Browsing by Subject "Greenhouse gas"

Now showing 1 - 6 of 6
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    An Environmental and Economic Analysis of Converting Duke University’s Police Fleet to Alternatively Powered Vehicles
    (2014-04-17) Culver, John
    Despite contributing only a small portion of total campus greenhouse gas emissions (GHG), Duke University’s Police fleet serves as a visible platform for demonstrating progress toward the University’s commitment to be carbon neutral by 2024. However, before the fleet can be modernized, adequate vehicle replacements are needed. By working with the Duke University’s Police Department and Duke’s Sustainability Office, an in-depth analysis of fleet characteristics and officer needs was performed with the intention of identifying suitable alternatively fueled or powered replacement fleet vehicles. By focusing on minimizing lifetime costs, annual fuel costs, and lifetime carbon dioxide (CO2) emissions, multiple vehicles and technologies have shown the potential to reduce lifetime fuel costs by over $100,000 and lifetime GHG emissions by 200 tons.
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    An Evaluation of Participation in Voluntary Greenhouse Gas Tracking and Reduction Programs
    (2008-08-27T23:51:57Z) Albertson, Katharine M.
    The debate on climate change has moved from a question of whether humans are responsible to how best to address man-made greenhouse gas (GHG) emissions that are the cause. The United States has yet to pass any legislation that aggressively and appropriately addresses this issue. In the absence of legislation mandating emission reductions, many voluntary GHG tracking and reduction programs have surfaced. The main objective of this project is to profile the participants of three differing GHG tracking and reduction programs in order to determine specific criteria used when deciding to join a particular program. The results conclude that the sector of the participant company could be a major determining factor when joining a voluntary program. Those companies in the highest emitting sectors tend to join the least stringent voluntary program that does not include reduction goals. Additionally, companies that are publically traded and produce end products for consumer use are more likely to join a more rigorous program that contains reduction goals. Finally, the creation of regulations for voluntary programs could serve as a basis for future mandatory legislation.
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    Reducing US Greenhouse Gas Emissions through a Replacement of Coal with Natural Gas in Power Generation
    (2010-04-29T21:52:36Z) Crowe, Parker D
    Currently, coal provides about 50% of U.S. electricity supply and releases 80% of electricity sector carbon dioxide (Annual Energy Outlook Early Release Overview, 2009). A conceptual instantaneous switch to modern natural gas plants of the same capacity would reduce these carbon dioxide emissions by 74% or 1.5 annual gigatons at the cost of $300 billion in construction capital and an increase in electricity rates of approximately 15%. This analysis is accomplished primarily through a comparison of derived marginal cost functions for gas and coal generation under the assumption that fuel choice for baseload power is driven primarily by the lowest available cost of operation. The use of comparative supply curves demonstrates the extent of the cost disadvantage of gas to coal and allows analysis of possible future scenarios through manipulation of model inputs of fuel and emissions costs. In order for gas power to become less expensive than that from coal, either the price of gas must fall or the price of coal must rise. Two likely future developments might cause both of these changes to occur. Newly expected natural gas supply from unconventional sources and international trade of liquefied methane will put downward pressure on gas prices. Perhaps at the same time, a U.S. federal climate law could introduce a price on carbon emissions which would disproportionately raise the price of coal power. This analysis shows that either situation will promote gas power if of great enough magnitude. The likelihood of a transition away from coal remains questionable but coal is no longer the obvious fuel choice in new baseload power plant construction.
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    Roadmap for Achieving Biogen’s Scope 3 Science-Based Target
    (2019-04-25) Barnes, Madison; Barry, Dieynabou; Coral Castellanos, Temis; Meltzer, Jeffrey
    Biogen has set a Science-Based Target (SBT) to reduce its absolute greenhouse gas (GHG) emissions 35 percent across its entire value chain (scopes 1, 2, and 3) by 2030 from a 2013 base-year. In this project, we focused primarily on scope 3 emissions for two reasons: (1) 70 percent of Biogen’s total emissions fall under scope 3 and (2) scope 3 emissions are the most difficult to reduce because suppliers are chiefly responsible for them and Biogen has little direct control over these emissions. This project provides recommendations for Biogen to meet its scope 3 emissions reduction goal. Through industry research, interviews with experts, and analyses of general supply chain emissions reductions trends and company data, we developed an internal, external, and industry-wide roadmap that identifies the most critical business practices to reaching Biogen’s SBT. Our research shows that these recommendations will strengthen Biogen’s reputation as a sustainability leader, attract and retain investors, mitigate climate-related risks to its business operations, and lead to higher financial performance.
