several applications. This heat can be used directly to heat a home or business, or used to generate energy through various means. In order to use the heat from the earth, we must first drill deep into the Earth’s Crust. The depth we must drill depends entirely on how thick the crust is at the location of drilling, or if there are any hot spots near the surface that could be used as a heat source. The figure below shows how a standard geothermal power plant works. The plant taps into a reservoir deep in the crust where it is very hot, and injects cold water into the reservoir. That cold water is heated by the rocks in the Earth, and once it is heated up enough, convection currents cause it to rise up a pipe that takes it into the power plant. Once the hot water has reached the Power plant, it is used to turn turbines using convection currents and steam to produce energy.[17]
2.5 Smart Grid
In development and in partial deployment in the US, in such cities such as Boulder, Colorado, is the smart grid. The smart grid will reduce the duration of power outages; allow the grid to demand additional energy from other resources to balance the flow of electricity through the grid. Additionally, the ability the smart grid will have the ability to monitor the status of components allowing their replacement before their failure improving the reliability of the grid[19]. The smart grid will also be able to handle non-constant power generation such as that produced by solar, or wind power; furthermore, the smart grid will be able to handle a more decentralized power production, allowing the construction and contribution of a number of small solar panels or other power plants. Currently, if any electricity is produced in excess of need, there is nowhere for it to go, so it travels the power lines until the energy is lost, however, part of the smart grid will involve the construction of large storage facilities for energy that was produced, but not needed at that point[20].
2.5.1 Boulder, Colorado and SmartGridCity
SmartGridCity is the name of the new grid system implemented in Boulder, Colorado. It is owned by Xcel Energy, the company supplying most of Boulder’s Energy, although the City does operate 8 hydroelectric plants that produce electricity that is sold directly to Xcel for distribution. The Boulder plants generate enough energy for 18% of the residential sector in Boulder while, at the same time, depressurizing the water supply for the City. SmartGridCity is the world’s first implementation of a “smart grid”, that is, an electrical infrastructure monitored and controlled by computers. The current abilities of the smart grid allow remote monitoring total electricity usage, voltage fluctuations in the line, as well as the ability to balance loads from different energy sources by way of remote shut-off. SmartGridCity reduces blackouts by finding voltage fluctuations and reacting to them, and it improves financial efficiency by making obsolete the old way of finding electricity usage with a physical reading of meters. Electrical efficiency is improved with the ability to balance loads, since it decreases the likelihood of power plants being forced to operate beyond their efficiency range during peak or low usage periods.
2.6 Municipal Energy Trends
In current events, it is more likely that a municipality will keep its utility assets rather than selling it to a company. This represents a shift from the days when electricity use was law and energy production was cheap. The rationale for keeping electricity distribution and production government-owned and operated is the awareness of environmental effects and the increasing use of electricity in general. In Sweden, municipalities play a large role in the distribution of electricity. Since the late 1970’s, Swedish Energy policy consists of four major themes: reduction of oil usage, phasing out nuclear power, improvement of municipal energy efficiency, and incorporation of renewable resources. Likewise, in Canada, a community-derived energy policy is favored. Motivations for this include the desire to reduce greenhouse gas emissions, to limit exposure to rising prices for centrally generated electricity, or to shift to a more self-sufficient energy system.
2.6.1 Farmington Electrical Utility Company
The City of Farmington operates an electric utility company that provides power for the entire San Juan County and a portion of the Rio Arriba County. The city has owned the electric utility since 1944. In 1982, FEUS purchased an 8.745% (42,000 kW) share in the PNM-owned San Juan Generation plant and, in 1995, FEUS completed the construction of its Animas Combined-Cycle (25,600kW) Plant to cope with increasing electrical demand. In 1999 FEUS installed meters that allow remote metering of power consumption. Despite all the growth that FEUS experienced, the electric utility rate did not increase between 1982 and 2007 and FEUS has remained out of debt.
2.7 Historical Example: Santa Fe Water Utility Purchase
In November of 2009, the City of Santa Fe issued bonds for the sum of $61 million for the acquisition and maintenance of its water utility, as well as the sourcing of funds for the Buckman Direct Diversion program. The raising of funds is in response to the water supply and the quality of water in Santa Fe. Acquiring the water utility allows plans pertaining to the Buckman program, an effort to reduce the City’s dependence on ground water, to proceed without the impedance of a private owner. Also, the city of Santa Fe will be able to cooperate with the Los Alamos National Laboratory to reduce water supply contamination.
