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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Organically preserved microbial endoliths from the late Proterozoic of East Greenland

Diverse microorganisms ranging from cyanobacteria to eukaryotic algae and fungi live endolithically within ooids, hardgrounds and invertebrate shells on the present-day sea floor. These organisms are involved in the mechanical destruction of carbonates, and are useful ecological indicators of water depth and pollution. The Phanerozoic history of microbial endoliths has been elucidated through the study of microborings (the trace fossils of endolithic microorganisms) and rare cellularly preserved individuals, but nothing was known of the possible Precambrian evolution of comparable microorganisms until Campbell documented the occurrence of microborings in late Proterozoic ooids from central East Greenland. We now report the discovery of large populations of organically preserved endolithic microorganisms in silicified pisolites from 700-800-Myr-old Limestone-Dolomite Series of East Greenland. This fossil assemblage is significant for three reasons: (1) It confirms the prediction that oolites, pisolites and hardgrounds--the substrates for pre-Phanerozoic endoliths--provide a hitherto poorly explored but rewarding set of environments into which the search for early microfossils must be broadened; (2) the assemblage is diverse, containing about 12 taxa of morphologically distinct and previously unknown endolithic cyanobacteria, plus associated epilithic and interstitial populations; and (3) at least six of the fossil populations are indistinguishable in morphology, pattern of development, reproductive biology and inferred ecology from distinctive cyanobacterial species that bore ooids today in the Bahama Banks.

Non-NASA Center↗
NASA NTRS1995

Integrated approaches to terminal Proterozoic stratigraphy: an example from the Olenek Uplift, northeastern Siberia

In the Olenek Uplift of northeastern Siberia, the Khorbusuonka Group and overlying Kessyusa and Erkeket formations preserve a significant record of terminal Proterozoic and basal Cambrian Earth history. A composite section more than 350 m thick is reconstructed from numerous exposures along the Khorbusuonka River. The Khorbusuonka Group comprises three principal sedimentary sequences: peritidal dolomites of the Mastakh Formation, which are bounded above and below by red beds; the Khatyspyt and most of the overlying Turkut formations, which shallow upward from relatively deep-water carbonaceous micrites to cross-bedded dolomitic grainstones and stromatolites; and a thin upper Turkut sequence bounded by karst surfaces. The overlying Kessyusa Formation is bounded above and below by erosional surfaces and contains additional parasequence boundaries internally. Ediacaran metazoans, simple trace fossils, and vendotaenids occur in the Khatyspyt Formation; small shelly fossils, more complex trace fossils, and acritarchs all appear near the base of the Kessyusa Formation and diversify upward. The carbon-isotopic composition of carbonates varies stratigraphically in a pattern comparable to that determined for other terminal Proterozoic and basal Cambrian successions. In concert, litho-, bio-, and chemostratigraphic data indicate the importance of the Khorbusuonka Group in the global correlation of terminal Proterozoic sedimentary rocks. Stratigraphic data and a recently determined radiometric date on basal Kessyusa volcanic breccias further underscore the significance of the Olenek region in investigations of the Proterozoic-cambrian boundary.

Non-NASA Center↗
NASA NTRS1992

The oldest records of photosynthesis

There is diverse, yet controversial fossil evidence for the existence of photosynthesis 3500 million years ago. Among the most persuasive evidence is the stromatolites described from low grade metasedimentary rocks in Western Australia and South Africa. Based on the understanding of the paleobiology of stromatolites and using pertinent fossil and Recent analogs, these Early Archean stromatolites suggest that phototrophs evolved by 3500 million years ago. The evidence allows further interpretation that cyanobacteria were involved. Besides stromatolites, microbial and chemical fossils are also known from the same rock units. Some microfossils morphologically resemble cyanobacteria and thus complement the adduced cyanobacterial involvement in stromatolite construction. If cyanobacteria had evolved by 3500 million years ago, this would indicate that nearly all prokaryotic phyla had already evolved and that prokaryotes diversified rapidly on the early Earth.