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    The effects of biochar on wetland and agricultural soil carbon and nitrogen emissions in North Carolina
    (2016-04-29) Keenan, Chandler
    Biochar is an increasingly popular topic in environmental management due to its potential effects on several ecosystem functions. Specifically, biochar has been linked to significant reductions in greenhouse gas emissions, including nitrous oxide, carbon dioxide and methane when used as a soil amendment. It has also been suggested as a long term mechanism to sequester carbon in soil. The magnitude of such an effect is highly dependent on a variety of environmental factors, as well as the feedstock and temperature at which the char was produced, so it is essential to put biochar studies in specific land use contexts to fully understand its potential impacts. Additionally, naturally occurring char material is a byproduct of prescribed burns and wildfires in fire-adapted ecosystems such as North Carolina peatlands. It is unclear to what extent this naturally occurring char aids in greenhouse gas suppression in these carbon sinks. In order to fully understand the existing and potential role of biochar for land use management in North Carolina, an experiment was designed to quantify the effect of biochar on soil greenhouse gas emission. This experiment looked at agricultural soils, organic peat soils, and heated peat soils. Treatment groups received a 10% by weight char amendment and incubated in the lab for seven months. Gas samples were collected from the headspace to determine gas emissions over time. This study finds modest effects of biochar on greenhouse gas emissions. Char-amended agricultural soils saw reduced nitrous oxide emissions, but increased carbon dioxide emissions. Peat soils saw non-significant reductions in emission rates for all three gases, including a 12% reduction in net methane emission and a 9% reduction in average carbon dioxide emission. Heated peat, which was produced to simulate the effect of a prescribed burn, released large amounts of carbon dioxide and methane in the first sampling date but stabilized to low levels after 17 days. This resulted in heated peat having net positive methane emissions, but lower net carbon dioxide outputs as compared to unheated peat. This study therefore finds evidence that fire regimes in natural peatlands disrupt normal carbon cycling even without igniting the peat, but that the presence of char in the soil contributes to stable carbon storage and greenhouse gas suppression. Effects on nitrogen flux from soils are less clear because changes in emission are driven by difference on individual sampling dates and not any apparent trend over time. Biochar addition to wetland peat soils may be a potential avenue for decreasing greenhouse gas emissions in order to maximize ecosystem services like carbon sequestration from these crucial habitats. However, more research is needed to understand impacts of biochar for agricultural management since results in this study were inconclusive. Additionally, the interaction of soil moisture and biochar on gas flux and a more holistic microcosm study design are recommended as future avenues for research.
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    Wal-Mart's Supply Chain Greenhouse Gas Analysis
    (2007-12-07T16:24:12Z) Jennrich, Katherine
    As part of Wal-Mart’s Sustainability 360 initiative, the company seeks to find and eliminate greenhouse gases (GHGs) in its products. Wal-Mart plans to engage its supply chain in a product-level analysis of GHGs. Ultimately, Wal-Mart plans to use a carbon scorecard for two purposes: (1) as a merchandising department tool to reward suppliers that demonstrate superior environmental performance, and (2) as a business development tool in other departments at Wal-Mart. This master’s project examines the initial pilot phase of the supply chain initiative, designed with three questions in mind: Where is the carbon in the supply chain? Can a dual-purpose scorecard exist? Is this scorecard commercially viable? The pilot introduced 35 vendors from 7 product categories to carbon footprinting and gave them a Carbon Disclosure Project (CDP) questionnaire specifically designed for Wal-Mart suppliers. The questionnaire requires the vendors to reach one step back in their own supply chain to determine direct and indirect sources of GHGs allocated to the products they make. The questionnaire results indicate a wide range of embedded carbon values and provide insight into the energy intensity of packaging formats; however, pilot participant feedback indicates data inaccuracy due to low response rates from vendors’ suppliers. Because it is infeasible to engage closely with Wal-Mart’s approximately 66,000 suppliers, focus after the pilot needs to concentrate on the most energy intensive products. Life cycle analyses (LCAs) of Wal-Mart’s 3,000 retail product categories can identify 20 percent (approximately 600) of the categories that are (1) most energy intensive, (2) show the greatest sales volume, and (3) provide Wal-Mart with an opportunity to assist in energy efficiency. Wal-Mart will ask representatives of the identified categories to fill out the CDP questionnaire. The resulting data will yield one of the two initiative purposes—Wal-Mart’s energy department could assist some suppliers in energy efficiency mechanisms, creating commercial viability for the scorecard. Fulfilling the second initiative will require a second scorecard to rate a firm’s climate strategy and yield a simple score Wal-Mart’s merchandising department can use to rank suppliers and reward top performers.