California Energy Commission Research Articles

Hydrogen Contaminant Detectors for Ensuring Hydrogen Fuel Quality

The California Energy Commission tracks Hydrogen Refueling Station (HRSs) installations within California and states that there are 66 light duty retail stations open within the State with another 34 in the planning stages.1 The hydrogen dispensed in these stations is expected to meet SAE J2719 standards for the maximum allowable concentration of various impurities.2 Currently HRSs have their fuel analyzed periodically to verify that they meet fuel specifications. However, this implies that any anomaly in the purification system resulting in contaminated hydrogen can result in significant damage to fuel cell vehicles before being detected. Therefore, the development of hydrogen contaminant detectors that can continuously monitor the hydrogen for impurities like Carbon monoxide (CO) and hydrogen Sulfide (H2S) is of great interest. LANL has developed a hydrogen contaminant detector based on a hydrogen pumping cell that is sensitive to < 200 ppb CO and < 4 ppb H2S.3,4 In this talk we will present details of the working mechanism of this hydrogen contaminant detector and present results from the field testing of the detector at a HRS. Acknowledgements This research is supported by the U.S. Department of Energy Fuel Cell Technologies Office, through the Safety, Codes & Standards (SCS) sub-program (Project Manager: Laura Hill).REFERENCES: https://www.energy.ca.gov/data-reports/energy-almanac/zero-emission-vehicle-and-infrastructure-statistics/hydrogen-refueling.San Marchi, E. S. Hecht, I. W. Ekoto, K. M. Groth, C. LaFleur, B. P. Somerday, R. Mukundan, T. Rockward, T; J. Keller, C. W. James, Int. J. Hydrogen Energy, 42(11), 7263-7274 (2017)Brosha, T. Rockward, C. J. Romero, M. S. Wilson, C. Kreller and R. Mukundan, U.S Patent # 10,490,833 (2019).R. Mukundan, E. L. Brosha, C. J. Romero, D. Poppe, T. Rockward, “Development of an electrochemical hydrogen contaminant detector”, Journal of The Electrochemical Society, 167(14), 147507 (2020)

Advancing California's microgrid communities through anticipatory energy resilience

Given the uncertainty around climate change and the need to design systems that anticipate future needs, risks, and costs or values related to resilience, the current rules-based regulatory and policy frameworks designed for the centralized system of large-scale energy generation and delivery may not be ‘fit for purpose' for smaller scale local installations centered on community microgrids. This research examines regulatory challenges and potential impediments to implementing a multi-customer community-based microgrid in California through discussion of lessons learned in current pilot projects supported in part by initiatives of the California Energy Commission's Electric Program Investment Charge (EPIC). The extent to which regulation has the flexibility to anticipate future needs and risks and support experimentation is evaluated in light of the state's complex and evolving energy system requirements. To illustrate challenges, two case studies of EPIC-supported projects are included. Multiple uncertainties, including future impacts of climate change, energy demands, and advances in technology, highlight the potential need to rethink best approaches to energy regulation. Principles drawn from Resilience Thinking and Anticipatory Regulation are discussed for their potential value in supporting development of new models for community-scale energy production, distribution, and use. Drawing on the experiences of the pilot projects, suggested principles to guide a new regulatory regime specific to microgrids are proposed.

Impact of Event-Based EV Charging Power Profile on Design and Control of Multi-Source DCFC Stations

