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DOE OSTI2012

DEVELOPMENT OF A SOFTWARE DESIGN TOOL FOR HYBRID SOLAR-GEOTHERMAL HEAT PUMP SYSTEMS IN HEATING- AND COOLING-DOMINATED BUILDINGS

This project provides an easy-to-use, menu-driven, software tool for designing hybrid solar-geothermal heat pump systems (GHP) for both heating- and cooling-dominated buildings. No such design tool currently exists. In heating-dominated buildings, the design approach takes advantage of glazed solar collectors to effectively balance the annual thermal loads on the ground with renewable solar energy. In cooling-dominated climates, the design approach takes advantage of relatively low-cost, unglazed solar collectors as the heat rejecting component. The primary benefit of hybrid GHPs is the reduced initial cost of the ground heat exchanger (GHX). Furthermore, solar thermal collectors can be used to balance the ground loads over the annual cycle, thus making the GHX fully sustainable; in heating-dominated buildings, the hybrid energy source (i.e., solar) is renewable, in contrast to a typical fossil fuel boiler or electric resistance as the hybrid component; in cooling-dominated buildings, use of unglazed solar collectors as a heat rejecter allows for passive heat rejection, in contrast to a cooling tower that consumes a significant amount of energy to operate, and hybrid GHPs can expand the market by allowing reduced GHX footprint in both heating- and cooling-dominated climates. The design tool allows for the straight-forward design of innovative GHP systems that currently pose a significant design challenge. The project lays the foundations for proper and reliable design of hybrid GHP systems, overcoming a series of difficult and cumbersome steps without the use of a system simulation approach, and without an automated optimization scheme. As new technologies and design concepts emerge, sophisticated design tools and methodologies must accompany them and be made usable for practitioners. Lack of reliable design tools results in reluctance of practitioners to implement more complex systems. A menu-driven software tool for the design of hybrid solar GHP systems is provided that is based on mathematically robust, validated models. An automated optimization tool is used to balance ground loads and incorporated into the simulation engine. With knowledge of the building loads, thermal properties of the ground, the borehole heat exchanger configuration, the heat pump peak hourly and seasonal COP for heating and cooling, the critical heat pump design entering fluid temperature, and the thermal performance of a solar collector, the total GHX length can be calculated along with the area of a supplemental solar collector array and the corresponding reduced GHX length. An economic analysis module allows for the calculation of the lowest capital cost combination of solar collector area and GHX length. ACKNOWLEDGMENTS This project was funded by the United States Department of Energy DOE-DE-FOA-0000116, Recovery Act Geothermal Technologies Program: Ground Source Heat Pumps. The lead contractor, The University of Hartford, was supported by The University of Dayton, and the Oak Ridge National Laboratories. All funding and support for this project as well as contributions of graduate and undergraduate students from the contributing institutions are gratefully acknowledged.

14 SOLAR ENERGY↗

DOE OSTI2011

Solid State Joining of High Temperature Alloy Tubes for USC and Heat-Exchanger Systems

The principal objective of this project was to develop materials enabling joining technologies for use in forward looking heat-exchanger fabrication in Brayton cycle HIPPS, IGCC, FutureGen concepts capable of operating at temperatures in excess of 1000°C as well as conventional technology upgrades via Ultra Super-Critical (USC) Rankine-cycle boilers capable of operating at 760°C (1400F)/38.5MPa (5500psi) steam, while still using coal as the principal fossil fuel. The underlying mission in Rankine, Brayton or Brayton-Rankine, or IGCC combined cycle heat engine is a steady quest to improving operating efficiency while mitigating global environmental concerns.

36 MATERIALS SCIENCE↗

DOE OSTI2013

Today's Leaders for a Sustainable Tomorrow

Today's Leaders for a Sustainable Tomorrow is a collaboration of five residential environmental learning centers (Audubon Center of the North Woods, Deep Portage Learning Center, Laurentian Environmental Center, Long Lake Conservation Center and Wolf Ridge Environmental Learning Center) that together increased energy efficiency, energy conservation and renewable energy technologies through a number of different means appropriate for each unique center. For energy efficiency upgrades the centers installed envelope improvements to seal air barriers through better insulation in walls, ceilings, windows, doors as well as the installation of more energy efficient windows, doors, lighting and air ventilation systems. Through energy sub-meter monitoring the centers are able to accurately chart the usage of energy at each of their campuses and eliminate unnecessary energy usage. Facilities reduced their dependence on fossil fuel energy sources through the installation of renewable energy technologies including wood gasification, solar domestic hot water, solar photovoltaic, solar air heat, geothermal heating and wind power. Centers also installed energy education displays on the specific renewable energy technologies used at the center.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2012

