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At least 991 records · Page 55

R&D for Safety Codes and Standards: Materials and Components Compatibility

A principal challenge to the widespread adoption of hydrogen infrastructure is the lack of quantifiable data on its safety envelope and concerns about additional risk from hydrogen. To convince regulatory officials, local fire marshals, fuel suppliers, and the public at large that hydrogen refueling is safe for consumer use, the risk to personnel and bystanders must be quantified and minimized to an acceptable level. Such a task requires strong confidence in the safety performance of high pressure hydrogen systems. Developing meaningful materials characterization and qualification methodologies in addition to enhancing understanding of performance of materials is critical to eliminating barriers to the development of safe, low-cost, high-performance high-pressure hydrogen systems for the consumer environment.

36 MATERIALS SCIENCE↗

Field data collection of miscellaneous electrical loads in Northern California: Initial results

This report describes efforts to measure energy use of miscellaneous electrical loads (MELs) in 880 San Francisco Bay Area homes during the summer of 2012. Ten regions were selected for metering: Antioch, Berkeley, Fremont, Livermore, Marin County (San Rafael, Novato, Fairfax, and Mill Valley), Oakland/Emeryville, Pleasanton, Richmond, San Leandro, and Union City. The project focused on three major categories of devices: entertainment (game consoles, set-top boxes, televisions and video players), home office (computers, monitors and network equipment), and kitchen plug-loads (coffee/espresso makers, microwave ovens/toaster ovens/toasters, rice/slow cookers and wine chillers). These categories were important to meter because they either dominated the estimated overall energy use of MELs, are rapidly changing, or there are very little energy consumption data published. A total of 1,176 energy meters and 143 other sensors were deployed, and 90% of these meters and sensors were retrieved. After data cleaning, we obtained 711 valid device energy use measurements, which were used to estimate, for a number of device subcategories, the average time spent in high power, low power and “off” modes, the average energy use in each mode, and the average overall energy use. Consistent with observations made in previous studies, we find on average that information technology (IT) devices (home entertainment and home office equipment) consume more energy (15.0 and 13.0 W, respectively) than non-IT devices (kitchen plug-loads; 4.9 W). Opportunities for energy savings were identified in almost every device category, based on the time spent in various modes and/or the power levels consumed in those modes. Future reports will analyze the collected data in detail by device category and compare results to those obtained from prior studies.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Market Brief: Status of the Voluntary Renewable Energy Certificate Market (2011 Data)

This report documents the status and trends of U.S. 'voluntary' markets -- those in which consumers and institutions purchase renewable energy to match their electricity needs on a voluntary basis. Voluntary REC markets continue to exhibit growth and spur renewable energy development. Voluntary green power markets provide an additional revenue stream for renewable energy projects and raise consumer awareness of the benefits of renewable energy. Although a full estimate of the size of the voluntary market is not available for 2011, this review uses indicative metrics to capture 2011 voluntary market trends.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Natural Gas Value-Chain and Network Assessments

The current expansion of natural gas (NG) development in the United States requires an understanding of how this change will affect the natural gas industry, downstream consumers, and economic growth in order to promote effective planning and policy development. The impact of this expansion may propagate through the NG system and US economy via changes in manufacturing, electric power generation, transportation, commerce, and increased exports of liquefied natural gas. We conceptualize this problem as supply shock propagation that pushes the NG system and the economy away from its current state of infrastructure development and level of natural gas use. To illustrate this, the project developed two core modeling approaches. The first is an Agent-Based Modeling (ABM) approach which addresses shock propagation throughout the existing natural gas distribution system. The second approach uses a System Dynamics-based model to illustrate the feedback mechanisms related to finding new supplies of natural gas - notably shale gas - and how those mechanisms affect exploration investments in the natural gas market with respect to proven reserves. The ABM illustrates several stylized scenarios of large liquefied natural gas (LNG) exports from the U.S. The ABM preliminary results demonstrate that such scenario is likely to have substantial effects on NG prices and on pipeline capacity utilization. Our preliminary results indicate that the price of natural gas in the U.S. may rise by about 50% when the LNG exports represent 15% of the system-wide demand. The main findings of the System Dynamics model indicate that proven reserves for coalbed methane, conventional gas and now shale gas can be adequately modeled based on a combination of geologic, economic and technology-based variables. A base case scenario matches historical proven reserves data for these three types of natural gas. An environmental scenario, based on implementing a $50/tonne CO 2 tax results in less proven reserves being developed in the coming years while demand may decrease in the absence of acceptable substitutes, incentives or changes in consumer behavior. An increase in demand of 25% increases proven reserves being developed by a very small amount by the end of the forecast period of 2025.

