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Sagebrush (Artemisia spp.)-dominated habitats in the western United States have experienced extensive, rapid changes due to development of natural-gas fields, resulting in localized declines of greater sage-grouse (Centrocercus urophasianus) populations. It is unclear whether population declines in natural-gas fields are caused by avoidance or demographic impacts, or the age classes that are most affected. Land and wildlife management agencies need information on how energy developments affect sage-grouse populations to ensure informed land-use decisions are made, effective mitigation measures are identified, and appropriate monitoring programs are implemented (Sawyer et al. 2006). We used information from radio-equipped...
Biomassfu els currently (1994) supplya round1 4% of the world’se nergy,b ut most of this is in the form of traditional fuelwood, residuesa ndd ung, which is often inefficienta nd can be environmentallyd etrimental.B iomassc an supplyh eat and electricity, liquid and gaseousfu els. A numbero f developedc ountriesd erive a significanta mounto f their primary energy from biomassU: SA 4%, Finland 18%, Sweden1 6%a ndA ustria 13%.P resentlyb iomasse nergy suppliesa t least2 EJ year-’ in WesternE uropew hich is about4 % of primarye nergy (54 ET). Estimates howa likely potentiali n Europei n 2050o f 9.0-13.5 El dependingo n land areas(1 0%o f useablela nd, 33 Mha), yields (lo-15 oven-dry tonnes( ODt) ha-‘), and recoverabler...
In this paper, we present an economic analysis of CO2-enhanced oil recovery (EOR). This technique entails injection of CO2 into mature oil fields in a manner that reduces the oil's viscosity, thereby enhancing the rate of extraction. As part of this process, significant quantities of CO2 remain sequestered in the reservoir. If CO2 emissions are regulated, oil producers using EOR should therefore be able to earn revenues from sequestration as well as from oil production. We develop a theoretical framework that analyzes the dynamic co-optimization of oil extraction and CO2 sequestration, through the producer's choice of the fraction of CO2 in the injection stream at each moment. We find that the optimal fraction of...
Reactions between CO2-charged brines and reservoir minerals might either enhance the long-term storage of CO2 in geological reservoirs or facilitate leakage by corroding cap rocks and fault seals. Modelling the progress of such reactions is frustrated by uncertainties in the absolute mineral surface reaction rates and the significance of other rate limiting steps in natural systems. Here we use the chemical evolution of groundwater from the Jurassic Navajo Sandstone, part of a leaking natural accumulation of CO2 at Green River, Utah, in the Colorado Plateau, USA, to place constraints on the rates and potential controlling mechanisms of the mineral–fluid reactions, under elevated CO2 pressures, in a natural system....
Increases in net primary production (NPP) may not necessarily result in increased C sequestration since an increase in uptake can be negated by concurrent increases in ecosystem C losses via respiratory processes. Continuous measurements of net ecosystem C exchange between the atmosphere and two experimental cheatgrass (Bromus tectorum L.) ecosystems in large dynamic flux chambers (EcoCELLs) showed net ecosystem C losses to the atmosphere in excess of 300 g C m?2 over two growing cycles. Even a doubling of net ecosystem production (NEP) after N fertilization in the second growing season did not compensate for soil C losses incurred during the fallow period. Fertilization not only increased C uptake in biomass but...
Some forms of renewable energy have long contributed to electricity generation, whereas others are just emerging. For example, large-scale hydropower is a mature technology generating about 16% of global electricity, and many smaller scale systems are also being installed worldwide. Future opportunities to improve the technology are limited but include upgrading of existing plants to gain greater performance efficiencies and reduced maintenance. Geothermal energy, widely used for power generation and direct heat applications, is also mature, but new technologies could improve plant designs, extend their lifetimes, and improve reliability. By contrast, ocean energy is an emerging renewable energy technology. Design,...
Some forms of renewable energy have long contributed to electricity generation, whereas others are just emerging. For example, large-scale hydropower is a mature technology generating about 16% of global electricity, and many smaller scale systems are also being installed worldwide. Future opportunities to improve the technology are limited but include upgrading of existing plants to gain greater performance efficiencies and reduced maintenance. Geothermal energy, widely used for power generation and direct heat applications, is also mature, but new technologies could improve plant designs, extend their lifetimes, and improve reliability. By contrast, ocean energy is an emerging renewable energy technology. Design,...
For carbon sequestration the issues of monitoring, risk assessment, and verification of carbon content and storage efficacy are perhaps the most uncertain. Yet these issues are also the most critical challenges facing the broader context of carbon sequestration as a means for addressing climate change. In response to these challenges, Carbon Sequestration and Its Role in the Global Carbon Cycle presents current perspectives and research that combine five major areas:• The global carbon cycle and verification and assessment of global carbon sources and sinks • Potential capacity and temporal/spatial scales of terrestrial, oceanic, and geologic carbon storage • Assessing risks and benefits associated with terrestrial,...
Carbon sequestration has been well recognized as a viable option to slow the rise in atmospheric greenhouse gas concentration. The main goals of this study were to assess the carbon sequestration potential (CSP) by afforestation of marginal agricultural land (MagLand) and to identify hotspots for potential afforestation activities in the U.S. Midwest region (Michigan (MI), Indiana (IN), Ohio, Kentucky (KY), West Virginia, Pennsylvania (PA) and Maryland (MD)). The 1992 USGS National Land Cover Dataset and the State Soil Geographic (STATSGO) database were used to determine MagLand. Two forest types (coniferous and deciduous) and two management practices (short-rotation versus permanent forest) were combined to form...
