Search

Arbuscular mycorrhizal fungi (AMF) derived refractory organic matter, mainly in glomalin-related soil protein (GRSP), stores globally significant amounts of carbon, attracting wide attention in response to climatic change. However, there is no synthesis review has been done so far to reveal global research progresses on GRSP, especially its ecological role for climate mitigation. Here,we conducted a bibliometric analysis of the papers on GRSP research from 1998 to 2021, based on the Web of Science (WOS) Core Collection.We collected a total of 634 papers and analyzed the characteristics of publication outputs in various countries and institutions. In addition, keywords analysis was conducted to reveal the main research directions and hot trends in the field of GRSP. We confirmed that 1) the number of papers published per year has gradually increased since 2010, and increased sharply in 2019; 2) the United States was the earliest country to conduct GRSP research, while China currently has the largest number of publications; 3) relevant studies focus on the role from AMF and GRSP in soil health and plant health; 4) the contribution of GRSP to soil carbon and its ecological function in mitigating climate change are the hotspot of research. The benefits of GRSP have become a consensus, however, the nature of glomalin and the mechanisms of GRSP-associated benefits still need to explore. As an important soil recalcitrant organic carbon, further studies are need to elucidate the land-ocean biogeochemical processes of GRSP and its contribution to global blue carbon. [ABSTRACT FROM AUTHOR]

A method is suggested for estimating additions to carbon stored in harvested wood products (HWP) and for evaluating uncertainty. The method uses data on HWP production and trade from several decades and tracks annual additions to pools of HWP in use, removals from use, additions to solid waste disposal sites (SWDS), and decay from SWDS. The method is consistent with IPCC guidance for estimating emissions from SWDS. Uncertainty is postulated in the form of probability density functions for 14 variables, using Monte Carlo simulation. Results for the United States suggest that uncertainty is most sensitive to uncertainty in production data for solidwood products, the factor used to convert products to carbon, and the proportion of solidwood and paper in SWDS. Uncertainty in the use (service) life of solidwood products has a limited effect because an error offsets changes in products in use and in SWDS. The method provides a starting point for meeting the aims of the IPCC Good Practice Guidance. [ABSTRACT FROM AUTHOR]

This paper is written in response to the paper "How green is blue hydrogen?" by R. W. Howarth and M. Z. Jacobson. It aims at highlighting and discussing the method and assumptions of that paper, and thereby providing a more balanced perspective on blue hydrogen, which is in line with current best available practices and future plant specifications aiming at low CO2 emissions. More specifically, in this paper, we show that: (i) the simplified method that Howarth and Jacobson used to compute the energy balance of blue hydrogen plants leads to significant overestimation of CO2 emissions and natural gas (NG) consumption and (ii) the assumed methane leakage rate is at the high end of the estimated emissions from current NG production in the United States and cannot be considered representative of all‐NG and blue hydrogen value chains globally. By starting from the detailed and rigorously calculated mass and energy balances of two blue hydrogen plants in the literature, we show the impact that methane leakage rate has on the equivalent CO2 emissions of blue hydrogen. On the basis of our analysis, we show that it is possible for blue hydrogen to have significantly lower equivalent CO2 emissions than the direct use of NG, provided that hydrogen production processes and CO2 capture technologies are implemented that ensure a high CO2 capture rate, preferably above 90%, and a low‐emission NG supply chain. [ABSTRACT FROM AUTHOR]

Many studies anticipate that carbon capture and sequestration (CCS) will be essential to decarbonizing the U.S. economy. However, prior work has not estimated the time required to develop, approve, and implement a geologic sequestration site in the United States. We generate such an estimate by identifying six clearance points that must be passed before a sequestration site can become operational. For each clearance point (CP), we elicit expert judgments of the time required in the form of probability distributions and then use stochastic simulation to combine and sum the results. We find that, on average, there is a 90% chance that the time required lies between 5.5 and 9.6 y, with an upper bound of 12 y. Even using the most optimistic expert judgements, the lower bound on time is 2.7 y, and the upper bound is 8.3 y. Using the most pessimistic judgements, the lower bound is 3.5 y and the upper bound is 19.2 y. These estimates suggest that strategies must be found to safely accelerate the process. We conclude the paper by discussing seven potential strategies. [ABSTRACT FROM AUTHOR]