03 NATURAL GAS↗

International comparison of product certification and verification methods for appliances

Enforcement of appliance standards and consumer trust in appliance labeling are important foundations of growing a more energy efficient economy. Product certification and verification increase compliance rates which in turn increase both energy savings and consumer trust. This paper will serve two purposes: 1) to review international practices for product certification and verification as they relate to the enforcement of standards and labeling programs in the U.S., E.U., Australia, Japan, Canada, and China; and 2) to make recommendations for China to implement improved certification processes related to their mandatory standards and labeling program such as to increase compliance rates and energy savings potential.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

International Comparison of Product Certification and Verification Methods for Appliances

Enforcement of appliance standards and consumer trust in appliance labeling are important foundations of growing a more energy efficient economy. Product certification and verification increase compliance rates which in turn increase both energy savings and consumer trust. This paper will serve two purposes: 1) to review international practices for product certification and verification as they relate to the enforcement of standards and labeling programs in the U.S., E.U., Australia, Japan, Canada, and China; and 2) to make recommendations for China to implement improved certification processes related to their mandatory standards and labeling program such as to increase compliance rates and energy savings potential.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Estimating Price Elasticity using Market-Level Appliance Data

This report provides and update to and expansion upon our 2008 LBNL report “An Analysis of the Price Elasticity of Demand for Appliances,” in which we estimated an average relative price elasticity of -0.34 for major household appliances (Dale and Fujita 2008). Consumer responsiveness to price change is a key component of energy efficiency policy analysis; these policies influence consumer purchases through price both explicitly and implicitly. However, few studies address appliance demand elasticity in the U.S. market and public data sources are generally insufficient for rigorous estimation. Therefore, analysts have relied on a small set of outdated papers focused on limited appliance types, assuming long-term elasticities estimated for other durables (e.g., vehicles) decades ago are applicable to current and future appliance purchasing behavior. We aim to partially rectify this problem in the context of appliance efficiency standards by revisiting our previous analysis, utilizing data released over the last ten years and identifying additional estimates of durable goods price elasticities in the literature. Reviewing the literature, we find the following ranges of market-level price elasticities: -0.14 to -0.42 for appliances; -0.30 to -1.28 for automobiles; -0.47 to -2.55 for other durable goods. Brand price elasticities are substantially higher for these product groups, with most estimates -2.0 or more elastic. Using market-level shipments, sales value, and efficiency level data for 1989-2009, we run various iterations of a log-log regression model, arriving at a recommended range of short run appliance price elasticity between -0.4 and -0.5, with a default value of -0.45.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