Non-NASA Center↗
NASA NTRS1994

Limits to randomness in paleobiologic models: the case of Phanerozoic species diversity

The question of how random, or unconstrained, paleobiologic models should be is examined with a case study: Signor's (1982, 1985) inverse calculation of levels of marine species diversity through the Phanerozoic. His calculation involved an ingenious model that estimated species numbers and species abundances in the world oceans of the past by correcting known numbers of fossil species for variations in sedimentary rocks available for sampling and in effort paleontologists might devote to sampling. The model proves robust to changes in possible shapes of species-abundance distributions, but it is sensitive to alterations in the assumption that paleontologists collect fossils at random. If it is assumed that ease of collecting varies with age of sediment (with the Cenozoic offering easy sampling) or that paleontologists tend to seek out rarer fossils, results of the inverse calculation change. In particular, the magnitude of the calculated Cenozoic diversity increase always declines from the factor of about seven as originally reported to something considerably smaller. This leaves open the problem of the magnitude of Cenozoic increase in marine species diversity, awaiting better empirical data and, perhaps, more exacting models, random or otherwise.

Non-NASA Center↗
NASA NTRS1996

Paleobiology, community ecology, and scales of ecological pattern

The fossil record provides a wealth of data on the role of regional processes and historical events in shaping biological communities over a variety of time scales. The Quaternary record with its evidence of repeated climatic change shows that both terrestrial and marine species shifted independently rather than as cohesive assemblages over scales of thousands of years. Larger scale patterns also show a strong individualistic component to taxon dynamics; assemblage stability, when it occurs, is difficult to separate from shared responses to low rates of environmental change. Nevertheless, the fossil record does suggest that some biotic interactions influence large-scale ecological and evolutionary patterns, albeit in more diffuse and protracted fashions than those generally studied by community ecologists. These include: (1) the resistance by incumbents to the establishment of new or invading taxa, with episodes of explosive diversification often appearing contingent on the removal of incumbents at extinction events; (2) steady states of within-habitat and global diversity at longer time scales (10(7)-l0(8) yr), despite enormous turnover of taxa; and (3) morphological and biogeographic responses to increased intensities of predation and substratum disturbance over similarly long time scales. The behavior of species and communities over the array of temporal and spatial scales in the fossil record takes on additional significance for framing conservation strategies, and for understanding recovery of species, lineages, and communities from environmental changes.

NASA Discipline Exobiology↗
NASA NTRS2013

Three Decades of Global Methane Sources and Sinks

Methane is an important greenhouse gas, responsible for about 20 of the warming induced by long-lived greenhouse gases since pre-industrial times. By reacting with hydroxyl radicals, methane reduces the oxidizing capacity of the atmosphere and generates ozone in the troposphere. Although most sources and sinks of methane have been identified, their relative contributions to atmospheric methane levels are highly uncertain. As such, the factors responsible for the observed stabilization of atmospheric methane levels in the early 2000s, and the renewed rise after 2006, remain unclear. Here, we construct decadal budgets for methane sources and sinks between 1980 and 2010, using a combination of atmospheric measurements and results from chemical transport models, ecosystem models, climate chemistry models and inventories of anthropogenic emissions. The resultant budgets suggest that data-driven approaches and ecosystem models overestimate total natural emissions. We build three contrasting emission scenarios which differ in fossil fuel and microbial emissions to explain the decadal variability in atmospheric methane levels detected, here and in previous studies, since 1985. Although uncertainties in emission trends do not allow definitive conclusions to be drawn, we show that the observed stabilization of methane levels between 1999 and 2006 can potentially be explained by decreasing-to-stable fossil fuel emissions, combined with stable-to-increasing microbial emissions. We show that a rise in natural wetland emissions and fossil fuel emissions probably accounts for the renewed increase in global methane levels after 2006, although the relative contribution of these two sources remains uncertain.

periodic variations↗
NASA NTRS2022

Source Decomposition of Eddy-Covariance CO 2 Flux Measurements for Evaluating a High-Resolution Urban CO 2 Emissions Inventory

