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At least 361 records · Page 20

New estimates of nitrous oxide emissions from biomass burning

The recent discovery of an artifact producing increased levels of N2O in combustion gas samples collected and stored in grab bottles before chemical analysis has resulted in the downgrading of fossil-fuel combustion and the questioning of biomass burning as important sources of N2O. As almost all reported analyses of N2O produced from biomass burning have involved essentially the same collection and analysis protocols as used in the fossil-fuel studies, this source of N2O must also be reexamined. Here, measurements of N2O made over a large prescribed fire using a near real-time in situ measurement technique are reported and compared with measurements of N2O from simultaneously collected grab-bottle samples. The results from 27 small laboratory biomass test fires are also used to help clarify the validity of earlier assessments. It is concluded that biomass burning contributes about seven percent of atmospheric N2O, as opposed to earlier estimates of several times this value.

Cofer, W. R., III↗

Proton Conduction in Exchange Membranes across Multiple Length Scales

Concerns over global climate change associated with fossil-fuel consumption continue to drive the development of electrochemical alternatives for energy technology. Proton exchange fuel cells are a particularly promising technology for stationary power generation, mobile electronics, and hybrid engines in automobiles. For these devices to work efficiently, direct electrical contacts between the anode and cathode must be avoided; hence, the separator material must be electronically insulating but highly proton conductive. As a result, researchers have examined a variety of polymer electrolyte materials for use as membranes in these systems. In the optimization of the membrane, researchers are seeking high proton conductivity, low electronic conduction, and mechanical stability with the inclusion of water in the polymer matrix. A considerable number of potential polymer backbone and side chain combinations have been synthesized to meet these requirements, and computational studies can assist in the challenge of designing the next generation of technologically relevant membranes. Such studies can also be integrated in a feedback loop with experiment to improve fuel cell performance. However, to accurately simulate the currently favored class of membranes, perfluorosulfonic acid containing moieties, several difficulties must be addressed including a proper treatment of the proton-hopping mechanism through the membrane and the formation of nanophase-separated water networks. We discuss our recent efforts to address these difficulties using methods that push the limits of computer simulation and expand on previous theoretical developments. We describe recent advances in the multistate empirical valence bond (MS-EVB) method that can probe proton diffusion at the nanometer-length scale and accurately model the so-called Grotthuss shuttling mechanism for proton diffusion in water. Using both classical molecular dynamics and coarse-grained descriptions that replace atomistic representations with collective coordinates, we investigated the proton conductivity of polymer membrane structure as a function of hydration level. Nanometer-sized water channels form torturous pathways that are traversed by the charges during fuel cell operation. Using a combination of coarse-grained membrane structure and novel multiscale methods, we demonstrate emerging approaches to treat proton motion at the mesoscale in these complex materials.

Jorn, Ryan↗

Western Wind and Solar Integration Study Phase 2 (Presentation)

This presentation accompanies Phase 2 of the Western Wind and Solar Integration Study, a follow-on to Phase 1, which examined the operational impacts of high penetrations of variable renewable generation on the electric power system in the West and was one of the largest variable generation studies to date. High penetrations of variable generation can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions. Phase 2 calculated these costs and emissions, and simulated grid operations for a year to investigate the detailed impact of variable generation on the fossil-fueled fleet. The presentation highlights the scope of the study and results.

14 SOLAR ENERGY↗

Strong regional atmospheric 14 C signature of respired CO 2 observed from a tall tower over the midwestern United States

Radiocarbon in CO 2 ( 14 CO 2 ) measurements can aid in discriminating between fast (<1 year) and slower (>5–10 years) cycling of C between the atmosphere and the terrestrial biosphere due to the 14 C disequilibrium between atmospheric and terrestrial C. However, 14 CO 2 in the atmosphere is typically much more strongly impacted by fossil fuel emissions of CO 2 , and, thus, observations often provide little additional constraints on respiratory flux estimates at regional scales. Here we describe a data set of 14 CO 2 observations from a tall tower in northern Wisconsin (USA) where fossil fuel influence is far enough removed that during the summer months, the biospheric component of the 14 CO 2 budget dominates. We find that the terrestrial biosphere is responsible for a significant contribution to 14 CO 2 that is 2–3 times higher than predicted by the Carnegie-Ames-Stanford approach terrestrial ecosystem model for observations made in 2010. This likely includes a substantial contribution from the North American boreal ecoregion, but transported biospheric emissions from outside the model domain cannot be ruled out. The 14 CO 2 enhancement also appears somewhat decreased in observations made over subsequent years, suggesting that 2010 may be anomalous. Furthermore, with these caveats acknowledged, we discuss the implications of the observation/model comparison in terms of possible systematic biases in the model versus short-term anomalies in the observations. Going forward, this isotopic signal could be exploited as an important indicator to better constrain both the long-term carbon balance of terrestrial ecosystems and the short-term impact of disturbance-based loss of carbon to the atmosphere.