AFIP-7 Tomography – 2013 Status Report

This project seeks to assess the geometric stability of the U-Mo monolithic fuel system by evaluating the radiation-induced changes in the AFIP-7 experiment device. Neutron radiography and computed tomography (CT) provide valuable information about the post-irradiation condition of the fuel specimen. Tomographic reconstructions of the AFIP-7 fuel element will be analyzed to assess the geometric condition of the element after irradiation and provide information regarding the condition of the fuel, including gross geometric defects, bowing, twist, plate buckling, cracks, and other defects. The INL, in collaboration with Oregon State University (OSU), Missouri University of Science and Technology (Missouri S&T), and Real Time Tomography, is developing advanced neutron detector systems and tomographic reconstruction techniques to evaluate the AFIP-7 fuel element. Neutron computed tomography using the current neutron radiography technique available at the Neutron Radiography reactor (NRAD) is impractical due to the long time and high cost to produce a set of images for tomographic reconstruction. Advanced neutron radiography systems such as the micro-channel plate (MCP) detector and neutron computed radiography (CR) may reduce the time and cost of acquiring images for neutron CT. The MCP detector system tested at OSU and Missouri S&T provides neutron radiographs and has lower gamma sensitivity compared to other digital acquisition image systems. However, some significant, but not prohibitive, challenges must be overcome to make its use for imaging nuclear fuel more practical. Images taken with the MCP require significant image processing to reduce distortions and correct for the dynamic detector response. Also, the small active area of the detector (~30 mm diameter) requires the collection and combination of several images of a specimen, which may become time-consuming. The MCP is tested in low gamma dose environments, but should also be tested in the gamma field at the INL. In addition to the MCP detector system, the INL is developing neutron computed radiography (CR), which uses the same foil transfer method currently employed at the NRAD, but replaces the film with a photostimulable storage phosphor imaging plate that is sensitive to the decay radiation from the activated transfer foils. Preliminary tests show that neutron CR provides lower, but comparable spatial resolution properties to film radiography images using the transfer method technique already employed at the NRAD. However, there are many factors that affect the spatial resolution of neutron CR that can be adjusted and possibly provide spatial resolution properties that exceed film radiography. The reduction in cost of neutron CR may be significant, which would make neutron imaging more appealing to programs that would benefit from this rare and valuable capability. Because transfer method neutron radiography is expensive and time-consuming, acquisition of a full set of radiographs for tomographic reconstruction is impractical. The INL is developing tomographic reconstruction techniques that require only a small set of radiographs of the AFIP-7 fuel element. These tomosynthesis techniques are tested using archived radiographs of TREAT experiments for CT as a proof of principle. These same techniques are applied to radiographs taken with an MCP detector of a mock-up of the AFIP-7 geometry. Acquisition angle should at least match the curvature of AFIP-7 plates. Lateral (in-plane) reconstruction resolution will be best when the projection angles include views at or near the desired reconstruction view angles. The ends of the fuel plates are angled at ±17.7° relative to the center of the plate. Increasing the number of projections is desirable, but given the constraint of minimizing the number of projections, the projection acquisition angle should also span at least ±17.7° to optimize the lateral resolution of the angled reconstruction planes used to visualize the gaps at the ends of the fuel plates. If possible, enough projections should be used within the initial acquisition angle of 35.4° (±17.7°) to bring the projection angular sampling closer to 1°. Further testing will determine a more specific recommendation for the number and angular distribution of neutron radiographs that will produce the highest quality tomographic reconstruction of the AFIP-7 fuel element.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Field Performance of Heat Pump Water Heaters in the Northeast

Heat pump water heaters (HPWHs) are finally entering the mainstream residential water heater market. Potential catalysts are increased consumer demand for higher energy efficiency electric water heating and a new Federal water heating standard that effectively mandates use of HPWHs for electric storage water heaters with nominal capacities greater than 55 gallons. When compared to electric resistance water heating, the energy and cost savings potential of HPWHs is tremendous. Converting all electric resistance water heaters to HPWHs could save American consumers 7.8 billion dollars annually ($182 per household) in water heating operating costs and cut annual residential source energy consumption for water heating by 0.70 quads. Steven Winter Associates, Inc. embarked on one of the first in situ studies of these newly released HPWH products through a partnership with two sponsoring electric utility companies, National Grid and NSTAR, and one sponsoring energy efficiency service program administrator, Cape Light Compact. Recent laboratory studies have measured performance of HPWHs under various operating conditions, but publically available field studies have not been as available. This evaluation attempts to provide publicly available field data on new HPWHs by monitoring the performance of three recently released products (General Electric GeoSpring(TM), A.O. Smith Voltex(R), and Stiebel Eltron Accelera(R) 300). Fourteen HPWHs were installed in Massachusetts and Rhode Island and monitored for over a year. Of the 14 units, ten were General Electric models (50 gallon units), two were Stiebel Eltron models (80 gallon units), and two were A.O. Smith models (one 60-gallon and one 80-gallon unit).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Field Performance of Heat Pump Water Heaters in the Northeast

