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At least 19 records

Guanajuato Policy Options for Land Transportation Greenhouse Gas Reduction [Slides]

NREL consulted the Mexican state of Guanajuato to help them identify and prioritize policies that are specifically applicable to their land transportation system and help them meet their greenhouse gas (GHG) reduction goals. Three focus groups were held across Guanajuato to get the input from a wide variety of users of the transportation system. These focus groups performed a SWOT (strengths, weaknesses, opportunities and threats) analysis of Guanajuato's transportation system and logged the policy goals of participants. NREL then developed a menu of policy options that have been used successfully in relevant countries and prioritized these policies based on the weighted input from stakeholder groups. The most applicable policies were a paid parking strategy, regional transit master plan, and expanded bike and pedestrian infrastructure. Case studies of these three policies, plus a few more, were then presented to inform Guanajuato of how these policies could successfully be implemented. Finally, the GHG reductions for five of the most applicable policies were estimated to reduce emissions from Guanajuato's land transportation system nearly 40% below business-as-usual emissions by 2050.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Design and Demonstration of a NH3-Fueled Two-Stroke Uniflow Engine for Greenhouse Gas Reduction

The maritime shipping industry is growing increasingly interested in both low and non-carbon-containing fuels to meet future greenhouse gas emission targets. Specifically of interest is ammonia, as it has a relatively high volumetric energy density compared to other future fuels, such as hydrogen, making it more economical to transport. The robust engine architecture of low-speed two-stroke marine engines makes them an ideal candidate for ammonia fuel, overcoming many of the issues surrounding its poor ignitability and low flame speed. If emissions and fueling system challenges can be addressed, retrofits of current low-speed two-stroke dual-fuel engines represent a viable pathway for bringing ammonia engines to market. This study explores these technical hurdles by describing the design, analysis, and experimental validation of a single cylinder research engine converted to operate on ammonia fuel. The engine is a reduced-scale uniflow two-stroke marine engine with two previous hardware configurations available – diesel and high-pressure CNG dual-fuel. A concept study was used to evaluate possible ammonia-fueled engine architectures and the associated tradeoffs and design considerations. With the chosen architecture, low-pressure dual fuel, 1D and 3D analysis tools were used to inform hardware selection and to determine hardware configurations which minimized ammonia-slip. In addition to these considerations the hardware and engine configuration were designed to provide a versatile and robust testing platform. This includes options to test both gaseous and liquid ammonia injection, as well as a wide range of performance parameters such as AFR, swirl, valve timing, SOI, and many others. Design constraints imposed by the existing engine hardware necessitated an iterative loop between design and analysis toolsets, ultimately converging on a final design for the ammonia-conversion hardware. The engine was rebuilt with the new hardware and evaluated in an engine test cell. A new control strategy developed and flashed onto a prototyping electronic control unit allowed for full control over all engine parameters. An initial calibration was developed, providing test data for validation of the engine 1D and 3D models. The impact of the design choices on engine operability and the ability to meet program targets is discussed as well as opportunities for further optimization of the ammonia-conversion hardware, informed by the validated models.

Kaul, Brian [ORNL] (ORCID:0000000184813620)↗

The Role of Synthetic Biology in Atmospheric Greenhouse Gas Reduction: Prospects and Challenges

