Distributed Generation Transcript

Distributed Generation P a g e | 1

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Distributed Generation Transcript

Slide 1: Distributed Generation Welcome to Distributed Generation. Slide 2: Pre-Requisites In order to fully appreciate this topic, you need to understand how energy is billed. Factors such as demand, demand ratchet and time of use all have an impact on the potential returns from your distributed generation strategy. If you do not have a thorough knowledge of these topics, please take Energy Rate Structures I and II first. Slide 3: Welcome For best viewing results, we recommend that you maximize your browser window now. The screen controls allow you to navigate through the eLearning experience. Using your browser controls may disrupt the normal play of the course. Click the attachments link to download supplemental information for this course. Click the Notes tab to read a transcript of the narration. Slide 4: Objectives At the completion of this course, you will be able to:

Identify important drivers for why distributed generation is gaining popularity as a source of energy Describe the primary categories of technology used to generate small-scale electricity; and you will be able to Discuss the main benefits and issues for each technology

Slide 5: Introduction Most industrial economies rely on very large central station power plants for electricity production. Such plants are fueled with natural gas, oil, coal, nuclear, and hydropower. Large central station power plants benefit from economies of scale to deliver high production efficiencies and/or at low production costs. However, they are usually located in remote areas and need to transmit electricity over long distances to end users located throughout a region. Transporting electricity over long distances over transmission wires results in lost energy. Slide 6: Introduction Distributed generation reduces energy losses by bringing energy production closer to the end user, sometimes even in the same physical building or campus. Distributed generation reduces the number and size of transmission and distribution wiring needed to serve modern-day energy needs. Slide 7: Introduction Capacity margin is the amount of unused available capability of an electric power system at peak load as a percentage of capacity resources. Due to significant growth, capacity margins are declining to alarming values. In many countries, the quality of electric power is poor in terms of frequent power interruptions, un-scheduled power reductions, voltage variations, frequency fluctuations, presence of harmonics, and other system instabilities. Slide 8: Introduction In almost all cases, the price of electricity is steadily increasing. The cost of fuel is pushed up by increasing global demand, and the cost of production is impacted by requirements to meet more stringent emissions regulations.



Many times, there are very few options that an end user can choose from for alternate sources of energy. They are captive to the existing electric grid. Slide 9: Introduction Recent electricity market deregulation, greater emphasis on environmental quality, and on-going concerns related to the high cost of electricity is resulting in a renewed interest for distributed generation throughout the world. Distributed generation provides an alternative to, or an enhancement of the traditional electric power system. The purpose of this course is to discuss various small-scale generation technologies that exist today. We will then move on with a discussion of the major benefits and issues of distributed generation. Lets begin with a discussion on the definition of distributed generation. Slide 10: What is Distributed Generation? Distributed generation (DG) is known by several different names including:

On-site Generation Dispersed Power Decentralized Energy or Decentralized Generation Distributed Energy Resource or Distributed Resources

Slide 11: What is Distributed Generation? Dispersed power is the use of small-scale power generation technologies located close to the load being served. In most cases, dispersed power with energy recovery provides multiple streams of energycleanly and efficiently. Combined-cycle using clean natural gas can be used for power production and district heating near populated areas. This type of power plant uses multiple cycles to increase efficiency - for example, using a generator to produce electricity, and taking the waste heat to make steam to generate more electricity. Renewables such as solar energy, wind power, and in some cases geothermal offer potential for energy production near populated areas as well. Battery storage and automotive application of electric vehicles are also being developed. These technologies can be used as electric energy sources on-demand when plugged into the grid. Distributed energy resources are any of these technologies introduced and include small-scale power generation technologies (typically in the range of 3 kW to 10,000 kW) used to provide an alternative to or an enhancement of the traditional electric power system. Slide 12: Major Drivers for Why Distributed Generation is Gaining Popularity Deregulation of electric markets and environmental concerns can be cited as the two main drivers for why distributed generation has gained popularity in recent years. Lets look at the deregulation of electric markets as the first driver. Slide 13: Major Drivers for Why Distributed Generation is Gaining Popularity Were seeing an increased interest by electricity suppliers in distributed generation because they see it as a tool that will help them to fill in niches in a deregulated market. In deregulated markets, customers look for the electricity service best suited for them. Naturally, different customers will attach different weights to features of the electricity supply. Distributed generation technologies can help electricity suppliers deliver the type of electricity service their customer prefers. Distributed generation allows competitors in the electricity sector to respond in a flexible way to changing market conditions.



