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Long-term sustainability of fracture conductivity is critical for commercial success of engineered geothermal system (EGS) and hydrogeothermal field sites. The injection of proppants has been suggested as a means to enhance the conductivity in these systems. Several studies have examined the chemical behavior of proppants that are not at chemical equilibrium with the reservoir rock and water. These studies have suggested that in geothermal systems, geochemical reactions can lead to enhance proppant dissolution and deposition alteration minerals. We hypothesize that proppant dissolution will decrease the strength of the proppant and can potentially reduce the conductivity of the fracture. To examine the geomechanical strength of proppants, we have performed modified crushing tests of proppants and reservoir rock material that was subjected to geothermal reservoir temperature conditions. The batch reactor experiments heated crushed quartz monzonite rock material, proppants (either quartz sand, sintered bauxite or kryptospheres) with Raft River geothermal water to 250 ºC for a period of 2 months. Solid and liquid samples were shipped to University of Utah for chemical characterization with ICP-OES, ICP-MS, and SEM. A separate portion of the rock/proppant material was subjected to a modified American Petroleum Institute ISO 13503-2 proppant crushing test. This test is typically used to determine the maximum stress level that can be applied to a proppant pack without the occurrence of unacceptable proppant crushing. We will use the test results to examine potential changes in proppant/reservoir rock geomechanical properties as compared to samples that have not been subjected to geothermal conditions. These preliminary results will be used to screen the proppants for long term use in EGS and hot hydrogeothermal systems.
1 online resource (607 KB ): digital, PDF file.
This paper presents a comparative techno-economic analysis of five conversion pathways from biomass to gasoline-, jet-, and diesel-range hydrocarbons via indirect liquefaction with specific focus on pathways utilizing oxygenated intermediates (derived either via thermochemical or biochemical conversion steps). The four emerging pathways of interest are compared with one conventional pathway (Fischer-Tropsch) for the production of the hydrocarbon blendstocks. The processing steps of the four emerging pathways include: biomass-to-syngas via indirect gasification, gas cleanup, conversion of syngas to alcohols/oxygenates, followed by conversion of alcohols/oxygenates to hydrocarbon blendstocks via dehydration, oligomerization, and hydrogenation. We show that the emerging pathways via oxygenated intermediates have the potential to be cost competitive with the conventional Fischer-Tropsch process. The evaluated pathways and the benchmark process generally exhibit similar fuel yields and carbon conversion efficiencies. The resulting minimum fuel selling prices are comparable to the benchmark at approximately $3.60 per gallon-gasoline equivalent, with potential for two new pathways to be more economically competitive. Additionally, the coproduct values can play an important role in the economics of the processes with oxygenated intermediates derived via syngas fermentation. Major cost drivers for the integrated processes are tied to achievable fuel yields and conversion efficiency of the intermediate steps, i.e., the production of oxygenates/alcohols from syngas and the conversion of oxygenates/alcohols to hydrocarbon fuels.
1 online resource (1.2 MB ): digital, PDF file.
Climate change is a problem that must be solved. The primary cause of this problem is burning of fossil fuels to generate energy. A dramatic reduction in carbon emissions must happen soon, and a significant fraction of this reduction must come from the transportation sector. This paper reviews existing literature to assess the consensus of the scientific and engineering communities concerning the potential for the United States' light-duty transportation sector to meet a goal of 80 percent reduction in vehicle emissions and examine what it will take to meet this target. It is unlikely that reducing energy consumption in just vehicles with gasoline-based internal combustion drivetrains will be sufficient to meet GHG emission-reduction targets. This paper explores what additional benefits are possible through the adoption of alternative energy sources, looking at three possible on-vehicle energy carriers: carbon-based fuels, hydrogen, and batteries. potential for the United States' light-duty transportation sector to meet a goal of 80 percent reduction in vehicle emissions and examine what it will take to meet this target. It is unlikely that reducing energy consumption in just vehicles with gasoline-based internal combustion drivetrains will be sufficient to meet GHG emission-reduction targets. This paper explores what additional benefits are possible through the adoption of alternative energy sources, looking at three possible on-vehicle energy carriers: carbon-based fuels, hydrogen, and batteries.
1 online resource.