An irrigated study was conducted at the Western Colorado Research Center at Fruita for 6 years to evaluate eight hybrid poplar clones under short-term, intensive culture. The eight clones included in the study were Populus nigra x P. maximowiczii (NM6), P. trichocarpa x P. deltoides (52225, OP367), and P. deltoides x P. nigra (Norway, Noreaster, Raverdaus, 14274, 14272). Data were collected for growth, aerial biomass yield, dry matter partitioning, carbon sequestration, and insect and disease infestation. OP367 and 52225 consistently had larger tree diameters than other hybrids for each of the 6 years. Averaged across clones, yield was 58.4 Mg ha?1. OP367 had the highest yield at 72.2 Mg ha?1 and 14274 had the lowest...
This paper investigates injection of CO2 into non-dome-shaped geological structures that do not provide the traps traditionally deemed necessary for the development of artificial CO2 reservoirs. We have developed a conceptual and two numerical models of the geology and groundwater along a cross-section lying approximately NW?SE and in the vicinity of the Hunter power station on the Colorado Plateau, Central Utah and identified a number of potential sequestration sites on this cross-section. Preliminary modeling identified the White Rim Sandstone as appearing to offer the properties required of a successful sequestration site. Detailed modeling of injection of CO2 into the White Rim Sandstone using the reactive chemical...
When agricultural land is no longer used for cultivation and allowed to revert to natural vegetation or replanted to perennial vegetation, soil organic carbon can accumulate. This accumulation process essentially reverses some of the effects responsible for soil organic carbon losses from when the land was converted from perennial vegetation. We discuss the essential elements of what is known about soil organic matter dynamics that may result in enhanced soil carbon sequestration with changes in land-use and soil management. We review literature that reports changes in soil organic carbon after changes in land-use that favour carbon accumulation. This data summary provides a guide to approximate rates of SOC sequestration...
Policymakers and managers in the U.S. energy sector will face complex multidimensional challenges as they confront potential supply shortfalls, infrastructure constraints, and environmental limitations in the years ahead. Using a technique known as scenario analysis, this paper investigates key energy issues and decisions that could improve or reduce the ability of the United States to deal with the uncertainties that may challenge the U.S. economy during the next fifty years. Four scenarios have been developed representing a diverse range of future worlds to explore the driving forces and critical uncertainties that may shape U.S. energy markets and the economy for the next fifty years. Each scenario has been quantified...
Agricultural ecosystems provide many ecosystem services (ES) which are essential to human health and well-being. In turn, some ES affect agricultural productivity. Managing agricultural lands to provide more ES and higher quality ES may be essential for the long-term sustainability of agricultural ecosystems. Most agricultural lands, however, are managed for the short-term production of food, fiber, and fuel, often at the expense of other ES. Proposed solutions to the underprovision of ES often involve government regulation or market incentives. A growing number of scholars, however, recognize the potential for a third approach—cooperative solutions. One important element in determining if an ES is a suitable candidate...
Photosynthetic assimilation of atmospheric carbon dioxide by land plants offers the underpinnings for terrestrial carbon (C) sequestration. A proportion of the C captured in plant biomass is partitioned to roots, where it enters the pools of soil organic C and soil inorganic C and can be sequestered for millennia. Bioenergy crops serve the dual role of providing biofuel that offsets fossil-fuel greenhouse gas (GHG) emissions and sequestering C in the soil through extensive root systems. Carbon captured in plant biomass can also contribute to C sequestration through the deliberate addition of biochar to soil, wood burial, or the use of durable plant products. Increasing our understanding of plant, microbial, and...
Nonrenewable energy consumption and greenhouse gas (GHG) emissions associated with ethanol (a liquid fuel) derived from corn grain produced in selected counties in Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin are presented. Corn is cultivated under no-tillage practice (without plowing). The system boundaries include corn production, ethanol production, and the end use of ethanol as a fuel in a midsize passenger car. The environmental burdens in multi-output biorefinery processes (e.g., corn dry milling and wet milling) are allocated to the ethanol product and its various coproducts by the system expansion allocation approach. The nonrenewable energy requirement for producing 1 kg of ethanol...
Biochar production and mixing in soil are seen as the best options for atmospheric carbon sequestration, providing simultaneous benefits to soil and opportunities for distributed energy generation. The proximity of biomass source and biochar dispersal greatly reduces the energy and emissions footprint of the whole process. The viability of the whole biochar process is examined from two boundary points: is there enough biomass around to have significant impact on the atmospheric CO2 levels and is there enough soil area for biochar dispersal. The answers are soundly positive, both for the world as a whole and for Canada, for which a more detailed analysis was done. However, the massive adoption of biochar solution...
Recent trends of increasing woody vegetation in arid and semiarid ecosystems may contribute substantially to the North American C sink. There is considerable uncertainty, however, in the extent to which woody encroachment alters dryland soil organic carbon (SOC) and total nitrogen (TN) pools. To date, studies assessing SOC and TN response to woody plant proliferation have not explicitly assessed the variability caused by shrub age or size and subcanopy spatial gradients. These factors were quantified via spatially intensive soil sampling around Prosopis velutina shrubs in a semidesert grassland, using shrub size as a proxy for age. We found that bulk density increased with distance from the bole (P < 0.005) and...
In this paper, we present an economic analysis of CO2-enhanced oil recovery (EOR). This technique entails injection of CO2 into mature oil fields in a manner that reduces the oil's viscosity, thereby enhancing the rate of extraction. As part of this process, significant quantities of CO2 remain sequestered in the reservoir. If CO2 emissions are regulated, oil producers using EOR should therefore be able to earn revenues from sequestration as well as from oil production. We develop a theoretical framework that analyzes the dynamic co-optimization of oil extraction and CO2 sequestration, through the producer's choice of the fraction of CO2 in the injection stream at each moment. We find that the optimal fraction of...
map background search result map search result map Production of hybrid poplar under short-term, intensive culture in Western Colorado