Prepared for the Clean Energy Regulatory Forum III, this presentation looks at the Western Wind and Solar Integration Study and reexamines the cost and emissions impacts of fossil fuel unit cycling.

Presentation on shaded PV power loss, practical issues with modeling shaded PV, and methods of implementing partially shaded PV modeling.

Because most sedimentary basins have been explored for oil and gas, well logs, temperatures at depth, and reservoir properties such as depth to basement and formation thickness are well known. The availability of this data reduces exploration risk and allows development of geologic exploration models for each basin. This study estimates the magnitude of recoverable geothermal energy from 15 major known U.S. sedimentary basins and ranks these basins relative to their potential. The total available thermal resource for each basin was estimated using the volumetric heat-in-place method originally proposed by (Muffler, 1979). A qualitative recovery factor was determined for each basin based on data on flow volume, hydrothermal recharge, and vertical and horizontal permeability. Total sedimentary thickness maps, stratigraphic columns, cross sections, and temperature gradient information was gathered for each basin from published articles, USGS reports, and state geological survey reports. When published data were insufficient, thermal gradients and reservoir properties were derived from oil and gas well logs obtained on oil and gas commission databases. Basin stratigraphy, structural history, and groundwater circulation patterns were studied in order to develop a model that estimates resource size, temperature distribution, and a probable quantitative recovery factor.

This briefing provides a high-level overview of historical, recent, and projected near-term PV system pricing trends in the United States, drawing on several ongoing research activities from the Lawrence Berkeley National Laboratory and the National Renewable Energy Laboratory. It also discusses the different methodologies and factors that impact the estimated price of a PV system, such as system size, location, technology, and reporting methods. These factors, including timing, can have a significant impact on system pricing.

This presentation addresses the engineering challenges of airborne wind technology.

Discussion of the formation of CdTe thin-film PV junctions and optimization of CdTe thin-film PV solar cells.

Three crystalline silicon module designs were distributed in five replicas each to five laboratories for testing according to the IEC 62804 (Committee Draft) system voltage durability qualification test for crystalline silicon photovoltaic (PV) modules. The stress tests were performed in environmental chambers at 60 degrees C, 85% relative humidity, 96 h, and with module nameplate system voltage applied.

This presentation summarizes findings of NREL's Renewable Electricity Futures study, published in June 2012. RE Futures investigated the challenges and impacts of achieving very high renewable electricity generation levels in the contiguous United States by 2050.

This presentation highlights the status of the voluntary green power market in 2012. The voluntary green power market totaled more than 48 million MWh in 2012, with about 1.9 million customers participating. The supply continues to be dominated by wind, though solar is increasing its share of utility green pricing programs. Prices for voluntary renewable energy certificates (RECs) increased to above $1/MWh.

The ability to accurately predict power delivery over the course of time is of vital importance to the growth of the photovoltaic (PV) industry. Two key cost drivers are the efficiency with which sunlight is converted into power and secondly how this relationship develops over time. The accurate knowledge of power decline over time, also known as degradation rates, is essential and important to all stakeholders?utility companies, integrators, investors, and scientist alike. Outdoor testing plays a vital part in quantifying degradation rates of different technologies in various climates. Due to seasonal changes, however, several complete cycles (typically 3-5 years) need to be completed traditionally to obtain reasonably accurate degradation rates. In a rapidly evolving industry such a time span is often unacceptable and the need exists to determine degradation rates more accurately in a shorter period of time. Advanced time series modeling such as ARIMA (Autoregressive Integrated Moving Average) modeling can be utilized to decrease the required time span and is compared with some non-linear modeling. In addition, it will be demonstrated how the JMP 9 map feature was used to reveal important technological trends by climate.

Presentation highlighting practical considerations for photovoltaic technologies and strategies for future reductions in cost and increases in efficiency.

Four levels of accelerated test standards for PV modules are described in the context of how the community can most quickly begin using these.

Regardless of cost and performance some wind projects are unable to proceed to commissioning as a result of deployment barriers. Principal deployment barriers in the industry today include: wildlife, public acceptance, access to transmission, and radar. To date, methods for understanding these non-technical barriers have failed to accurately characterize the costs imposed by deployment barriers and the degree of impact to the industry. Analytical challenges include limited data and modeling capabilities. Changes in policy and regulation, among other factors, also add complexity to analysis of impacts from deployment barriers. This presentation details preliminary results from new NREL analysis focused on quantifying the impact of deployment barriers on the wind resource of the United States, the installed cost of wind projects, and the total electric power system cost of a 20% wind energy future. In terms of impacts to wind project costs and developable land, preliminary findings suggest that deployment barriers are secondary to market drivers such as demand. Nevertheless, impacts to wind project costs are on the order of $100/kW and a substantial share of the potentially developable windy land in the United States is indeed affected by deployment barriers.