Forests in the United States provide important carbon sequestration services that could be leveraged for climate change mitigation. There is increased interest among decision makers and investors to extend forest carbon payment programs to family forest owners (FFOs), the largest category of private forest owners. Since FFOs manage forests for multiple objectives, it is unclear which contract requirements and payment levels will appeal to early adopters and perhaps establish the direction of innovation. To answer this question, we conducted a comprehensive review of the research literature assessing forest owner preferences for carbon payment programs. Out of 22 papers reviewed, a total of 13 stated preference studies were included in the meta-analysis. Robust regression modeling and benefit transfer techniques were used to generate estimates for carbon payment contracts for different categories of FFOs. Results show significant variation in forest owner willingness to accept (WTA) as a function of management objectives, contract length, number of forest acres, management plan requirement, and management restrictions. Average annual per acre payment values were lowest for conservation-oriented forest owners, followed by passive and production-oriented forest owners. Overall, findings suggest the need for diverse types of contracts and payment levels in order to have widespread participation in carbon programs by forest owners. [ABSTRACT FROM AUTHOR]

CO2 capture and storage (CCS) can be an important feature of a decarbonization strategy involving electricity generation. According to the recently revised Section 45Q tax credits, said credits will be provided for implementing CCS, which is motivating some United States (US) electricity generation companies to revisit their business strategies for CCS. This paper discusses alternative business models being considered by companies for undertaking CCS, including providing a 'template' for evaluating the cost‐effectiveness of CCS with Section 45Q tax credits and storage in saline reservoirs. Using stylized illustrative examples, the paper indicates how use of Section 45Q tax credits should be expected to change dispatch at an electricity generating unit. For situations similar to the examples, the paper suggests that Section 45Q tax credits may need to be modified to achieve its intended impact. Modifications can include extending the time period of tax credit availability beyond the current 12 years. In addition, continued R&D investments in CCS and specific support for first‐of‐a‐kind CCS demonstrations would be valuable complements for the deployment of the Section 45Q tax credit. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

To limit global warming and mitigate climate change, the global economy needs to decarbonize and reduce emissions to net-zero by mid-century. The asymmetries of the global energy system necessitate the deployment of a suite of decarbonization technologies and an all-of-the-above approach to deliver the steep CO2-emissions reductions necessary. Carbon capture and storage (CCS) technologies that capture CO2 from industrial and power-plant point sources as well as the ambient air and store them underground are largely seen as needed to address both the flow of emissions being released and the stock of CO2 already in the atmosphere. Despite the pressing need to commercialize the technologies, their large-scale deployment has been slow. Initial deployment, however, could lead to near-term cost reduction and technology proliferation, and lowering of the overall system cost of decarbonization. As of November 2019, more than half of global large-scale CCS facilities are in the USA, thanks to a history of sustained government support for the technologies. Recently, the USA has seen a raft of new developments on the policy and project side signaling a reinvigorated push to commercialize the technology. Analysing these recent developments using a policy-priorities framework for CCS commercialization developed by the Global CCS Institute, the paper assesses the USA's position to lead large-scale deployment of CCS technologies to commercialization. It concludes that the USA is in a prime position due to the political economic characteristics of its energy economy, resource wealth and innovation-driven manufacturing sector. [ABSTRACT FROM AUTHOR]

Energy from biomass is potentially an important contributor to U.S. climate change mitigation efforts. However, large-scale implementation of bioenergy competes with other uses of land, including agriculture and forest production and terrestrial carbon storage in non-commercial lands. And with trade, bioenergy could mean greater reliance on imported energy. Based on EMF-24 policy specifications, this paper explores these dimensions of bioenergy's role in U.S. climate policy and the relationship to alternative measures for ameliorating the trade and land use consequences. It shows how widespread use of biomass in the U.S. could lead to imports; and it highlights that the relative stringency of domestic and international carbon mitigation policy will heavily influence the amount of imports. It demonstrates that limiting biomass imports could alter the balance of trade in other agricultural products. Finally, it shows that increasing efforts to protect both U.S. and international forests could also affect the balance of trade in other agricultural products. [ABSTRACT FROM AUTHOR]

This paper develops structural dynamic methods to project future carbon fluxes in forests. These methods account for land management changes on both the intensive and extensive margins, both of which are critical components of future carbon fluxes. When implemented, the model suggests that U.S. forests remain a carbon sink through most of the coming century, sequestering 128 Tg C y-1. Constraining forestland to its current boundaries and constraining management to current levels reduce average sequestration by 25 to 28 Tg C y-1. An increase in demand leads to increased management and greater sequestration in forests. The results are robust to climate change. [ABSTRACT FROM AUTHOR]