Since the 2009 American Recovery and Reinvestment Act the U.S. Department of Energy’s Geothermal Technologies Office has funded $33.7 million for multiple data digitization and aggregation projects focused on making vast amounts of geothermal relevant data available to industry for advancing geothermal exploration. These projects are collectively part of the National Geothermal Data System (NGDS), a distributed, networked system for maintaining, sharing, and accessing data in an effort to lower the levelized cost of electricity (LCOE). Determining “who owns” and “who maintains” the NGDS and its data nodes (repositories in the distributed system) is yet to be determined. However, the invest- ment in building and populating the NGDS has been substantial, both in terms of dollars and time; it is critical that this investment be protected by ensuring sustainability of the data, the software and systems, and the accessibility of the data. Only then, will the benefits be fully realized. To keep this operational system sustainable will require four core elements: continued serving of data and applications; maintenance of system operations; a governance structure; and an effective business model. Each of these presents a number of challenges. Data being added to the NGDS are not strictly geothermal but data considered relevant to geothermal exploration and develop- ment, including vast amounts of oil and gas and groundwater wells, among other data. These are relevant to a broader base of users. By diversifying the client base to other users and other fields, the cost of maintaining core infrastructure can be spread across an array of stakeholders and clients. It is presumed that NGDS will continue to provide free and open access to its data resources. The next-phase NGDS operation should be structured to eventually pursue revenue streams to help off-set sustainability expenses as necessary and appropriate, potentially including income from: grants and contracts (agencies, foundations, pri- vate sector), membership, fees for services (consulting, training, customization, ‘app’ development), repository services (data, services, apps, models, documents, multimedia), advertisements, fees for premier services or applications, subscriptions to value added services, licenses, contributions and donations, endow- ments, and sponsorships.
1 online resource.
The inherent variability in corn stover productivity due to variations in soils and crop management practices might contribute to a variation in corn stover-based bioethanol sustainability. This study was carried out to examine how changes in soil types and crop management options would affect corn stover yield (CSY) and the sustainability of the stover-based ethanol production in the Delta region of Mississippi. Based on potential acreage and geographical representation, three locations were selected. Using CERES-Maize model, stover yields were simulated for several scenarios of soils and crop management options. Based on 'net energy value (NEV)' computed from CSYs, a sustainability indicator for stover-based bioethanol production was established. The effects of soils and crop management options on CSY and NEV were determined using ANOVA tests and regression analyses. Both CSY and NEV were significantly different across sandy loam, silt loam, and silty clay loam soils and also across high-, mid-, and low-yielding cultivars. With an increase in irrigation level, both CSY and NEV increased initially and decreased after reaching a peak. A third-degree polynomial relationship was found between planting date and CSY and NEV each. By moving from the lowest to the highest production scenario, values of CSY and NEV could be increased by 86 to 553%, depending on location and weather condition. The effects of variations in soils and crop management options on NEV were the same as on CSY. The NEV was positive for all scenarios, indicating that corn stover-based ethanol production system in the Delta region is sustainable.
2.7 MB : digital, PDF file.
This presentation addresses the recognition that the sustainability of the bioeconomy requires strong interlinkages between existing and developing industries in agriculture (terrestrial and aquatic); forestry; waste and residue management in rural, industrial, and urban environments; the chemicals and biotechnology industry in terms of production of substitutes or better performing materials and chemicals; and in the fuels and power sectors. The transition to a low-carbon intensity economy requires the integration of systems and uses circular economy concepts to increase resource use efficiency and security for all biomass and other resources used as well. It requires innovation along the whole supply chains as well as research, development, and demonstration of the integrated systems with strong partnerships from the landscapes and watersheds where biomass is planted all the way to the many applications.
The U.S. Department of Energy (DOE) aims to displace 30% of the 2004 gasoline use (60 billion gal/yr) with biofuels by 2030 as outlined in the Energy Independence and Security Act of 2007, which will require 700 million tons of biomass to be sustainably delivered to biorefineries annually. Lignocellulosic biomass will make an important contribution towards meeting DOE’s ethanol production goals. For the biofuels industry to be an economically viable enterprise, the feedstock supply system (i.e., moving the biomass from the field to the refinery) cannot contribute more that 30% of the total cost of the biofuel production. The Idaho National Laboratory in collaboration with Oak Ridge National Laboratory, University of California, Davis and Kansas State University are developing a set of tools for identifying economical, sustainable feedstocks on a regional basis based on biorefinery siting.
1 online resource (p. 300-301 ): digital, PDF file.