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;The availability of DC Fast Charging Stations (DCFCs) is considered a fundamental step for the widespread adoption of electric vehicles (EVs). To mitigate the impact of high-power charging events on the grid, DCFCs are often equipped with stationary energy storage and renewable energy resources. In literature, many methods have been proposed to design, control, and optimize the performance of multi-sources DCFCs. Many of the research contributions use the averaged EV charging power consumption as input, not the real-time event-based power request. This paper aims at comparing the effects of average-based and event-based EV charging power profile&lt;b&gt;s&lt;/b&gt; on the design and control of multi-sources DCFCs. An algorithm that generates event-based EV charging power profiles has been developed based on the data from the California Energy Commission (CEC) report and NREL's EVI-Pro I tool. Multiple scenarios can be generated based on different weekday and weekend energy consumptions, EV penetrations, and the number or power level of chargers. The case scenario in this paper considers a 150kW charging station with second life energy storage and photovoltaic (PV) plant with a low power grid connection (&amp;lt;50kW). The utilization of local distributed energy resources is fundamental for enabling EV charging power delivery. Event-based and average-based EV charging power profiles, having the same energy requirements, are used to assess the impact on the design and control of the stations.&lt;/div&gt;&lt;/div&gt;

Earthquake Algorithm-Based Voltage Referenced MPPT Implementation through a Standardized Validation Frame

This paper presents a new direct maximum power point tracking (MPPT) with a reference voltage (Vref) based on the metaheuristic earthquake algorithm (EA) where the optimization variable is the Vref for hard-switching converters. The efficiency and performance of EA-MPPT-Vref is compared with the perturb-and-observe (P&amp;O) counterpart technique due to the fact that it is widely used for commercial products. Static and dynamic responses for both MPPT strategies are evaluated, which correspond to steady-state oscillations when they are near the maximum power point (MPP), and the tracking-speed, respectively. The efficiency was evaluated with the EN 50530 standard. The results show that the new MPPT proposed is a competitive method using the EA to obtain the optimal voltage reference. From static results, EA-MPPT VP presented a better efficiency of 5.13% and 3.23% for European and California energy commission (CEC) efficiency, respectively. Whereas, from dynamic results, MPPT-Vref techniques presented an efficiency from 95.13% to 99.91%, and 99.01% to 99.91% of the total power of the PV system for P&amp;O and EA strategies, respectively.

Comparison of CCM- and CRM-Based Boost Parallel Active Power Decoupler for PV Microinverter

Single-phase inverter or rectifier systems often make use of an active power decoupler (APD) to balance the mismatch between constant dc power and fluctuating ac power. This article deals with the comparison of continuous conduction mode (CCM) and critical conduction mode (CRM) operation-based design of a parallel boost-type APD for photovoltaic microinverter applications. From a design perspective, multiobjective analysis of efficiency, volume, and cost is explored within a decision space including planar inductors, gallium nitride based devices, film capacitors, switching frequency, and modulation (CCM vs. CRM). The theoretical study analyzes all possible design configurations within CCM and CRM and identifies Pareto-optimal designs, from which the selected CRM design can achieve reduced system volume and lower cost with the use of smaller inductor core, while operating with similar California Energy Commission efficiency drop as the selected CCM design. From a control perspective, a pulsewidth modulation based control strategy is proposed to implement closed-loop CRM modulation that does not rely on zero-crossing detection. Closed-loop systems are designed for the optimal CCM and CRM realizations, and the final system characteristics are compared. Experimental results, obtained using two separate 40-V, 400-W hardware prototypes for CCM and CRM, are presented to verify the analyses.

Integrated solid oxide fuel cell, solar PV, and battery storage system to achieve zero net energy residential nanogrid in California

