## References

Caldwell, R.H., Merkel, J.L., and Hansen, J., Study to gauge impact of technology advances, Oil Gas J., Feb. 12, 1996. Chambers, M.R., Multilateral technology gains broader acceptance, Oil Gas J., November 23, 1998. Fisher, W.L., How technology has confounded U.S. gas resource estimators, Oil Gas J., October 24, 1994. Funk, J.M., The Gulf of Mexico Economics of the U.S. Gas Breadbasket, presentation given at the 1995 Natural Gas Summit, Calgary, Alberta, Canada, November 1995. Hubbert, M.K.,...

## Solution

There are two equivalent ways of solving for rd0. The first is to take the real growth factor, 8.0 3.04, and set it equal to (1 + rd0)N. The result is rd0 5.52 . The second method is to calculate the market rate rd by setting the market growth in current dollars equal to (1 + rd)N and calculating the inflation by setting the CPI increase equal to (1 + rin)N. One finds that rd 12.246 and rinf 6.371 . Then Eq. 8.7 can be solved for rd0, with the result Choosing a discount rate is not without...

## 18 Communications and Controls Technologies Dr Sunil Cherian Sixth Dimension

Historically, there was no demand for command and control solutions for distributed resources that had to take into account the diverse interests seen today. However, the emerging competitive energy environment brings this need to the forefront as a necessary ingredient for optimal market operation it should be possible to buy and sell various value components of distributed resources in an open market. The current debates around distributed generation are a manifestation of various interested...

## 10313 Noise

Although fuel cells are relatively expensive to install, they are being tested in a number of sites, typically where the cost of a power outage is significant to lost revenues or lost productivity and uninterrupted power is mandatory. Stirling engines should also do well in these markets. Their relatively quiet operation has appeal and, thus, these units are being installed in congested commercial areas. Locating a turbine or engine in a residential area usually requires special consideration...

## 8551 Why Use Energy Swaps

An energy producer that is constantly selling energy into the open market is exposing its revenue stream to the volatility of the market. The company's risk can be neutralized by converting the variable market price that it receives on its sales to a fixed price. A swap is then set up in which the company receives fixed payments from the buyer, based on the fixed price, and pays a variable amount to the buyer, based on the index. An energy consumer, who is concerned about rising prices, takes...

## 124US Power Generation Assets

In 1996, the U.S. had a total electricity-generating capability of 775,872 megawatts (MW) 91.5 was owned by utilities. The largest portion of utility capability in the country is fueled by coal. The largest plant, Grand Coulee of the Bureau of Reclamation, is a hydroelectric plant on the Columbia River in Washington. The largest utility in the country is the Tennessee Valley Authority (TVA), which provides electricity to seven southeastern states. Although investor-owned utilities account for...

## 6111Cost Reduction

The high capital cost for fuel cells is by far the largest factor contributing to the small market penetration of fuel cell technology. The high capital cost (on a kW basis) has led to an electric power sector wary of installing fuel cells or using them in other systems (e.g., transportation applications). Reducing the installed cost of fuel cell technology is perhaps the most important driver of fuel cell research, development, and demonstration (RD& D) today. This RD& D encompasses many...

## Contents

Natural gas-fired combustion turbines are the most widely adopted prime movers for new power generation worldwide, based on the aggregated power rating in the year 2000, over 4000 units were sold or ordered. The benefits of gas turbines in power generation are fivefold (1) comparatively low installation cost per MW output, (2) increasing availability of natural gas for low fixed-price contracts, (3) explosion of demand for peaking capacity in a deregulated energy marketplace combined with (4)...

## 93 Electric Utility Industry Restructuring and DG

The fate of distributed generation is tied to how the provisions of EUIR legislation are written and implemented in restructured states and specifically whether the distribution utility rules in any state, restructured or not, are opened to allow market access by new technologies. By way of background, the intense EUIR debate began soon after the passage of EPAct. The early tier of EUIR states, such as California and New England, had high electric rates. These were followed by many other...

