1,329 research outputs found
Transitioning Montana to a Renewable Energy Future: The Social and Economic Impacts
Montana is home to the second-largest coal-fired power plant in the West, the Colstrip Generating Station. The value and demand for coal both domestically and globally is quickly diminishing, while the renewable energy industries of wind and solar are booming. As utilities in the Northwest transition their investments from coal to renewable energy, Montana faces a critical decision on the future of its energy system that will impact the lives of generations of Montanans to come.
This five-part report aims to aid in the discussion and decision-making process by reviewing the most up-to-date economic data on renewable energy; discussing the social and economic impacts of the Colstrip community’s transition out of the coal industry; and highlighting the perspectives of some of the most directly-impacted stakeholders in Montana’s energy industry.
Part 1 is a summary of Montana’s vast renewable energy potential and the urgent need to invest in these technologies for its long-term social and economic wellbeing. Part 2 is an analysis of the economic benefits of investing in a renewable energy economy, particularly the technologies of wind and solar energy. Part 3 is a discussion of the current trajectory of the Colstrip Generating Station in Colstrip, MT, and the social, environmental and economic impacts of plant closure on the local community. Part 4 is a literature review of recent academic literature (2010-present) on the economics of solar and wind energy. This is section is separated from the data presented in Part 2 to maintain a distinction from industry-based information. Finally, Part 5 of the report respectfully provides suggestions for its target organization, 350 Montana, for moving forward in the push for the statewide energy transition
Strip casting with fluxing agent applied to casting roll
A strip caster (10) for producing a continuous strip (24) includes a tundish (12) for containing a melt (14), a pair of horizontally disposed water cooled casting rolls (22) and devices (29) for electrostatically coating the outer peripheral chill surfaces (44) of the casting rolls with a powder flux material (56). The casting rolls are juxtaposed relative to one another for forming a pouting basin (18) for receiving the melt through a teeming tube (16) thereby establishing a meniscus (20) between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed through a supply line (28) to a sealing chamber (26). A preferred flux is boron oxide having a melting point of about 550° C. The flux coating enhances wetting of the steel melt to the casting roll and dissolves any metal oxide formed on the roll
Multimode Memories in Atomic Ensembles
The ability to store multiple optical modes in a quantum memory allows for
increased efficiency of quantum communication and computation. Here we compute
the multimode capacity of a variety of quantum memory protocols based on light
storage in ensembles of atoms. We find that adding a controlled inhomogeneous
broadening improves this capacity significantly.Comment: Published version. Many thanks are due to Christoph Simon for his
help and suggestions. (This acknowledgement is missing from the final draft:
apologies!
Efficient spatially-resolved multimode quantum memory
We propose a method that enables efficient storage and retrieval of a
photonic excitation stored in an ensemble quantum memory consisting of
Lambda-type absorbers with non-zero Stokes shift. We show that this can be used
to implement a multimode quantum memory storing multiple frequency-encoded
qubits in a single ensemble, and allowing their selective retrieval. The
read-out scheme applies to memory setups based on both
electromagnetically-induced transparency and stimulated Raman scattering, and
spatially separates the output signal field from the control fields
Crossing the phantom divide in an interacting generalized Chaplygin gas
Unified generalized Chaplygin gas models assuming an interaction between dark
energy and dark matter fluids have been previously proposed. Following these
ideas, we consider a particular relation between dark densities, which allows
the possibility of a time varying equation of state for dark energy that
crosses the phantom divide at a recent epoch. Moreover, these densities decay
during all the evolution of the Universe, avoiding a Big Rip. We find also a
scaling solution, i.e. these densities are asymptotically proportional in the
future, which contributes to the solution of the coincidence problem.Comment: Improved version, 10 pages, 4 figures, References adde
Weighed scalar averaging in LTB dust models, part I: statistical fluctuations and gravitational entropy
We introduce a weighed scalar average formalism ("q-average") for the study
of the theoretical properties and the dynamics of spherically symmetric