California is seeking to mandate Zero Net Energy (ZNE) buildings by 2030 as part of its efforts to combat climate change. A ZNE building is required to compensate its annual energy consumption from the grid (electricity or gas) by injecting clean electricity back to the grid. So far, the most common approach for a ZNE building is utilizing solar photovoltaic (PV) or a PV and battery energy storage system. One key problem is the feasibility of installing PV if the surface area requirement is too large to achieve ZNE; another issue is grid congestion during the off-peak hours of midday when a large number of houses export their excess solar power to the grid. Hence, other ZNE home scenarios need to be evaluated to tackle these restrictions in achieving California’s climate goals.In this work, we proposed and evaluated different system arrangements to reduce the required PV installation that is commonly installed as power generation source for ZNE residential units in California. The aim of this technical analysis is to provide a societal level policy guidance to accelerate fulfilling the ZNE home mandate. Due to the availability of the gas grid and potential for having more renewable gas in the grid, we investigated using gas-based heat generation versus only electric-based heat appliances. In addition, we incorporated a residential solid oxide fuel cell (SOFC) on the building site as a micro combined heat and power (mCHP) to facilitate achieving ZNE. The impact and contributions of different components, including energy storage, on grid-dependence, and the overall energy demand are also studied. With analysis of different mix of technologies that could be used for a ZNE home, we propose the potential solutions and discuss their strengths and weakness.In this paper, energy performance and optimal PV capacity are assessed for a ZNE home in all 16 climate zones of California established by California Energy Commission (CEC). The ZNE measurements for all four scenarios are based on three metrics of energy evaluation: (1) site energy (energy measured by the meter used at the building site); (2) source energy (raw fuel consumption at the source of energy generation to account for energy loss in production and distribution); and (3) time dependent valuation (TDV) of energy, which has been developed by the CEC to comply with its building energy efficiency standards. The TDV of each energy type depends on the time of use, climate, grid constraints, and other factors that reflect its societal value at any given hour of the year. The PV size required by each ZNE metric is calculated and compared. The results proved that relying on some gas in addition to electricity improves the practicality of required PV for ZNE homes particularly in regions with high heating demands. It was found that depending on the energy metric (site, source, and TDV), a different arrangement is required for the most efficient ZNE performance. Unlike the site metric, using source and TDV metrics where electricity is more valuable than gas shows that having both gas and electricity significantly reduces the PV size. This encourages investment in introduction of more renewable gas in the grid as one possible solution to achieving ZNE in individual homes. The great impact of an mCHP SOFC on a ZNE home in terms of reliability and feasibility points to the need for research, development, and commercialization to reduce the cost of mCHP SOFCs in residential application. Also, the addition of a battery does not reduce the PV size with site and source metrics; it only reduces the electric grid reliance. However, with TDV, where the time of energy consumption affects its value, not only does it reduce grid reliance during peak hours, but also less PV is required to achieve ZNE.

Evaluating satellite and in situ monitoring technologies for leak detection and response

AbstractThe California Energy Commission funded a study to evaluate two technologies to assess their usefulness as an early leak detection tool for alerting field teams and to better understand the impact on energy savings through managing water loss. Specifically, the latest in advanced correlating continuous acoustic monitoring and satellite imagery leak detection technologies were examined over a period of 12 months in the Duarte system of California with 4.9 mgd production capacity and representing several pressure zones in the service area. A key conclusion was that both technologies improved the effectiveness of locating subsurface leaks that would have been invisible to the casual observer, and both were potential candidates for future applications. When implemented together in this study, the two technologies found leaks that would have resulted in between 57–170 mil gal of lost water during the study period. This equates to 140–419 MWh of energy savings in California, amounting to cost savings of at least $100,000 for the Duarte system alone during the 12‐month study period.

Single-Stage Isolated AC-AC Converter Without Commutation Problem

A single-stage isolated ac–ac converter without the commutation problem is proposed. The proposed converter has the step-up/down function dependence on the phase shift control which provides zero-voltage switching zero-voltage switching (ZVS) for all switches in rated condition. Also, the commutation paths of the secondary side switches are provided for any switching case by adding a single capacitor; originally, a filter capacitor is used for the switching mode power supply input, and in this case, this filter capacitor also solves the primary-side commutation problem. The ZVS and solving the commutation problem increase the power efficiency and reliability. The proposed converter achieves high power quality with a simple control algorithm. A 1 kW/ 220 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> prototype is implemented to verify the theoretical analysis and performance of the proposed converter. The California energy commission efficiency is 97.3%, the total harmonic distortion (THD) of the input current is 2.45% at full load, and the THD of the output voltage is 1.07% at full load.