Heat pump water heaters (HPWHs) are finally entering the mainstream residential water heater market. Potential catalysts are increased consumer demand for higher energy efficiency electric water heating and a new Federal water heating standard that effectively mandates use of HPWHs for electric storage water heaters with nominal capacities greater than 55 gallons. When compared to electric resistance water heating, the energy and cost savings potential of HPWHs is tremendous. Converting all electric resistance water heaters to HPWHs could save American consumers 7.8 billion dollars annually ($182 per household) in water heating operating costs and cut annual residential source energy consumption for water heating by 0.70 quads.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Hige Compression Ratio Turbo Gasoline Engine Operation Using Alcohol Enhancement

The overall objective of this project was to quantify the potential for improving the performance and efficiency of gasoline engine technology by use of alcohols to suppress knock. Knock-free operation is obtained by direct injection of a second “anti-knock” fuel such as ethanol, which suppresses knock when, with gasoline fuel, knock would occur. Suppressing knock enables increased turbocharging, engine downsizing, and use of higher compression ratios throughout the engine’s operating map. This project combined engine testing and simulation to define knock onset conditions, with different mixtures of gasoline and alcohol, and with this information quantify the potential for improving the efficiency of turbocharged gasoline spark-ignition engines, and the on-vehicle fuel consumption reductions that could then be realized. The more focused objectives of this project were therefore to: Determine engine efficiency with aggressive turbocharging and downsizing and high compression ratio (up to a compression ratio of 13.5:1) over the engine’s operating range; Determine the knock limits of a turbocharged and downsized engine as a function of engine speed and load; Determine the amount of the knock-suppressing alcohol fuel consumed, through the use of various alcohol-gasoline and alcohol-water gasoline blends, for different driving cycles, relative to the gasoline consumed; Determine implications of using alcohol-boosted engines, with their higher efficiency operation, in both light-duty and medium-duty vehicle sectors.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Silicon Carbide Temperature Monitor Processing Improvements. Status Report

Silicon carbide (SiC) temperature monitors are used as temperature sensors in Advanced Test Reactor (ATR) irradiations at the Idaho National Laboratory (INL). Although thermocouples are typically used to provide real-time temperature indication in instrumented lead tests, other indicators, such as melt wires, are also often included in such tests as an independent technique of detecting peak temperatures incurred during irradiation. In addition, less expensive static capsule tests, which have no leads attached for real-time data transmission, often rely on melt wires as a post-irradiation technique for peak temperature indication. Melt wires are limited in that they can only detect whether a single temperature is or is not exceeded. SiC monitors are advantageous because a single monitor can be used to detect for a range of temperatures that occurred during irradiation. As part of the process initiated to make SiC temperature monitors available at the ATR, post-irradiation evaluations of these monitors have been previously completed at the High Temperature Test Laboratory (HTTL). INL selected the resistance measurement approach for determining irradiation temperature from SiC temperature monitors because it is considered to be the most accurate measurement. The current process involves the repeated annealing of the SiC monitors at incrementally increasing temperature, with resistivity measurements made between annealing steps. The process is time consuming and requires the nearly constant attention of a trained staff member. In addition to the expensive and lengthy post analysis required, the current process adds many potential sources of error in the measurement, as the sensor must be repeatedly moved from furnace to test fixture. This time-consuming post irradiation analysis is a significant portion of the total cost of using these otherwise inexpensive sensors. An additional consideration of this research is that, if the SiC post processing can be automated, it could be performed in an MFC hot cell, further reducing the time and expense of lengthy decontaminations prior to processing. Sections of this report provide a general description of resistivity techniques currently used to infer peak irradiation temperature from silicon carbide temperature monitors along with some representative data, the proposed concepts to improve the process of analyzing irradiated SiC temperature monitors, the completed efforts to prove the proposed concepts, and future activities. The efforts detailed here succeeded in designing and developing a real-time automated SiC resistivity measurement system, and performed two initial test runs. Activities carried out include the assembly and integration of the system hardware; the design and development of a preliminary monitor fixture; the design of a technique to automate the data analysis and processing; the development of the communication, coordination, and user software; and the execution and troubleshooting of test run experiments using the box furnace. Although the automation system performed as required, the designed fixture did not succeed in establishing the needed electrical contacts with the SiC monitor.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