## 551Working Fluids

Water has been the dominant fluid for use in high temperature Rankine cycle systems because of its large latent heat of vaporization, good transport properties, availability, and ease of use. However, in low temperature heat source Rankine cycles such as heat recovery applications, the large latent heat of vaporization of water results in low boiling temperature and low cycle efficiency. Organic fluids are superior to water in these applications. A wide variety of organic (carbon-atom based)...

## 10311Quality of Recoverable Heat

The thermal requirements of the end user may dictate the feasibility of a CHP system or the selection of the prime mover. Gas turbines offer the highest quality heat that is often used to generate power in a steam turbine. Gas turbines reject heat almost exclusively in their exhaust gas streams. The high temperature of this exhaust can be used to generate high-pressure steam or lower-temperature applications such as low-pressure steam or hot water. Larger gas turbines (typically above 25 MW)...

## 4611 Safety Standards

Safety standards are important to continue the safe operation of distribution systems. Changes in other requirements should not unduly compromise safety standards. Safe operation is a concern of the host utility, the owners of distributed generation, and the operators of these facilities. Safety standards implemented by most electric utilities have a long history. Safety must not be unduly compromised in order to implement distributed generation in the State of Texas. However, in order to...

## 631 Fuel Cell Design

A fuel cell power system embodies more than just the fuel cell stack, and the design of a fuel cell system involves more than the optimization of the fuel Comparison of Key Features of the Four Fuel Cell Types Under Serious Consideration for Distributed Power Generation (Hirschenhofer et al., 1998, with permission) Comparison of Key Features of the Four Fuel Cell Types Under Serious Consideration for Distributed Power Generation (Hirschenhofer et al., 1998, with permission) cell section with...

## 12511 Protective Relaying

The primary function of a protective relay scheme for a grid-parallel DG unit should be to separate the power sources on the occurrence of an anomaly. It is taken on faith at this point in the discussion that both power sources will be adequately protected with a proper scheme (though it remains to be discussed herein). Therefore, if the sources are properly protected as isolated sources, then the only action to take when the sources are paralleled is to separate them so that each may initiate...

## 1821Distributed Control

Traditionally, distributed control refers to a class of concepts and techniques used to solve complex control problems which may be formulated as a number of smaller interconnected sub-problems. The sub-problems involve some degree of coordination in their solutions. Distributed control systems are appropriate for large-scale systems with hundreds of variables that make centralized control infeasible. A typical application of distributed control is for designing fault tolerant systems where the...

## 651 Temperature

The operating temperature of a fuel cell affects the change in entropy associated with the electrochemical reactions that occur within that cell. As operating temperature increases, the entropy change increases, leading to a reduction in the reversible potential of the fuel cell (see Figure 6.4). Therefore, with all other parameters unchanged, increases in operating temperature reduce fuel cell performance and efficiency. However, as shown in Figure 6.4, practical cell voltages tend to increase...

## 652 Pressure

The direct effect of the operating pressure of a fuel cell is to change the concentration of reactants at the electrode surfaces. Thus, according to the Nernst equation, as operating pressure increases, partial pressures of reactants increase and the reversible cell potential increases. In addition, as operating pressure increases, gas solubility and mass transfer rates increase, reducing some overpotential associated with these processes. Electrolyte loss by vaporization is typically reduced...

## 5121 Combustor Overiew

Scaling techniques for the design of mini combustors are less defined, due, in part, to the effects of (1) surface area volume changes with size, (2) increased effects of wall quenching, (3) low fuel flows necessitating a small number of injectors and orifice sizing, and (4) increased effect of leakage gaps on pattern factor. As a consequence, there is reluctance to directly apply scaling from larger combustors, and alternative design solutions have been considered, for example, by Rodgers...

