3,880 research outputs found

    The cost of reducing utility S02 emissions : not as low as you might think

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    A common assertion in public policy discussions is that the cost of achieving the SO2 emissions reductions under the acid rain provisions of the Clean Air Act ("Title IV") has been only one-tenth or less of what Title IV was originally expected to cost. Initial cost estimates are cited in the range of 1000to1000 to 2000 per ton of SO2 reduction and contrasted to SO2 allowance prices of about 100perton.Unfortunately,theseare"applestooranges"comparisons,leadingtoerroneousconclusionsthatgreatlyoverstatethetruedivergenceofactualcostsfrominitialcostestimates.Whenthefactsareviewedinaconceptuallyappropriate,"applestoapples"context,onefindsthatactualcostsforSO2reductionshavebeenandarelikelytoremainnearthelowendoftheinitialrangeofestimates.WeallmustlearntorecognizeconceptualpitfallsintheseassessmentsoftheSO2program,toavoidunrealisticexpectationsofmajornewregulatoryinitiatives.Forexample,manyregulatoryadvocatesarenowusingtheerroneouscharacterizationofTitleIVcostsbeingonetenthorlessoftheiroriginallyprojectedlevelstoarguethatthenewmarketbasedregulatoryapproachesrenderexantecostestimatesmeaninglessoratleastmuchtoohigh.Thisfundamentallyincorrectlineofreasoningalreadyhasbeenusedtodismissconcernovercostestimatesfornewregulations,suchasthePM2.5andozoneairqualitystandards.Theseandothermajorpolicyinitiativesdeservetobedebatedinlightofappropriateandrealisticassessmentsoftheirlikelycosts.ThisrequirescorrectingthecurrentmisunderstandingsabouttheactualcostsoftheTitleIVSO2emissionsallowancemarket.ThefollowingpaperleadsthereaderthroughaninterpretationofthefactsregardingtheestimatedandactualcostsoftheSO2program.Someofthekeypointsinclude:(1)InitialcostestimatesfortheTitleIVSO2programwerenotover100 per ton. Unfortunately, these are "apples-to-oranges" comparisons, leading to erroneous conclusions that greatly overstate the true divergence of actual costs from initial cost estimates. When the facts are viewed in a conceptually appropriate, "apples-to-apples" context, one finds that actual costs for SO2 reductions have been and are likely to remain near the low end of the initial range of estimates.We all must learn to recognize conceptual pitfalls in these assessments of the SO2 program, to avoid unrealistic expectations of major new regulatory initiatives. For example, many regulatory advocates are now using the erroneous characterization of Title IV costs being one-tenth or less of their originally projected levels to argue that the new market-based regulatory approaches render ex ante cost estimates meaningless or at least much too high. This fundamentally incorrect line of reasoning already has been used to dismiss concern over cost estimates for new regulations, such as the PM2.5 and ozone air quality standards. These and other major policy initiatives deserve to be debated in light of appropriate and realistic assessments of their likely costs. This requires correcting the current misunderstandings about the actual costs of the Title IV SO2 emissions allowance market.The following paper leads the reader through an interpretation of the facts regarding the estimated and actual costs of the SO2 program. Some of the key points include: (1) Initial cost estimates for the Title IV SO2 program were not over 1000 per ton. (2) Initial cost estimates for a fully-implemented Phase II cap ranged from 225500perton,andcostswereprojectedtobelowerthanthisuntilthePhaseIIcapwouldbefullyachieved,abouttenyearsfromnow.(3)Muchconfusionhasarisenfromcomparingdifferentcostandpriceconceptsthatbecomeimportantinanallowancetradingsystem,suchasaverageandmarginalcost,andthepriceofanallowance.(4)Whenamarkethasatemporaryoversupply(whichhasbeentrueoftheSO2allowancemarket),spotmarketallowancepriceswillfailtoreflectthecapitalcostportionofcontrolcosts,whichcanbealargepartofthetotalcosts.(5)Theallowancepricemayreflectfuturecontrolcosts,butregulatoryuncertaintymaycausefuturecoststobehighlydiscounted.TheaveragecontrolcostactuallyexperiencedinPhaseIhasbeenabout225-500 per ton, and costs were projected to be lower than this until the Phase II cap would be fully achieved, about ten years from now. (3) Much confusion has arisen from comparing different cost and price concepts that become important in an allowance trading system, such as average and marginal cost, and the price of an allowance. (4) When a market has a temporary oversupply (which has been true of the SO2 allowance market), spot market allowance prices will fail to reflect the capital cost portion of control costs, which can be a large part of the total costs. (5) The allowance price may reflect future control costs, but regulatory uncertainty may cause future costs to be highly discounted.The average control cost actually experienced in Phase I has been about 200 per ton. This is within the range that was initially projected. Today's most up-to-date estimates for Phase II (future) average costs are about 185to185 to 220 per ton. This is at the low end of the initial range of estimates. Allowance prices have been much lower, but we explain how they are consistent with actual average costs of $200 per ton.Partially supported by John Kinsman and Edison Electric Institute