Existing estimates of the climate mitigation potential from cropland carbon sequestration (C‐sequestration) are limited because they tend to assume constant rates of soil organic carbon change over all available cropland area, use relatively coarse land delineations, and often fail to adequately consider the agronomic and socioeconomic dimensions of agricultural land use. This results in an inflated estimate of the C‐sequestration potential. We address this gap by defining a more appropriate land base for cover cropping in the United States for C‐sequestration purposes: stable croplands in annual production systems that can integrate cover cropping without irrigation. Our baseline estimate of this suitable stable cropland area is 32% of current U.S. cropland extent. Even an alternative, less restrictive definition of stability results in a large reduction in area (44% of current U.S. croplands). Focusing cover crop implementation to this constrained land base would increase durability of associated C‐sequestration and limit soil carbon loss from land conversion to qualify for carbon‐specific incentives. Applying spatially‐variable C‐sequestration rates from the literature to our baseline area yields a technical potential of 19.4 Tg CO2e yr−1 annually, about one‐fifth of previous estimates. We also find the cost of realizing about half (10 Tg CO2e yr−1) of this potential could exceed 100 USD Mg CO2e−1, an order of magnitude higher than previously thought. While our economic analyses suggest that financial incentives are necessary for large‐scale adoption of cover cropping in the U.S., they also imply any C‐sequestration realized under such incentives is likely to be additional. Plain Language Summary: As a "Nature‐based Climate Solution" (NCS), the practice of cover cropping has received widespread attention and investment recently. Through cover cropping, croplands may be able to absorb and hold more carbon in soil, drawing down CO2 in the atmosphere (i.e., sequester carbon). However, the sequestration that is feasible, which reflects socioeconomic and land use considerations, remains unquantified. We estimate this feasible potential for carbon sequestration in the U.S. croplands from cover cropping and find it to be a fraction of previous estimates. A large portion of the reduction is due to our use of a more realistic and rigorous definition of the land area suitable for cover cropping for climate mitigation purposes. This land area comprises "croplands remaining croplands" (or stable croplands) that are planted to annual crops, like corn and soybeans, because they can more easily integrate the practice. We exclude irrigated croplands to conserve water resources. At just under 44 million ha, our baseline area estimate is 32% of the current U.S. cropland extent. The rest of the reduction is associated with our use of more conservative rates of increase in soil carbon from cover cropping than earlier studies that are more realistic for assessing soil carbon sequestration potential over large areas. Our economic analyses suggests that without financial incentives, implementing cover cropping could be expensive for most U.S. farmers. This high cost hurdle needs to be evaluated against the cost‐effectiveness of alternatives that compete for the same limited resources for climate mitigation. Key Points: For U.S. croplands, the feasible potential of carbon sequestration from cover cropping is a fraction of previous estimatesDefining the land base suitable for mitigation practices more realistically and rigorously is critical to estimating the feasible potentialCover cropping, though beneficial for soil health, may not be a low‐cost pathway for climate mitigation at scale in the U.S. [ABSTRACT FROM AUTHOR]

Carbon sequestration in the forests of the eastern United States is an important offset to the country's CO2 emissions. Much of the eastern forestland is the product of reforestation of abandoned agricultural land or recovery following clear‐cutting over a century ago. This has led to concerns that eastern forests are even‐aged and that rates of carbon sequestration will decline as forests increase in carbon. Our objective was to examine the successional dynamics of forest carbon sequestration—using live tree carbon stocks as a proxy for successional status—for the six broadly defined forest types present in the region. We used datasets from the National Forest Inventory (NFI) for the 31 US states from Minnesota south to Louisiana and eastward and analyzed live tree net carbon increment for 2007–2021, the period for which NFI plot remeasurement data were available for all 31 states. Spruce–fir and southern pines were the only forest types for which carbon increment declined even modestly over a significant fraction of the range of live tree carbon observed in the region, and southern pine–hardwood forests were the only forests in which predicted sequestration in live tree carbon declined to zero within the range of carbon stocks observed in the region. Northern hardwood–conifer forests, oak–hickory forests, and lowland forests experienced either no decline or a slight increase in sequestration in live tree carbon across the range of successional status observed in the region. Thus, the average stocks of live tree carbon per unit area increased steadily over the study period. At some point in succession, rates of mortality are expected to increase and balance gross growth, leading to zero net sequestration in live tree carbon. Mature and old‐growth stands, however, are rare in all six forest types, and mortality as a fraction of live tree carbon for all six forest types declined across the range of successional status present in the region. Our results thus provide no support for the hypothesis that the successional dynamics of forests in this region can be expected to lead to near‐term declines in net carbon sequestration. [ABSTRACT FROM AUTHOR]