We present the comparison of source-partitioned CO2 flux measurements with a high-resolution urban CO 2 emissions inventory (Hestia). Tower-based measurements of CO and 14 C are used to partition net CO 2 flux measurements into fossil and biogenic components. A flux footprint model is used to quantify spatial variation in flux measurements. We compare the daily cycle and spatial structure of Hestia and eddy-covariance derived fossil fuel CO 2 emissions on a seasonal basis. Hestia inventory emissions exceed the eddy-covariance measured emissions by 0.36 µ mol m −2 s −1 (3.2%) in the cold season and 0.62 µ mol m −2 s −1 (9.1%) in the warm season. The daily cycle of fluxes in both products matches closely, with correlations in the hourly mean fluxes of 0.86 (cold season) and 0.93 (warm season). The spatially averaged fluxes also agree in each season and a persistent spatial pattern in the differences during both seasons that may suggest a bias related to residential heating emissions. In addition, in the cold season, the magnitudes of average daytime biological uptake and nighttime respiration at this flux site are approximately 15% and 27% of the mean fossil fuel CO 2 emissions over the same time period, contradicting common assumptions of no significant biological CO 2 exchange in northern cities during winter. This work demonstrates the effectiveness of using trace gas ratios to adapt eddy-covariance flux measurements in urban environments for disaggregating anthropogenic CO 2 emissions and urban ecosystem fluxes at high spatial and temporal resolution.

eddy-covariance flux measurements↗
DOE OSTI2012

A Streamlined Strategy for Biohydrogen Production with an Alkaliphilic Bacterium

Biofuels are anticipated to enable a shift from fossil fuels for renewable transportation and manufacturing fuels, with biohydrogen considered attractive since it could offer the largest reduction of global carbon budgets. Currently, biohydrogen production remains inefficient and heavily fossil fuel-dependent. However, bacteria using alkali-treated biomass could streamline biofuel production while reducing costs and fossil fuel needs. An alkaliphilic bacterium, Halanaerobium strain sapolanicus, is described that is capable of biohydrogen production at levels rivaling neutrophilic strains, but at pH 11 and hypersaline conditions. H. sapolanicus ferments a variety of 5- and 6- carbon sugars derived from hemicellulose and cellulose including cellobiose, and forms the end products hydrogen and acetate. Further, it can also produce biohydrogen from switchgrass and straw pretreated at temperatures far lower than any previously reported and in solutions compatible with growth. Hence, this bacterium can potentially increase the efficiency and efficacy of biohydrogen production from renewable biomass resources.

08 HYDROGEN↗
DOE OSTI2016

Variable Nuclear Electricity with Base-Load Reactor, Closed Brayton Power Cycle and Firebrick Resistance-Heated Energy Storage (Fires)

Power cycle choices are determined by markets and available technologies. Two changes are occurring in the electricity sector. First, the world is beginning to move away from fossil fuels because of concerns about climate change. What replaces fossil fuels for variable electricity production? Second, there have been extraordinary technological advances in gas turbine technology. The changes in market requirements and technology suggest the need to reexamine nuclear power cycles. One option is to couple high-temperature base-load nuclear reactors to closed Brayton cycles (helium, nitrogen, etc.) with Firebrick Resistance-Heated Energy Storage (FIRES). The reactor operates at base-load but not the power cycle. When electricity prices are low, firebrick is electrically heated to high temperatures using base-load electricity and/or electricity from the grid. The gas turbine can use nuclear heat for base-load operation and produce added peak electricity by sending the compressed heated gas through hot firebrick after nuclear heating to further raise power cycle gas temperatures and power output from the turbine-creating a nuclear plant with a thermodynamic topping (NUTOP) cycle. If such cycles can be developed, they would increase plant revenue and enable a low-carbon electricity grid. Such cycles can be coupled to Fluoride-salt-cooled High-temperature Reactors (FHRs), molten salt reactors (MSRs), high-temperature gas-cooled reactors (HTGRs), sodium-cooled fast reactors (SFRs) and lead-cooled fast reactors (LFRs). We discuss (1) market changes, (2) previous work on Nuclear Air-Brayton Combined cycles (NACC) with base-load reactors and variable power to the electricity grid and (3) options for closed Brayton cycles with variable power while the reactor operates at base load. Market (customer) requirements ultimately drive selection of power cycles. A low-carbon electricity grid requires dispatchable nuclear electricity to replace the traditional role of fossil fuels in the electricity grid. While reactors can be operated at part load, this is expensive for a capital-intensive low-operating-cost technology. Brayton power cycles with FIRES have the potential capability to provide that variable electricity while the reactor operates at base load to (1) improve economics and (2) enable a zero-carbon electrical grid. Open Brayton cycles have been investigated. Work has now started on developing closed Brayton cycles with FIRES. Only limited work has been done to date has been done for closed cycles with FIRES. (authors)