54 ENVIRONMENTAL SCIENCES↗

WZ Sagittae, SN 1054 and SN 1006 space weather

Statement of the Problem: The earth’s atmosphere experience changes that are caused by pollution from debris streams from exploding stars, nova and supernova. The debris streams also cause global warming. Earth’s sensitivity to the energy added to the biosphere is shown by the areas of major sea ice loss through recent years. Methodology & Theoretical Orientation: By knowing the year of arrival of debris streams at planet earth the longitudinal locations of observations of changing sea ice can be correlated to specific debris stream’s termini. The actual termini points are identified for WZ Sagittae, SN 1006 and SN 1054. Findings: Global warming effects have been correlated with the arrival time of nova and supernova explosions through disappearing sea ice over the past nine years. Conclusion & Significance: The current trend for global warming specialist to blame fossil fuels and CO2 for the increase of planetary temperatures may be incorrect and the true source of our current global warming may be due to debris impact streams from nova WZ Sagittae, SN 1054 and SN 1006. The incentive to inhibit the fossil fuel industry could be changed to design a mechanism or system to stop the incoming particle stream from exploding stars to protect living organisms on our planet. The disappearance of sea ice areas that are correlated with the debris streams being studied is proof of the Supernova and Nova Impact Theory (SNIT).

Sokeland, William P.↗

Global carbon - nitrogen - phosphorus cycle interactions: A key to solving the atmospheric CO2 balance problem?

If all biotic sinks of atmospheric CO2 reported were added a value of about 0.4 Gt C/yr would be found. For each category, a very high (non-conservative) estimate was used. This still does not provide a sufficient basis for achieving a balance between the sources and sinks of atmospheric CO2. The bulk of the discrepancy lies in a combination of errors in the major terms, the greatest being in a combination of errors in the major terms, the greatest being in the net biotic release and ocean uptake segments, but smaller errors or biases may exist in calculations of the rate of atmospheric CO2 increase and total fossil fuel use as well. The reason why biotic sinks are not capable of balancing the CO2 increase via nutrient-matching in the short-term is apparent from a comparison of the stoichiometry of the sources and sinks. The burning of fossil fuels and forest biomass releases much more CO2-carbon than is sequestered as organic carbon.

Peterson, B. J.↗

Today's Energy Challenges, Tomorrow's Solutions: Electrons to Molecules: Building a New Foundation for Industrial Processes

The vast majority of global goods and materials we use on a daily basis are manufactured from fossil fuel precursors - chemical building blocks strung together using combinations of heat, pressure, and chemical catalysis. NREL, along with energy industry partners, is exploring the use of renewable, affordable electricity as the driving force for the conversion of low-energy molecules - such as water and carbon dioxide (CO2) - to generate other molecules that could be used as chemicals, materials, fuels, or energy storage.Through this research, NREL and its partners are working together to determine the most efficient and cost-effective solutions for energy storage as well as safer ways to create chemicals and plastics that do not rely solely on fossil fuels.

affordable electricity↗

T-Q Diagram and Heat Source Assessment – Preliminary Evaluation

Presentation of a preliminary assessment of the fossil fuel heat sources for integration with the supercritical CO2 cycle: (1) PC, Air/Oxy, (2) CFB, Air/Oxy, (3) PFBC, Air/Oxy. It shows the development of T-Q diagrams to evaluate the effectiveness of various heat sources for the supercritical CO2 cycle. Heat sources include fossil fuels, Nuclear, and Solar. Conclusions include: (1) Current CFB (Air/Oxy) T-Q profile more suited to sCO2 cycle (for TIT < CFB furnace temperature), (2) PC/CFB design needs to be modified to take advantage of the high efficiency sCO2 cycle and (3) sCO2 cycle should be optimized to match the heat source better.