A model to evaluate 100-year energy mix scenarios to facilitate deep decarbonization in the southeastern United States

The Southeast United States consumes approximately one billion megawatt-hours of electricity annually; roughly two-thirds from carbon dioxide (CO 2 ) emitting sources. The balance is produced by non-CO 2 emitting sources: nuclear power, hydroelectric power, and other renewables. Approximately 40% of the total CO 2 emissions come from the electric grid. The CO 2 emitting sources, coal, natural gas, and petroleum, produce approximately 372 million metric tons of CO 2 annually. The rest is divided between the transportation sector (36%), the industrial sector (20%), the residential sector (3%), and the commercial sector (2%). An Energy Mix Modeling Analysis (EMMA) tool was developed to evaluate 100-year energy mix strategies to reduce CO 2 emissions in the southeast. Current energy sector data was gathered and used to establish a 2016 reference baseline. The spreadsheet-based calculation runs 100-year scenarios based on current nuclear plant expiration dates, assumed electrical demand changes from the grid, assumed renewable power increases and efficiency gains, and assumed rates of reducing coal generation and deployment of new nuclear reactors. Within the model, natural gas electrical generation is calculated to meet any demand not met by other sources. Thus, natural gas is viewed as a transitional energy source that produces less CO 2 than coal until non-CO 2 emitting sources can be brought online. The annual production of CO 2 and spent nuclear fuel and the natural gas consumed are calculated and summed. A progression of eight preliminary scenarios show that nuclear power can substantially reduce or eliminate demand for natural gas within 100 years if it is added at a rate of only 1000 MWe per year. Any increases in renewable energy or efficiency gains can offset the need for nuclear power. However, using nuclear power to reduce CO 2 will result in significantly more spent fuel. More efficient advanced reactors can only marginally reduce the amount of spent fuel generated in the next 100 years if they are assumed to be available beginning around 2040. Thus closing the nuclear fuel cycle to reduce nuclear spent fuel inventories should be considered. Future work includes the incorporation of economic features into the model and the extension of the evaluation to the industrial sector. It will also be necessary to identify suitable sites for additional reactors.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Development of a Field Demonstration for Cost-Effective Low-Grade Heat Recovery and Use Technology Designed to Improve Efficiency and Reduce Water Usage Rates for a Coal-Fired Power Plant

Coal-based power generation systems provide reliable, low-cost power to the domestic energy sector. These systems consume large amounts of fuel and water to produce electricity and are the target of pending regulations that may require reductions in water use and improvements in thermal efficiency. While efficiency of coal-based generation has improved over time, coal power plants often do not utilize the low-grade heat contained in the flue gas and require large volumes of water for the steam cycle make-up, environmental controls, and for process cooling and heating. Low-grade heat recovery is particularly challenging for coal-fired applications, due in large part to the condensation of acid as the flue gas cools and the resulting potential corrosion of the heat recovery materials. Such systems have also not been of significant interest as recent investments on coal power plants have primarily been for environmental controls due to more stringent regulations. Also, in many regions, fuel cost is still a pass-through to the consumer, reducing the motivation for efficiency improvements. Therefore, a commercial system combining low-grade heat-recovery technologies and associated end uses to cost effectively improve efficiency and/or reduce water consumption has not yet been widely applied. However, pressures from potential new regulations and from water shortages may drive new interest, particularly in the U.S. In an effort to address this issue, the U.S. Department of Energy (DOE) has sought to identify and promote technologies to achieve this goal.