The presentation provides an overview of the Biodiesel Cellulosic Ethanol Research Project (Hendry County Sustainable Biofuels Center). It summarizes the project history, timeline, budget, partners, objectives, goals, future plans and in closer detail reviews the used approaches and technical accomplishments. The main project goals were (1) developing strategies and tools that assist in the creation of economically and environmentally sustainable bioenergy industries within ecologically-sensitive regions such as South Florida and, in particular, the greater Everglades, (2) using these bioenergy strategies and tools in evolving the existing agricultural, urban, and ecological sectors towards more sustainable structures and practices and (3) using bioenergy as a focal point in the larger effort to mitigate climate change and sea level rise, realities with particularly catastrophic consequences for South Florida. The project started on Oct 1, 2010 and ended on Feb 28, 2013. It yearly average budget was $369,770, with the Dept. of Energy annual cost share of $317,167. The main project partners were Hendry County, University of Florida - Institute of Food and Agricultural Sciences, Intelligentsia International, Inc., Edison State College and University of South Florida. Used approaches, main accomplishments and results in the categories of (1) technical research, (2) education and (3) business development are presented in detail. The project uniqueness is mainly related to the use of system approaches and integrating several systems analyses. Relevance of the project applicable to sustainability of bioenergy, food production, & restoration is explained, critical success factors are challenges are outlined and future work drafted. Finally, the main publications and presentations catalogue list is presented.
What does Sustainability mean, and why should people in the thermophysical properties business care? This paper will describe sustainability in the context of product development, which is where much of the buzz is currently being generated. Once described, it will discuss how expectations for Sustainability are changing product lines, and then discuss the controversial issues now emerging from trying to measure Sustainability. One of the most organized efforts in the U.S. is the U.S. Green Building Council revolutionizing how the built environment is conceptualized, designed, built, used, and disposed of - and born again. The appeal of the US Green Building Council is that it has managed to checklist how to "do" Sustainability. By following this checklist, better described as a rating system, a more Sustainable product should be achieved. That is, a product that uses less energy, less water, is less noxious to the user, and consumes fewer resources. We care because these Sustainable products are viewed as preferable by a growing number of consumers and, consequently, are more valuable. One of the most interesting aspects of the Sustainability movement is a quantitative assessment of how sustainable a product is. Life Cycle Assessment techniques (not to be confused with life cycle economic costs) developed since the early 1990s are gaining ground as a less biased method to measure the ultimate "bad" consequences of creating a product (depletion of natural resources, nutrification, acid rain, air borne particulates, solid waste, etc.). For example, one assertion is that these studies have shown that recycling can sometimes do more environmental harm than good.
The DOE Biomass Program recently implemented the Biofuels Initiative, or 30x30 program, with the dual goal of reducing U.S. dependence on foreign oil by making cellulosic ethanol cost competitive with gasoline by 2012 and by replacing 30 percent of gasoline consumption with biofuels by 2030. Experience to date with increasing ethanol production suggests that it distorts agricultural markets and therefore raises concerns about the sustainability of the DOE 30 X 30 effort: Can the U.S. agricultural system produce sufficient feedstocks for biofuel production and meet the food price and availability expectations of American consumers without causing environmental degradation that would curtail the production of both food and fuel? Efforts are underway to develop computer-based modeling tools that address this concern and support the DOE 30 X 30 goals. Beyond technical agronomic and economic concerns, however, such models must account for the publics’ growing interest in sustainable agriculture and in the mitigation of predicted global climate change. This paper discusses ongoing work at the Center for Advanced Energy Studies that investigates the potential consequences and long-term sustainability of projected biomass harvests by identifying and incorporating “sustainable harvest indicators” in a computer modeling strategy.
1 online resource (5 p.) : digital, PDF file.
If society is to meet its objective of sustainable growth, then issues relating to energy conservation and environmental stewardship need to be in the forefront of engineering concerns. It has been proposed that both energy efficiency and the environment can be improved by switching to hydrogen as the primary source of energy in our economy. While production of hydrogen introduces some environmental issues, the overall impact on air pollution should be positive because of the lack of emissions at point-of-use during combustion of the fuel; the only by-product is water. By comparison, elaborate pollution control strategies, both in engine design and operation and in exhaust clean-up via catalytic removal of unburned hydrocarbons, carbon monoxide and oxides of nitrogen, and particulate matter in the case of diesel, are needed to enable us to use liquid fuels for transportation. One of the promising ways to utilize hydrogen is to release its chemical energy in a fuel cell.