A Blueprint for Cogeneration at State Facilities

At the June 3, 1980, meeting of the Governor’s Cogeneration TaskForce, Governor Edmund G. Brown Jr., challenged utilities and indus-tries to develop 6,000 megawatts (MW) of electricity in California duringthe 1980s through cogeneration. The Governor also announced that thestate will take the lead by beginning immediately to develop 400 MW ofcogeneration at state facilities.As a first step, the Governor requested the Department of GeneralServices, the Office of Appropriate Technology, and the Department ofWater Resources to prepare a blueprint for developing this capacity. TheGovernor called for identification of feasible cogeneration projects thatcan be implemented without delay; establishment of an overall time-table for additional planning, feasibility studies, design and construc-tion; and a discussion of potential sources of funds.Since the Governor’s announcement, the California Energy Com-mission, the Department of General Services, the Office of AppropriateTechnology, the University of California, and the state university andcolleges, with the cooperation of the Departments of DevelopmentalServices, Mental Health, Corrections, and Health Services have initiated,continued work on, or completed feasibility studies or engineering de-sign work for state facilities totaling more than 177 MW of cogenerationcapacity. The Department of Water Resources has conducted preliminarysite investigations at thirteen additional state facilities.

Impact of Temperature &amp; Illumination for Improvement in Photovoltaic System Efficiency

Temperature and Illumination has strong impact on photovoltaic systems output power. This research is focused to boost up the annual power production by investigating combined effect of temperature and Illumination. For this purpose, two solutions are purposed to improve annual power production and efficiency. First purposed solution is solar radiation tracker system to track sun for the optimal amount of radiations depending on the annual weather data available for Pakistan. The tracking system is studied for Horizontal, Vertical and dual axes trackers. It is found that this technique is very useful to boost the power production in most of the months of year over the fixed PV system approach. Second purposed solution is selection of suitable PV module types in which the act of changing the PV module types was investigated. Two types (California Energy Commission module and Sandia module) are used over the conventional simplified silicon crystalline module. The results are very promising, in which a significant improvement is noted in both radiation harvesting and power production over the simplified module. Both these purposed solutions are examined in detail and it shows 20% annual power production improvement for the case of Pakistan.

Impact of Grid Voltage and Grid-Supporting Functions on Efficiency of Single-Phase Photovoltaic Inverters

High penetrations of rooftop photovoltaic (PV) systems are creating several challenges for distribution network operators, most critically overvoltage during periods of peak solar generation. To assist with voltage regulation across distribution networks, grid-supporting functions, such as Volt–Watt ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$P(V)$</tex-math></inline-formula> ) and Volt–VAr ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q(V)$</tex-math></inline-formula> ) response modes, are now part of many grid connection standards for PV inverters. The constantly varying voltage profile during daylight hours, particularly in networks with high penetrations of PV systems, requires an inverter operation to vary from nonunity power factor with connection voltages that depart from their nominal values. However, current discussions on PV inverter efficiency focus on calculations and measurements under a unity-power-factor operation while assuming nominal voltage conditions. This article measures and analyzes the efficiency of commercial PV inverters across a more comprehensive and realistic range of voltage and power factors. The impact of grid-supporting modes on PV inverter efficiency is also evaluated experimentally. The definitions of the European and California Energy Commission efficiencies are expanded from a single value to an efficiency curve accounting for the impact of the grid voltage and the power factor. A <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">voltage-weighted PV inverter efficiency</i> metric is proposed that collectively considers the combined impact of solar irradiance, grid-supporting functions, and grid voltages. Experimental measurements from eight commercial PV inverters demonstrate that PV inverters under abnormal grid voltage conditions and with grid-supporting functionalities show lower efficiency values.