## 113 Distribution System Economics

While this section is not intended to be a comprehensive treatment of distribution system economics, it may be instructive to the reader to understand some fundamental economic issues associated with distribution system planning and operations. Transmission and distribution system equipment must be sized to accommodate the maximum load to which the equipment will be subjected. Because average demand is usually much less than maximum demand (as shown in Figure 11.4), there is normally a lot of...

## 97 Regulation of Air Pollution from Small Generators

Since DG spans the spectrum of technologies, the DG plants produce varying degrees of environmental impact. Some technologies, such as fuel cells or photovoltaics, can receive a blanket exemption from air regulation, while others, such as a diesel-powered backup generator pressed into service as a system peaking resource, will have limitations on the number of operating hours in certain locations. At the high-size end of the DG spectrum, a 50 MW unit combustion turbine will naturally require a...

## 682 Utility Interconnection

A fuel cell can be designed and installed in a number of different modes. The various modes of operation include parallel operation with the utility grid to supply a user, direct connection to the utility grid, backup power to a normally grid-connected load, and connection to a dedicated load. The most commonplace installations to date are those of the first type. In all of the modes of operation listed above, except the last case, some interaction with the utility grid is required....

## 1321 Compressed Natural Gas CNG

CNG is stored in welding bottle-like tanks at pressures over 3000 psig. CNG and LNG are both delivered to the internal combustion engines at low vapor pressure (< 300 psig). A complication with all natural gas and NGL fuels is that they are naturally odorless. A sulfur-bearing amyl mercaptan that is readily identified by smell is added for safety. Even trace amounts of the mer-captans are detrimental to the performance of advanced internal combustion (IC) engine emission reduction systems and...

## 1362 Biomass Fuel Characteristics

Biomass is produced by complex photochemical and biological reactions that involve the conversion of carbon dioxide and water to stored chemical energy. The simplified reaction scheme is 6CO2 + 6H2O C6H12O6 (hexose) + 6O2 Because biomass resources are very diverse, their characteristics as energy feedstocks also vary significantly. As shown in Table 13.3, the energy content of woody biomass is typically about 19 to 20 MJ kg (HHV, dry basis, or about 8300 BTU lb), while that of other biomass or...

## 1732Global Warming

Global warming is climate change postulated to be caused by the release of greenhouse gases. While CO2 emissions are the primary global warming pollutant, other anthropogenic compounds of concern include nitrous oxide and halogenated fluorocarbons. The electric utility industry accounts for approximately 35 of total U.S. CO2 emission inventory. CO2 is not currently regulated under the CAA. However, if the U.S. ratifies the Kyoto Protocol (i.e., the international treaty mandating control of...

## Economic and Financial Aspects of Distributed Generation

8.1 Comparing Present and Future Costs 8.1.1 The Effect of Time on the Value of Money 8.1.2 Discounting of Future Cash Flows 8.1.3 Equivalent Cash Flows and Levelizing 8.1.4 Discrete and Continuous Cash Flows 8.1.5 The Rule of Seventy for Doubling Times 8.2.3 Depreciation and Tax Credit 8.2.5 The Complete Cost Equation 8.2.6 Cost per Unit of Delivered Electrical Energy 8.3 Economic Evaluation Criteria 8.4.2 The Cost of Misoptimization 8.5 Basics of Electrical Energy Financial Transactions...

## 22 Past and Current Trends in Engine Development

Natural gas engines have been used for power generation since the mid-1940s, and have evolved steadily. The earliest gas engines were derived from diesel blocks and incorporated many of the same components as diesel engines. Spark plugs and carburetors replaced fuel injectors, magnetos replaced fuel pumps, and lower compression-ratio pistons were substituted to run the engines on gaseous fuels. The first gas engines were set to run at optimum power output without regard to emissions and fuel...