Slide 14: Major Drivers for Why Distributed Generation is Gaining Popularity In deregulated markets, it is important to adapt to the changing economic environment in the most flexible way. Distributed generation technologies generally provide this flexibility because of their small size and the short construction lead times compared to larger central power plants. It should be noted that the lead time reduction is not always realized due to difficulty obtaining permits as well as other factors, and a fair amount of public resistance may still exist with regards to very large wind energy generators. Slide 15: Major Drivers for Why Distributed Generation is Gaining Popularity As distributed generation becomes more prevalent throughout the world, we can expect to see increased interest in peak use capacity (peak shaving) and other demand response opportunities. There will be significant technical emphasis in areas related to standby capacity, reliability, and power quality. There are also opportunities and concerns related to alternative expansion of use of the local grid network, and increased demand for grid support. Slide 16: Major Drivers for Why Distributed Generation is Gaining Popularity Environmental policies and concerns are also a growing driving force behind demand for distributed generation. Environmental regulations force participants in the electricity market to look for cleaner energy, and in turn, more cost-efficient solutions. Distributed generation can play a role here, as it allows for optimizing energy consumption of firms that have significant requirements for both electricity and heat. Now lets move on and discuss engine types. Slide 17: Types of Engines Internal combustion engines are available in spark ignition or compression ignition types. Compression ignition engines are commonly available in two-stroke and four-stroke cycles. Four-stroke engines are available in medium-speed and high-speed versions. Reciprocating engines may be fueled by diesel or natural gas, and have varying emission outputs. Slide 18: Reciprocating Diesel or Natural Gas Engines Lets look at one form of distributed generation - engine generator sets. Reciprocating engines were developed more than 100 years ago. These were among the first examples of distributed generation technologies. Both the spark ignition and the diesel cycle (also called compression ignition) engines have gained widespread acceptance in almost every sector of the economy. They are used on many scales, with applications ranging from fractional horsepower units that power small tools to enormous 60 MW base load electric power plants. Smaller engines are primarily designed for transportation and can usually be converted to power generation with little modification. Larger engines are more frequently designed for power generation, mechanical drive, or marine propulsion. Slide 19: Reciprocating Diesel or Natural Gas Engines Most engines used for power generation are four-stroke and operate in four cycles:



Intake (Induction) Compression Combustion (Ignition), and Exhaust

Slide 20: Reciprocating Diesel or Natural Gas Engines The process begins with fuel and air being mixed. In turbocharged applications, the air is compressed before mixing with fuel. The fuel/air mixture is introduced into the engine cylinder, compressed and ignited with a spark.

For diesel units, the air and fuel are introduced separately with fuel being injected after the air is compressed ignition is accomplished through heat-of-compression.



Reciprocating engines are currently available from many manufacturers in many size ranges. They are typically used for either continuous power or backup emergency power. Cogeneration configurations are available with heat recovery engine cooling, and from hot engine exhaust gas. A significant amount of energy from an engine generator is available for low-temperature heating processes which are shown in the pie chart as heat rejected losses.

Slide 21: Reciprocating Diesel or Natural Gas Engines The slow-speed diesel engine, with its flat fuel consumption curve over a wide load range (50%-100%), compares very favorably over other prime movers such as medium speed diesel engines, steam turbines and gas turbines. With the arrival of modern, high efficiency turbochargers, it is possible to use an exhaust gas driven turbine generator to further increase the engines rated output. The net result is lower fuel consumption per kWh and an increase in overall thermal efficiency. Slide 22: Microturbines Another form of distributed generation is microturbine generators. A class of small-scale distributed power generation in the 30-400 kW size range is emerging as microturbines. The basic technology for a microturbine is drawn from:

Automotive designs Aircraft auxiliary power systems, and Diesel engine turbochargers

A number of companies are currently field-testing demonstration units, and several commercial units are available for purchase. A simple internet search will yield the name of companies in your area. Slide 23: Microturbines Microturbines consist of a generator, compressor, combustor, and turbine. The compressors and turbines are typically radial-flow designs, and resemble automotive engine turbochargers. Most designs are single-shaft and use a high-speed permanent magnet generator producing variable voltage, variable frequency alternating current (AC)



power. Most microturbine units are designed for continuous-duty operation and many are recuperated to reduce fuel consumption. A recuperated unit is fitted with a heat exchanger to recover some of the heat from the exhaust. This is used to pre-heat the incoming air, boosting the fuel efficiency, but leaving less heat available for recovery for other uses.

Slide 24: Combustion Gas Turbines Another form of distributed generation includes larger combustion turbine generator sets.

Combustion turbines range in size from simple cycle units starting at about 1 MW to several hundred MW when configured as a combined cycle power plant. Units from 1-15 MW are generally referred to as industrial turbines or sometimes as miniturbines. This differentiates them both from larger utility grade turbines and smaller microturbines. Industrial turbines are currently available from numerous manufacturers. Historically, they were developed as aero derivatives - spawned from engines used for aircraft propulsion. Slide 25: Combustion Gas Turbines Some, however, are designed specifically for stationary power generation or compression applications in the oil and gas industries. Multi-stage axial compressors and complex turbine geometries differentiate these sophisticated machines from the smaller micro-turbines described previously. Combustion turbines have relatively low emissions, low installation costs, and infrequent maintenance requirements. However, their low efficiency has limited turbines to serving peaking unit and combined heat and power (CHP) applications. Cogeneration distributed generation installations are especially beneficial when a continuous supply of steam or hot water is desired. Slide 26: Steam Turbines Steam turbine generator sets can also be a form of distributed generation.



