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Micro Generation and Customer Side Smart Grid Infrastructures

Micro Generation and Customer Side Smart Grid Infrastructures

Micro Generation and Customer Side Infrastructures

Thomas M. Korman1, Ph.D., P.E.,

1Professor, Construction Management Department, California Polytechnic State University, San Luis Obispo, CA 93407-0284 (805-270-5072, [email protected])

ABSTRACT: The implementation of the Smart Grid is gradually changing the nature of the electrical distribution system in the United States. With the Smart Grid, electrical power generation and distribution is becoming a two-way process between customers and generators. Being a bi-way process, there are two sides of the smart grid; the first being the utility side and second being the customer side. As the utility side smart grid is implemented, customers will have the opportunity to tailor their electrical power usage and reduce costs through the customer side components of the smart grid. This includes energy management systems, micro-generation, and systems. This presents many new opportunities for electrical contractors to enhance existing systems in residential, commercial, and industrial facilities. This paper focuses on the wide range of energy management applications and electrical service provider interactions, including: On-site generation, , Electrical storage, management, Forward power usage estimation, Load shedding capability estimation, End load monitoring (sub metering), Power quality of service monitoring, Utilization of historical energy consumption data, and Responsive energy control.

INTRODUCTION

Many consider traditional building systems to be ineffective at automatically adjusting to user needs because they require complex programming that is not flexible or adaptable with changing environments and different end users. Smart grid technologies, however, are designed to be adaptive and self-programing to the needs of the user. They have the potential to save energy consumers up to 15 to 30 percent in energy costs (Thompson 2012). Additional long term savings can be achieved through reduction in maintenance costs. Although the cost of these systems is currently greater than that of traditional systems, long term benefits for energy consumers can be substantial. With the help of electrical contractors, these sophisticated systems can help propel facilities into the future and set new standards of efficiency and usability. Owners and electrical contractors have the potential to see a greater return on investment of installed systems in terms of energy consumption. However, these systems are currently in their infancy and require the services of electrical contractors for successful implementation. Small scale smart grid operations have been installed by the United States military and serve as a proof-of-concept model for customer side smart grid installations in the civilian consumer market. These installations were first installed on experimental military bases using digital control systems that sought to balance electrical production, storage, and demand dynamics (Cacas 2013). The goal was to match correct production of power-to-load based on the demand at any point in time.

IMPLEMENTATION OF THE SMART GRID:

The implementation of the smart grid is essentially the digitization of , where there is an increased ability to communicate and control power flow to improve the operating efficiency and reliability of the U.S. electric infrastructure. Essentially, it is an integration of the entire electrical energy supply chain, where there is no storage of and supply and demand is constantly being balanced. The Department of Energy describes the smart grid as have the following five elements: • Integrated communications for real-time control • Monitoring to provide real-time system conditions • Control and monitoring capability to permit timely reaction to system changes and problems • Improved interfaces throughout the system and decision-support tools • Development and deployment of advanced transmission and distribution equipment and materials

While this reference refers to the national grid, which includes a proposed new 765 kV backbone to work with the existing 765 kV system, the National Institute of Standards and Technology (NIST) defines the term “Smart Grid” as: “a modernization of the system so it monitors, protects and automatically optimizes the operation of its interconnected elements – from the central and distributed generator through the high- transmission network and the distribution system, to industrial users and building systems, to energy storage installations and to end-use consumers and their thermostats, electric vehicles, appliances and other household devices.” This definition includes consumers and their role in the customer side of the smart grid.