2.7.1 Government Bonds and Santa Fe
The conventional way that municipalities raise money for services (such as building schools, or buying city utilities) is through the sale of bonds. A government bond is a loan to the government that yields interest over time, eventually reaching maturity at some point determined by the seller of bonds (usually the city). Selling bonds starts with the issuance of bonds by the government entity that needs them. The issuer works with a municipal bond dealer, usually a bank or financial firm that takes on government dealings, to set interest rates and maturation dates. Once the bonds are approved, they are sold to private investors, banks, insurance companies, or any other entity that can produce the funds.
In this way, Santa Fe raised the necessary money to purchase its water and sewage system. It appears that bonds can have different maturation dates and different yields. For example, the first year of maturation in the chart below shows that the total amount of bond value maturing this year (2010) is 150,000 and the interest yield is 2% annually. The bonds maturing this year are comparatively low in value and yield when regarding the other values in the chart. This is probably to give the city of Santa Fe headroom to cover costs during its “start-up” year. The chart also shows A and B-type bonds, the latter meant for long term investing.
Figure 9: Bond Maturation and Yield, A-Type (Top) and B-Type (Bottom)
2.7.2 Increase in Water Utility Rates
To pay for the bonds that made the purchase possible, Santa Fe has adopted a plan that progressively increases the water billing rate 8.2% per year for 5 years, which started in 2008. Spreading out the increase over 5 years “allows for better planning and helps avoid large, single-year corrections to the rates,” according to Santa Fe Water Utility webpage. From a consumer standpoint, this translates to a less drastic adaptation to household spending. By spreading out the increase, time is given for household incomes to adapt which places less strain on citizens. This is especially important for the low-come sector of Santa Fe.
Figure 10: Water Bond Repayment Financial Plan
Figure 11: Estimated Monthly Water Bill Over the Next 5 Years for a Household
Residential 5/8" (4/6 Kgals) | |
Existing | $31.50 |
1st Year (2009) | $34.10 |
2nd Year (2010) | $36.90 |
3rd Year (2011) | $39.90 |
4th Year (2012) | $43.20 |
5th Year (2013) | $46.70 |
Before preparing a bond plan, the city’s electrical infrastructure must be assessed for value to account for depreciation and inefficiencies in the system. It would be reasonable to add renovation of the power system in Santa Fe to the total cost of the purchase, since making the infrastructure more efficient would reduce operating costs and lessen payback time. Investing in solar energy may also be a consideration at the planning stages. Doing so will be conducive to helping the city achieve its renewable energy and carbon reduction quotas.
The following are preliminary calculations based on power system component values and statistics from the WPI Boylston Electric System IQP:
159.86 miles of line @ $9820.80 = $1569924
8438 poles @ 1 pole per 100 feet for 159.86 miles of lines, all assumed to be $155 (the price for a medium-sized pole) = $1308022
2134 transformers @ $1100 = $2336756
32815 meters @ $120 = $3937800
8438 poles @ 1 pole per 100 feet for 159.86 miles of lines, all assumed to be $155 (the price for a medium-sized pole) = $1308022
2134 transformers @ $1100 = $2336756
32815 meters @ $120 = $3937800
Total= $9152592
The preceding calculations form a rough estimate of the value of what the city would be purchasing. There are other small components, such as hand holes, that have not been accounted for. [1] http://www.eia.doe.gov/cneaf/electricity/epm/table1_1.html
[2] http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation.html
[3] http://en.wikipedia.org/wiki/Transformer
[4] http://mysite.du.edu/~jcalvert/tech/transfor.htm
[5] http://upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Single-phase_transformer.svg/689px-Single-phase_transformer.svg.png
[6] http://upload.wikimedia.org/wikipedia/en/1/1c/Polemount-singlephase-closeup.jpg
[7] http://www.psc.state.fl.us/consumers/utilitypole/en/AllUtilityPoleInfo.aspx
[8] http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/transmission_lines.html
[9] http://www.usbr.gov/power/data/fist/fist3_10/vol3-10.pdf
[10] http://www.cbc.ca/news/background/energy/smartmeters.html
[12] http://www.tdsurplus.com/images/ElectricMeterFront005.jpg
[15] Matthey Wald - "Turning Glare Into Watts”
[19] http://www.oe.energy.gov/DocumentsandMedia/Utilities.pdf
[20] http://www.oe.energy.gov/DocumentsandMedia/Environmentalgroups.pdf
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