For years, steam turbines have been used as prime movers for industrial cogeneration systems. High-pressure steam raised in a conventional boiler is expanded within the turbine to produce mechanical energy, which may then be used to drive an electric generator. The power produced depends on how much the steam pressure can be reduced through the turbine before being required to meet the site heat energy needs. A steam turbine will generate less electrical energy per unit of fuel than a gas turbine or reciprocating engine-driven cogeneration system, although its overall efficiency may be up to 84% higher - because it is generating both heat and electricity (based on fuel gross calorific value). Slide 27: Steam Turbines For viable power generation, the steam input must be at a high pressure and corresponding temperature. Sometimes, the residual heat output is relatively low grade. The higher the turbine inlet pressure, the greater the power output. Higher steam pressures entails progressively greater boiler capital and running costs. Optimum pressure will depend on the size of the plant along with the required process steam pressures. Steam cycles have an immense advantage in that the associated boiler plant can be designed to operate on virtually any fuel, including:

Coal Gas Heavy fuel oil (HFO) Residues and municipal or other wastes, and are Often capable of operating on more than just one fuel.

Slide 28: Steam Turbines A high-pressure boiler is required to produce steam at pressures and temperatures needed to make power generation economical. This type of power plant is very capital intensive to construct. An existing site supplied by low pressure boilers will normally need to replace the existing boilers with high-pressure equipment. It may be desired to retain the original equipment as stand-by. Steam cycles normally consume a large amount of energy compared with the electrical output. Steam turbine plants also have high equipment and installation costs. Slide 29: Steam Turbines Integrating an incineratorburning waste fuels, such as clinical waste, farm wastes or municipal solid wastewith a steam turbine based cogeneration unit, can become cost-effectivewith power outputs of greater than 500 kW electric. However, incineration typically raises concerns over the production of undesirable emissions. As an alternative, some types of waste can be gasified and the resultant gas used to fuel a gas turbine installationor



possibly even a gas engine. Slide 30: Steam Turbines Steam turbines fall into two types, according to exit pressure of the steam from the turbine: Back-pressure turbines -The exit pressure is greater than atmospheric pressure, and Condensing turbines -Where the exit pressure is lower than atmospheric pressure and a surface condenser is required

The simplest arrangement is the back-pressure turbine in which all the steam flows through the machine and is exhausted from the turbine at a single, relatively low pressuresuitable for use on-site. Using the exhausted steam for process or other heating makes a contribution to the overall efficiency of the site. However, if this exhaust is not used, the energy contained within it is wasted. In a moment, we'll see how the second type of turbine handles this. Slide 31: Steam Turbines Here's a diagram illustrating how a back pressure steam turbine supplies power and also steam to meet site or process heat demand.



The site heat load requirements dictate the amount of steam produced. The steam passes through the turbine and contributes to power generation, and then exits the turbine to satisfy the heating requirements. Hence the power output is dependent on site heat load. When more heat is required by the site, more steam is produced, and more power is produced as well. Where more than one grade of heat is required, the higher grade is served by extraction steam at the appropriate pressure part-way along the turbine. Taking steam out of the turbine means there is less energy available for making electricity, but if the extracted steam can be used for useful process heat that can lead to higher overall cycle efficiency.

Slide 32: Steam Turbines As we just saw, the first type of turbine exhausts steam at relatively low pressure - but still above atmospheric pressure. In a fully condensing turbine, instead of making that low pressure steam available for heating, the turbine design captures as much of that energy as possible for power generation. Slide 33: Steam Turbines To achieve this, the steam expands through the turbine down to a very low pressure, which is actually a vacuum, below atmospheric pressure, and exhausts to a surface condenser.

This means the turbine gets as much energy as possible out of the steam. The surface condenser captures the water that condenses out of the steam and returns it to the boiler. Some energy does escape from the turbine and passes through the condenser during the process of condensation. However this is generally not recoverable, and is usually rejected to the environmentas heat or waterand is lost.



Slide 34: Steam Turbines Let's look at an application. District heat is a system for distributing heat generated in a centralized location to a group of residences and/or commercial buildings to provide heating requirements such as space heating and water heating. Instead of each house or business having their own boiler, there is one central heating system which they all use. In district heat designs that include cogeneration, the system deals with production of power as well as heat. The steam turbine is used to produce power, but is set up with the turbine condenser operating near or even above atmospheric pressure. In effect, this is deliberately running the turbine to produce less power, so that the steam which leaves the turbine and enters the condenser still contains considerable energy. This guarantees that the condenser cooling water picks up enough heat to supply the district heating circuit. Slide 35: Wind Turbines Wind turbines are a form of distributed generation.