Purpose — The purpose of this paper is to identify and describe key economic and policy-related issues with regard to terrestrial C sequestration and provide an overview of the economics of C sequestration on agricultural soils in the USA. Design/methodology/approach — Recent economic literature on carbon sequestration was reviewed to gather insights on the role of agriculture in greenhouse gas emissions mitigation. Results from the most salient studies were presented in an attempt to highlight the general consensus on producer-level responses to C sequestration incentives and the likely mechanisms used to facilitate C sequestration activities on agricultural soils. Findings — The likely economic potential of agriculture to store soil C appears to be considerably less than the technical potential. Terrestrial C sequestration is a readily implementable option for mitigating greenhouse gas emissions and can provide mitigation comparable in cost to current abatement options in other industries. Despite considerable research to date, many aspects of terrestrial C sequestration in the USA are not well understood. Originality/value — The paper provides a useful synopsis of the terms and issues associated with C sequestration, and serves as an informative reference on the economics of C sequestration that will be useful as the USA debates future greenhouse gas emissions mitigation policies. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Public Policy is the property of University of Toronto Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• UCCS research, initiated in the 1990s, is following a sigmoidal growth pattern. • No highly active research group has been identified in UCCS research. • USA and China are currently leading countries in UCCS research. • More systematic studies are required to promote UCCS for real applications. • Findings can be used by stakeholders such as governments, among others. In this study, a scientometric comprehensive analysis has been executed in order to explore the scientific situation of research efforts performed previously with regard underground CO 2 sequestration and encapsulation. To this end, a total of 1280 bibliographic records from the Web of Science (WoS) database were extracted and analysed to report the analysis of scientific state of the authors, journals, countries, and categories. Eventually, geospatial maps of the progress in this field are created and presented. As per the results obtained, efforts on this subject have been initiated significantly since 1990s. Scientific articles and proceeding papers share nearly 63% and 31% of the documents published. The results indicate that USA and China are the most contributing countries. Among the active journals, international journal of greenhouse gas control impact is the most active journal. It may be concluded that no highly active research group has yet been emerged. Hence, more supports and scientific efforts are needed to promote carbon dioxide capture and storage technologies. [ABSTRACT FROM AUTHOR]

This paper discusses the current guidance given by the United States Environmental Protection Agency (EPA) on delineating the so-called Area of Review (AoR) for the permitting of geologic carbon sequestration (GCS) projects. According to the EPA's regulatory framework for GCS, the AoR refers to the region surrounding the CO2 injection well(s) wherein leakage of CO2 and/or the migration of formation fluids could possibly endanger overlying groundwater resources. Our evaluation of the current framework for delineating the size of this area finds unnecessary conservatism in the definition of the critical pressure, which could lead to a heavy burden on permit applicants that seek to get regulatory compliance, in particular for very large GCS projects. We propose a risk-based re-interpretation of this framework, separating the total Area of Review into different sub-areas with different regulatory requirements depending on whether the concern is about free-phase CO2 or pressure-driven brine migration. This leads to a tiered AoR definition in which the projected region of CO2 plume extent would have the highest regulatory standards regarding site characterization, monitoring, and corrective action. The requirements in the AoR outside this central region would be less burdensome because of a narrower focus on major pathways for brine leakage such as unplugged wellbores and large faults. We expect that this revised framework would allow for a reduction in the cost of regulatory compliance for projects with very large injection volumes, while ensuring that the objective of protecting valuable groundwater resources is preserved. [ABSTRACT FROM AUTHOR]