In this context, “thermostats, electric vehicles, appliances and other household devices” may be considered “utilization equipment”. The NIST Smart Grid Collaboration Site (http://www.nist.gov/smartgrid/twiki.cfm) lists a wide range of energy management applications and electrical service provider interactions, including: 1. On-site generation 2. Demand response 3. Electrical storage 4. Peak demand management 5. Forward power usage estimation 6. Load shedding capability estimation 7. End load monitoring (sub metering) 8. Power quality of service monitoring 9. Utilization of historical energy consumption data 10. Responsive energy control

The implementation of the Smart Grid is gradually changing the nature of the electrical distribution system in the United States. With the Smart Grid, electrical power generation and distribution is becoming a two-way process between customers and generators. Being a bi-way process, there are two sides of the smart grid; the first being the utility side and second being the customer side. As the utility side smart grid is implemented, customers will have the opportunity to tailor their electrical power usage and reduce energy consumption costs through the customer side components of the smart grid. This includes energy management systems, micro- generation, and energy storage systems. This presents many new opportunities for electrical contractors to enhance existing systems in residential, commercial, and industrial facilities.

Energy Generation Most utilities will not pay the same price for the electricity being distributed back into the grid as they charge for the electricity that they produce. The reason being that their cost for the electricity includes generation, transmission, maintenance, billing, etc. Therefore, it is more economical for a customer to consume the electricity they produce on-site and reduce the amount of electricity they purchase from a utility. A customer may not be able to consume all of the electricity that they produce at the time of generation, therefore, they have the option of storing the electricity for future consumption. If customers to a time of use pricing system, they can benefit by shifting non time-specific loads to operate during cheaper times, optimizing micro-generation systems for maximum output at high price times, and using on-site storage to supply the grid or the home at high price times. This includes all power distribution and control systems throughout a facility. There are several methods to generate electricity on site. This includes , Built-In PV’s, Small Scale Wind Turbines, Micro-Hydro, Cells, and Combined Heat and Power Units.

Regardless of the method utilized to generate electricity on the customer side there are four primary configurations: 1). battery-based off-grid systems, 2.) batteryless off-grid systems, 3.) battery-based on-grid systems, and 4.) batteryless on- grid systems. The selection depends on the site, budget, and energy needs.

Battery-based off-grid systems are appropriate for smaller systems far from utility lines, where the peak load exceeds the peak generation on a regular basis. Batteryless off-grid systems are appropriate when the generating capacity is 2 kW or more. Because the system cannot store energy, considerable amounts of power are typically diverted Battery-based on-grid systems are very similar to their off-grid counterparts. The first of two primary differences is that excess energy can be sold to the grid for payment or credit. Batteryless on-grid systems use the grid as the “dump load,” sending excess energy back to the utility’s grid for their customers to use. These systems still may require a controller and dump load that only comes into play in the event of a utility outage. Batteryless grid-tied systems are considered to be the simplest and most reliable systems because they incorporate no batteries but have the grid available. Their drawback is the lack of backup for any utility outages. Photovoltaics (PV) and Built-In PV’s

Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into (DC) electricity using semiconductors that exhibit a . Photovoltaic power generation employs solar panels comprising a number of cells containing a photovoltaic material. Photovoltaic arrays are often associated with buildings; either integrated into them, mounted on them, or mounted nearby on the ground. Arrays are most often retrofitted into existing buildings, usually mounted on top of the existing roof structure or on existing walls. Alternatively, an array can be located separate from a building but connected via cabling to supply power to the building.

Building-integrated Photovoltaics (BIPV) are increasingly incorporated into new domestic and industrial buildings as a principal or ancillary source of electrical power. Typically, an array is incorporated into the roof or walls of a building. Roof tiles with integrated PV cells are also becoming more common. Installation Considerations

PV system can either be grid-connected where power is available, or “stand alone” and can be backed up with a generator. A Grid-connected system uses power from the electric utility provider when needed and supplies surplus generated power back to the utility provider. This is known as a “parallel” system. A “stand-alone” does not use any electric utility power. They typically require batteries to store power for the times when the sun is not shining. Stand-alone systems are generally considered as a “separate system”. The terminology of “separate system” applies if a building has electricity supplied to it from an electric utility provider if they are completely separated.

The interface between the power produced can be metered in a manner that when power is produced by the PV’s and sent into the grid the meter will run backwards. When power is brought in from the grid the meter will run in the regular direction. This is referred to as “”. Either approach (stand-alone or grid interface) can be done partially; with PV’s being used in conjunction with a generator in a stand-alone system, or with the central grid power serving as a primary power source in a grid-interface system.