42 ENGINEERING↗
DOE OSTI2015

Land carbon sequestration within the conterminous United States: Regional‐ and state‐level analyses

Abstract A quantitative understanding of the rate at which land ecosystems are sequestering or losing carbon at national‐, regional‐, and state‐level scales is needed to develop policies to mitigate climate change. In this study, a new improved historical land use and land cover change data set is developed and combined with a process‐based ecosystem model to estimate carbon sources and sinks in land ecosystems of the conterminous United States for the contemporary period of 2001–2005 and over the last three centuries. We estimate that land ecosystems in the conterminous United States sequestered 323 Tg C yr −1 at the beginning of the 21st century with forests accounting for 97% of this sink. This land carbon sink varied substantially across the conterminous United States, with the largest sinks occurring in the Southeast. Land sinks are large enough to completely compensate fossil fuel emissions in Maine and Mississippi, but nationally, carbon sinks compensate for only 20% of U.S. fossil fuel emissions. We find that regions that are currently large carbon sinks (e.g., Southeast) tend to have been large carbon sources over the longer historical period. Both the land use history and fate of harvested products can be important in determining a region's overall impact on the atmospheric carbon budget. While there are numerous options for reducing fossil fuels (e.g., increase efficiency and displacement by renewable resources), new land management opportunities for sequestering carbon need to be explored. Opportunities include reforestation and managing forest age structure. These opportunities will vary from state to state and over time across the United States.

Lu, Xiaoliang↗
DOE OSTI2011

Health, safety, and environmental risks from energy production: A year-long reality check