## 824 Demand Charges

The cost of producing electricity has two major components fuel and capital (for power plant and distribution system). As a consequence, the cost of electricity varies with the total load on the grid. To the extent that it is practical, deregulated electric utilities will try to base the rate schedule on their production cost. Even without full deregulation, rates for large customers contain two items one part of the bill is proportional to the energy and another part is proportional to the...

## 1364Transportation and Storage Costs

Biomass is delivered by trucks or rail transportation to power generation facilities as a solid fuel. Individual power producers establish specifications for the material they will accept. The specifications define the average size of the material (i.e., chips 1 to 3), the acceptable limits for fines, the maximum inorganic content, average moisture, and similar parameters. The necessity of meeting these requirements falls upon the feedstock producer, who is usually independent of the power...

## 1052 Emissions Reductions

By increasing the efficiency of energy use, CHP can significantly reduce emissions of criteria pollutants, such as NOx and SO2, and noncriteria greenhouse gases, such as CO2. Figures 10.7 and 10.8 show NOx and CO2 emissions comparisons respectively by power generation technology and fuel type. While reductions in both NOx and CO2 result from moving from solid and liquid fuels to natural gas, the figures show the added reductions that efficiency can provide. CHP technologies can significantly...

## 859 Banking Aspects

Multinational banks and energy companies have always had a strong business relationship due to the large capital needs and worldwide operations of the oil industry. Banks have provided services related to taxation, cash management, and foreign exchange and interest rate risk management. Many energy transactions are not new business, but are merely renewals of funding for existing facilities these capital requirements are high and provide profitable margins for lending banks. Moreover,...

## 46 The Utility Interface

The interface between distributed power sources and electric power systems is the point at which new standards for interconnection will apply. Although at the present time standards are still evolving, the key issues as they apply to PV systems can be summarized. Since the PV industry has taken the lead in the new DG technologies (microturbines, fuel cells, and PV), it is likely that these three, at least, will end up with similar standards. Interconnection standards result in safe and reliable...

## 1823 Embedded Hardware

There are two ways to communicate with DG systems from a remote location. The most common approach is to use a simple data acquisition unit such as an RTU for data collection and communication. Back-end applications periodically poll the remote data acquisition system and send command signals to initiate some action. This approach works well for static systems with a well defined hierarchical control structure. The decision-making intelligence of the system is centrally located, and the remote...

## 10223 Industrial Commercial and Institutional Applications

In industrial applications, steam turbines may drive an electric generator or equipment such as boiler feedwater pumps, process pumps, air compressors, or refrigeration chillers. Turbines used as industrial drivers are almost always a single casing machine, either single stage or multistage. They can be either condensing or noncondensing depending on steam conditions and the value of the steam. Steam turbines can operate at a single speed to drive an electric generator or operate over a speed...

## 1324Propane

Propane in the U.S. is a mixture of approximately 85 propane and 15 butane small amounts of pentane and isobutane are also incorporated. Outside the U.S. and Canada, the mixture can vary greatly from 80 20 to 30 70 propane to butane. Propane has a boiling point of -42 C (-44 F) at atmospheric pressure therefore, when kept in a sealed vessel, propane has a vapor pressure that moves depending on outside temperature. For example, at 70 F, the vapor pressure of propane is 127 psi and of butane is...

## 4141 Single Crystal and Polycrystalline Silicon

Single crystal silicon cells are produced by a series of processes (1) growing crystalline ingots of p-silicon, (2) slicing wafers from the ingots, (3) polishing and cleaning the surface, (4) doping with n material to form the p-n junction, (5) deposition of electrical contacts, (6) application of antireflection coating, and (7) encapsulation. The Czochralski process is the most common method of growing single crystal ingots. A seed crystal is dipped in molten silicon doped with a p-material...

## 63 Comparison of Fuel Cell Types

Table 6.1 presents a summary comparison of the four primary fuel cell types under serious consideration for distributed power generation (e.g., MCFC, PAFC, PEMFC, and SOFC). Notice that the higher-temperature fuel cells do not require an external reformer. The PAFC and PEMFC units tend to use precious metal catalysts, while catalysts of the MCFC and SOFC units are typically nickel based. These differences lead to many variations in design and function which will be described in more detail in...