CFB↗

The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500

Anthropogenic increases in atmospheric greenhouse gas concentrations are the main driver of current and future climate change. The integrated assessment community has quantified anthropogenic emissions for the shared socio-economic pathway (SSP) scenarios, each of which represents a different future socio-economic projection and political environment. Here, we provide the greenhouse gas concentrations for these SSP scenarios using the reduced-complexity climate–carbon-cycle model MAGICC7.0. We extend historical, observationally based concentration data with SSP concentration projections from 2015 to 2500 for 43 greenhouse gases with monthly and latitudinal resolution. CO 2 concentrations by 2100 range from 393 to 1135 ppm for the lowest (SSP1-1.9) and highest (SSP5-8.5) emission scenarios, respectively. We also provide the concentration extensions beyond 2100 based on assumptions regarding the trajectories of fossil fuels and land use change emissions, net negative emissions, and the fraction of non-CO 2 emissions. By 2150, CO 2 concentrations in the lowest emission scenario are approximately 350 ppm and approximately plateau at that level until 2500, whereas the highest fossil-fuel-driven scenario projects CO 2 concentrations of 1737 ppm and reaches concentrations beyond 2000 ppm by 2250. We estimate that the share of CO 2 in the total radiative forcing contribution of all considered 43 long-lived greenhouse gases increases from 66% for the present day to roughly 68% to 85% by the time of maximum forcing in the 21st century. For this estimation, we updated simple radiative forcing parameterizations that reflect the Oslo Line-By-Line model results. In comparison to the representative concentration pathways (RCPs), the five main SSPs (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) are more evenly spaced and extend to lower 2100 radiative forcing and temperatures. Performing two pairs of six-member historical ensembles with CESM1.2.2, we estimate the effect on surface air temperatures of applying latitudinally and seasonally resolved GHG concentrations. We find that the ensemble differences in the March–April–May (MAM) season provide a regional warming in higher northern latitudes of up to 0.4 K over the historical period, latitudinally averaged of about 0.1 K, which we estimate to be comparable to the upper bound (~5 % level) of natural variability. In comparison to the comparatively straight line of the last 2000 years, the greenhouse gas concentrations since the onset of the industrial period and this studies' projections over the next 100 to 500 years unequivocally depict a “hockey-stick” upwards shape. The SSP concentration time series derived in this study provide a harmonized set of input assumptions for long-term climate science analysis; they also provide an indication of the wide set of futures that societal developments and policy implementations can lead to – ranging from multiple degrees of future warming on the one side to approximately 1.5°C warming on the other.

54 ENVIRONMENTAL SCIENCES↗

Solar Canopy Expansion Project (Final Technical Report)

This project is a parking-lot canopy solar photovoltaic system, consisting of four canopy structures and 1,080 470-watt (W) modules. The nameplate rating of the project is 507.6 kilowatts direct current (kWDC) at Standard Test Condition (STC), and 448 kilowatts alternating current (kWAC). It is interconnected to the existing Tribe-owned medium-voltage micro-grid generation system via a step-up transformer and short medium-voltage line. This project offsets energy usage from more expensive existing sources, specifically the Tribe-owned gas-fired engine generators providing the primary power source for existing Tribal facilities and the electric utility, which provides an alternate source. The solar photovoltaic system is a renewable source, which has the benefit of reducing reliance on fossil-fuel burning sources. By reducing demand on existing Tribe-owned conventional generators, the project has avoided the need to add more conventional generation and has prolonged the lifespan of existing gas-fired engine generators. The project reduced energy costs and reliance on fossil-fuel burning power sources, increasing Tribe-owned generating sources and self-reliance, and prolonging the lifespan of existing generators. A side benefit to the project is the production of dozens of covered parking spaces in the existing parking lot.

14 SOLAR ENERGY↗

Status of wind-energy conversion

The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems; a sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to: (1) fossil fuel systems; (2) hydroelectric systems; or (3) dispersing them throughout a large grid network. Wind energy appears to have the potential to meet a significant amount of our energy needs.

Thomas, R. L.↗

Status of wind-energy conversion

The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems. A sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short-term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to fossil fuel systems, hydroelectric systems, or dispersing them throughout a large grid network. The NSF and NASA-Lewis Research Center have sponsored programs for the utilization of wind energy.