    Talking On Your Cell Phone and Ethical Responsibility: How Many Children Died for Your Battery?

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    Ethics has been an increasingly important topic in business and many issues stem from this broad subject.Especially when companies cross borders to conduct business, the lines for what is ethical begin to blur whencosts and profits are concerned. Thus, many issues emerge when looking at environmental and socialresponsibility, such as environmental friendliness, local manufacturing, and child labor. These ethical issues havebrought about standards of conduct for businesses as consumers tend to react poorly when an ethical line hasbeen crossed. This study attempts to look at how one such issue, child labor, impacts the purchasing behaviorsof consumers for the cell phone industry. Coltan is a raw mineral that is used in many technologies, including thebatteries of cell phones and computers. This mineral is currently being mined using child labor in Africa,specifically the country of Congo. Unfortunately, this issue has not been publicized and cell phone companies arenot currently being held accountable for where the coltan for their cell phones is coming from. Thus, the purposeof this study is to expose this ethical dilemma and measure the potential effect on consumers within the cellphone industry

    Underground mining of aggregates. Main report

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    This report examines the economic feasibility of underground mining for crushed rock aggregates in the UK, but particularly in the London, South East and East of England regions (the South East area of England). These regions import substantial volumes of crushed rock, primarily from the East Midlands and South West regions, requiring relatively long transport distances to market for this bulk commodity. A key part of the research was to determine whether or not aggregate could be produced and delivered to a local market from an underground aggregates operation at a cost comparable with that for production and transport of the commodity from traditional surface quarries located further afield. In essence the investigation asked – could the reduced transport costs compensate for the higher production costs underground so that underground crushed rock aggregates producers can compete with the established Leicestershire and Somerset surface quarries exporting to the South East? Work Programme The research effort involved establishing and verifying cost models for aggregates production, stone processing (sizing and sorting), haulage of product to market, environmental impact mitigation, health and safety, decommissioning and restoration. Another major element of the work was the re-examination of the BGS exploratory borehole and geophysical databases to identify potential areas of crushed rock aggregates resource at depth in the South East area of England. Land use pressure is typically higher in this area of England than elsewhere so another major part of the research was the identification of potential concurrent uses of land around the surface facilities of underground aggregates mines. The value, development costs for specific developments and determination of yields expected, from these uses were estimated. These were also used to investigate potential economic benefits associated with after uses of remediated surface land above potential underground aggregates mines and also for the new underground space that would be created. Key technical issues such as subsidence within relatively heavily populated areas of the South East area of England were also addressed. Economic Results The discounted cost of aggregate delivered at a discount rate of 10% was the metric used to appraise the options. This is the price of aggregate that leads to a zero net present value of project cash flows realised over the aggregates project life. The results show that the discounted costs of aggregate delivered to a local South East area of England market from an underground mine producing 3.5 million tonnes per annum (MTPA) of crushed rock aggregates, are in the range of £13.03 per tonne to £13.93 per tonne for the top six prospect locations. These are greater than the corresponding cost for a “reference” quarry in Leicestershire producing 3.5 MTPA (£10.95 per tonne), but lower than a “reference” quarry in Leicestershire producing 1.25 MTPA (£16.48 per tonne). These figures indicate that underground crushed rock aggregate mines located within the South East area of England may be able to compete for a share in the overall market by replacing / displacing aggregate imported from the quarries in Leicestershire and Somerset producing around or less than 1.25 MTPA. The surprise in these figures is not really that the more remote surface quarry has a lower discounted cost of aggregate delivered, but that the values for the quarry and underground mine are so close. The capital intensity for the development of underground aggregates mines was found to be higher than that required for surface quarries of comparable scale, by a factor ranging from 1.33 to 1.65 and thus may represent a disincentive for aggregates operators. Carbon Emissions The total carbon emissions of the ‘reference’ 3.5 MTPA quarry in Leicestershire were estimated at 9.28 kg CO2/tonne aggregate delivered and this is to be compared with carbon emissions for the 150 metre deep underground mines serving the local market which were estimated at 9.31 kg CO2/tonne delivered for a Bletchley prospect using an adit to access the sub-surface and 14.25 kg CO2/tonne delivered for a prospect based on the Chitty bore hole using a shaft. Depth of the mine is a key factor in determination of the relative carbon emissions from each of the underground mining operations considered as electricity consumption for ventilation, pumping and winding is proportional to depth. Recommendations The current research generated seven principal recommendations which are discussed in detail in the concluding section of the report. These are: Appraise policy incentives for underground aggregates mining. Conduct an industry-wide consultation on findings from the current research. Obtain public and stakeholder opinion on new uses for underground space. Conduct research to reducing the energy intensity of mine services. Develop a deep level aggregates-specific drilling campaign. Investigate underground aggregates mines developed from existing surface quarries. Investigate underground aggregates as co-products of industrial minerals mining