Interfacial Engineering for Highly Efficient-Conjugated Polymer-Based Bulk Heterojunction Photovoltaic Devices

The aim of our proposal is to apply interface engineering approach to improve charge extraction, guide active layer morphology, improve materials compatibility, and ultimately allow the fabrication of high efficiency tandem cells. Specifically, we aim at developing: i. Interfacial engineering using small molecule self-assembled monolayers; ii. Nanostructure engineering in OPVs using polymer brushes; iii. Development of efficient light harvesting and high mobility materials for OPVs; iv. Physical characterization of the nanostructured systems using electrostatic force microscopy, and conducting atomic force microscopy; v. All-solution processed organic-based tandem cells using interfacial engineering to optimize the recombination layer currents; vi. Theoretical modeling of charge transport in the active semiconducting layer. The material development effort is guided by advanced computer modeling and surface/ interface engineering tools to allow us to obtain better understanding of the effect of electrode modifications on OPV performance for the investigation of more elaborate device structures. The materials and devices developed within this program represent a major conceptual advancement using an integrated approach combining rational molecular design, material, interface, process, and device engineering to achieve solar cells with high efficiency, stability, and the potential to be used for large-area roll-to-roll printing. This may create significant impact in lowering manufacturing cost of polymer solar cells for promoting clean renewable energy use and preventing the side effects from using fossil fuels to impact environment.

14 SOLAR ENERGY↗

DOE OSTI2013

Low-temperature Stirling Engine for Geothermal Electricity Generation

Up to 2700 terawatt-hours per year of geothermal electricity generation capacity has been shown to be available within North America, typically with wells drilled into geologically active regions of the earth's crust where this energy is concentrated (Huttrer, 2001). Of this potential, about half is considered to have temperatures high enough for conventional (steam-based) power production, while the other half requires unconventional power conversion approaches, such as organic Rankine cycle systems or Stirling engines. If captured and converted effectively, geothermal power generation could replace up to 100GW of fossil fuel electric power generation, leading to a significant reduction of US power sector emissions. In addition, with the rapid growth of hydro-fracking in oil and gas production, there are smaller-scale distributed power generation opportunities in heated liquids that are co-produced with the main products. Since 2006, Cool Energy, Inc. (CEI) has designed, fabricated and tested four generations of low-temperature (100°C to 300°C) Stirling engine power conversion equipment. The electric power output of these engines has been demonstrated at over 2kWe and over 16% thermal conversion efficiency for an input temperature of 215°C and a rejection temperature of 15Â°C. Initial pilot units have been shipped to development partners for further testing and validation, and significantly larger engines (20+ kWe) have been shown to be feasible and conceptually designed. Originally intended for waste heat recovery (WHR) applications, these engines are easily adaptable to geothermal heat sources, as the heat supply temperatures are similar. Both the current and the 20+ kWe designs use novel approaches of self-lubricating, low-wear-rate bearing surfaces, non-metallic regenerators, and high-effectiveness heat exchangers. By extending CEI's current 3 kWe SolarHeart® Engine into the tens of kWe range, many additional applications are possible, as one 20 kWe design produces nearly seven times the power output of the 3 kWe unit but at only 2.5 times the estimated fabrication cost. Phase I of the proposed SBIR program will therefore study the feasibility of generating electricity with one or more 20 kWe or larger Stirling engines, powered by geothermal heat produced by current and possibly some forward-looking borehole extraction methods, and from producing oil and gas wells. The feasibility study will include full analysis of the thermodynamic and heat transfer processes within the engine (necessary to produce optimum theoretical designs and performance maps), the cost of pumping the geothermal heat recovery fluid, and how the system tradeoffs impact the overall system economics. The goal is a geothermal system design that could be demonstrated during a Phase II follow-on program at a field test site.

15 GEOTHERMAL ENERGY↗

DOE OSTI2013

Technical Support to SBIR Phase II Project: Improved Conversion of Cellulose Waste to Ethanol Using a Dual Bioreactor System: Cooperative Research and Development (Final Report)

Over-dependence on fossil fuel has spurred research on alternative energy. Inedible plant materials such as grass and corn stover represent abundant renewable natural resources that can be transformed into biofuel. Problems in enzymatic conversion of biomass to sugars include the use of incomplete synergistic enzymes, end-product inhibition, and adsorption and loss of enzymes necessitating their use in large quantities. Technova Corporation will develop a defined consortium of natural microorganisms that will efficiently break down biomass to energy-rich soluble sugars, and convert them to cleaner-burning ethanol fuel. The project will also develop a novel biocatalytic hybrid reactor system dedicated to this bioprocess, which embodies recent advances in nanotechnology. NREL will participate to develop a continuous fermentation process.