20 FOSSIL-FUELED POWER PLANTS↗

Development and Evaluation of Algorithms to Improve Small- and Medium-Size Commercial Building Operations

Small- and medium-sized (<100,000 sf) commercial buildings (SMBs) represent over 95% of the U.S. commercial building stock and consume over 60% of total site energy consumption. Many of these buildings use rudimentary controls that are mostly manual, with limited scheduling capability, no monitoring or failure management. Therefore, many of these buildings are operated inefficiently and consume excess energy. SMBs typically utilize packaged rooftop units (RTUs) that are controlled by an individual thermostat. There is increased urgency to improve the operating efficiency of existing commercial building stock in the U.S. for many reasons, chief among them is to mitigate the climate change impacts. Studies have shown that managing set points and schedules of the RTUs will result in up to 20% energy and cost savings. Another problem associated with RTUs is short-cycling, where an RTU goes through ON and OFF cycles too frequently. Excessive cycling can lead to excessive wear and lead to premature failure of the compressor or its components. The short cycling can result in a significantly decreased average efficiency (up to 10%), even if there are no physical failures in the equipment. Also, SMBs use a time-of-day scheduling is to start the RTUs before the building will be occupied and shut it off when unoccupied. Ensuring correct use of the zone set points and eliminating frequent cycling of RTUs thereby leading to persistent building operations can significantly increase the operational efficiency of the SMBs. A growing trend is to use low-cost control infrastructure that can enable scalable and cost-effective intelligent building operations. The work reported in this report describes three algorithms for detecting the zone set point temperature, RTU cycling rate and occupancy schedule detection that can be deployed on the low-cost infrastructure. These algorithms only require the zone temperature data for detection. The algorithms have been tested and validated using field data from a number of RTUs from six buildings in different climate locations. Overall, the algorithms were successful in detecting the set points and ON/OFF cycles accurately using the peak detection technique and occupancy schedule using symbolic aggregate approximation technique. The report describes the three algorithms, results from testing the algorithms using field data, how the algorithms can be used to improve SMBs efficiency, and presents related conclusions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Regional Charging Infrastructure for Plug-In Electric Vehicles: A Case Study of Massachusetts

Given the complex issues associated with plug-in electric vehicle (PEV) charging and options in deploying charging infrastructure, there is interest in exploring scenarios of future charging infrastructure deployment to provide insight and guidance to national and regional stakeholders. The complexity and cost of PEV charging infrastructure pose challenges to decision makers, including individuals, communities, and companies considering infrastructure installations. The value of PEVs to consumers and fleet operators can be increased with well-planned and cost-effective deployment of charging infrastructure. This will increase the number of miles driven electrically and accelerate PEV market penetration, increasing the shared value of charging networks to an expanding consumer base. Given these complexities and challenges, the objective of the present study is to provide additional insight into the role of charging infrastructure in accelerating PEV market growth. To that end, existing studies on PEV infrastructure are summarized in a literature review. Next, an analysis of current markets is conducted with a focus on correlations between PEV adoption and public charging availability. A forward-looking case study is then conducted focused on supporting 300,000 PEVs by 2025 in Massachusetts. The report concludes with a discussion of potential methodology for estimating economic impacts of PEV infrastructure growth.