## Additional Reading

Means Mechanical Cost Data 2001 Book, Kingston, MA. Solar turbines, Inc., Fuel Flexibility in Industrial Gas Turbines, 1998. Product and Technology Development Strategy, Solar Turbines, Inc., 1998. Kluka, J.A. and Wilson, D.G., Low-leakage modular regenerators for gas turbine turbines, Trans. ASME, 120, 358, 1998. Horlock, J.H., Aero-Turbine derivative gas turbines for power generation thermodynamic and economic perspectives, J. Turbineering Gas Turbines Power, 119,...

## 126 Summary

Despite the perception of DG as a suite of breakthrough technologies and applications that cannot be installed and operated safely without further analysis, the technical reality appears more sanguine. Available today are the requisite protective devices and relays to enable a variety of electrical schemes. Parallel codes and standards contain an understanding of fuel, electrical, fire, and life safety protection. The challenge is to bring all concerned parties to a common understanding so that...

## 222 Engine Speed

The output power of an engine is the product of its torque and its speed therefore, higher speed engines have higher power densities. However, piston size and weight limit the speed at which an engine can operate. The speed at which the flame front travels through the compressed gas also limits the speed. Slower speed engines are more efficient and can burn lower grade, less expensive fuels. Engines are usually directly coupled to the generator and operate at synchronous speeds (Table 2.1)....

## 121The US Transmission System

The North American transmission system has historically provided relatively open, non-competitive bulk power supply across the continent through voluntary compliance of public and privately owned electric utilities. Deregulation of the electric utility industry has eroded that spirit of cooperation, transforming the transmission and distribution (T& D) network from a delivery vehicle into a competitive tool. For DG technologies, the physics and financing of the U.S. power transmission system...

## 10211 Heat Recovery

Energy in the fuel is released during combustion and converted to shaft work and heat. Shaft work drives the generator while heat is released from the engine through coolant, exhaust gas, and surface radiation. Approximately 60 to 70 of the total energy input is converted to heat that can be recovered from the engine exhaust and jacket coolant. Smaller amounts of heat are also available from the lube oil cooler and, if available, the turbocharger's intercooler and aftercooler. Steam or hot...

## 542 Engine Operating Conditions

One obvious way to raise system efficiency is to operate gas turbines with more aggressive operating conditions, i.e., higher pressure ratios and or greater TITs. For example, the designer can choose to operate at higher TITs or to increase pressure ratios in the system. As Figure 5.15 illustrates, substantial system efficiency improvements are possible with either of these approaches for a typical simple-cycle engine in the MT size range. However, the strict cost constraints require use of...

## 241Open Transition Transfer Switch

Historically, standby power systems have used conventional double-throw transfer switches for shifting from one power source to another. These systems (sometimes referred to as break before make) are the simplest arrangements, requiring no interface or coordination with and no protection from the power utility source, since there is never a possibility of interconnection. The obvious drawback to open-transition transfer switches is an inherent momentary power interruption to the load during...

## 68 Interconnection and Control 681 Power Conditioning

Power conditioning for a fuel cell power plant includes power consolidation, current control, direct current (DC) to alternating current (AC) inversion Typical relationship between voltage and power for fuel cells. Typical relationship between voltage and power for fuel cells. (unless the application is DC), and stepping the voltage up through a transformer. In addition, power quality aspects such as maintaining consistent voltage and frequency with low harmonic distortion, as well as the...

## 10221 Technology Description

The thermodynamic cycle for the steam turbine is the Rankine cycle. The cycle is the basis for conventional power generating stations. In this cycle, a heat source (boiler) converts water to high-pressure steam. The steam expands in a turbine to produce power. The steam exiting the turbine is condensed and returned to the boiler to repeat the process. A steam turbine consists of a stationary set of blades (called nozzles) and a moving set of adjacent blades (called buckets or rotor blades)...