Planar Transformer With Asymmetric Integrated Leakage Inductance Using Horizontal Air Gap

This article presents a novel planar-based transformer winding and core structure with controllable leakage inductance generation for integrated magnetics applications. As a result of limitations in integrated magnetics from the literature, a new approach is proposed utilizing semi-interleaved windings and controllable leakage via a leakage flux core leg featuring a horizontal air gap. The proposed transformer design is analyzed via detailed reluctance modeling to determine closed-form equations for the magnetizing and asymmetrically distributed leakage inductances. Next, a genetic-algorithm-based multiobjective design optimization problem is developed, seeking to minimize the core and winding losses of the proposed transformer subject to a set of parametric and geometric constraints in a dc-ac dual-active-bridge topology for microinverter applications. The optimization was extended to include other integrated magnetic structures from the literature, where it is determined that the proposed transformer is superior from the perspectives of efficiency, footprint area, and parasitic capacitance. Based on the results of the optimization analysis, two designs with theoretical transformer California Energy Commission (CEC) efficiency drops (i.e., CEC efficiency reduction specifically due to the transformer loss mechanisms) of 1.19% and 0.83% were fabricated and evaluated for electrical and thermal performance in the proposed 40 V, 400 W microinverter.

Cross-sector storage and modeling needed for deep decarbonization

Noah Kittner is an assistant professor in energy in the Department of Environmental Sciences and Engineering, Gillings School of Global Public Health and in the Environment, Ecology, and Energy Program at the University of North Carolina at Chapel Hill. His research examines the role of energy storage in the transition to low-carbon energy systems and deep decarbonization. Sergio Castellanos is an assistant professor in the Department of Civil, Architectural and Environmental Engineering at the University of Texas at Austin, where he leads the Rapid, Equitable & Sustainable Energy Transitions (RESET) Lab focusing on equitable pathways for decarbonized energy systems. Patricia Hidalgo-Gonzalez is an assistant professor in the Jacobs School of Engineering and an affiliate member in the Center for Energy Research at the University of California, San Diego. She is the director of the Renewable Energy and Advanced Mathematics Laboratory. She is one of the academic co-leads of the IEEE Power & Energy Society Task Force "Data-Driven Controls for Distributed Systems." Her research focuses on high penetration of renewable energy using optimization, control theory, and machine learning with safety guarantees. Daniel M Kammen is the James and Katherine Lau Distinguished Chair in Sustainability, and Chair of the Energy and Resources Group, Professor in the Goldman School of Public Policy, and Professor of Nuclear Engineering at the University of California, Berkeley. He has served as Chief Technical Specialist for Renewable Energy and Energy Efficiency at the World Bank, and Science Envoy in the US Department of State. His work is focused on the science and policy of decarbonization at scales from homes to villages to large utility-scale systems. He has been a Coordinating Lead Author for the IPCC since 1999. Sarah Kurtz is a Professor at the University of California Merced. She spent more than 30 years at the National Renewable Energy Laboratory studying multi-junction III-V solar cells, reliability of photovoltaic modules and systems, and other solar-related projects. She is now leading a study of the value of long-duration storage, funded by the California Energy Commission.

ENERGY AND WATER PERFORMANCE OF AN OFF-GRID TINY HOUSE IN CALIFORNIA

ABSTRACT The impetus for buildings to decarbonize and move towards radical energy and water efficiency is increasingly strong and identified as a priority within the green building sector. The tiny house movement offers an opportunity to both address the challenges of affordable housing and contribute to residential building decarbonization. Tiny houses de-emphasize mass consumption and excessive belongings and have potential to address equity issues such as gentrification by providing living spaces to low-income residents in desirable housing locations. This paper analyzes the Tiny House in My Backyard (THIMBY) project, investigating building sustainability concepts through the design-build-occupy process in a three-year-old structure. THIMBY demonstrates energy and water efficiency technologies inside an award-winning small living space (18.5 m2). THIMBY was designed to reduce energy and water use by 87 and 82% compared to California residential averages. In practice, it has reduced site energy by 88% and has emitted 96% fewer carbon emissions than a 2100 square foot California Energy Commission 2016 Title 24 minimally compliant home. We discuss the differences between design and performance of energy and water systems, which we find offer important lessons for the further expansion of the tiny house movement and other alternative and micro green housing types. We find that optimizing such houses through integration of energy and water saving technologies, home energy management systems, and strong communication between modelers, builders and occupants will be essential to achieving dramatic energy (87%), water (82%), and carbon (96%) savings.