Wind turbines are packaged systems that include the rotor, generator, turbine blades, and drive or coupling device. As wind blows through the blades, the air exerts aerodynamic forces that cause the blades to turn the rotor. As the rotor turns, its speed is altered to match the operating speed of the generator. Windmill graphic is courtesy of the U.S. Department of Energy. Slide 36: Wind Turbines Most systems have a gearbox and generator in a single unit behind the turbine blades. As with photovoltaic (PV) systems, the output of the generator is processed by an inverter that changes the electricity from DC to AC so that the



electricity can be used locally, or on the electric grid. Slide 37: Wind Turbines Windmills have been used for many years to harness wind energy for mechanical work like pumping water. Before a centralized supply of electric power became the norm, many rural areas were using windmills to produce various forms of energy. Advances are also being made into vertical-axis wind turbines, which are seen as an alternate to traditional propeller designs. Slide 38: Wind Turbines During the 1970s energy crisis, wind energy became a significant focus for research and development as a potential renewable energy source. Wind turbines, basically windmills dedicated to producing electricity, were considered the most economically viable choice within the renewable energy portfolio. Slide 39: Wind Turbines Attention continues to remain focused on this technology as an environmentally sound and convenient alternative to fossil fuels. Wind turbines produce electricity without requiring additional investments in infrastructure such as new transmission lines, and are commonly employed for remote power applications. Theyre currently available from many manufacturers and improvements in installed cost and efficiency continue. Slide 40: Photovoltaics Solar power is a form of distributed generation. Photovoltaics were first discovered in 1839, by the French physicist Edmund Becquerel. He discovered that certain materials produced small electric currents when exposed to light. Slide 41: Photovoltaics His early experiments were about 1 to 2 percent efficient in converting light to electricity and led to research into these photovoltaic effects. The science surrounding photovaltacis continued to evolve. In 1954, Bell Labs was able to develop a silicon photovoltaic cell that increased the light to electricity conversion efficiency to 4 percent. Slide 42: Photovoltaics Photovoltaic systems are commonly known as solar panels. PV (Photovoltaic) solar panels are made up of discrete cells connected together that convert light radiation into electricity.

PV cells produce direct-current (DC) electricity, which must then be inverted for use in an AC system. Today, PV units have efficiencies of 24% in the lab and 10% in actual use, which is far below the 30% maximum theoretical efficiency



that can be attained by a PV cell. Slide 43: Photovoltaics Insolation is a term used to describe available solar energy that can be converted to electricity. The factors that affect insolation are the intensity of the light and the operating temperature of the PV cells. Light intensity is dependent on the local latitude and climate and generally increases as the PV site gets closer to the equator. Slide 44: Photovoltaics The main benefits of photovoltaic systems are that they produce no emissions, are reliable, and require minimum maintenance to operate. They are currently available from a number of manufacturers for both residential and commercial applications, and manufacturers continue to reduce installed costs as well as increase efficiency. Applications for using them as a remote power source are quite common. Slide 45: Emerging Technologies Now, lets discuss some emerging technologies in distributed generation. First, lets look at fuel cells.

Slide 46: Fuel Cells The first fuel cell was developed in 1839 by Sir William Grove. Fuel cells were not put to practical use until the 1960s when NASA installed this technology to generate electricity on the Gemini and Apollo spacecrafts. Slide 47: Fuel Cells There currently are many types of fuel cells under development in the 5-1000+ kW range size, including:

Direct methanol Proton exchange membrane Solid oxide Molten carbonate Alkaline, and Phosphoric acid

The first systems demonstrated were 200-kW phosphoric acid units from International Fuel Cells (International Fuel Cells - also known as ONSI, UTC Fuel Cells). A number of companies are close to commercializing proton exchange membrane fuel cells, with marketplace introductions expected soon. Slide 48: Fuel Cells While the numerous types of fuel cells differ in their electrolytic material, they all use the same basic theory:



A fuel cell consists of two electrodes separated by an electrolyte Hydrogen fuel is fed into the anode of the fuel cell Oxygen (or air) enters the fuel cell through the cathode With the aid of a catalyst, the hydrogen atom splits into a proton (H+) and an electron The proton passes through the electrolyte to the cathode and then the electrons travel in an external circuit As the electrons flow through an external circuit, connected as a load, they create a DC current At the cathode, protons combine with hydrogen and oxygen, producing water and heat Fuel cells have very low levels of nitric oxide and carbon dioxide emissions because the power conversion is

an electrochemical process The part of a fuel cell that contains the electrodes and electrolytic material is called the "stack," and is a major

contributor to the total cost of the system Stack replacement is very costly but becomes necessary when efficiency degrades over time

Slide 49: Fuel Cells Fuel cells require hydrogen for operation, but it is generally impractical to use hydrogen as a direct fuel source. Instead, it must be extracted from hydrogen-rich sources such as gasoline, propane, or natural gas. Efficient, cost effective fuel reformers that convert various fuels to hydrogen are necessary to enable fuel cells to have increased flexibility necessary for commercial feasibility. Slide 50: Stirling Engines Now lets move on and discuss Stirling engines.

The Stirling engine has been around for over 60 years. This engine is an external combustion device and as a result, differs substantially from the conventional combustion plant where the fuel burns inside the machine. Heat is supplied to the Stirling engine by an external source, such as a burning gas, waste heat, or solar energy. This makes a working fluid - for example - helium, expand and causes one of the two pistons to move inside a cylinder. This is known as the working piston. (Stirling engine images and diagrams courtesy of www.stirlingengines.com) Slide 51: Stirling Engines A second piston, known as a displacer, then relocates the gas to a cool zone where it is recompressed by the working piston. The displacer then moves the compressed gas or air to the hot region and the cycle continues.