Thomas, R. L.↗

A study of some economic factors relating to the development and implementation of a satellite power system

Areas are examined relating to the design, development and implementation of a satellite power system (SPS): an analysis of the effect of energy R&D programs in general and SPS in particular on optimal fossil fuel consumption patterns, a study of alternative uses of SPS technologies, and a study of the electric power market penetration potential for SPS. It is shown that a credible program of R&D on long-range energy alternatives leads to lower optimal prices for fossil fuels, resulting in large short-term benefits accruing to the specific program elements. Several alternative uses of SPS technologies were identified; however the markets for these technologies are generally quite diffuse and difficult to assess. The notable exception is solar array technology which has, potentially, a very large non-SPS market. It is shown that the market for SPS units derives from two components of demand: the demand created by growth in the electrical energy demand which leads to an increased demand for baseload generating capacity, and a demand created by the need to replace retiring capacity.

Source record↗

CO 2 Capture Going BIG

“Currently, the world is way off track in meeting the Paris Agreement climate goals. It cannot get back on track without CCS”. This statement, issued by the Global CCS Institute in its recent report on The Global Status of CCS (Carbon Capture and Storage), underlines the importance of developing new methods and technologies to reduce the amount of greenhouse gases in the atmosphere. Since the beginning of the industrial revolution, the atmospheric CO 2 concentration has increased from 280 to 410 parts per million (ppm), which is a 46% increase. Most of the added CO 2 can be attributed to fossil fuel emissions from energy production (i.e., burning coal, natural gas, and oil) and other industries (e.g., cement, steel). The CO 2 level will likely continue to rise in the coming decades, as the world population and the energy consumption continue to increase and rely on fossil fuels. While the Earth’s ecosystems have mechanisms for reducing the amounts of CO 2 present in the atmosphere, absorbing roughly half of our annual emissions, the other half, consisting of about 18 gigatonnes of carbon dioxide per year, will have to be addressed through CCS technologies. At the same time, the global average temperature has already risen about 1 °C over the course of the 20th century, and will likely exceed the 1.5 °C increase limit in a few decades. Undeniably, as the Earth is out of energy balance with the current atmospheric composition, there is more warming in the pipeline even if the global emissions were to be cut to zero today. A recent report from the U.S. National Academy of Sciences concluded that limiting the increase in the global temperature to less than 2 °C by the end of this century becomes exceedingly challenging without large-scale deployment of Negative Emissions Technologies (NETs). NETs, such as Direct Air Capture (DAC), remove CO 2 out of the atmosphere, in effect reducing past emissions. They also can address dispersed emissions from transportation and buildings, which currently account to about 50% of global annual emissions.

01 COAL, LIGNITE, AND PEAT↗

A nuclear wind/solar oil-shale system for variable electricity and liquid fuels production

The recoverable reserves of oil shale in the United States exceed the total quantity of oil produced to date worldwide. Oil shale contains no oil, rather it contains kerogen which when heated decomposes into oil, gases, and a carbon char. The energy required to heat the kerogen-containing rock to produce the oil is about a quarter of the energy value of the recovered products. If fossil fuels are burned to supply this energy, the greenhouse gas releases are large relative to producing gasoline and diesel from crude oil. The oil shale can be heated underground with steam from nuclear reactors leaving the carbon char underground - a form of carbon sequestration. Because the thermal conductivity of the oil shale is low, the heating process takes months to years. This process characteristic in a system where the reactor dominates the capital costs creates the option to operate the nuclear reactor at base load while providing variable electricity to meet peak electricity demand and heat for the shale oil at times of low electricity demand. This, in turn, may enable the large scale use of renewables such as wind and solar for electricity production because the base-load nuclear plants can provide lower-cost variable backup electricity. Nuclear shale oil may reduce the greenhouse gas releases from using gasoline and diesel in half relative to gasoline and diesel produced from conventional oil. The variable electricity replaces electricity that would have been produced by fossil plants. The carbon credits from replacing fossil fuels for variable electricity production, if assigned to shale oil production, results in a carbon footprint from burning gasoline or diesel from shale oil that may half that of conventional crude oil. The U.S. imports about 10 million barrels of oil per day at a cost of a billion dollars per day. It would require about 200 GW of high-temperature nuclear heat to recover this quantity of shale oil - about two-thirds the thermal output of existing nuclear reactors in the United States. With the added variable electricity production to enable renewables, additional nuclear capacity would be required. (authors)

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Emissions reduction scenarios in the Argentinean Energy Sector