This research is to illustrate the use of statistical inference techniques in order to quantify the uncertainty surrounding reliability estimates in a step-stress accelerated degradation testing (SSADT) scenario. SSADT can be used when a researcher is faced with a resource-constrained environment, e.g., limits on chamber time or on the number of units to test. We apply the SSADT methodology to a degradation experiment involving concentrated solar power (CSP) mirrors and compare the results to a more traditional multiple accelerated testing paradigm. Specifically, our work includes: (1) designing a durability testing plan for solar mirrors (3M's new improved silvered acrylic "Solar Reflector Film (SFM) 1100") through the ultra-accelerated weathering system (UAWS), (2) defining degradation paths of optical performance based on the SSADT model which is accelerated by high UV-radiant exposure, and (3) developing service lifetime prediction models for solar mirrors using advanced statistical inference. We use the method of least squares to estimate the model parameters and this serves as the basis for the statistical inference in SSADT. Several quantities of interest can be estimated from this procedure, e.g., mean-time-to-failure (MTTF) and warranty time. The methods allow for the estimation of quantities that may be of interest to the domain scientists.

This presentation summarizes the scope and results of the Western Wind and Solar Integration Study Phase 2, which examined operational impacts of high penetrations of variable renewable generation in the West.

Overview of the PV module model. PVWatts module power estimates were compared with those using the Sandia model for three modules and data sets.

NREL has developed and maintains a variety of infrastructure analysis models for the U.S. Department of Energy. Business case analysis has recently been added to this tool set. This presentation focuses on cash flow analysis. Cash flows depend upon infrastructure costs, optimized spatially and temporally, and assumptions about financing and revenue. NREL has incorporated detailed metrics on financing and incentives into the models. Next steps in modeling include continuing to collect feedback on regional/local infrastructure development activities and 'roadmap' dynamics, and incorporating consumer preference assumptions on infrastructure to provide direct feedback between vehicles and station rollout.

The optical transmittance of encapsulation materials is a key characteristic for their use in photovoltaic (PV) modules. Changes in transmittance with time in the field affect module performance, which may impact product warranties. Transmittance is important in product development, module manufacturing, and field power production (both immediate and long-term). Therefore, an international standard (IEC 62788-1-4) has recently been proposed by the Encapsulation Task-Group within the Working Group 2 (WG2) of the International Electrotechnical Commission (IEC) Technical Committee 82 (TC82) for the quantification of the optical performance of PV encapsulation materials. Existing standards, such as ASTM E903, are general and more appropriately applied to concentrated solar power than to PV. Starting from the optical transmittance measurement, the solar-weighted transmittance of photon irradiance, yellowness index (which may be used in aging studies to assess durability), and ultraviolet (UV) cut-off wavelength may all be determined using the proposed standard. The details of the proposed test are described. The results of a round-robin experiment (for five materials) conducted at seven laboratories to validate the test procedure using representative materials are also presented. For example, the Encapsulation Group actively explored the measurement requirements (wavelength range and resolution), the requirements for the spectrophotometer (including the integrating …

Overview of nominal operating cell temperature research, hypothesis, and testing at NREL.

Recent research suggests that an emerging power cycle technology using supercritical carbon dioxide (s-CO2) operated in a closed-loop Brayton cycle offers the potential of equivalent or higher cycle efficiency versus supercritical or superheated steam cycles at temperatures relevant for CSP applications. Preliminary design-point modeling suggests that s-CO2 cycle configurations can be devised that have similar overall efficiency but different temperature and/or pressure characteristics. This paper employs a more detailed heat exchanger model than previous work to compare the recompression and partial cooling cycles, two cycles with high design-point efficiencies, and illustrates the potential advantages of the latter. Integration of the cycles into CSP systems is studied, with a focus on sensible heat thermal storage and direct s-CO2 receivers. Results show the partial cooling cycle may offer a larger temperature difference across the primary heat exchanger, thereby potentially reducing heat exchanger cost and improving CSP receiver efficiency.

This presentation describes the Battery Second Use Project. Preliminary analysis results show (1) the impact of competing technologies, (2) potential revenue generation, and (3) supply and demand of the second use of plug-in electric vehicle batteries. The impact of competing technologies are: maximum salve value of a used battery will be limited by future battery prices, under favorable conditions, second use can only discount today's battery prices by 12% or less, however, second use will offer batteries to second applications at reduced cost (typically < $170/kWh). Revenue streams are highly variable, allowable battery costs are highly sensitive to balance-of-system costs, and batteries need to be very cheap for these applications to be viable. Supply and demand show that high-value applications have both competition and small markets, and supply from plug-in electric vehicles has the potential to overwhelm many second use markets.

This presentation describes the basic components of software-based energy analysis for residential buildings, explores the concepts of 'error' and 'accuracy' when analysis predictions are compared to measured data, and explains how NREL is working to continuously improve the accuracy of energy analysis methods.

2010 International Pyrheliometer Comparisons, IPC-XI Conference presentation titled: Uncertainty in Pyranometer and Pyrheliometer Calibrations Using GUM for NREL's ISO-17025 Accreditation Effort.

Recent advancements in utility-scale wind turbine technology and pricing have vastly increased the potential land area where turbines can be deployed in the United States. This presentation quantifies the new developable land potential (e.g., capacity curves), visually identifies new areas for possible development (e.g., new wind resource maps), and begins to address deployment barriers to wind in new areas for modern and future turbine technology.