Large-scale carbon dioxide capture and storage (CCS) offers the benefit of reducing CO{sub 2} emissions and thereby mitigating climate change risk, but it will also bring its own health, safety, and environmental risks. Curtis M. Oldenburg, Editor-in-Chief, considers these risks in the context of the broader picture of energy production. Over the last year, there have been major acute health, safety, and environmental (HSE) consequences related to accidents involving energy production from every major primary energy source. These are, in chronological order: (i) the Upper Big Branch (coal) Mine disaster, (ii) the Gulf of Mexico Macondo (oil) well blowout, (iii) the San Bruno (natural gas) pipeline leak and explosion, and (iv) the Fukushima (nuclear) reactor radioactivity releases. Briefly, the Upper Big Branch Mine disaster occurred in West Virginia on April 5, 2010, when natural methane in the mine ignited, causing the deaths of 29 miners, the worst coal mine disaster in the USA since 1970. Fifteen days later, the Macondo oil well in the Gulf of Mexico suffered a blowout, with a gas explosion and fire on the floating drilling platform that killed 11 people. The oil and gas continued to flow out of the well at the seafloor until July 15, 2010, spilling a total of approximately 5 million barrels of oil into the sea. On September 9, 2010, a 30-inch (76-cm) buried, steel, natural gas pipeline in San Bruno, California, leaked gas and exploded in a residential neighborhood, killing 8 people in their homes and burning a total of 38 homes. Flames were up to 1000 ft (300 m) high, and the initial explosion itself reportedly measured 1.1 on the Richter scale. Finally, on March 11, 2011, a magnitude 9.0 earthquake off the coast of Japan's main island, Honshu, caused a tsunami that crippled the backup power and associated cooling systems for six reactor cores and their spent fuel storage tanks at the Fukushima nuclear power plant. At time of writing, workers trying to bring the crisis under control have been exposed to dangerous levels of radiation, and radioactive water and particulates have been released to the sea and atmosphere. These four disasters, all of which occurred within the past 12 months, were not unprecedented; similar events differing only in detail have happened around the world before, and such events will occur again. Today, developed nations primarily use fossil fuels to create affordable energy for comforts such as lighting, heating and air-conditioning, refrigeration, transportation, education, and entertainment, as well as for powering manufacturing, which creates jobs and a wealth of material goods. In addition to the risks of the existing energy infrastructure that have become obvious through these recent disasters, there is also the ongoing risk of climate change that comes from the vast emissions of greenhouse gases, primarily CO{sub 2}, from the burning of fossil fuels. The implementation of CO{sub 2} capture and storage (CCS) will help mitigate CO{sub 2} emissions from fossil fuel energy, but it also carries with it HSE risks. In my personal interactions with the public and with students, the main concern voiced is whether CO{sub 2} could leak out of the deep reservoirs into which it is injected and rise up out of the ground, smothering people and animals at the ground surface. Another concern expressed is that CO{sub 2} pipelines could fail and cause similar gaseous plumes of CO{sub 2}. The widespread concerns about CO{sub 2} leaking out over the ground surface may be inspired by events that have happened within natural systems in equatorial Africa, in Indonesia, and in Italy. Researchers have been investigating a wide variety of HSE risks of geologic CO{sub 2} storage for some time and have determined that wells are the main potential pathways for significant leakage from the deep subsurface. I discuss the acute HSE risks of CO{sub 2} leakage through wells and from pipelines, and compare the behavior of failures in CO{sub 2} wells and pipelines with oil and gas analogues from which most of our experience derives.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

On carbon footprints and growing energy use

Could fractional reductions in the carbon footprint of a growing organization lead to a corresponding real reduction in atmospheric CO{sub 2} emissions in the next ten years? Curtis M. Oldenburg, head of the Geologic Carbon Sequestration Program of LBNL’s Earth Sciences Division, considers his own organization's carbon footprint and answers this critical question? In addressing the problem of energy-related greenhouse gas (GHG) emissions and climate change, it is essential that we understand which activities are producing GHGs and the scale of emission for each activity, so that reduction efforts can be efficiently targeted. The GHG emissions to the atmosphere of an individual or group are referred to as the ‘carbon footprint’. This terminology is entirely appropriate, because 85% of the global marketed energy supply comes from carbon-rich fossil fuel sources whose combustion produces CO{sub 2}, the main GHG causing global climate change. Furthermore, the direct relation between CO2 emissions and fossil fuels as they are used today makes energy consumption a useful proxy for carbon footprint. It would seem to be a simple matter to reduce energy consumption across the board, both individually and collectively, to help reduce our carbon footprints and therefore solve the energyclimate crisis. But just how much can we reduce carbon footprints when broader forces, such as growth in energy use, cause the total footprint to simultaneously expand? In this feature, I present a calculation of the carbon footprint of the Earth Sciences Division (ESD), the division in which I work at Lawrence Berkeley National Laboratory (LBNL), and discuss the potential for reducing this carbon footprint. It will be apparent that in terms of potential future carbon footprint reductions under projections of expected growth, ESD may be thought of as a microcosm of the situation of the world as a whole, in which alternatives to the business-as-usual use of fossil fuels are needed if absolute GHG emission reductions are to be achieved.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Comparison of δ 13 C analyses of individual foraminifer ( Orbulina universa ) shells by secondary ion mass spectrometry and gas source mass spectrometry