09 BIOMASS FUELS↗

DOE OSTI2013

Energy Transmission and Infrastructure Northern Ohio (OH)

The objective of Energy Transmission and Infrastructure Northern Ohio (OH) was to lay the conceptual and analytical foundation for an energy economy in northern Ohio that will: • improve the efficiency with which energy is used in the residential, commercial, industrial, agricultural, and transportation sectors for Oberlin, Ohio as a district-wide model for Congressional District OH-09; • identify the potential to deploy wind and solar technologies and the most effective configuration for the regional energy system (i.e., the ratio of distributed or centralized power generation); • analyze the potential within the district to utilize farm wastes to produce biofuels; • enhance long-term energy security by identifying ways to deploy local resources and building Ohio-based enterprises; • identify the policy, regulatory, and financial barriers impeding development of a new energy system; and • improve energy infrastructure within Congressional District OH-09. This objective of laying the foundation for a renewable energy system in Ohio was achieved through four primary areas of activity: 1. district-wide energy infrastructure assessments and alternative-energy transmission studies; 2. energy infrastructure improvement projects undertaken by American Municipal Power (AMP) affiliates in the northern Ohio communities of Elmore, Oak Harbor, and Wellington; 3. Oberlin, OH-area energy assessment initiatives; and 4. a district-wide conference held in September 2011 to disseminate year-one findings. The grant supported 17 research studies by leading energy, policy, and financial specialists, including studies on: current energy use in the district and the Oberlin area; regional potential for energy generation from renewable sources such as solar power, wind, and farm-waste; energy and transportation strategies for transitioning the City of Oberlin entirely to renewable resources and considering pedestrians, bicyclists, and public transportation as well as drivers in developing transportation policies; energy audits and efficiency studies for Oberlin-area businesses and Oberlin College; identification of barriers to residential energy efficiency and development of programming to remove these barriers; mapping of the solar-photovoltaic and wind-energy supply chains in northwest Ohio; and opportunities for vehicle sharing and collaboration among the ten organizations in Lorain County from the private, government, non-profit, and educational sectors. With non-grant funds, organizations have begun or completed projects that drew on the findings of the studies, including: creation of a residential energy-efficiency program for the Oberlin community; installation of energy-efficient lighting in Oberlin College facilities; and development by the City of Oberlin and Oberlin College of a 2.27 megawatt solar photovoltaic facility that is expected to produce 3,000 megawatt-hours of renewable energy annually, 12% of the College’s yearly power needs. Implementation of these and other projects is evidence of the economic feasibility and technical effectiveness of grant-supported studies, and additional projects are expected to advance to implementation in the coming years. The public has benefited through improved energy-delivery systems and reduced energy use for street lighting in Elmore, Oak Harbor, and Wellington; new opportunities for assistance and incentives for residential energy efficiency in the Oberlin community; new opportunities for financial and energy savings through vehicle collaboration within Lorain County; and decreased reliance on fossil fuels and expanded production of renewable energy in the region. The dissemination conference and the summary report developed for the conference also benefited the public, but making the findings and recommendations of the regional studies broadly available to elected officials, city managers, educators, representatives of the private sector, and the general public.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2013