National Electrical Code (NEC) requirements apply to PV systems. Article 690 of the NEC specifically addresses PV systems. There are other sections that also apply to PV’s but when there is a conflict Article 690 takes precedence. Article 480 deals with battery safety along with Article 690. Electrical contractors are recommend to confirm if there are specific guidelines for PV’s; private power producing systems must be verified by the local electrical utility provider, as there may be specific information relevant to the installation of a PV systems (grid connected or stand- alone) in their jurisdiction. Currently, the primary manufactures of PV panels include the following: Suntech, First Solar, Sungen Solar, Sharp, BP, SunPower, Hanwha Solarone, Jinko, and REC. Small Scale Wind Turbines

Wind turbines provide a means for the conversion of wind energy into electricity. Small-scale is the name given to wind generation systems with the capacity to produce up to 50 kW of electrical power. Buildings that might otherwise rely on diesel generators may use wind turbines to decrease consumption. Individuals may purchase these systems to reduce or eliminate their dependence on grid electricity for economic or other reasons, or to reduce their carbon footprint. Wind turbines are becoming more frequently used for household in conjunction with battery storage. Grid-connected wind turbines may use , displacing purchased energy with local production when available. Off-grid system users can either adapt to intermittent power or use batteries, photovoltaic, or diesel systems to supplement the . Equipment such as parking meters or wireless internet gateways may be powered by a wind turbine that charges a small battery, replacing the need for a connection to the power grid.

Options for small scale wind turbines include roof and ground mounted wind turbines and built-in Integrated Wind Turbine.

Micro-Hydro Generators Microhydro is a term used for hydroelectric power installations that typically produce up to 100 kW of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without the purchase of fuel.

Micro hydro systems complement photovoltaic systems because in many areas, water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum. Micro hydro is accomplished with a pelton wheel to generate high head, low flow water supply. The installation requires a small dammed pool, at the top of a waterfall, with several hundred feet of pipe leading to a small generator housing.

Through the use of power control devices, generators can be operated at arbitrary frequencies and feed through an inverter to produce output to match the grid frequency. Very small installations - a few kilowatts or smaller - may generate direct current and charge batteries for peak use times. Installation Considerations

Most sites vary considerably in flow between winter and summer, which is due to the differences in rainfall. Electrical contractors need to make sure that the flow is sufficient to run the turbine. To extract maximum power from the turbine site, it is often desirable to install two turbines, switching in the second machine, when the water flow allows. The following equation can be used to calculate power at a site: Power () = Head (m) x Flow (liters/sec) x 9.81 (gravitational constant ‘g’) A typical water to wire efficiency is approximately 70%, therefore, a multiplier of 0.7 should be sued to obtain the actual amount of electricity that can be expected from the site. Currently, the primary manufactures of micro hydro generators include: Brownell Micro Hydro, Micro Hydro Power, and PowerSpout.

Fuel Cells and Microbial Fuel Cells A is an electrochemical cell that converts a source fuel into an electric current. It generates electricity inside a cell through a reaction between a fuel and an oxidant, triggered in the presence of an electrolyte. The reactants flow into the cell, and the reaction products flow out of it, while the electrolyte remains within it. Fuel cells can operate continuously as long as the necessary reactant and oxidant flows are maintained. Many combinations of and oxidants are now possible. For example, a fuel cell uses hydrogen as its fuel and (usually from air) as its oxidant. Other fuels include and alcohols. Other oxidants include chlorine and chlorine dioxide. Some of the more well-known fuel cell technologies include: proton exchange membrane (PEMPC) and (SOFC).