Rationale: The use of secondary ion mass spectrometry (SIMS) to perform micrometer-scale in situ carbon isotope (δ 13 C) analyses of shells of marine microfossils called planktic foraminifers holds promise to explore calcification and ecological processes. The potential of this technique, however, cannot be realized without comparison to traditional whole-shell δ 13 C values measured by gas source mass spectrometry (GSMS). Methods: Paired SIMS and GSMS δ 13 C values measured from final chamber fragments of the same shell of the planktic foraminifer Orbulina universa are compared. The SIMS–GSMS δ 13 C differences (Δ 13 C SIMS-GSMS ) were determined via paired analysis of hydrogen peroxide-cleaned fragments of modern cultured specimens and of fossil specimens from deep-sea sediments that were either untreated, sonicated, and cleaned with hydrogen peroxide or vacuum roasted. After treatment, fragments were analyzed by a CAMECA IMS 1280 SIMS instrument and either a ThermoScientific MAT-253 or a Fisons Optima isotope ratio mass spectrometer (GSMS). Results: Paired analyses of cleaned fragments of cultured specimens (n = 7) yield no SIMS–GSMS δ 13 C difference. However, paired analyses of untreated (n = 18) and cleaned (n = 12) fragments of fossil shells yield average Δ 13 C SIMS-GSMS values of 0.8‰ and 0.6‰ (±0.2‰, 2 SE), respectively, while vacuum roasting of fossil shell fragments (n = 11) removes the SIMS–GSMS δ 13 C difference. Conclusions: The noted Δ 13 C SIMS-GSMS values are most likely due to matrix effects causing sample–standard mismatch for SIMS analyses but may also be a combination of other factors such as SIMS measurement of chemically bound water. The volume of material analyzed via SIMS is ~10 5 times smaller than that analyzed by GSMS; hence, the extent to which these Δ 13 C SIMS-GSMS values represent differences in analyte or instrument factors remains unclear.

58 GEOSCIENCES↗
DOE OSTI2012

Economic comparison of open pond raceways to photo bio-reactors for profitable production of algae for transportation fuels in the Southwest

As energy prices continue to climb there is an increasing interest in alternative, renewable energy sources. Currently, “most of the energy consumed in the U.S. comes from fossil fuels - petroleum, coal, and natural gas, with crude oil-based petroleum products as the dominant source of energy”. The use of renewable energy has grown, but is only making a small dent in current consumption at about eight percent of the United States total. Another concern with the use of fossil fuels is the emission of carbon dioxide into the atmosphere and complications to the climate. This is because, according to the U.S. Energy Information Administration (EIA) “fossil fuels are responsible for 99% of CO 2 emissions”.

09 BIOMASS FUELS↗
DOE OSTI2016

One-pot bioconversion of algae biomass into terpenes for advanced biofuels and bioproducts

In this study, rising demand for transportation fuels, diminishing reserved of fossil oil, and the concerns with fossil fuel derived environmental pollution as well as the green-house gas emission derived climate change have resulted in the compelling need for alternative, sustainable new energy sources(1). Algae-based biofuels have been considered one of the promising alternatives to fossil fuels as they can overcome some of these issues (2-4). The current state-of-art of algal biofuel technologies have primarily focused on biodiesel production through prompting high algal lipid yields under the nutrient stress conditions. There are less interests of using algae-based carbohydrate and proteins as carbon sources for the fermentative production of liquid fuel compounds or other high-value bioproducts(5-7).

09 BIOMASS FUELS↗
DOE OSTI2020

Life-cycle analysis of soybean meal, distiller-dried grains with solubles, and synthetic amino acid-based animal feeds for swine and poultry production