Multitasking mesoporous nanomaterials for biorefinery applications

Mesoporous silica nanoparticles (MSNs) have attracted great interest for last two decades due to their unique and advantageous structural properties, such as high surface area, pore volume, stable mesostructure, tunable pore size and controllable particle morphology. The robust silica framework provides sites for organic modifications, making MSNs ideal platforms for adsorbents and supported organocatalysts. In addition, the pores of MSNs provide cavities/ channels for incorporation of metal and metal oxide nanoparticle catalysts. These supported metal nanoparticle catalysts benefit from confined local environments to enhance their activity and selectivity for various reactions. Biomass is considered as a sustainable feedstock with potential to replace diminishing fossil fuels for the production of biofuels. Among several strategies, one of the promising methods of biofuel production from biomass is to reduce the oxygen content of the feedstock in order to improve the energy density. This can be achieved by creating C-C bonds between biomass derived intermediates to increase the molecular weight of the final hydrocarbon molecules. In this context, pore size and organic functionality of MSNs are varied to obtain the ideal catalyst for a C-C bond forming reaction: the aldol condensation. The mechanistic aspects of this reaction in supported heterogeneous catalysts are explored. The modification of supported organocatalyst and the effect of solvent on the reaction are rationalized. The significance of two functional surfaces of MSNs is exploited by enzyme immobilization on the external surface and organo catalyst functionalization on the internal surface. Using this bifunctional catalyst, the tandem conversion of small chain alcohols into longer chain hydrocarbon molecules is demonstrated. The ability to incorporate metal and metal oxide nanoparticles in the pores and subsequent functionalization led to develop organic modified magnetic MSNs (OM-MSNs) for applications in microalgae biorefinery. Two different integrated biorefinery systems are highlighted. (i) OM-MSNs are used to harvest microalgae and selectively sequester free fatty acids (FFAs). (ii) OM-MSNs are shown to selectively sequester FFAs and convert them into diesel-range liquid hydrocarbon fuels. A similar MSN supported metal nanoparticle catalyst is demonstrated to transform FFAs into green diesel with even greater activity and selectivity. The incorporation of a different organic functional group into MSN provides a selective adsorbent for separation and purification of α-tocopherol from microalgae oil. The functional group with electron deficient aromatic rings demonstrated high sequestration capacity and selectivity of {alpha}-tocopherol.

09 BIOMASS FUELS↗

DOE OSTI2013

Transitioning to High Performance Homes: Successes and Lessons Learned From Seven Builders

As homebuyers are becoming increasingly concerned about rising energy costs and the impact of fossil fuels as a major source of greenhouse gases, the returning new home market is beginning to demand energy-efficient and comfortable high-performance homes. In response to this, some innovative builders are gaining market share because they are able to market their homes’ comfort, better indoor air quality, and aesthetics, in addition to energy efficiency. The success and marketability of these high-performance homes is creating a builder demand for house plans and information about how to design, build, and sell their own low-energy homes.

Building America↗

DOE OSTI2012

Development of a National Center for Hydrogen Technology. A Summary Report of Activities Completed at the National Center for Hydrogen Technology - Year 6

The Energy & Environmental Research Center (EERC) located in Grand Forks, North Dakota, has operated the National Center for Hydrogen Technology (NCHT) since 2005 under a Cooperative Agreement with the U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL). The EERC has a long history of hydrogen generation and utilization from fossil fuels, and under the NCHT Program, the EERC has accelerated its research on hydrogen generation and utilization topics. Since the NCHT's inception, the EERC has received more than $65 million in funding for hydrogen-related projects ($24 million for projects in the NCHT, which includes federal and corporate partner development funds) involving more than 85 partners (27 with the NCHT). The NCHT Program's nine activities span a broad range of technologies that align well with the Advanced Fuels Program goals and, specifically, those described in the Hydrogen from Coal Program research, development, and demonstration (RD&D) plan that refers to realistic testing of technologies at adequate scale, process intensification, and contaminant control. A number of projects have been completed that range from technical feasibility of several hydrogen generation and utilization technologies to public and technical education and outreach tools. Projects under the NCHT have produced hydrogen from natural gas, coal, liquid hydrocarbons, and biomass. The hydrogen or syngas generated by these processes has also been purified in many of these instances or burned directly for power generation. Also, several activities are still undergoing research, development, demonstration, and commercialization at the NCHT. This report provides a summary overview of the projects completed in Year 6 of the NCHT. Individual activity reports are referenced as a source of detailed information on each activity.

08 HYDROGEN↗

DOE OSTI2013

Wind Turbine Modeling for Computational Fluid Dynamics

With the shortage of fossil fuel and the increasing environmental awareness, wind energy is becoming more and more important. As the market for wind energy grows, wind turbines and wind farms are becoming larger. Current utility-scale turbines extend a significant distance into the atmospheric boundary layer. Therefore, the interaction between the atmospheric boundary layer and the turbines and their wakes needs to be better understood. The turbulent wakes of upstream turbines affect the flow field of the turbines behind them, decreasing power production and increasing mechanical loading. With a better understanding of this type of flow, wind farm developers could plan better-performing, less maintenance-intensive wind farms. Simulating this flow using computational fluid dynamics is one important way to gain a better understanding of wind farm flows. In this study, we compare the performance of actuator disc and actuator line models in producing wind turbine wakes and the wake-turbine interaction between multiple turbines. We also examine parameters that affect the performance of these models, such as grid resolution, the use of a tip-loss correction, and the way in which the turbine force is projected onto the flow field.