SUMMARY To meet next generation energy needs such as wind- and solar-generated electricity, enhanced oil recovery (EOR), CO2 capture and storage (CCS), and biofuels, the US will have to construct tens to hundreds of thousands of kilometers of new transmission lines and pipelines. Energy network models are central to optimizing these energy resources, including how best to produce, transport, and deliver energy-related products such as oil, natural gas, electricity, and CO2. Consequently, understanding how to model new transmission lines and pipelines is central to this process. However, current energy models use simplifying assumptions for deploying pipelines and transmission lines, leading to the design of more costly and inefficient energy networks. In this paper, we introduce a two-stage optimization approach for modeling CCS infrastructure. We show how CO2 pipelines with discrete capacities can be 'linearized' without loss of information and accuracy, therefore allowing necessarily complex energy models to be solved. We demonstrate the new approach by designing a CCS network that collects large volumes of anthropogenic CO2 (up to 45 million tonnes of CO2 per year) from ethylene production facilities and delivers the CO2 to depleted oil fields to stimulate recovery through EOR. Utilization of anthropogenic CO2 has great potential to jumpstart commercial-scale CCS while simultaneously reducing the carbon footprint of domestic oil production. Model outputs illustrate the engineering challenge and spatial extent of CCS infrastructure, as well as the costs (or profits) of deploying CCS technology. We show that the new linearized approach is able to offer insights that other network approaches cannot reveal and how the approach can change how we develop future energy systems including transporting massive volumes of shale gas and biofuels as well as electricity transmission for wind and solar energy. Published 2012. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

This paper summarizes a strategy for supplying ecosystem services in urban areas through a participatory planning process targeting multifunctional green infrastructure. We draw from the literature on landscape multifunctionality, which has primarily been applied to agricultural settings, and propose opportunities to develop urban green infrastructure that could contribute to the sustainable social and ecological health of the city. Thinking in terms of system resilience, strategies might focus on the potential for green infrastructure to allow for adaptation and even transformation in the face of future challenges such as climate change, food insecurity, and limited resources. Because planning for multiple functions can be difficult when many diverse stakeholders are involved, we explored decision support tools that could be applied to green infrastructure planning in the early stages, to engage the public and encourage action toward implementing a preferred solution. Several specific ecosystem services that could be relevant for evaluating current and future urban green spaces include: plant biodiversity, food production, microclimate control, soil infiltration, carbon sequestration, visual quality, recreation, and social capital. Integrating such ecosystem services into small-scale greening projects could allow for creativity and local empowerment that would inspire broader transformation of green infrastructure at the city level. Those cities committing to such an approach by supporting greening projects are likely to benefit in the long run through the value of ecosystem services for urban residents and the broader public. [ABSTRACT FROM AUTHOR]

Abstract: Building sustainability assessments are driving greater market demand for sustainable buildings in the developed world. However, do such assessments actually demonstrate building sustainability? Some critics of building sustainability assessment argue that the methods should evolve toward an “absolute” assessment of building sustainability. That is, rather than assessing a building relative to a average like-type building as is typically done, the assessment should be made to whatever is deemed sustainable using a credible science. One possible form of absolute assessment is using the indicator of sustainability known as carrying capacity. After discussing the opportunities with a carrying-capacity-based assessment of buildings, this paper proposes a computational model that provides such an assessment. There are four main components to the presented computational model. The first is the amount of carbon (C) stored on the building site in its native state. This native-site carbon storage is defined as the baseline carbon storage and represents the carrying capacity of the building project. The second is land use change, which accounts for the removal or addition of vegetation and other carbon storing elements to the project site. The third and fourth carbon emissions sources in the model are building construction and operation. A building is considered sustainable in the model if by the end of its expected lifetime the total amount of carbon emissions are completely offset. Building designers and their clients can use this model to more comprehensively account for carbon emissions and identify options for reducing and offsetting them. To drive greater adoption, the model has been developed into an online resource, Green Footstep (www.greenfootstep.org). To demonstrate the usefulness of the model, this paper presents a case study of an institutional building in Lake Placid, Florida, USA. The case study shows that the design team used the model to better understand what it means to have a “low-carbon” goal. The model showed them that over one hundred years, the building project must reduce and offset carbon emissions at a rate of 16 tonnes C per year. [Copyright &y& Elsevier]