Here in this paper the LEAP, TIAM-ECN, and GCAM models were applied to evaluate the impact of a variety of climate change control policies (including carbon pricing and emission constraints relative to a base year) on primary energy consumption, final energy consumption, electricity sector development, and CO 2 emission savings of the energy sector in Argentina over the 2010-2050 period. The LEAP model results indicate that if Argentina fully implements the most feasible mitigation measures currently under consideration by official bodies and key academic institutions on energy supply and demand, such as the ProBiomass program, a cumulative incremental economic cost of 22.8 billion US$(2005) to 2050 is expected, resulting in a 16% reduction in GHG emissions compared to a business-as-usual scenario. These measures also bring economic co-benefits, such as a reduction of energy imports improving the balance of trade. A Low CO 2 price scenario in LEAP results in the replacement of coal by nuclear and wind energy in electricity expansion. A High CO 2 price leverages additional investments in hydropower. An emission cap scenario (2050 emissions 20% lower than 2010 emissions) is feasible by including such measures as CCS and Bio CCS, but at a significant cost. By way of cross-model comparison with the TIAM-ECN and GCAM global integrated assessment models, significant variation in projected emissions reductions in the carbon price scenarios was observed, which illustrates the inherent uncertainties associated with such long-term projections. These models predict approximately 37% and 94% reductions under the High CO 2 price scenario, respectively. By comparison, the LEAP model, using an approach based on the assessment of a limited set of mitigation options, predicts a 11.3% reduction under the ‘high’ carbon tax. The main reasons for this difference are differences in assumptions about technology cost and availability, CO 2 storage capacity, and the ability to import bioenergy. In terms of technology pathways, the models agree that fossil fuels, in particular natural gas, will remain an important part of the electricity mix in the core baseline scenario. Finally, according to the models there is agreement that the introduction of a carbon price will lead to a decline in absolute and relative shares of aggregate fossil fuel generation. However, predictions vary as to the extent to which coal, nuclear and renewable energy play a role.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

System-of-Systems Considerations in the Notional Development of a Metropolitan Aerial Transportation System

There are substantial future challenges related to sustaining and improving efficient, cost-effective, and environmentally friendly transportation options for urban regions. Over the past several decades there has been a worldwide trend towards increasing urbanization of society. Accompanying this urbanization are increasing surface transportation infrastructure costs and, despite public infrastructure investments, increasing surface transportation "gridlock." In addition to this global urbanization trend, there has been a substantial increase in concern regarding energy sustainability, fossil fuel emissions, and the potential implications of global climate change. A recently completed study investigated the feasibility of an aviation solution for future urban transportation (refs. 1, 2). Such an aerial transportation system could ideally address some of the above noted concerns related to urbanization, transportation gridlock, and fossil fuel emissions (ref. 3). A metro/regional aerial transportation system could also provide enhanced transportation flexibility to accommodate extraordinary events such as surface (rail/road) transportation network disruptions and emergency/disaster relief responses.

Alonso, Juan J.↗

Climate Impact of Primary Plastic Production

Plastics show the strongest production growth of all bulk materials over the last decade. The industry’s current growth trajectory is exponential and plastic production is expected to double or triple by 2050. The rapidly increasing production of plastics and the continued reliance on fossil fuels for production, have contributed to numerous environmental problems and health harms. As a result, plastic pollution has become an increasing threat to natural ecosystems, human health and climate. However, there is a lack of granularity on the contribution of the primary plastics specifically to greenhouse gas (GHG) emissions and their impact on the remaining global carbon budget needed to stay below a 1.5°C or 2°C global average temperature rise. In this report, we explore the contribution of primary plastic production to climate change disaggregated by polymer and technology. To this end, we have developed comprehensive bottom-up modeling of GHG emissions from global primary plastic production, with a special focus on polymer value chains. We have analyzed the results under various growth scenarios in the context of carbon budgets compatible with a 1.5°C global trajectory. Modeling includes the material flows of all production stages, processes and technologies used in primary plastic production value chains, including from the extraction of fossil fuels required for production to shaping the final product. We specifically focus on nine major types of fossil fuelbased plastic polymers that are produced and consumed in large quantities: three types of polyethylene (PE) – low-density (LDPE), linear low-density (LLDPE), and high-density (HDPE) – as well as polypropylene (PP); polyethylene terephthalate (PET); polyvinyl chloride (PVC); polystyrene (PS) and other key styrene-based plastics such as styrene acrylonitrile (SAN) and acrylonitrile butadiene styrene (ABS), and polyurethane (PU). Together these account for about 80% of plastics production.

54 ENVIRONMENTAL SCIENCES↗