17 WIND ENERGY↗

DOE OSTI2013

Solar Thermal Conversion of Biomass to Synthesis Gas (CRADA Final Report)

The CRADA is established to facilitate the development of solar thermal technology to efficiently and economically convert biomass into useful products (synthesis gas and derivatives) that can replace fossil fuels. NREL's High Flux Solar Furnace will be utilized to validate system modeling, evaluate candidate reactor materials, conduct on-sun testing of the process, and assist in the development of solar process control system. This work is part of a DOE-USDA 3-year, $1M grant.

09 BIOMASS FUELS↗

DOE OSTI2013

Boston Architectural College Urban Sustainability Initiative

The Boston Architectural College's Urban Sustainability initiative is a demonstration project as defined by the National Energy Technology Laboratory. BAC's proposed project with the U.S. Department of Energy - NETL, is a large part of that overall initiative. The BAC's Urban Sustainability Initiative is a multi-part project with several important goals and objectives that will have a significant impact on the surrounding neighborhood including: energy conservation, reduction of storm water runoff, generation of power through alternative energy sources, elimination/reduction of BAC carbon footprint, and to create a vehicle for ongoing public outreach and education. Education and outreach opportunities will serve to add to the already comprehensive Sustainability Design courses offered at BAC relative to energy savings, performance and conservation in building design. At the finish of these essential capital projects there will be technical materials created for the education of the design, sustainability, engineering, community development and historic preservation communities, to inform a new generation of environmentally-minded designers and practitioners, the city of Boston and the general public. The purpose of the initiative, through our green renovations program, is to develop our green alley projects and energy saving renovations to the BAC physical plant, to serve as a working model for energy efficient design in enclosed 19th century and 20th century urban sites and as an educational laboratory for teaching ecological and sustainable technologies to students and the public while creating jobs. The scope of our project as it relates to the BAC and the U.S. Department of Energy- NETL combined efforts includes: Task I of the project is Phase II (Green Alley). Task I encompasses various renovation activities that will demonstrate the effectiveness of permeable paving and ground water recharge systems. It will aid in the reduction of storm water runoff into the Charles River Basin in one of its most significantly polluted sections and, will provide a green renovation mechanism for the redirected storm water of a public alley way. This activity is designed to improve the quality of water recharging the ground water and protecting the vulnerable wood pilings under many of the historic masonry buildings in Boston's Back Bay. Sustainable design research and system monitoring opportunities will also be incorporated, providing ongoing tools for public outreach and education through innovative signage and "virtual tour" technology. The monitoring will include a "building performance dash board" that reflects real time operating conditions and improvements in environmental and economic performance to be prominently displayed on the face of our 320 Newbury Street building (approximately 1.5 million people walk by annually). The project site and demonstration area is located at the rear of 951 Boylston Street, Boston, MA 02115 and the parking area adjacent to Public Alley #444 in Boston's historic Back Bay. Task II of the project is Geothermal Solution. This task involves the installation of approximately seven Geothermal wells which will tap into the earth's constant underground temperatures to provide air-conditioning and heating for BAC facilities. The environmentally friendly geothermal system uses no fossil fuel, produces no emissions and runs silently, providing a sustainable model for commercial and residential buildings throughout Boston. Ultimately the combination of this project and other projects will assist in making the BAC "carbon-neutral", and could generate enough additional energy to provide free power to the Engine 33 and Ladder 15 Firehouse located at 941 Boylston Street. The project is located at the rear of 951 Boylston Street, Boston, MA 02115 and the parking area adjacent to Public Alley #444 in Boston's historic Back Bay. Task III of the project is the Sustainability Design Curriculum at the BAC. The BAC is the nation’s largest independent, multi-disciplinary college of spatial design, and a leader in sustainable design education. The Sustainabiltiy Design program, in particular, focuses on energy efficiency,energy performance, energy modeling, energy and air quality principles, green building, renewable energy alternatives and much more. Additionally, the Urban Sustainability Initiative has an objective of providing courses relative to the BAC's demonstration project with DOE, the project’s period of performance activities, subsequent performance data and anticipated sustainability teaching tools. In keeping with BAC's practice based curriculum, students have been involved in the discussion and planning of this project since its inception and sustainability issues have become a part of other programs throughout the college as well. Students will continue to benefit from this hands-on learning opportunity. The project is located at 320 Newbury Street Boston, MA 02115. Task IV of the project is Program Management and Reporting. This task will involve BAC's oversight and general management of the entire project including subcontract administration, contracts administration, technical and financial reporting, design and renovation assistance, other deliverables in accordance with the Federal Assistance reporting Checklist and other contractual obligations and provisions.