Experimental and Theoretical Validation of One Diode and Three Parameters–Based PV Models

The present paper defines and assesses a new simplified method to represent the photovoltaic (PV) modules’ electrical behavior, based on the commonly used one diode and three parameters (1D + 3P) model, addressing two main objectives. The first one is to quantify and assess, at different operating conditions, the PV modules electrical behavior estimations’ accuracy provided by the well-known 1D + 3P, through a comparison based on experimental and theoretical results. The second one concerns the performance assessment of the 1D + 3P model’s suggested approximation, aiming at simplifying the mathematics instead of solving complex iterative equations, which hinges on higher computational time to obtain accurate results. Hence, experimental and theoretical data were considered, aiming at performing a thorough comparison with more than 17,000 PV modules being assessed, which was achieved by using both the California Energy Commission (CEC) database and PVsyst software. The findings show that the already known 1D + 3P model delivers satisfactory power output estimations for crystalline silicon modules and high irradiance conditions. However, its performance worsens when considering Low Irradiance and thin-film technology. In comparison with the original model, accurate results were obtained with the new simplified suggested 1D + 3P for all irradiance conditions and technologies assessed, thus proving its validity and capability of circumventing the aforementioned challenges.

A complete framework for the simulation of photovoltaic arrays under mismatch conditions

The mismatch is a phenomenon intrinsically related to photovoltaic (PV) arrays, either because they are eventually subject to non-uniform irradiance and temperature conditions, or because of inner variations on the components, ageing or occurrence of failures. Despite mismatch losses being so present in the life of a PV system, the available tools for the study of PV arrays response through simulation today present limitations for the handling of mismatch conditions. Most of them do not support non-uniform conditions, and the ones that do, solely explore irradiance and temperature variations, ignoring other causes for mismatches, such as defects on PV cells. This paper proposes a simulation framework that allows manipulation of each parameter in each cell individually to reproduce mismatch conditions, including failures. Each PV cell is represented by the one diode equivalent circuit model, for which two different parameterisation methods were tested: California Energy Commission (CEC) and PVSyst. The proposed simulation framework was validated with laboratory measurements of a PV module under 15 different mismatch conditions of partial shading and failure (short circuit). The results showed a consistent similarity between calculated and measured I–V curves, and errors at the curves’ maximum power points stayed within the instruments’ accuracy range, roughly 1.0 V and 0.2 A. The proposed simulation framework brings great flexibility to the studies of mismatch through simulation, allowing the calculation of the I–V curve of PV strings and small arrays subjected to mismatch conditions due to non-uniform irradiance and temperature profiles, but most significantly failures in the cells.

Parameter extraction of photovoltaic modules using a heuristic iterative algorithm

The single diode Rsh-model is considered to be an accurate and time-efficient modeling method for photovoltaic (PV) modules. However, the implicit equation in the model increases the complexity of solution. In this paper, after analyzing the parameters on the electrical characteristics of PV modules, a pure heuristic iterative method is proposed to extract the five parameters and to solve the implicit voltage and current equation simultaneously. Only three electrical key points specified in the manufacturer’s nameplate together with the Shockley equation are useful. Meanwhile, some pure heuristic strategies are used to minimize the error of the model curve. In order to evaluate the effectiveness of the method, parameters of three different PV modules are extracted, i.e., poly-crystalline, mono-crystalline, and thin-film silicon module. The results show competitive and superior performance to the De Soto model and analytic algorithms in terms of accuracy and computation speed, especially a-Si PV cell types. In addition, 99.45% of PV modules from California Energy Commission (CEC) database are identified successfully to verify the robustness. Further, the field data also indicate that the proposed algorithm can used to predict the real-time generation power of a PV power station at various operating conditions. Therefore, the proposed method can be an effective and efficient alternative for parameter extraction of all kinds of PV modules and arrays.