The long atmospheric residence time of CO 2 creates an urgent need to add atmospheric carbon drawdown to CO 2 regulatory strategies. Synthetic and systems biology (SSB), which enables manipulation of cellular phenotypes, offers a powerful approach to amplifying and adding new possibilities to current land management practices aimed at reducing atmospheric carbon. The participants (in attendance: Christina Agapakis, George Annas, Adam Arkin, George Church, Robert Cook-Deegan, Charles DeLisi, Dan Drell, Sheldon Glashow, Steve Hamburg, Henry Jacoby, Henry Kelly, Mark Kon, Todd Kuiken, Mary Lidstrom, Mike MacCracken, June Medford, Jerry Melillo, Ron Milo, Pilar Ossorio, Ari Patrinos, Keith Paustian, Kristala Jones Prather, Kent Redford, David Resnik, John Reilly, Richard J. Roberts, Daniel Segre, Susan Solomon, Elizabeth Strychalski, Chris Voigt, Dominic Woolf, Stan Wullschleger, and Xiaohan Yang) identified a range of possibilities by which SSB might help reduce greenhouse gas concentrations and which might also contribute to environmental sustainability and adaptation. These include, among other possibilities, engineering plants to convert CO 2 produced by respiration into a stable carbonate, designing plants with an increased root-to-shoot ratio, and creating plants with the ability to self-fertilize. A number of serious ecological and societal challenges must, however, be confronted and resolved before any such application can be fully assessed, realized, and deployed.

59 BASIC BIOLOGICAL SCIENCES↗

Biofuel Production and Greenhouse Gas Reduction Potential

Under two biomass supply scenarios presented in this study, between 56 and 81 B GGE/year of biofuel could be produced. The corresponding GHG reduction potential is between to 410 million 635 billion Mt CO2e/year. This volume of biofuel is sufficient to replace a majority of fuel demand in hard-to-electrify aviation, marine, rail and off-road transportation by 2050. Through pathway selection and process design, sufficient sustainable aviation fuel (SAF) could be produced to exceed the projected 35 B gpy of domestic aviation fuel demand by 2050. The external hydrogen required to produce this volume of fuel is estimated to be between 3.5 to 5.2 Mt/year.

09 BIOMASS FUELS↗

Framework for Greenhouse Gas Emissions Reduction Planning: Industrial Portfolios

The Framework for Greenhouse Gas Emissions Reduction Planning: Industrial Portfolios articulates a process to help industrial organizations develop a specific, actionable plan to achieve Scope 1 and Scope 2 greenhouse gas (GHG) emissions reduction – an Emissions Reduction Plan (ERP). An ERP covers an entire portfolio of facilities, yet contains enough detail to be practically useful at the facility level.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Framework for Greenhouse Gas Emissions Reduction Planning: Building Portfolios

The goal of this framework for greenhouse gas (GHG) emissions reduction planning (ERP) is to provide guidance to organizations seeking to reduce GHG emissions for their building portfolios and vehicle fleets. The process described in this framework helps organizations develop an actionable plan that prioritizes emissions reduction measures, identifies solutions, and lays out a phased pathway to achieve deep emissions reductions. The plan aims to result in the achievement of Scope 1 and 2 GHG emissions reduction targets, in alignment with goals set within the U.S. Department of Energy’s (DOE’s) Better Climate Challenge, as well as longer term emissions reduction goals.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Framework for Greenhouse Gas Emissions Reduction Planning: Building Portfolios

The goal of this Framework for greenhouse gas (GHG) emissions reduction planning (ERP) is to provide guidance to organizations seeking to reduce GHG emissions for their building portfolios and vehicle fleets. The process described in this framework helps organizations develop an actionable plan that prioritizes emissions reduction measures, identifies solutions, and lays out a phased pathway to achieve deep emissions reductions The plan aims to result in the achievement of Scope 1 and 2 GHG emissions reduction targets, in alignment with goals set within the U.S. Department of Energy’s (DOE’s) Better Climate Challenge, as well as longer term emissions reduction goals.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

PCAST: Report to the President on Accelerating Effective Reduction of Greenhouse Gas Emissions

The President’s Council of Advisors on Science and Technology (PCAST) is the sole body of advisors from outside the federal government charged with making science, technology, and innovation policy recommendations to the President and the White House. Established by Executive Order, it is an independent Federal Advisory Committee comprised of distinguished individuals from industry, academia, and non-profit organizations with a range of perspectives and expertise. On February 20, 2024, PCAST sent a report to the President with recommendations to expedite the reduction of greenhouse gas emissions through whole-of-country coordinated efforts and expanded assessment and verification systems.