A Microbial Fuel Cell (MFC) is a device that converts chemical energy to electrical energy by the catalytic reaction of microorganisms. A typical microbial fuel cell consists of anode and cathode compartments separated by a cation (positively charged ion) specific membrane. In the anode compartment, fuel is oxidized by microorganisms, generating electrons and protons. Electrons are transferred to the cathode compartment through an external electric circuit, and the protons are transferred to the cathode compartment through the membrane. Electrons and protons are consumed in the cathode compartment, combining with oxygen to form water. In general, there are two types of microbial fuel cells: mediator and mediator-less. Microbial fuel cells have a number of potential uses. The first and most obvious is harvesting the electricity produced for a power source. Virtually any organic material could be used to “feed” a fuel cell. It is conceivable that MFCs could be installed in septic tanks, where bacteria would consume waste material from the water and produce supplementary power for a building. MFCs are a clean and efficient method of energy production. Installation Considerations

Fuels offer great potential; however, there are currently no manufacturers for residential or commercial use. Redox Power is working on small units that will provide safe, efficient, reliable, uninterrupted power, on–site and optionally off the grid, at a price competitive with current energy sources. Combined Heat and Power (CHP) and Micro CHP (MicroCHP) Installations Combined Heat and Power (CHP) fuel cells have demonstrated superior efficiency for years in industrial plants, universities, hotels, and hospitals. Residential and small- scale commercial fuel cells are now becoming available to fulfill both electricity and heat demand from one system. Fuel cell technology in a compact system is currently available to convert or propane into both electricity and heat. In the future, new developments in fuel cell technologies will likely allow these power systems to be fueled from instead of fossil fuels, directly converting a into a technology.

Micro Combined Heat and Power (MicroCHP) systems such as home fuel cells and co-generation for commercial office buildings and industrial facilities are currently in development. The system generates constant electric power (selling excess power back to the grid when it is not consumed), and produces hot air and water from the waste heat. MicroCHPs are usually less than 5 kWh for a residential or commercial building fuel cell.

MicroCHP fit either inside a mechanical room or outside the primary structure. They operate like a combination furnace, where hot water and electricity are produced from one compact unit. They can generate between 1 to 5 kWh in addition to providing heat for hot water applications. MicroCHP’s are designed to operate 24 hours a day. They are connected to the grid through the main service panel. Most equipment is designed to integrate with existing building electrical and hydronic system. In the event of an interruption of electric power via the grid, the MicroCHP are able to switch to a grid-independent operational mode to provide continuous backup power for dedicated circuits. In addition, most designs also allow for off-the- grid operation.

Direct Current (DC) Consumption With many customers choosing to generate electricity on site, more manufactures are choosing to manufacturer appliances that use direct current. An evaluation of electrical loads will be necessary to determine the amount of DC current that can be used directly. The greatest advantage is that neither a charge controller nor inverter is required. There are options available to store DC current for later use. In this case, a battery system and charge controller would be needed, but an inverter would not be required.

ENERGY STORAGE The term energy storage refers to devices designed to store energy to accommodate periods when the demand of energy exceeds what the utility grid is able to supply. Currently, the primary storage devices include, but are not limited to the following: batteries, uninterruptible power supply systems, and , chemical, biological, electrochemical, electrical, mechanical, thermal, and fuel conservation storage. Each of these methods is described below.

Batteries Batteries are the most common method of storing energy for the periods when power cannot be produced on the customer side. Batteries must be able to handle deep discharges that occur when power is generated on the customer side.

EV Storage Plug-in vehicles fall into one of two categories: Plug-in Hybrid Electric Vehicles (PHEV) or Plug-in Electric Vehicles (PEV). The primary difference between plug-in electric vehicles and fossil fuel-powered vehicles is that they are able to utilize electricity for the powertrain of the vehicle. Plug-in vehicles require frequent charging from an external source of energy.

PHEV and PEV that are manufactured today can be charged from conventional power outlets or dedicated charging stations. Depending on the voltage available (120, 208, 240, or 480 V), the process may take only a fraction of an hour to several hours. For residential applications, since the charging voltage is limited to 240V the process will usually take several hours. There is a corresponding relationship between the number of PHEV and PEV that are manufactured and sold and the increased demand for power from the grid. There is a common concern that the distribution system, and specifically distribution system , will be undersized to accommodate the needs of PEV nighttime charging.