(Diagram courtesy of www.stirlingengines.com) Slide 52: Stirling Engines The Stirling engine has fewer moving parts than conventional engines, and no valves, tappets, fuel injectors or spark ignition systems. As a result, it is quieter than normal engines. The low noise levels in a Stirling engine is also attributed to the continuous, rather than pulsed, combustion of fuel. Slide 53: Stirling Engines Stirling engines also require little maintenance. Emissions of particulates, nitrogen oxides, and unburned hydrocarbons are low. The efficiency of these machines is potentially greater than that of internal combustion or gas turbine devices. (Stirling engine image courtesy of www.stirlingengines.com) Slide 54: Stirling Engines The advantages of the Stirling engine are: fewer moving parts and low friction, no need for an extra boiler, no internal burner chamber, high theoretical efficiency and very well suited for mass production.

The external burner or heat source allows for a very clean exhaust and gives the possibility of controlling the electrical output of the engine by reducing the temperature of the hot side. So there is the possibility of varying the electrical production regardless of the need for thermal heat demand. (Stirling engine images courtesy of www.stirlingengines.com)



Slide 55: Advantages and Disadvantages As we discussed, each technology has advantages and disadvantages. Its important to weigh these advantages and disadvantages prior to selecting a distributed generation technology. To assist you with weighing these issues, weve attached a downloadable table that lists out the basic advantages and disadvantages of each technology. Weve also included some additional resource information that addresses the topic of distributed generation in more depth. Slide 56: Technology Comparison And finally, weve also included a chart comparison of each technology with regards to size, installed cost, electrical efficiency, overall efficiency, total maintenance costs, footprint and emissions.

Slide 57: Summary Lets conclude with a brief summary. Today we identified deregulation of electric markets and environmental concerns as the major drivers for why distributed generation is gaining popularity as a source of energy. We described the major categories of technology used to generate small scale electricity, including:

Reciprocating engines Microturbines Combustion gas turbines Steam turbines Wind turbines Photovoltaics, as well as the Emerging technologies

Lastly, we discussed the major benefits and issues for each of these technologies.



Slide 58: Thank You! Thank you for participating in this course.

Distributed GenerationSlide 1: Distributed GenerationWelcome to Distributed Generation.

Slide 2: Pre-RequisitesIn order to fully appreciate this topic, you need to understand how energy is billed. Factors such as demand, demand ratchet and time of use all have an impact on the potential returns from your distributed generation strategy. If you do not have a ...

Slide 3: WelcomeFor best viewing results, we recommend that you maximize your browser window now. The screen controls allow you to navigate through the eLearning experience. Using your browser controls may disrupt the normal play of the course. Click the attachments ...

Slide 4: ObjectivesAt the completion of this course, you will be able to: Identify important drivers for why distributed generation is gaining popularity as a source of energy Describe the primary categories of technology used to generate small-scale electricity; and you will be able to Discuss the main benefits and issues for each technology

Slide 5: IntroductionMost industrial economies rely on very large central station power plants for electricity production. Such plants are fueled with natural gas, oil, coal, nuclear, and hydropower. Large central station power plants benefit from economies of scale to ...

Slide 6: IntroductionDistributed generation reduces energy losses by bringing energy production closer to the end user, sometimes even in the same physical building or campus. Distributed generation reduces the number and size of transmission and distribution wiring need...

Slide 7: IntroductionCapacity margin is the amount of unused available capability of an electric power system at peak load as a percentage of capacity resources. Due to significant growth, capacity margins are declining to alarming values. In many countries, the quality ...

Slide 8: IntroductionIn almost all cases, the price of electricity is steadily increasing. The cost of fuel is pushed up by increasing global demand, and the cost of production is impacted by requirements to meet more stringent emissions regulations.Many times, there are very few options that an end user can choose from for alternate sources of energy. They are captive to the existing electric grid.

Slide 9: IntroductionRecent electricity market deregulation, greater emphasis on environmental quality, and on-going concerns related to the high cost of electricity is resulting in a renewed interest for distributed generation throughout the world. Distributed generation...

Slide 10: What is Distributed Generation?Distributed generation (DG) is known by several different names including: On-site Generation Dispersed Power Decentralized Energy or Decentralized Generation Distributed Energy Resource or Distributed Resources

Slide 11: What is Distributed Generation?Dispersed power is the use of small-scale power generation technologies located close to the load being served. In most cases, dispersed power with energy recovery provides multiple streams of energycleanly and efficiently. Combined-cycle using clean...Renewables such as solar energy, wind power, and in some cases geothermal offer potential for energy production near populated areas as well. Battery storage and automotive application of electric vehicles are also being developed. These technologies...

Slide 12: Major Drivers for Why Distributed Generation is Gaining PopularityDeregulation of electric markets and environmental concerns can be cited as the two main drivers for why distributed generation has gained popularity in recent years. Lets look at the deregulation of electric markets as the first driver.

Slide 13: Major Drivers for Why Distributed Generation is Gaining PopularityWere seeing an increased interest by electricity suppliers in distributed generation because they see it as a tool that will help them to fill in niches in a deregulated market. In deregulated markets, customers look for the electricity service best ...Distributed generation technologies can help electricity suppliers deliver the type of electricity service their customer prefers. Distributed generation allows competitors in the electricity sector to respond in a flexible way to changing market cond...