54 ENVIRONMENTAL SCIENCES↗

Life-cycle greenhouse gas emissions reduction potential for corn ethanol refining in the USA

This study evaluates how low-carbon production technologies applicable to ethanol plants may reduce the life-cycle greenhouse gas emission (GHG) intensities of corn ethanol production in the USA. Results indicate that options focusing on incremental energy efficiency (e.g., combined heat and power) and yield improvements have a limited impact on GHG reductions. To achieve deep decarbonization (>50% GHG reduction compared to current corn ethanol production), a fuel switch from natural gas (NG) to alternative low-carbon fuels is needed. Replacing 50% of NG demand at ethanol plants with syngas from biomass through gasification or renewable natural gas from animal waste could achieve significant GHG reductions (11.7–23.5 g CO 2 e/MJ ethanol). Adding multiple technologies, including carbon capture and storage, to existing ethanol plants may further reduce GHG emissions to –18.4 g CO 2 e MJ –1 ethanol (including land-use change emissions), which is 120% lower than the carbon intensity of pure gasoline. These results could inform how the ethanol industry could move toward net-zero ethanol production.

09 BIOMASS FUELS↗

Analyzing Potential Greenhouse Gas Emissions Reductions from Plug-In Electric Vehicles: Report for CRC Project, "Carbon Return on Investment for Electrified Vehicles"

Investment in battery and electrification technologies has the potential to greatly reduce vehicular greenhouse gas (GHG) emissions, as a battery-electric vehicle (BEV) will have zero tailpipe emissions. However, there will be GHG emissions associated with production of the vehicle including its battery, and with any carbon-emitting electricity sources used to charge the vehicle. This study explores the GHG reduction benefits of different plug-in electric vehicle (PEV) designs in the context of factors such as electricity production mix, per-vehicle battery requirements, and varying battery market growth scenarios. The analyses focus on the U.S. light-duty vehicle (LDV) market, which accounts for nearly 60% of U.S. transportation sector GHG emissions - over twice as much as the next largest contributing transportation sub-sector.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Adoption of Plug-in Electric Vehicles: Local Fuel Use and Greenhouse Gas Emissions Reductions Across the U.S.

The dependence on gasoline-powered light-duty automobiles has made U.S. households vulnerable to the burden of fuel costs. Tailpipe emissions from these vehicles constitute 58% of greenhouse gas (GHG) emissions in the U.S., which are damaging to the environment (EPA, 2023). The adoption of plug-in electric vehicles (PEVs) has been shown to effectively reduce fuel costs and GHG emissions. However, local effects on these benefits are not well understood by American consumers, potentially limiting adoption and therefore the realization of PEV benefits at scale (MacInnis & Krosnick, 2020; EY Americas, 2023). To fill this research gap, this study estimates the fuel cost savings and GHG emission reductions at the state and ZIP code levels by considering local fuel prices, vehicle class preference, average vehicle model year, fuel efficiencies, and driving intensities. The study's findings reveal that the adoption of PEVs can yield substantial benefits in terms of fuel cost savings and GHG emission reductions nationwide. Specifically, driving a battery electric vehicle (BEV) is estimated to result in annual savings of up to $\$2,200$, while driving a plug-in hybrid electric vehicle (PHEV) can lead to savings up to $\$1,500$, when compared to an internal combustion engine vehicle (ICEV) of equivalent size. Moreover, using population-weighted averages by ZIP code, BEVs and PHEVs show the potential to save 400 and 200 grams of carbon dioxide equivalent per mile, respectively, compared to a representative ICEV of the same class. The magnitude of fuel cost savings and emissions reduction vary by region due to various factors. Generally, regions with high gasoline prices, low electricity prices, preferences for larger vehicles, and high driving intensities tend to see relatively large fuel savings. The emissions reductions are more pronounced in areas with clean grids where consumer preferences lie with large vehicles. This regional variability underscores the importance of considering local contextual factors when assessing the potential benefits of PEV adoption. In more than 99% of U.S. ZIP codes, PEVs result in overall savings in fuel use (and subsequent costs) and GHG emissions. While not a central focus of this analysis, reductions in GHG tailpipe emissions from PEV adoption would also come with reductions in criteria pollutant emissions, contributing to improved local air quality depending on the PEV penetration, population density, and electricity generation infrastructure in the locality.