Lemaitre-Tolman-Bondi (LTB) dust models models. The "q-scalars" that emerge by
applying the q-averages to the density, Hubble expansion and spatial curvature
(which are common to FLRW models) are directly expressible in terms of
curvature and kinematic invariants and identically satisfy FLRW evolution laws
without the back-reaction terms that characterize Buchert's average. The local
and non-local fluctuations and perturbations with respect to the q-average
convey the effects of inhomogeneity through the ratio of curvature and
kinematic invariants and the magnitude of radial gradients. All curvature and
kinematic proper tensors that characterize the models are expressible as
irreducible algebraic expansions on the metric and 4-velocity, whose
coefficients are the q-scalars and their linear and quadratic local
fluctuations. All invariant contractions of these tensors are quadratic
fluctuations, whose q-averages are directly and exactly related to statistical
correlation moments of the density and Hubble expansion scalar. We explore the
application of this formalism to a definition of a gravitational entropy
functional proposed by Hosoya et al (2004 Phys. Rev. Lett. 92 141302). We show
that a positive entropy production follows from a negative correlation between
fluctuations of the density and Hubble scalar, providing a brief outline on its
fulfillment in various LTB models and regions. While the q-average formalism is
specially suited for LTB and Szekeres models, it may provide a valuable
theoretical insight on the properties of scalar averaging in inhomogeneous
spacetimes in general.Comment: 27 pages in IOP format, 1 figure. Matches version accepted for
publication in Classical and Quantum Gravit
Atmospheric greenhouse gases retrieved from SCIAMACHY: comparison to ground-based FTS measurements and model results
SCIAMACHY onboard ENVISAT (launched in 2002) enables the retrieval of global long-term column-averaged dry air mole fractions of the two most important anthropogenic greenhouse gases carbon dioxide and methane (denoted XCO_2 and XCH_4). In order to assess the quality of the greenhouse gas data obtained with the recently introduced v2 of the scientific retrieval algorithm WFM-DOAS, we present validations with ground-based Fourier Transform Spectrometer (FTS) measurements and comparisons with model results at eight Total Carbon Column Observing Network (TCCON) sites providing realistic error estimates of the satellite data. Such validation is a prerequisite to assess the suitability of data sets for their use in inverse modelling.
It is shown that there are generally no significant differences between the carbon dioxide annual increases of SCIAMACHY and the assimilation system CarbonTracker (2.00 ± 0.16 ppm yr^(−1) compared to 1.94 ± 0.03 ppm yr−1 on global average). The XCO_2 seasonal cycle amplitudes derived from SCIAMACHY are typically larger than those from TCCON which are in turn larger than those from CarbonTracker. The absolute values of the northern hemispheric TCCON seasonal cycle amplitudes are closer to SCIAMACHY than to CarbonTracker and the corresponding differences are not significant when compared with SCIAMACHY, whereas they can be significant for a subset of the analysed TCCON sites when compared with CarbonTracker. At Darwin we find discrepancies of the seasonal cycle derived from SCIAMACHY compared to the other data sets which can probably be ascribed to occurrences of undetected thin clouds. Based on the comparison with the reference data, we conclude that the carbon dioxide data set can be characterised by a regional relative precision (mean standard deviation of the differences) of about 2.2 ppm and a relative accuracy (standard deviation of the mean differences) of 1.1–1.2 ppm for monthly average composites within a radius of 500 km.
For methane, prior to November 2005, the regional relative precision amounts to 12 ppb and the relative accuracy is about 3 ppb for monthly composite averages within the same radius. The loss of some spectral detector pixels results in a degradation of performance thereafter in the spectral range currently used for the methane column retrieval. This leads to larger scatter and lower XCH_4 values are retrieved in the tropics for the subsequent time period degrading the relative accuracy. As a result, the overall relative precision is estimated to be 17 ppb and the relative accuracy is in the range of about 10–20 ppb for monthly averages within a radius of 500 km.
The derived estimates show that the SCIAMACHY XCH_4 data set before November 2005 is suitable for regional source/sink determination and regional-scale flux uncertainty reduction via inverse modelling worldwide. In addition, the XCO2 monthly data potentially provide valuable information in continental regions, where there is sparse sampling by surface flask measurements
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