    A Dense Gas Trigger for OH Megamasers

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    HCN and CO line diagnostics provide new insight into the OH megamaser (OHM) phenomenon, suggesting a dense gas trigger for OHMs. We identify three physical properties that differentiate OHM hosts from other starburst galaxies: (1) OHMs have the highest mean molecular gas densities among starburst galaxies; nearly all OHM hosts have = 10^3-10^4 cm^-3 (OH line-emitting clouds likely have n(H2) > 10^4 cm^-3). (2) OHM hosts are a distinct population in the nonlinear part of the IR-CO relation. (3) OHM hosts have exceptionally high dense molecular gas fractions, L(HCN)/L(CO)>0.07, and comprise roughly half of this unusual population. OH absorbers and kilomasers generally follow the linear IR-CO relation and are uniformly distributed in dense gas fraction and L(HCN), demonstrating that OHMs are independent of OH abundance. The fraction of non-OHMs with high mean densities and high dense gas fractions constrains beaming to be a minor effect: OHM emission solid angle must exceed 2 pi steradians. Contrary to conventional wisdom, IR luminosity does not dictate OHM formation; both star formation and OHM activity are consequences of tidal density enhancements accompanying galaxy interactions. The OHM fraction in starbursts is likely due to the fraction of mergers experiencing a temporal spike in tidally driven density enhancement. OHMs are thus signposts marking the most intense, compact, and unusual modes of star formation in the local universe. Future high redshift OHM surveys can now be interpreted in a star formation and galaxy evolution context, indicating both the merging rate of galaxies and the burst contribution to star formation.Comment: 5 pages, 3 figures, 1 table, accepted by ApJ Letter

    The Observed Trend of Boron and Oxygen in Field Stars of the Disk

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    Oxygen abundances are derived in a sample of 13 field F and G dwarfs and subgiants with metallicities in the range of -0.75 < [Fe/H] < +0.15. This is the same sample of stars for which boron abundances have been derived earlier from archived spectra obtained with the Hubble Space Telescope. In a log-log comparison of the B versus the O abundances, a slope of m(BO)=1.39 is found, indicating that in the disk, the abundance of B relative to O is intermediate between primary and secondary production (hybrid behavior). This relation of B versus O for disk stars is compared to the same relation for halo stars.Comment: 14 pages, 3 figures, 1 table. In press to The Astronomical Journal (July 2001