The Regional Greenhouse Gas Initiative for the northeastern states of the U.S. allows for terrestrial carbon (C) sequestration offsets generated by afforestation activities only. This paper estimates the maximum potential quantity and associated costs of increasing the storage of carbon by afforestation of existing agricultural land in the 11 states of the Northeast United States. The focus of the work was to describe location, the quantity, and at what cost it would be economically attractive to shift agricultural production to afforestation to increase carbon storage in the region. Widely available data sets were used to (1) identify spatially-explicit areas for lower costs carbon offsets and (2) estimate carbon supply curves related to afforestation of agricultural land over three time periods (10, 20, and 40 years). Carbon accumulation and total carbon offset project costs were estimated at a county scale and combined to identify expected costs per ton of carbon dioxide equivalents (COe). Large variation in estimated costs per ton of COe are driven by varying carbon accumulation potentials and opportunity costs of taking land out of agricultural production, as well as the duration of the project activity. Results show that the lowest cost carbon offset projects will be in certain counties of Maine, Vermont, and New York. Pasture land, with lower opportunity costs, generally presents the opportunity for lower cost carbon offset projects relative to cropland. This analysis estimates that afforestation of pasture land in the northeast will not become economically attractive until the price rises above $10 per metric tonne (MT) COe and that up to 583 million MT could be economically sequestered if the price were to rise to $50 per MT COe, based on a 40-year project life. With regard to cropland in the northeast, afforestation does not become economically advantageous for land owners until the price rises above $40 per MT COe. It is estimated that up to 487,000 MT could be sequestered from cropland if the price were to rise to $50 per MT COe, based on a 40-year project life. [ABSTRACT FROM AUTHOR]

Abstract: Alstom is developing a portfolio of solutions to address CO2 emission reductions. Among them is CO2 Capture and Storage (CCS) for which Alstom is developing several CO2 capture systems based on post-combustion and oxycombustion processes. This paper will be oriented to utility and industrial companies that would like to be prepared to CCS challenges and understand the key features of the CO2 capture technologies, in this article focus will be on oxy-combustion. This paper is also oriented to “oxy-experts” community for an update coming from pilots operation. It will describe key features of the different pilot projects with Alstom’s involvement and will describe the work performed in there. The development of CO2 capture technologies are being pursued by European and US suppliers in collaboration with utility companies, academia, the US DOE, the European Union, and universities. The first part of this article will address the work of Alstom and corresponding results in three major oxy pilots: • Vattenfall Schwarze Pumpe Oxy-combustion pilot plant (30 MWth, coal)) and corresponding results (pilot is in operation since September 2008, a full PC oxy-combustion chain has been under evaluation there). • An oxy tangentially fired boiler development project (coal) with co-funding from the US DOE and other organizations, which includes pilot testing at the 15 MWth scale, conducted in Windsor CT (US). This pilot has started operation in September 2009. • The TOTAL Lacq Oxy-combustion pilot plant (30 MWth, natural gas) where Alstom did the retrofit of a conventional boiler for its conversion into oxy-combustion. Considerable knowledge has been gained with these pilots through different considerations, both on boiler components but also on the integrated oxy chain. All these positive outcomes confirm the expectations of the community in oxy-development and open the door to the next development step of ∼250 MWel large scale oxy-fired carbon capture and storage (CCS) demonstration plants. This paper provides an update about the CO2 capture pilot plant operation and also present the technical challenges expected to be demonstrated during large scale demonstration plants. [Copyright &y& Elsevier]

Abstract: This paper summarizes recent numerical modeling activities investigating geological CO2 sequestration project at the Cranfield field, Mississippi, USA, performed with the commercial compositional flow simulator CMG-GEM. The oilfield was produced from the 1940’s to the 1960’s but has been the recent recipient of an enhanced oil recovery (EOR) CO2 flood. The subset of actual site operations of interest to the BEG consists of (1) an early phase, object of this paper, in which CO2 is injected into the oil-bearing reservoir (the so-called Phase II) and (2) a second phase (started on December 1, 2009) in which CO2 is injected at a high rate (>100 kt/yr for several years) in the saline aquifer down dip of the reservoir (Phase III). We present the modeling efforts related to the early phase of injection (Phase II, started in July 2008) in which CO2 is injected into the oil-bearing reservoir. The objectives of the modeling effort are to (i) to gain insights on how to approach CO2 injection modeling at the site, (ii) to match recent pressure measurements at several wells including a dedicated observation well, and (iii) to vindicate the necessity of monitoring of reservoir pressure. Its intent is not necessarily to do a full-fledged history match of the historical production period (1940’s–1960’s). We conducted numerous repeat simulation runs to modify boundary conditions, fluid properties, and reservoir properties to match observed fluid responses to production and to injection. A good understanding of subsurface heterogeneities, and composition of the oil and gas components, and boundary conditions of the reservoir is the key to successful history matching. However, allocating the correct distribution of rock properties based on historical geophysical logs remained an area of uncertainty even as additional new data were obtained during characterization because of the complex interplay between depositional environment and strong overprint of diagenetic events. Parameters of utmost importance for a correct description of a flow field, in particular the relationship between porosity and permeability and the nature of permeability spatial variations remain uncertain as well as boundary conditions. The uncertainty was dealt with through sensitivity analyses. Ultimately, the constructed model shows a reasonable match with the data. [Copyright &y& Elsevier]