Performance evaluation of first full-scale primary filtration using a fine pore cloth media disk filter.

Over the past 20years, various new filter technologies have been developed that can be used to (a) enhance the performance of or (b) replace conventional primary treatment facilities. To enhance the performance of a primary sedimentation facility, primary effluent is filtered to further reduce the constituent concentrations discharged to the secondary treatment facilities. This form of primary enhancement is known as primary effluent filtration (PEF). In the second case, where some type of filter technology is used to replace primary sedimentation, the process application is known as primary filtration (PF). The principal focus of this paper is on the performance of the first full-scale PF project using a fine pore cloth media disk filter to maximize the diversion of carbon for the production of energy and to reduce energy usage. Performance data from related pilot-scale cloth disk primary filter (CDPF) systems are included for process verification. The removal performance for total suspended solids (TSS) from the three CDPF installations varied from 83% to 85%, as compared to 55%-60% typically achieved with primary sedimentation. The total overall TSS removal performance achieved with PF is essentially the same as that achieved with PEF, without the need for a primary sedimentation tank. The removal performance for five-day biochemical oxygen demand (BOD5 ) from the three CDPF installations varied from 46% to 58%, as compared to 32%-38% BOD removal typically achieved with primary sedimentation. The full-scale CDPF results reported in this paper are from an on-going research and demonstration project, conducted for the California Energy Commission (CEC), to demonstrate the potential energy savings that can be achieved through the implementation of PF. PRACTITIONER POINTS: The performance of the first full-scale primary filtration system using a fine pore cloth disc filter is evaluated in this project. Design and operational criteria of the primary filtration technology were established in this project to implement in full scale installations. Primary filtration was demonstrated to increase the diversion of carbon for the production of energy and to reduce energy usage. Significant decrease in aeration power requirement and increase in digester gas production are possible with primary filtration. Footprint reduction (both for primary and secondary treatment) are other important attributes of primary filtration.

Analyzing California’s framework for estimating greenhouse gas emissions associated with retail electricity sales

Accurately attributing greenhouse gas (GHG) emissions in the electric power sector is critical to measuring progress towards climate policy goals. We evaluate a new methodology adopted by the California Energy Commission to calculate the GHG emissions intensity of retail electricity providers. In the long run, the new regulations better align with the physical nature of grid operation than did past practices, but policymakers should monitor a set of potential challenges as market structures evolve.

Magnetics-Based Efficiency Optimization for Low Power Cascaded-Buck-Boost Converter

This paper presents various techniques to achieve high efficiency for the bidirectional Cascaded-Buck-Boost converter. This converter has the features of low voltage across the switches and positive output voltage. The objective of this paper is to optimize the magnetics design to reduce the total losses in a low power non-isolated DC-DC circuit. A rigorous loss model with component nonlinearities is developed to determine the power loss distribution. It is validated by simulations and experiments. Based on the results of the power loss analysis and due to the low inductor profile and high efficiency target, nanocrystalline material will be the best candidate. Therefore, a new small volume low profile planar-nanocrystalline inductor is designed. Various deep de sign aspects for core and copper are discussed. The Finite-Element-Analysis (FEA) method is used to examine and visualize the inductor design. By implementing the planar-nanocrystalline inductor, a California Energy Commission (CEC) weighted efficiency of 99.05% for the buck mode and 98.98% for the boost mode are achieved with a peak efficiency of 99.24% and 99.21%, respectively.