33 ADVANCED PROPULSION SYSTEMS↗

Retrospective analysis of the U.S. corn ethanol industry for 2005–2019: implications for greenhouse gas emission reductions

Since 2000, corn ethanol production in the USA has increased significantly – from 1.6 to 15 billion gallons (6.1 to 57 billion liters) – due to supportive biofuel policies. In this study, we conduct a retrospective analysis of the changes in US corn ethanol greenhouse gas emission intensity, sometimes known as carbon intensity (CI), over the 15 years from 2005 to 2019. Our analysis shows a significant decrease in CI: from 58 to 45 gCO 2 e/MJ of corn ethanol (a 23% reduction). This is due to several factors. Corn grain yield has increased continuously, reaching 168 bushels/acre (10.5 metric tons/ha, a 15% increase) while fertilizer inputs per acre have remained constant, resulting in decreased intensities of fertilizer inputs (e.g., 7% and 18% reduction in nitrogen and potash use per bushel of corn grain harvested, respectively). A 6.5% increase in ethanol yield, from 2.70 to 2.86 gal/bushel corn (0.402 to 0.427 L kg -1 corn), and a 24% reduction in ethanol plant energy use, from 32 000 to 25 000 Btu/gal ethanol (9.0 to 6.9 MJ L -1 ethanol) also helped reduce the CI. The total GHG emission reduction benefits through the reduction in the CI and increased ethanol production volume are estimated at 140 million metric tons (MMT) from 2005 to 2019 in the ethanol industry. Displacement of petroleum gasoline by corn ethanol in the transportation fuel market resulted in a total GHG emission reduction benefit of 544 MMT CO 2 e during the period 2005 to 2019.

09 BIOMASS FUELS↗

High-ambition climate action in all sectors can achieve a 65% greenhouse gas emissions reduction in the United States by 2035

Under the next cycle of target setting under the Paris Agreement, countries will be updating and submitting new nationally determined contributions (NDCs) over the coming year. To this end, there is a growing need for the United States to assess potential pathways toward a new, maximally ambitious 2035 NDC. In this study, we use an integrated assessment model with state-level detail to model existing policies from both federal and non-federal actors, including the Inflation Reduction Act, Bipartisan Infrastructure Law, and key state policies, across all sectors and gases. Additionally, we develop a high-ambition scenario, which includes new and enhanced policies from these actors. We find that existing policies can reduce net greenhouse gas (GHG) emissions by 44% (with a range of 37% to 52%) by 2035, relative to 2005 levels. The high-ambition scenario can deliver net GHG reductions up to 65% (with a range of 59% to 71%) by 2035 under accelerated implementation of federal regulations and investments, as well as state policies such as renewable portfolio standards, EV sales targets, and zero-emission appliance standards. This level of reductions would provide a basis for continued progress toward the country’s 2050 net-zero emissions goal.

54 ENVIRONMENTAL SCIENCES↗

Greenhouse gas emissions reduction strategies that maximize portfolio-wide life cycle cost reduction, resilience, and environmental justice benefits