Slide 14: Major Drivers for Why Distributed Generation is Gaining PopularityIn deregulated markets, it is important to adapt to the changing economic environment in the most flexible way.Distributed generation technologies generally provide this flexibility because of their small size and the short construction lead times compared to larger central power plants.It should be noted that the lead time reduction is not always realized due to difficulty obtaining permits as well as other factors, and a fair amount of public resistance may still exist with regards to very large wind energy generators.

Slide 15: Major Drivers for Why Distributed Generation is Gaining PopularityAs distributed generation becomes more prevalent throughout the world, we can expect to see increased interest in peak use capacity (peak shaving) and other demand response opportunities. There will be significant technical emphasis in areas related ...There are also opportunities and concerns related to alternative expansion of use of the local grid network, and increased demand for grid support.

Slide 16: Major Drivers for Why Distributed Generation is Gaining PopularityEnvironmental policies and concerns are also a growing driving force behind demand for distributed generation.Environmental regulations force participants in the electricity market to look for cleaner energy, and in turn, more cost-efficient solutions. Distributed generation can play a role here, as it allows for optimizing energy consumption of firms that ha...

Slide 17: Types of EnginesInternal combustion engines are available in spark ignition or compression ignition types. Compression ignition engines are commonly available in two-stroke and four-stroke cycles. Four-stroke engines are available in medium-speed and high-speed ver...

Slide 18: Reciprocating Diesel or Natural Gas EnginesLets look at one form of distributed generation - engine generator sets.Reciprocating engines were developed more than 100 years ago. These were among the first examples of distributed generation technologies. Both the spark ignition and the diesel cycle (also called compression ignition) engines have gained widespread...Smaller engines are primarily designed for transportation and can usually be converted to power generation with little modification. Larger engines are more frequently designed for power generation, mechanical drive, or marine propulsion.

Slide 19: Reciprocating Diesel or Natural Gas EnginesMost engines used for power generation are four-stroke and operate in four cycles: Intake (Induction) Compression Combustion (Ignition), and Exhaust

/Slide 20: Reciprocating Diesel or Natural Gas EnginesThe process begins with fuel and air being mixed. In turbocharged applications, the air is compressed before mixing with fuel.The fuel/air mixture is introduced into the engine cylinder, compressed and ignited with a spark./For diesel units, the air and fuel are introduced separately with fuel being injected after the air is compressed ignition is accomplished through heat-of-compression./Reciprocating engines are currently available from many manufacturers in many size ranges. They are typically used for either continuous power or backup emergency power. Cogeneration configurations are available with heat recovery engine cooling, and ...

Slide 21: Reciprocating Diesel or Natural Gas EnginesThe slow-speed diesel engine, with its flat fuel consumption curve over a wide load range (50%-100%), compares very favorably over other prime movers such as medium speed diesel engines, steam turbines and gas turbines.With the arrival of modern, high efficiency turbochargers, it is possible to use an exhaust gas driven turbine generator to further increase the engines rated output. The net result is lower fuel consumption per kWh and an increase in overall thermal...

Slide 22: MicroturbinesAnother form of distributed generation is microturbine generators. A class of small-scale distributed power generation in the 30-400 kW size range is emerging as microturbines. The basic technology for a microturbine is drawn from: Automotive designs Aircraft auxiliary power systems, and Diesel engine turbochargersA number of companies are currently field-testing demonstration units, and several commercial units are available for purchase. A simple internet search will yield the name of companies in your area.

Slide 23: MicroturbinesMicroturbines consist of a generator, compressor, combustor, and turbine. The compressors and turbines are typically radial-flow designs, and resemble automotive engine turbochargers. Most designs are single-shaft and use a high-speed permanent magnet...

/Slide 24: Combustion Gas TurbinesAnother form of distributed generation includes larger combustion turbine generator sets./Combustion turbines range in size from simple cycle units starting at about 1 MW to several hundred MW when configured as a combined cycle power plant. Units from 1-15 MW are generally referred to as industrial turbines or sometimes as miniturbines. T...

Slide 25: Combustion Gas TurbinesSome, however, are designed specifically for stationary power generation or compression applications in the oil and gas industries. Multi-stage axial compressors and complex turbine geometries differentiate these sophisticated machines from the smalle...

Slide 26: Steam TurbinesSteam turbine generator sets can also be a form of distributed generation.For years, steam turbines have been used as prime movers for industrial cogeneration systems. High-pressure steam raised in a conventional boiler is expanded within the turbine to produce mechanical energy, which may then be used to drive an electric ...The power produced depends on how much the steam pressure can be reduced through the turbine before being required to meet the site heat energy needs.A steam turbine will generate less electrical energy per unit of fuel than a gas turbine or reciprocating engine-driven cogeneration system, although its overall efficiency may be up to 84% higher - because it is generating both heat and electricity (...

Slide 27: Steam TurbinesFor viable power generation, the steam input must be at a high pressure and corresponding temperature. Sometimes, the residual heat output is relatively low grade.The higher the turbine inlet pressure, the greater the power output. Higher steam pressures entails progressively greater boiler capital and running costs.Optimum pressure will depend on the size of the plant along with the required process steam pressures.Steam cycles have an immense advantage in that the associated boiler plant can be designed to operate on virtually any fuel, including: Coal Gas Heavy fuel oil (HFO) Residues and municipal or other wastes, and are Often capable of operating on more than just one fuel.