This paper describes the design and development of a conceptual framework for creating and implementing a cyberinfrastructure model to support interdisciplinary science associated with geologic carbon sequestration at the University of Wyoming. "Cyberinfrastructure" is a term increasingly used within the scientific community to represent information infrastructure networks connecting technology, data, and people to support research activities and the dissemination of its results. In this study, a cyberinfrastructure was designed for a multi-team, multi-task project case study centered on carbon sequestration research in the Moxa Arch, Wyoming. The design was based on a needs assessment conducted to identify information technology practices and requirements for each science team, resulting in a prototype carbon capture and storage knowledge-base work flow model. Major components of the work flow model include social networking functionality and geographic information system-based data management and visualization. The long-term goal of the effort is to build a cyberinfrastructure that fosters and enhances collaboration across research involved with geologic characterization, reservoir modeling, and long-term monitoring of geologic sequestration activities in Wyoming and throughout the Rocky Mountain Region. [ABSTRACT FROM AUTHOR]

CO2 pilot injection studies, with site-specific geologic assessment and engineering reservoir design, can be instrumental for demonstrating both incremental enhanced oil recovery and permanent geologic storage of greenhouse gases. The purpose of this paper is to present the geologic and reservoir analyses in support of a field pilot test that will evaluate the technical and economic feasibility of commercial-scale CO2-enhanced oil recovery to increase oil recovery and extend the productive life of the Citronelle Oil Field, the largest conventional oil field in Alabama (SE USA). Screening of reservoir depth, oil gravity, reservoir pressure, reservoir temperature, and oil composition indicates that the Cretaceous-age Donovan sand, which has produced more than 169 × 106 bbl in Citronelle Oil Field, is amenable to miscible CO2 flooding. The project team has selected an 81 ha (200 ac) 5-spot test site with one central gas injector, two producers, and two initially temporarily abandoned production wells that are now in production. Injection is planned in two separate phases, each consisting of 6,804 t (7,500 short tons) of food-grade CO2. The Citronelle Unit B-19-10 #2 well (Permit No. 3232) is the CO2 injector for the first injection test. The 14-1 and 16-2 sands of the upper Donovan are the target zones. These sandstone units consist of fine to medium-grained sandstone that is enveloped by variegated mudstone. Both of these sandstone units were selected based on the distribution of perforated zones in the test pattern, production history, and the ability to correlate individual sandstone units in geophysical well logs. The pilot injections will evaluate the applicability of tertiary oil recovery to Citronelle Field and will provide a large volume of information on the pressure response of the reservoirs, the mobility of fluids, time to breakthrough, and CO2 sweep efficiency. The results of the pilot injections will aid in the formulation of commercial-scale reservoir management strategies that can be applied to Citronelle Field and other geologically heterogeneous oil fields and the design of similar pilot injection projects. [ABSTRACT FROM AUTHOR]

Abstract: The IEA 2007 World Energy Outlook forecasts that fossil fuels will continue to dominate the energy mix until 2030, including large economies such as the EU, Japan, US and China. A growing concern among many countries is the design o f mechanism s that will finance clean coal technologies and in particular carbon capture and storage projects. To illustrate, it is estimated that the United States will require 170 GW of new coal -fired capacity prior to 2030 with 90% of that being post 2015. Therefore substantial government and private investment into carbon capture and storage (CCS ) projects will be required and m echanisms designed to facilitate that investment. Many organizations are examining this issue including the IEA Clean Coal Centre, IEA Greenhouse Gas R&D Programme, Clean Coal Power Initiative and the Carbon Sequestration Leadership Forum (CSLF). In 2007 and 2008 two expert meetings on financing post-demonstration CCS projects were organised in London and New York by the IEA Greenhouse Gas R&D Programme and the IEA Clean Coal Centre, with the support of the World Coal Institute and sponsorship from Chevr on and Rio Tinto. This paper reports back the results of those meetings in regard to identifying the key drivers for financing post-demonstration CCS projects in Europe and North America. This is of particular interest with the restructuring of the USA Fut ureGen Programme as well as the proposed inclusion of CCS within the European Union Emissions Trading Scheme (EU-ETS) in the future. Different options for financing such projects are explored and compared with a focus on how they could assist in the realisation of commercial CCS projects. In addition, this paper examines the response by the insurance, banking and other financial sectors to the potential investment opportunities CCS projects could provide in dealing with issues such as liability and project investment. Lastly, the paper analyses the knowledge and awareness of CCS technology within the financial community in general. [Copyright &y& Elsevier]