While strategies to achieve net-zero emissions at an individual site are well understood, new analysis methods are required for organizations seeking to achieve net-zero across multiple facilities, each with concurrent priority goals. At a portfolio level, distinct locations present varied challenges that cannot be addressed through singular solutions, and competing goals can take precedence with the assumption that net-zero emissions strategies deter from energy resilience and cost savings, therefore negatively impacting nearby communities. This study tests these assumptions by analyzing 16 diverse sites (varying in size, climate, and energy use) to identify strategies that reduce emissions and assess the impact these strategies have on life cycle costs, resilience, and communities with environmental justice concerns. Methods were developed to approximate missing information essential to net-zero evaluation. Established methods were augmented to evaluate life cycle costs, resilience, and environmental justice impacts across a set of strategies and accommodate the multi-criteria analyses. Potential benefits from identified strategies were quantified using site characteristics and a set of corresponding metrics. The net-zero analysis found that 11 sites could use on-site strategies to eliminate all but 2% of emissions generated. The remaining emissions can be offset, for instance through sequestration, executed at the portfolio scale. On-site carbon-free energy was found to reduce 51% of emissions across all sites; efficiency reduced 19% of emissions; sequestration 16%; procured carbon-free energy 15%; fuel switching 1.6%; and fleet electrification 1.3%. Building electrification, however, increased emissions by 4.4%. Different strategies also provide cost, resilience, and/or environmental justice benefits—the degree to which varies with individual site conditions. The findings indicate an advantage to considering the strategies as a comprehensive set, which leads to co-benefits, both in the ability to achieve net-zero goals and in advancing other goals. The results present the case for comprehensive advanced planning at the portfolio level to prioritize investments that will balance the minimization of emissions and life cycle cost with the maximization of resilience and environmental justice benefits. The novel methods for evaluation and integration, valuation of benefits, and consideration at the portfolio scale allow organizations to select investments that simultaneously address multiple key priorities.

Net-Zero Emissions↗

The geographies, typologies, and trends of community-based organizations for solar energy in the United States

Community-based organizations (CBOs)1 play an important role in developing solar energy in low- and moderate-income (LMI) communities. This article shares the perspectives of CBO leaders in LMI communities, identifies and addresses solar information gaps, and provides recommendations State Energy Agencies and other government leaders can use to better involve CBOs in solar program initiatives. Using semi-structured interviews and focus groups with CBOs from across the United States (US) we develop typologies of CBO structure and function, and determine the primary motivations, challenges, opportunities, and communication barriers CBOs face. We explore the correlation between key typologies such as tenure, staff capacity, population served, organizational structure, and region with the organizational activities performed by solar-related CBOs. CBOs operate in disparate regional political and economic ecologies. Our findings suggest strategies for states to support their engagement in solar-related endeavors, particularly with respect to the dissemination of the Bipartisan Infrastructure Law, Inflation Reduction Act, and the EPA Greenhouse Gas Reduction Fund: Solar for All. Developing policies that encourage CBOs to enter the solar training and installation domains, alongside targeted grants and capacity-building initiatives can help maximize community benefits. Furthermore, states can additionally contribute to the positive trajectory and collaboration between state agencies and CBOs in advancing solar energy adoption by fostering a supportive environment.

14 SOLAR ENERGY↗

Recovery of Natural Gas Equipment Emissions into Gas Compression Engines for the Reduction of Potential Greenhouse Gas Emissions