## 1241 Non Utility Owned Power Generation

Several industries rely heavily on their own power sources for protection from outages, reduced dependency on grid-supplied electricity, greater control over power quality, or as a means to control energy costs. Figure 1.5 displays the industries with the greatest concentration of non-utility power generation assets by capacity (MW). Such information hides the tens of thousands of small generators in homes, clinics, and schools that barely register when counted as an aggregate. It is, however,...

## Installation and Interconnection

Daley and Anne-Marie Borbely 12.5.5.1 Descriptions of the Devices 12.5.9.2 Closed Transition Transfer 12.5.9.3 Extended Parallel Operation 12.5.10Permissive Relaying 12.5.11Protective Relaying Installing new electricity-producing equipment near, on, or within buildings requires the same permit evaluation process as any other modification to the site, with one telling exception the existing code structure was never designed for wide-scale deployment of electric generators outside the...

## 1144 Power Quality

Distributed resources must provide the intended services to the users and electrical power networks. Fundamentally, these services are simply to provide high quality electric power in a safe manner when it is needed (i.e., reliability of supply) and in the quantity demanded. (Reliability in the narrowest sense, the minimization of outages of any duration is now considered by many to be a component of power quality.) New high technology equipment requires higher quality power. Furthermore, the...

## 7412Reliability

Each DG installation must provide reasonable dispatch control regardless of Internet, radio frequency (RF), fiber, cable, or telephonic connection status. This means that each site will continue to operate independently in the event of a loss of communication with the central station and that the DG equipment will not default to an all-on or all-off mode. This implies that some degree of optimization capability must reside within the local controller. Thus, the local controller will need to be...

## 1721 Federal Regulations

The Clean Air Act (1963) imposes a complex regulatory structure on air pollution sources (Leonard, 1997). From a historical perspective, the regulatory environment for a major emission source has been largely dependent on two factors where the facility is located (that is, whether in an area meeting clean air standards or not) and the facility age (new or old source). At the federal level, the CAA and its various amendments (1965, 1967, 1970, 1977, and 1990) provide the critical statute for...

## 1113System Protection

To protect distribution system equipment from damaging overloads, that equipment contains protective devices. This protection can be manifest in a * A common way to denote three-phase service is to list the line-to-neutral followed by the line-to-line voltage. Three-phase circuits are defined by the line-to-line voltage, with its line-to-neutral voltage multiplied by J3 . variety of forms, but usually through fuses or circuit breakers. The devices sometimes employed to provide the logic to...

## 45 PV System Capacity Credit

PV systems differ from other DG systems in that they are not dispatchable unless equipped with storage. For that reason, they have been viewed as generator fuel saving. However, recent work has shown that there is significant PV capacity credit for grid penetrations of 20 or less. Using the standard Institute of Electrical and Electronic Engineers (IEEE) load duration curves, Rahim and Kreider (1992) showed, using an hourly simulation, that the equivalent load carrying capacity (ELCC) of a PV...

## Combustion Engine Generator Sets

Eric Wong, Herb Whitall, and Paul Dailey 2.1 Internal Combustion Engine Design Overview 2.1.1 Two-Stroke versus Four-Stroke 2.2 Past and Current Trends in Engine Development 2.2.1 New Developements in Gas Engine Gensets 2.3 Utilizing Existing Standby Power Gensets for DG 2.3.2 Systems Considerations for DG Applications for Combustion Engines 2.4 The Utility Interconnection 2.4.1 Open-Transition Transfer Switch 2.4.2 Closed-Transition Transfer Switch 2.4.3 Soft Loading Transfer System 2.5...