Swine and poultry meat production are two important sectors in the U.S. economy. They play an important role in environmental sustainability because they contribute to the greenhouse gas (GHG) emissions as the result of agricultural and production activities. To improve the sustain ability of swine and poultry meat production, it is important to understand the environmental effects and identify the key drivers of the production activities. In this work, we presented an environmental assessment of the production of swine (i.e., pork) and poultry (i.e., broiler chicken). We conducted a life-cycle analysis of formulating animal feeds using soybean meal, corn, distiller-dried grains with solubles (DDGS), and synthetic amino acids as candidate ingredients to produce swine and poultry. We evaluated GHG emissions, fossil fuel consumption, and water consumption from formulating and utilizing a variety of animal feeds based on these ingredients for swine and poultry production, using an expanded version of the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET (R)) model. With pork and broiler chicken as the finished products, the functional unit was defined as one kg of live-weight animal at the farm gate. Feed production was the major contributor to the life-cycle GHG emissions (88 % and 91 % of the total GHG emissions for swine and poultry production, respectively) and fossil fuel consumption (79 % and 84 % of the total fossil fuel consumption for swine and poultry process, respectively). Among the four ingredient types, amino acids had the biggest GHG emission footprint; however, DDGS had the largest effect on increasing GHG emissions of swine and poultry production.

animal feed production↗
DOE OSTI2024

The role of the iron and steel sector in achieving net zero U.S. CO 2 emissions by 2050

The U.S. steel sector is a hard-to-abate sector because of its heavy dependence on fossil fuels and its high capital requirements. In 2015, the sector was one of the major carbon emitters, contributing 10 % of the U.S. industrial CO 2 emissions. The ability to decarbonize the U.S. iron and steel sector directly affects the ability of the U.S. to achieve economy-wide net zero CO 2 by 2050. In this paper, we use the Global Change Analysis Model (GCAM) to analyze different U.S. steel sector decarbonization pathways under varying technology, policy, and demand futures. These pathways provide insights on how various low-carbon steelmaking technologies such as those using carbon capture and storage (CCS), hydrogen, or scrap could help reduce U.S. steel emissions by mid-century. In our primary decarbonization pathway, we find that nearly all of the conventional fossil-based steelmaking capacity is fully integrated with CCS by 2050. However, without CCS availability, almost all of the conventional fossil-based steelmaking is phased-out by 2050 and is replaced by hydrogen-based production. Scrap-based production continues to remain vital across both of these decarbonization pathways. Furthermore, we find that demand reduction could help reduce the required levels of CCS and hydrogen-based production in the decarbonization pathways. Implementation of advanced energy efficiency measures could help substantially reduce the sector's energy usage. Finally, we observe that addressing the embodied carbon transfer associated with steel imports will be crucial for fully decarbonizing the U.S. steel sector.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

The Economic Impacts of High Wind Penetration Scenarios in the United States

The U.S. electric sector is experiencing rapid increases in renewable generation with an expectation of continued growth. We examine the impacts of increased wind electricity on the U.S. economy using a hybrid model that links a detailed electric sector model (the National Renewable Energy Laboratory's Regional Energy Deployment System [ReEDS]) with a computable general equilibrium model of the U.S. economy (the Massachusetts Institute of Technology's U.S. Regional Energy Policy [USREP] model). Increasing wind capacity displaces fossil fuels for electricity generation, which depresses fossil fuel prices and reduces economy-wide CO 2 emissions. Competitive wind deployment in the reference scenario achieves these outcomes with lower electricity prices than a scenario with wind capacity fixed at 2016 levels. Lower fossil fuel and electricity prices benefit low-income households, but the dominant economic impacts are driven by increased electric sector investment and capital returns, which primarily benefit those with higher incomes. Overall, cost-competitive wind provides benefits to the U.S. economy that are initially low but rise beyond 2030 to achieve cumulative welfare and GDP improvements of $110 and $111 billion through 2050. Prescribing additional wind deployment (meeting 35% of demand by 2050) increases post-2030 electricity prices but not more so than keeping wind capacity fixed at 2016 levels. The negative effect of higher prices on welfare, however, is outweighed by higher returns from the additional wind investment. While these changes favor higher income classes, we find economy-wide benefits through 2040. These benefits diminish by 2050, but the cumulative additional gains through 2050, beyond the reference case, are $192 billion in welfare and $150 billion in GDP.

17 WIND ENERGY↗