Emerging cellulosic bioenergy markets can provide land managers with additional options for crop production decisions. Integrating dedicated bioenergy crops such as perennial grasses and short rotation woody species within the agricultural landscape can have positive impacts on several environmental processes including increased soil organic matter in degraded soils, reduced sediment loading in watersheds, lower green house gas (GHG) fluxes, and reduced nutrient loading in watersheds. Implementing this type of diverse bioenergy production system in a way that maximizes potential environmental benefits requires a dynamic integrated modeling and data management strategy. This paper presents a strategy for designing diverse bioenergy cropping systems within the existing row crop production landscape in the midwestern United States. The integrated model developed quantifies a wide range environmental processes including soil erosion from wind and water, soil organic matter changes, and soil GHG fluxes within a geospatial data management framework. This framework assembles and formats information from multiple spatial and temporal scales. The data assembled includes yield and productivity data from harvesting equipment at the 1m scale, surface topography data from LiDAR mapping at the less than 1m scale, soil data from US soil survey databases at the 10m to 100m scale, and climate data at the county scale. These models and data tools are assembled into an integrated computational environment that is used to determine sustainable removal rates for agricultural residues for bioenergy production at the sub-field scale under a wide range of land management practices. Using this integrated model, innovative management practices including cover cropping are then introduced and evaluated for their impact on bioenergy production and important environmental processes. The impacts of introducing dedicated energy crops onto high-risk landscape positions currently being manage in row crop production are also investigated.
Hendry County Sustainable Bio-Fuels Center (HCSBC) is introduced and its main components are explained. These primarily include (1) farming systems, (2) sustainability analysis, (3) economic analysis and (4) educational components. Each of these components is discussed in further details, main researchers and their responsibility areas and introduced. The main focus of this presentation is a new farming concept. The proposed new farming concept is an alternative to the current "two sides of the ditch" model, in which on one side are yield-maximizing, input-intensive, commodity price-dependent farms, while on the other side are publicly-financed, nutrient-removing treatment areas and water reservoirs trying to mitigate the externalized costs of food production systems and other human-induced problems. The proposed approach is rental of the land back to agriculture corporations during the restoration transition period in order to increase water storage (allowing for greater water flow-through and/or water storage on farms), preventing issues such as nutrients removal, using flood-tolerant crops and reducing soil subsidence. Various pros and cons of the proposed agricultural eco-services are discussed - the advantages include flexibility for participating farmers to achieve environmental outcomes with reduced costs and using innovative incentives; the minuses include the fact that the potential markets are not developed yet or that existing regulations may prevent agricultural producers from selling their services.
1 online resource (9 pp. ) : digital, PDF file.
The subject of sustainable energy development has been widely discussed and debated in recent years. However, despite widespread interest, progress toward this goal has been limited. This paper will build on current thinking related to sustainable development, energy forecasting, and complexity theory and show how past roadmapping methodologies fall short. While proposing ways of thinking about our responses to global changes, we consider how we can create and discover the pathways through those unpredictable changes toward high global renewables penetration.
1 online resource (10.72 MB) : digital, PDF file.
This presentation discusses NREL's Energy System Integrations Facility and NREL's holistic design approach to sustainable data centers that led to the world's most energy-efficient data center. It describes Peregrine, a warm water liquid cooled supercomputer, waste heat reuse in the data center, demonstrated PUE and ERE, and lessons learned during four years of operation.