33 ADVANCED PROPULSION SYSTEMS↗

Impacts of the EISA 2007 Energy Efficiency Standard on General Service Lamps

The Energy Policy and Conservation Act of 1975, as amended by the Energy Independence and Security Act of 2007 (EISA 2007), requires that, effective beginning January 1, 2020, the Secretary of Energy shall prohibit the sale of any general service lamp (GSL) that does not meet a minimum efficacy standard of 45 lumens per watt. This is referred to as the EISA 2007 backstop. The U.S. Department of Energy recently revised the definition of the term GSL to include certain lamps that were either previously excluded or not explicitly mentioned in the EISA 2007 definition. For this subset of GSLs, we assess the impacts of the EISA 2007 backstop on national energy consumption, carbon dioxide emissions, and consumer expenditures. To estimate these impacts, we projected the energy use, purchase price, and operating cost of representative lamps purchased during a 30-year analysis period, 2020-2049, for cases in which the EISA 2007 backstop does and does not take effect; the impacts of the backstop are then given by the difference between the two cases. In developing the projection model, we also performed the most comprehensive assessment to date of usage patterns and lifetime distributions for the analyzed lamp types in the United States. There is substantial uncertainty in the estimated impacts, which arises from uncertainty in the speed and extent of the market conversion to solid state lighting technology that would occur in the absence of the EISA 2007 backstop. In our central estimate we find that the EISA 2007 backstop results in significant energy savings of 27 quads and consumer net present value of $120 billion (at a seven percent discount rate) for lamps shipped between 2020 and 2049, and carbon dioxide emissions reduction of 540 million metric tons by 2030 for those GSLs not explicitly included in the EISA 2007 definition of a GSL.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

The Price-Concentration Relationship in Early Residential Solar Third-Party Markets

The market for residential solar photovoltaic (PV) systems in the United States has experienced tremendous growth over the past decade, with installed capacity more than doubling between 2014 and 2016 alone (SEIA, 2016). As the residential market continues to grow, it prompts new questions about the nature of competition between solar installers and how this competition, or lack thereof, affects the prices consumers are paying. It is often assumed that more competition leads to lower prices, but this is not universally true. For example, some studies have shown that factors such as brand loyalty could lead to a negative relationship between concentration and price in imperfectly competitive markets (Borenstein, 1985; Holmes, 1989). As such, the relationship between prices and market concentration is an open empirical question since theory could predict either a positive or negative relationship. Determining a relationship between prices and market concentration is challenging for several reasons. Most significantly, prices and market structure are simultaneously determined by each other -- the amount of competition a seller faces influences the price they can command, and prices determine a seller's market share. Previous studies have examined recent PV pricing trends over time and between markets (Davidson et al., 2015a; Davidson and Margolis 2015b; Nemet et al., 2016; Gillingham et al., 2014; Barbose and Darghouth 2015). While these studies of solar PV pricing are able to determine correlations between prices and market factors, they have not satisfactorily proven causation. Thus, to the best of our knowledge, there is little work to date that focuses on identifying the causal relationship between market structure and the prices paid by consumers. We use a unique dataset on third-party owned contract terms for the residential solar PV market in the San Diego Gas and Electricity service territory to better understand this relationship. Surprisingly, we find that firms charged higher prices in more competitive markets in our sample. The finding is robust across multiple definitions of firm concentration. There are at least two potential explanations for our findings. First, firms could be conducting entry deterrence strategies. It is possible that firms are acting in a non-competitive way and setting prices lower than they would be otherwise. Setting low prices that are below potential competitors' marginal costs could deter entrants and ensure a larger market share. Second, there could be a group of dominant firms (with a competitive fringe), and the dominant firms may occasionally engage in price wars. If this is true, prices should be lower in more concentrated markets during the price wars (Salinger, 1990). As the rooftop PV market continues to grow, market structure will remain a relevant policy issue in consideration of the potential for rooftop solar to contribute to de-carbonization efforts or other policy objectives. This paper adds to a growing emphasis on understanding supply-side factors in scaling up solar markets in the residential sector. Generally, solar markets have become more competitive over the same time period that solar technology costs decreased. While solar system hard costs have come down, our research suggests that total costs are more nuanced in early solar system TPO markets. Policymakers should consider these findings when designing markets, and have the data needed to make informed decisions.

14 SOLAR ENERGY↗