15 GEOTHERMAL ENERGY↗

DOE OSTI2013

Electric Vehicle Preparedness Task 2: Identification of Joint Base Lewis McChord Vehicles for Installation of Data Loggers

The U.S. Department of Energy and the U.S. Department of Defense signed a memorandum of understanding on July 22, 2010, for the purpose of strengthening the coordination of efforts to enhance national energy security and to demonstrate federal government leadership in transitioning America to a low-carbon economy. The memorandum of understanding included efforts in the areas of energy efficiency, fossil fuels, alternative fuels, efficient transportation technologies and fueling infrastructure, grid security, smart grid, and storage. In support of the memorandum of understanding, the Idaho National Laboratory, with funding provided by the U.S. Department of Energy’s Vehicle Technologies Office and Federal Energy Management Program, directed ECOtality North America to conduct several U.S. Department of Defense base studies to identify potential U.S. Department of Defense transportation systems that are strong candidates for introduction or expansion of electric drive vehicles.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2013

Electric Vehicle Preparedness Task 1: Assessment of Data and Survey Results for Joint Base Lewis McChord

The U.S. Department of Energy and the U.S. Department of Defense signed a memorandum of understanding on July 22, 2010, for the purpose of strengthening the coordination of efforts to enhance national energy security and to demonstrate federal government leadership in transitioning America to a low-carbon economy. The memorandum of understanding included efforts in the areas of energy efficiency, fossil fuels, alternative fuels, efficient transportation technologies and fueling infrastructure, grid security, smart grid, and storage. In support of the memorandum of understanding, the Idaho National Laboratory, with funding provided by U.S. Department of Energy’s Vehicle Technologies Office and Federal Energy Management Program, directed ECOtality North America to conduct several U.S. Department of Defense base studies to identify potential U.S. Department of Defense transportation systems that are strong candidates for the introduction or expansion of electric drive vehicles.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2013

Electric Vehicle Preparedness Task 1: Assessment of Data and Survey Results for NAS Jacksonville and NS Mayport

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2013

Assessment of Energy Production Potential from Ocean Currents along the United States Coastline

Increasing energy consumption and depleting reserves of fossil fuels have resulted in growing interest in alternative renewable energy from the ocean. Ocean currents are an alternative source of clean energy due to their inherent reliability, persistence and sustainability. General ocean circulations exist in the form of large rotating ocean gyres, and feature extremely rapid current flow in the western boundaries due to the Coriolis Effect. The Gulf Stream system is formed by the western boundary current of the North Atlantic Ocean that flows along the east coastline of the United States, and therefore is of particular interest as a potential energy resource for the United States.

16 TIDAL AND WAVE POWER↗

DOE OSTI2013

Kalman-filtered compressive sensing for high resolution estimation of anthropogenic greenhouse gas emissions from sparse measurements.

The estimation of fossil-fuel CO2 emissions (ffCO2) from limited ground-based and satellite measurements of CO2 concentrations will form a key component of the monitoring of treaties aimed at the abatement of greenhouse gas emissions. The limited nature of the measured data leads to a severely-underdetermined estimation problem. If the estimation is performed at fine spatial resolutions, it can also be computationally expensive. In order to enable such estimations, advances are needed in the spatial representation of ffCO2 emissions, scalable inversion algorithms and the identification of observables to measure. To that end, we investigate parsimonious spatial parameterizations of ffCO2 emissions which can be used in atmospheric inversions. We devise and test three random field models, based on wavelets, Gaussian kernels and covariance structures derived from easily-observed proxies of human activity. In doing so, we constructed a novel inversion algorithm, based on compressive sensing and sparse reconstruction, to perform the estimation. We also address scalable ensemble Kalman filters as an inversion mechanism and quantify the impact of Gaussian assumptions inherent in them. We find that the assumption does not impact the estimates of mean ffCO2 source strengths appreciably, but a comparison with Markov chain Monte Carlo estimates show significant differences in the variance of the source strengths. Finally, we study if the very different spatial natures of biogenic and ffCO2 emissions can be used to estimate them, in a disaggregated fashion, solely from CO2 concentration measurements, without extra information from products of incomplete combustion e.g., CO. We find that this is possible during the winter months, though the errors can be as large as 50%.

Ray, Jaideep↗