## Contributors

Curtiss Jeffrey Dagle Peter Fusaro Michael Godec Yogi Goswami Bruce Hedman Tina Kaarsberg Jan F. Kreider Ken Nichols Ari Rabl Colin Rodgers Pacific Northwest National Laboratory, Richland, Washington Solar Turbines Incorporated, Washington, D.C. University of California, National Fuel Cell Research Center, Irvine, California Sixth Dimension, Inc., Fort Collins, Colorado Kreider and Associates, LLC, Boulder, Colorado Pacific Northwest National Laboratory, Richland,...

## 7416Cost Function Minimization

The cost function for the DG control is the sum of all operating costs. Components of the cost equation that increase the operating costs include Grid electricity consumption at meter (in kWh) Grid electricity demand (in kW) Grid gas consumption at meter (in either energy content or volume used) Grid gas consumption by DG equipment (in either energy content or volume used) Operation and maintenance costs (variable as a function of run time see below for fixed O& M costs) Components of the...

## 10314 Footprint

Three technologies in particular offer compact packaging and have an appeal to end users seeking an unobtrusive CHP system. Stirling engines are the smallest, followed by fuel cells and microturbines. Larger steam turbines, gas turbines, and reciprocating engines are generally isolated in either a factory enclosure or a separate building along with ancillary equipment. Table 10.2 shows equivalent footprint size for several different CHP types. Equivalent Footprint Size for Different CHP Types...

## 99 Participation at the PUC

Advocates of distributed generation (including Discos, manufacturers, customers, and others) will strategize on how best to seek the rules and rates from PUCs. As mentioned before, the regulatory focus is concentrated on the 5000 megawatt level utility system. Of course, regulators do focus on customers, but primarily as a matter of rate design, not so much as a matter of engineering design. There is a threshold, often at a level of 10 megawatts or less, where PUCs allow utilities to make...

## 852 Futures Markets

The introduction of financial futures futures on currencies and interest rates during the 1970s transformed the futures markets, which had been trading agricultural commodities for more than 100 years. Financial futures brought new participants and new strategies to the futures markets, and many more types of risk could now be hedged. The commodity concept has broadened to include energy, beginning with heating oil futures in 1978 many of the strategies that were devised for financial futures...

## 8571 Natural Gas Swaps

Because of the high volatility of North American natural gas prices (40 annualized price volatility) and the increasing use of natural gas futures to manage short-term price risk, the natural gas swap market took off during 1992 and continued to grow through the 1990s. Both natural gas producers and consumers, such as utilities and cogenerators, are becoming involved in swaps to protect themselves from adverse price movements. The emergence and growth of natural gas swap brokers during the...

## 256Costs

Free-piston Stirling cycle engines and generators are currently available on a prototype basis for development and technology evaluation programs. Work is under way to have several sizes of generators mass produced. Full scale production of STC's 1 kW generator is planned for the year 2002, with limited production of the 3 kW generator to follow. Early commercial engines will have higher capital costs than IC generators, but lower than initial costs for PV and thermoelectric systems. Despite...

## 255Utility Interfacing

As previously noted, Stirling generators can be used for both on- and off-grid applications. It is left to the utility companies and their customers to decide what is most appropriate. Stirling generators are reliable enough that a utility company may consider leasing a unit to a remote off-grid customer, thus avoiding the costs of building power lines or larger generators on site. An off-grid Stirling micro-cogeneration system is a very reliable and cost-effective solution for providing heat...

## 1026 Stirling Engines

The Stirling engine so named because it is based on the Stirling thermo-dynamic cycle was conceived more than a century ago. Stirling engines produce power not by explosive internal combustion, but by an external heat source usually a continuous-combustion burner. Until recently, reliability problems have limited their use to hobbyists. It is only in the past generation that a viable free-piston Stirling was developed. All Stirling engines can be operated with a wide variety of fuels, including...