As more PHEV and PEV are in use, they may become part of this grid energy storage system, referred to as vehicle-to-grid energy storage. Instead of PHEV and PEV just taking energy from the grid, they would be able to release energy back into the grid in times of very high demand. EVs are an example of a technology that serves both as an electricity use (load) and an electricity source (supplying power back to the grid). They can compensate for varying grid conditions by providing or absorbing energy to help correct system voltage or frequency. Placing an energy storage device in the distribution grid to serve as both a load and as a Distributed Energy Resource (DER) also offers new integration challenges and opportunities for increased reliability. An presents challenges in minimizing the grid impact of its charging and also in the opportunity for its use as a DER.

Integrated Storage Grid energy storage refers to a process where electricity generators distribute excess electricity into the grid to electricity storage sites. Community Energy Storage (CES) refers to the storage of energy in small, distributed energy storage systems. The concept behind CES systems is that they are available to a group of people who are connected or who opt in the system. Residential CES are typically 25 kW or less and have a 1 to 2 hour back-up time serving up to a dozen residences. They are designed to create an energy cushion in the event of a power failure from the grid. The primary difference between a commercial and residential CES is that commercial CES are able to supply 3 phase 277/480 volts.

CES units store 120/240-volt power for individual customers and are connected on the low-voltage side of the utility . The intent is to place a utility- controlled device at the edge of the grid to provide voltage control and improve service reliability. As more sophisticated electronic loads, such as computers, appliances, etc. (which require greater service reliability) are added - along with additional PHEV charging units - greater control of voltage and power fluctuations to the customer will be required. With the addition of more EMCS that will enable energy flowing back into the grid when the power demand of specific customers is less than what they are producing, the amount of energy that dissipates back into the utility network can precede the customer load peak by two to three hours each workday. It is envisioned that CES units located throughout the network would allow excess energy to be captured locally with less line losses and re-dispatched back to the same customers when needed.

As mentioned above, as more PHEV and PEV are utilized, the charging demand will affect load on the grid. CES is one method of balancing the demand of power from the grid in such instances if all neighbors where to plug-in their vehicles at the same time.

Another technology that has received renewed interest is direct current (DC), especially in localized grids called “microgrids.” For example, solar photovoltaic produces DC, batteries store DC, and loads such as computer equipment and variable speed motors operate on DC. The grid operates mainly on (AC), and conversions need to take place between AC and DC to interconnect DC generation or loads to the AC grid.

In order to improve efficiency, the number of such individual conversions should be minimized, leading to exploring new concepts for managing electricity at locations involving these generation sources, storage methods, and loads. Also, local electricity generation, storage, and distribution systems should be improved to increase the self- sufficiency of end users. UPS

Uninterruptible Power Supplies (UPS) systems are another option for energy storage. UPS systems utilize batteries to store energy and provide a short duration (five to ten minutes) safety net in the event of a power failure. UPS are frequently installed solely to protect and provide power to select loads. The majority of UPS systems in place is relatively small and are installed with personal computers to allow properly shut down in the event a power failure. UPS systems range in size, but most only supply loads of 500 watts or less. In a smart grid environment, a UPS’s storage batteries could lower demand or supply the grid during peak hours or in response to an electricity provider’s request.

CONCLUSION

All energy sources have an impact on the environment. Concerns about the greenhouse effect and global warming, air pollution, and have led to increasing interest and more development in renewable energy sources such as solar, wind, geothermal, and hydrogen. Electricity that we depend on every day comes from a large variety of sources. Each energy source has its advantages and disadvantages, but will continue to advance and develop. There will likely never be one clear source of energy that will serve all our needs, but a combination of all technologies can that compensate for each other seems to be the best bet for providing our energy needs.

ACKNOWLEDGEMENTS

The author wishes to thank the support of Electri-International for their support of this research project.

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