    GHOSTS I: A New Faint very Isolated Dwarf Galaxy at D = 12 +/- 2 Mpc

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    We report the discovery of a new faint dwarf galaxy, GHOSTS I, using HST/ACS data from one of our GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disk, and Star clusters) fields. Its detected individual stars populate an approximately one magnitude range of its luminosity function (LF). Using synthetic color-magnitude diagrams (CMDs) to compare with the galaxy's CMD, we find that the colors and magnitudes of GHOSTS I's individual stars are most consistent with being young helium-burning and asymptotic giant branch stars at a distance of 12 +/- 2 Mpc. Morphologically, GHOSTS I appears to be actively forming stars, so we tentatively classify it as a dwarf irregular (dIrr) galaxy, although future HST observations deep enough to resolve a larger magnitude range in its LF are required to make a more secure classification. GHOSTS I's absolute magnitude is MV=9.850.33+0.40M_V = -9.85^{+ 0.40}_{- 0.33}, making it one of the least luminous dIrr galaxies known, and its metallicity is lower than [Fe/H] =-1.5 dex. The half-light radius of GHOSTS I is 226 +/- 38 pc and its ellipticity is 0.47 +/- 0.07, similar to Milky Way and M31 dwarf satellites at comparable luminosity. There are no luminous massive galaxies or galaxy clusters within ~ 4 Mpc from GHOSTS I that could be considered as its host, making it a very isolated dwarf galaxy in the Local Universe.Comment: 8 pages, 7 figures. Accepted for publication in Ap

    Stellar intensity interferometry: Experimental steps toward long-baseline observations

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    Experiments are in progress to prepare for intensity interferometry with arrays of air Cherenkov telescopes. At the Bonneville Seabase site, near Salt Lake City, a testbed observatory has been set up with two 3-m air Cherenkov telescopes on a 23-m baseline. Cameras are being constructed, with control electronics for either off- or online analysis of the data. At the Lund Observatory (Sweden), in Technion (Israel) and at the University of Utah (USA), laboratory intensity interferometers simulating stellar observations have been set up and experiments are in progress, using various analog and digital correlators, reaching 1.4 ns time resolution, to analyze signals from pairs of laboratory telescopes.Comment: 12 pages, 3 figur

    Bacterial transcriptional response to labile exometabolites from photosynthetic picoeukaryote Micromonas commoda

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    Dissolved primary production released into seawater by marine phytoplankton is a major source of carbon fueling heterotrophic bacterial production in the ocean. The composition of the organic compounds released by healthy phytoplankton is poorly known and difficult to assess with existing chemical methods. Here, expression of transporter and catabolic genes by three model marine bacteria (Ruegeria pomeroyi DSS-3, Stenotrophomonas sp. SKA14, and Polaribacter dokdonensis MED152) was used as a biological sensor of metabolites released from the picoeukaryote Micromonas commoda RCC299. Bacterial expression responses indicated that the three species together recognized 38 picoeukaryote metabolites. This was consistent with the Micromonas expression of genes for starch metabolism and synthesis of peptidoglycan-like intermediates. A comparison of the hypothesized Micromonas exometabolite pool with that of the diatom Thalassiosira pseudonana CCMP1335, analyzed previously with the same biological sensor method, indicated that both phytoplankton released organic acids, nucleosides, and amino acids, but differed in polysaccharide and organic nitrogen release. Future ocean conditions are expected to favor picoeukaryotic phytoplankton over larger-celled microphytoplankton. Results from this study suggest that such a shift could alter the substrate pool available to heterotrophic bacterioplankton

    Ensemble-based docking: From hit discovery to metabolism and toxicity predictions

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    This paper describes and illustrates the use of ensemble-based docking, i.e., using a collection of protein structures in docking calculations for hit discovery, the exploration of biochemical pathways and toxicity prediction of drug candidates. We describe the computational engineering work necessary to enable large ensemble docking campaigns on supercomputers. We show examples where ensemble-based docking has significantly increased the number and the diversity of validated drug candidates. Finally, we illustrate how ensemble-based docking can be extended beyond hit discovery and toward providing a structural basis for the prediction of metabolism and off-target binding relevant to pre-clinical and clinical trials
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