Slide 28: Steam TurbinesA high-pressure boiler is required to produce steam at pressures and temperatures needed to make power generation economical. This type of power plant is very capital intensive to construct.An existing site supplied by low pressure boilers will normally need to replace the existing boilers with high-pressure equipment. It may be desired to retain the original equipment as stand-by.Steam cycles normally consume a large amount of energy compared with the electrical output. Steam turbine plants also have high equipment and installation costs.

Slide 29: Steam TurbinesIntegrating an incineratorburning waste fuels, such as clinical waste, farm wastes or municipal solid wastewith a steam turbine based cogeneration unit, can become cost-effectivewith power outputs of greater than 500 kW electric.However, incineration typically raises concerns over the production of undesirable emissions.As an alternative, some types of waste can be gasified and the resultant gas used to fuel a gas turbine installationor possibly even a gas engine.

Slide 30: Steam TurbinesSteam turbines fall into two types, according to exit pressure of the steam from the turbine: Back-pressure turbines-The exit pressure is greater than atmospheric pressure, and Condensing turbines-Where the exit pressure is lower than atmospheric pressure and a surface condenser is required/The simplest arrangement is the back-pressure turbine in which all the steam flows through the machine and is exhausted from the turbine at a single, relatively low pressuresuitable for use on-site.Using the exhausted steam for process or other heating makes a contribution to the overall efficiency of the site. However, if this exhaust is not used, the energy contained within it is wasted. In a moment, we'll see how the second type of turbine ...

Slide 31: Steam TurbinesHere's a diagram illustrating how a back pressure steam turbine supplies power and also steam to meet site or process heat demand.The site heat load requirements dictate the amount of steam produced. The steam passes through the turbine and contributes to power generation, and then exits the turbine to satisfy the heating requirements.Hence the power output is dependent on site heat load. When more heat is required by the site, more steam is produced, and more power is produced as well.Where more than one grade of heat is required, the higher grade is served by extraction steam at the appropriate pressure part-way along the turbine. Taking steam out of the turbine means there is less energy available for making electricity, but if...

/Slide 32: Steam TurbinesAs we just saw, the first type of turbine exhausts steam at relatively low pressure - but still above atmospheric pressure. In a fully condensing turbine, instead of making that low pressure steam available for heating, the turbine design captures as...

Slide 33: Steam TurbinesTo achieve this, the steam expands through the turbine down to a very low pressure, which is actually a vacuum, below atmospheric pressure, and exhausts to a surface condenser./This means the turbine gets as much energy as possible out of the steam. The surface condenser captures the water that condenses out of the steam and returns it to the boiler. Some energy does escape from the turbine and passes through the condenser...

Slide 34: Steam TurbinesLet's look at an application. District heat is a system for distributing heat generated in a centralized location to a group of residences and/or commercial buildings to provide heating requirements such as space heating and water heating. Instead o...In district heat designs that include cogeneration, the system deals with production of power as well as heat. The steam turbine is used to produce power, but is set up with the turbine condenser operating near or even above atmospheric pressure. In...

Slide 35: Wind TurbinesWind turbines are a form of distributed generation./Wind turbines are packaged systems that include the rotor, generator, turbine blades, and drive or coupling device. As wind blows through the blades, the air exerts aerodynamic forces that cause the blades to turn the rotor. As the rotor turns, its ...

Slide 36: Wind TurbinesMost systems have a gearbox and generator in a single unit behind the turbine blades. As with photovoltaic (PV) systems, the output of the generator is processed by an inverter that changes the electricity from DC to AC so that the electricity can be...

Slide 37: Wind TurbinesWindmills have been used for many years to harness wind energy for mechanical work like pumping water. Before a centralized supply of electric power became the norm, many rural areas were using windmills to produce various forms of energy.Advances are also being made into vertical-axis wind turbines, which are seen as an alternate to traditional propeller designs.

Slide 38: Wind TurbinesDuring the 1970s energy crisis, wind energy became a significant focus for research and development as a potential renewable energy source. Wind turbines, basically windmills dedicated to producing electricity, were considered the most economically ...

Slide 39: Wind TurbinesAttention continues to remain focused on this technology as an environmentally sound and convenient alternative to fossil fuels. Wind turbines produce electricity without requiring additional investments in infrastructure such as new transmission lin...

Slide 40: PhotovoltaicsSolar power is a form of distributed generation. Photovoltaics were first discovered in 1839, by the French physicist Edmund Becquerel. He discovered that certain materials produced small electric currents when exposed to light.

Slide 41: PhotovoltaicsHis early experiments were about 1 to 2 percent efficient in converting light to electricity and led to research into these photovoltaic effects. The science surrounding photovaltacis continued to evolve. In 1954, Bell Labs was able to develop a sil...