Agriculture can simultaneously address global food, feed, fiber, and energy challenges provided our soil, water, and air resources are not compromised in doing so. As we embark on the 19th Triennial Conference of the International Soil and Tillage Research Organization (ISTRO), I am pleased to proclaim that our members are well poised to lead these endeavors because of our comprehensive understanding of soil, water, agricultural and bio-systems engineering processes. The concept of landscape management, as an approach for integrating multiple bioenergy feedstock sources, including biomass residuals, into current crop production systems, is used as the focal point to show how these ever-increasing global challenges can be met in a sustainable manner. Starting with the 2005 Billion Ton Study (BTS) goals, research and technology transfer activities leading to the 2011 U.S. Department of Energy (DOE) Revised Billion Ton Study (BT2) and development of a residue management tool to guide sustainable crop residue harvest will be reviewed. Multi-location USDA-Agricultural Research Service (ARS) Renewable Energy Assessment Project (REAP) team research and on-going partnerships between public and private sector groups will be shared to show the development of landscape management strategies that can simultaneously address the multiple factors that must be balanced to meet the global challenges. Effective landscape management strategies recognize the importance of nature’s diversity and strive to emulate those conditions to sustain multiple critical ecosystem services. To illustrate those services, the soil quality impact of harvesting crop residues are presented to show how careful, comprehensive monitoring of soil, water and air resources must be an integral part of sustainable bioenergy feedstock production systems. Preliminary analyses suggest that to sustain soil resources within the U.S. Corn Belt, corn (Zea mays L.) stover should not be harvested if average grain yields are less than 11 Mg ha-1 (175 bu ac-1) unless more intensive landscape management practices are implemented. Furthermore, although non-irrigated corn grain yields east and west of the primary Corn Belt may not consistently achieve the 11 Mg ha-1 yield levels, corn can still be part of an overall landscape approach for sustainable feedstock production. Another option for producers with consistently high yields (> 12.6 Mg ha-1 or 200 bu ac-1) that may enable them to sustainably harvest even more stover is to decrease their tillage intensity which will reduce fuel use, preserve rhizosphere carbon, and/or help maintain soil structure and soil quality benefits often attributed to no-till production systems. In conclusion, I challenge all ISTRO scientists to critically ask if your research is contributing to improved soil and crop management strategies that effectively address the complexity associated with sustainable food, feed, fiber and fuel production throughout the world.
1 online resource (21 p.) : digital, PDF file.
The public purchase of farmlands in the EAA provides an opportunity for transforming farming systems into truly sustainable systems and these can support the Everglades restoration efforts. The concept proposed in this presentation is that by reducing the yield intensity of farms and adding ecosystem services, public farm lands can serve both restoration and the economy more effectively and more efficiently. This working hypothesis will be evaluated by applying systems analysis approaches including life cycle analysis and embodied energy analysis. The rationale for pursuing new approaches ranges from the fact that climate change threats are global, not local, to the fact that eliminating Florida farms and moving production elsewhere yields no net ecological benefit. Historic water flow from Lake Okeechobee to Everglades is shown and the current concept of moving water explained. Southern Flow Way Plan 6 is explained and sustainable farming system in this newly acquired land presented. To determine if an EAA pulse-way strategy would work and meet the sustainability criteria requires integrated analysis of several systems - water budget, soil & water nutrient dynamics, prospects for new sugarcane varieties, soil subsidence and overall energy and carbon budget.
Threats to ecosystems are not local; they have to be handled with the global view in mind. Eliminating Florida farms, in order to meet its environmental goals, would simply move the needed agricultural production overseas, where environmentally less sensitive approaches are often used, thus yielding no net ecological benefit. South Florida is uniquely positioned to lead in the creation of sustainable agricultural systems, given its population, technology, and environmental restoration imperative. Florida should therefore aggressively focus on developing sustainable systems that deliver both agricultural production and environmental services. This presentation introduces a new farming concept of dealing with Florida’s agricultural land issues. The state purchases large land areas in order to manage the land easily and with ecosystem services in mind. The proposed new farming concept is an alternative to the current “two sides of the ditch” model, in which on one side are yield-maximizing, input-intensive, commodity price-dependent farms, while on the other side are publicly-financed, nutrient-removing treatment areas and water reservoirs trying to mitigate the externalized costs of food production systems and other human-induced problems. The proposed approach is rental of the land back to agriculture during the restoration transition period in order to increase water storage (allowing for greater water flow-through and/or water storage on farms), preventing issues such as nutrients removal, using flood-tolerant crops and reducing soil subsidence. Since the proposed approach is still being developed, there exist various unknown variables and considerations. However, working towards a long-term sustainable scenario needs to be the way ahead, as the threats are global and balancing the environment and agriculture is a serious global challenge.
1 online resource (25 pp. ) : digital, PDF file.
Countries can use low-emission development strategies (LEDS) to advance sustainable development, promote private-sector growth, and reduce greenhouse gas emissions. This paper proposes a framework -- or support infrastructure -- to enable the efficient exchange of LEDS-related knowledge and technical assistance. Under the proposed framework, countries share LEDS-related resources via coordinating forums, 'knowledge platforms, ' and networks of experts and investors. The virtual 'knowledge platforms' foster learning by allowing countries to communicate with each other and share technical reports, data, and analysis tools in support of LEDS development. Investing in all elements of the framework in an integrated fashion increases the efficacy of support for country-driven LEDS.


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