## 254 Controls and Communications Dispatchability

The characteristics of Stirling generators allow them to be located inside homes, businesses, and similar environments where IC generators would be intolerable because of their high noise and maintenance levels. The most popular application of Stirling generators is in micro-cogeneration systems. In these systems, the generator is coupled to a household boiler (a water heater for hydronic space heating), so electricity and hot water are produced simultaneously from the same fuel. Stirling...

## 25 Stirling External Combustion Engines

A Stirling engine is an external combustion heat engine and, therefore, does not require a specific fuel a Stirling engine-generator can convert any sufficient heat source into useful electrical power. These generator sets are also physically small and very efficient even below 100 W (e). With the added advantages of high reliability, long life, very low noise, and maintenance-free operation, Stirling engines are ideal for distributed generation applications where the generator must be located...

## 252 Fuels

One of the singular advantages Stirling engines have over internal combustion engines is that they are truly multi-fuel capable. The Stirling cycle requires only a sufficient heat source to operate and does not rely on carefully timed fuel injection and combustion processes as do internal combustion engines. Practical Stirling cycle engines may be operated using propane, natural gas, gasoline, diesel, radioisotopes, solar energy, and even wood or other biomass. The only limitation on fuel...

## 51 Single Shaft Gas Microturbines

The classic open Brayton cycle described in Chapter 3 is also the basis of gas-fired microturbine (MT) engines. The reader is referred to that chapter for cycle basics. Several single-shaft MTs have been developed recently by Capstone, Elliott, and Honeywell with ratings between about 20-150 kW. Some published specifications for these four MTs are listed in Table 5.1. A number of MT flow-path configurations are depicted in Figure 5.1, the most compact of which is the wrap-around recuperator...

## 251 Design

Stirling engines operate on a closed thermodynamic cycle where a temperature differential is converted into mechanical and or electrical power. External heat is supplied at a high temperature to the engine heater head, and thermodynamic waste heat is rejected to ambient temperature. An internal displacer piston physically shuttles the helium working fluid between the hot and cold regions, creating a varying pressure value. That pressure wave causes the power piston to reciprocate. The...

## 1041 CHP Technology Cost and Performance Characteristics

Table 10.4 shows characteristics for application sizes from as small as 50 kW to as large as 25 MW. The heat rates and recoverable thermal energy factors are based on commercial product specifications, with the exception of the microturbine, for which performance factors are estimated. Microturbine cost factors were estimated based on assessment of early market entry economics and not manufacturers' projections for high volume production. Package costs, heat recovery equipment costs, and...

## 253 Technical Developments and Outstanding Barriers

Stirling cycle engines have developed considerably in recent years. The free-piston configuration has served as an enabling technology for a great deal of energy conversion development. Stirling Technology Company (STC) and Sun Power Inc. are the leading developers of free-piston Stirling cycle engine generators with capacities ranging from 10 W to 5 kW. These generators have demonstrated maintenance-free operating lives far beyond that of gasoline or diesel engine generators. Ongoing endurance...

## 14 The Distributed Generation Technologies

Distributed generation is any small-scale electrical power generation technology that provides electric power at or near the load site it is either interconnected to the distribution system, directly to the customer's facilities, or both. According to the Distributed Power Coalition of America (DPCA), research indicates that distributed power has the potential to capture up to 20 of all new generating capacity, or 35 Gigawatts (GW), over the next two decades. The Electric Power Research...

## What Is The Future Of Fuel Cells

Distributed Generation An Introduction Anne-Marie Borbely and Jan F. Kreider Distributed Centralized Distributed Again 1.1.2 De-Integration of Vertical Stages 1.1.3 Convergence of Utility Companies 1.2.1 The U.S. Transmission System 1.2.2 Utility Choices and Deregulation 1.2.3 Transmission Loading Relief TLR 1.2.4 U.S. Power Generation Assets 1.2.4.1 Non Utility-Owned Power Generation 1.2.5 Double Counting How Much Is Really Out There 1.3.1 Restructuring and Competition 1.3.2 The Future of...