Slide 42: PhotovoltaicsPhotovoltaic systems are commonly known as solar panels. PV (Photovoltaic) solar panels are made up of discrete cells connected together that convert light radiation into electricity./PV cells produce direct-current (DC) electricity, which must then be inverted for use in an AC system. Today, PV units have efficiencies of 24% in the lab and 10% in actual use, which is far below the 30% maximum theoretical efficiency that can be at...

Slide 43: PhotovoltaicsInsolation is a term used to describe available solar energy that can be converted to electricity. The factors that affect insolation are the intensity of the light and the operating temperature of the PV cells. Light intensity is dependent on the l...

Slide 44: PhotovoltaicsThe main benefits of photovoltaic systems are that they produce no emissions, are reliable, and require minimum maintenance to operate. They are currently available from a number of manufacturers for both residential and commercial applications, and ...

Slide 45: Emerging TechnologiesNow, lets discuss some emerging technologies in distributed generation. First, lets look at fuel cells.

/Slide 46: Fuel CellsThe first fuel cell was developed in 1839 by Sir William Grove. Fuel cells were not put to practical use until the 1960s when NASA installed this technology to generate electricity on the Gemini and Apollo spacecrafts.

Slide 47: Fuel CellsThere currently are many types of fuel cells under development in the 5-1000+ kW range size, including: Direct methanol Proton exchange membrane Solid oxide Molten carbonate Alkaline, and Phosphoric acidThe first systems demonstrated were 200-kW phosphoric acid units from International Fuel Cells (International Fuel Cells - also known as ONSI, UTC Fuel Cells). A number of companies are close to commercializing proton exchange membrane fuel cells, wit...

Slide 48: Fuel CellsWhile the numerous types of fuel cells differ in their electrolytic material, they all use the same basic theory: A fuel cell consists of two electrodes separated by an electrolyte Hydrogen fuel is fed into the anode of the fuel cell Oxygen (or air) enters the fuel cell through the cathode With the aid of a catalyst, the hydrogen atom splits into a proton (H+) and an electron The proton passes through the electrolyte to the cathode and then the electrons travel in an external circuit As the electrons flow through an external circuit, connected as a load, they create a DC current At the cathode, protons combine with hydrogen and oxygen, producing water and heat Fuel cells have very low levels of nitric oxide and carbon dioxide emissions because the power conversion is an electrochemical process The part of a fuel cell that contains the electrodes and electrolytic material is called the "stack," and is a major contributor to the total cost of the system Stack replacement is very costly but becomes necessary when efficiency degrades over time

/Slide 49: Fuel CellsFuel cells require hydrogen for operation, but it is generally impractical to use hydrogen as a direct fuel source. Instead, it must be extracted from hydrogen-rich sources such as gasoline, propane, or natural gas. Efficient, cost effective fuel refo...

Slide 50: Stirling EnginesNow lets move on and discuss Stirling engines.The Stirling engine has been around for over 60 years. This engine is an external combustion device and as a result, differs substantially from the conventional combustion plant where the fuel burns inside the machine. Heat is supplied to the Stirling...(Stirling engine images and diagrams courtesy of www.stirlingengines.com)

Slide 51: Stirling EnginesA second piston, known as a displacer, then relocates the gas to a cool zone where it is recompressed by the working piston. The displacer then moves the compressed gas or air to the hot region and the cycle continues./(Diagram courtesy of www.stirlingengines.com)

Slide 52: Stirling EnginesThe Stirling engine has fewer moving parts than conventional engines, and no valves, tappets, fuel injectors or spark ignition systems. As a result, it is quieter than normal engines. The low noise levels in a Stirling engine is also attributed to t...

Slide 53: Stirling EnginesStirling engines also require little maintenance. Emissions of particulates, nitrogen oxides, and unburned hydrocarbons are low. The efficiency of these machines is potentially greater than that of internal combustion or gas turbine devices.(Stirling engine image courtesy of www.stirlingengines.com)

Slide 54: Stirling EnginesThe advantages of the Stirling engine are: fewer moving parts and low friction, no need for an extra boiler, no internal burner chamber, high theoretical efficiency and very well suited for mass production./The external burner or heat source allows for a very clean exhaust and gives the possibility of controlling the electrical output of the engine by reducing the temperature of the hot side. So there is the possibility of varying the electrical product...(Stirling engine images courtesy of www.stirlingengines.com)

Slide 55: Advantages and DisadvantagesAs we discussed, each technology has advantages and disadvantages. Its important to weigh these advantages and disadvantages prior to selecting a distributed generation technology. To assist you with weighing these issues, weve attached a downloada...

Slide 56: Technology ComparisonAnd finally, weve also included a chart comparison of each technology with regards to size, installed cost, electrical efficiency, overall efficiency, total maintenance costs, footprint and emissions.

/Slide 57: SummaryLets conclude with a brief summary. Today we identified deregulation of electric markets and environmental concerns as the major drivers for why distributed generation is gaining popularity as a source of energy. We described the major categories of ... Reciprocating engines Microturbines Combustion gas turbines Steam turbines Wind turbines Photovoltaics, as well as the Emerging technologiesLastly, we discussed the major benefits and issues for each of these technologies.

Slide 58: Thank You!Thank you for participating in this course.

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Distributed Generation Transcript