Since the turn of the millennium, the United States (U.S.) oil and natural gas (ONG) industry has nearly doubled its natural gas production rate. As a result, the ONG industry has recently come under increasing scrutiny for its contributions to greenhouse gas (GHG) emissions. Consequently, various solutions to this problem have been proposed and formulated to reduce the impacts of GHG emissions on the environment. West Virginia University (WVU) have found it important to research the impacts of recovering vented gas streams into prime-mover engines. The U.S. Department of Energy (DOE) and National Energy Technology Laboratory (NETL) have granted WVU funding to research and develop a “Methane Mitigator” (M2) - a “Scalable Vent Mitigation Strategy to Simultaneously Reduce Methane Emissions and Fuel Consumption from the Compression Industry.” One of the main areas of interest for this research was the collection of emissions from natural gas equipment into a Caterpillar G3508J natural gas compression engine. The parameters being analyzed from the engine were brake-specific emissions and power output. The emissions sources considered for this research were pneumatic controllers (PCs), reciprocating compressor vents, and the engine’s open crankcase breather. The compressor vent and PC emissions were simulated using a mass flow controller (MFC) and flowed into the engine using two separate methods: (1) directly into the air intake, and (2) through a retrofitted closed crankcase ventilation system (CCV), serving as a buffer volume. The crankcase emissions were quantified without the CCV, and the impact on exhaust emissions from circulating the crankcase gases into the intake was measured. The simulated compressor vent and PC flows from the MFC had limited effect on the steady state operation of the engine and resulting performance. When the simulated flows were fed directly into the engine’s air intake, the changes within the engine’s continuous performance and emission parameters were larger but lasted for shorter durations. Conversely, when the simulated flows were fed into the CCV before entering the air intake, the changes in the engine’s performance and emission parameters were less pronounced for continuous analysis but lasted for longer durations. In either case, the continuous emission changes in both emissions and performance varied in size depending on the test scenario being run, but the cycle average changes in emissions and performance showed little impact overall compared to the engine’s baseline operation. As a result, the inclusion of a CCV shows a decrease in baseline carbon dioxide equivalent (CO2-eq.) engine emissions (from combined exhaust and open crankcase) of almost 4%. Likewise, the CCV inclusion reduced baseline total methane (CH4) from combined exhaust and open crankcase by upwards of 16%. These atmospheric emissions only decreased further with the inclusions of collected PC and compressor vent flows. The resulting changes in time-averaged rated exhaust behavior (or lack thereof) prove that the proposed M2 system could likely be deployed at sites with modern lean-burn natural gas engines as a viable option for reducing and eliminating potential GHG sources that would have otherwise been unutilized as energy sources.

03 NATURAL GAS↗

The future of ship engines: Renewable fuels and enabling technologies for decarbonization

Shipping is one of the most efficient transportation modes for moving freight globally. International regulations concerning decarbonization and emission reduction goals drive rapid innovations to meet the 2030 and 2050 greenhouse gas reduction targets. The internal combustion engines used for marine vessels are among the most efficient energy conversion systems. Internal combustion engines dominate the propulsion system architectures for marine shipping, and current marine engines will continue to serve for several decades. However, to meet the aggressive goals of low-carbon-intensity shipping, there is an impetus for further efficiency improvement and achieving net zero greenhouse gas emissions. These factors drive the advancements in engine technologies, low-carbon fuels and fueling infrastructure, and emissions control systems. This editorial presents a perspective on the future of ship engines and the role of low-life cycle-carbon-fuels in decarbonizing the marine shipping sector. A selection of zero-carbon, net-zero carbon, and low-lifecycle-carbon-fuels are reviewed. This work focuses on the opportunities and challenges of displacing distillate fossil fuels for decarbonizing marine shipping. In conclusion, enabling technologies such as next-generation air handling, fuel injection systems, and advanced combustion modes are discussed in the context of their role in the future of low-CO 2 intensity shipping.

33 ADVANCED PROPULSION SYSTEMS↗

Clean Air Policies Are Key for Successfully Mitigating Arctic Warming

A tighter integration of modeling frameworks for climate and air quality is urgently needed to assess the impacts of clean air policies on future Arctic and global climate. We combined a new model emulator and comprehensive emissions scenarios for air pollutants and greenhouse gases to assess climate and human health co-benefits of emissions reductions. Fossil fuel use is projected to rapidly decline in an increasingly sustainable world, resulting in far-reaching air quality benefits. Despite human health benefits, reductions in sulfur emissions in a more sustainable world could enhance Arctic warming by 0.8 °C in 2050 relative to the 1995–2014, thereby offsetting climate benefits of greenhouse gas reductions. Targeted and technically feasible emissions reduction opportunities exist for achieving simultaneous climate and human health co-benefits. It would be particularly beneficial to unlock a newly identified mitigation potential for carbon particulate matter, yielding Arctic climate benefits equivalent to those from carbon dioxide reductions by 2050.

Atmospheric chemistry↗