Abstract: Over the past few years, several pieces of legislation have been introduced in Congress aimed at reducing US greenhouse (GHG) emissions by setting emission targets by specified years. One of the latest bills, America’s Climate Security Act of 2007 (S.2191) was introduced in October 2007 and sets a US GHG emissions target for 2050 that is 85% below the governments business-as-usual forecast. DOE/NETL has employed a multi-sector emissions accounting tool, CarBen, that identifies emission abatement options and their contribution, via a wedge analysis, to the total GHG emissions reduction needed to meet the 2050 emissions target laid out in S.2191. This paper begins with a review of expected greenhouse (GHG) emissions in the United States through 2050. Historical and projected trends in U.S. energy use per GDP and GHG emission per unit of energy delivered are assessed. The paper then explores “technical possibilities” that exist for the U.S. to mitigate its GHG emissions in line with S.2191. Within the power sector, these options include nuclear power, renewable power generation, refurbishing existing coal power plants, retrofitting existing coal power plants with carbon capture and storage (CCS) and deploying new coal and natural gas power plants with CCS Outside of the power sector abatement options cover non-CO2 GHG emissions abatement, terrestrial offsets, international credits, improved vehicle efficiency and electrification of the transportation sector through hybrid electric vehicles. The methodology for calculating the wedges and allocating emissions reduction among the different options is described. [Copyright &y& Elsevier]

Abstract: Carbon dioxide capture and storage (CCS) involves the capture of CO2 at a large industrial facility, such as a power plant, and its transport to a geological (or other) storage site where CO2 is sequestered. Previous work has identified pipeline transport of liquid CO2 as the most economical method of transport for large volumes of CO2. However, there is little published work on the economics of CO2 pipeline transport. The objective of this paper is to estimate total cost and the cost per tonne of transporting varying amounts of CO2 over a range of distances for different regions of the continental United States. An engineering-economic model of pipeline CO2 transport is developed for this purpose. The model incorporates a probabilistic analysis capability that can be used to quantify the sensitivity of transport cost to variability and uncertainty in the model input parameters. The results of a case study show a pipeline cost of US$ 1.16 per tonne of CO2 transported for a 100km pipeline constructed in the Midwest handling 5 million tonnes of CO2 per year (the approximate output of an 800MW coal-fired power plant with carbon capture). For the same set of assumptions, the cost of transport is US$ 0.39 per tonne lower in the Central US and US$ 0.20 per tonne higher in the Northeast US. Costs are sensitive to the design capacity of the pipeline and the pipeline length. For example, decreasing the design capacity of the Midwest US pipeline to 2 million tonnes per year increases the cost to US$ 2.23 per tonne of CO2 for a 100km pipeline, and US$ 4.06 per tonne CO2 for a 200km pipeline. An illustrative probabilistic analysis assigns uncertainty distributions to the pipeline capacity factor, pipeline inlet pressure, capital recovery factor, annual O&M cost, and escalation factors for capital cost components. The result indicates a 90% probability that the cost per tonne of CO2 is between US$ 1.03 and US$ 2.63 per tonne of CO2 transported in the Midwest US. In this case, the transport cost is shown to be most sensitive to the pipeline capacity factor and the capital recovery factor. The analytical model elaborated in this paper can be used to estimate pipeline costs for a broad range of potential CCS projects. It can also be used in conjunction with models producing more detailed estimates for specific projects, which requires substantially more information on site-specific factors affecting pipeline routing. [Copyright &y& Elsevier]

Abstract: Land-use systems are characterized by complex interactions between human decision-makers and their biophysical environment. Mismatches between the scale of human drivers and the impacts of human decisions potentially threaten the ecological sustainability of these systems. This article reviews sources of complexity in land-use systems, moving from the human decision level to human interactions to effects over space, time and scale. Selected challenges in modeling such systems and potential resolutions are discussed, including strategies to empiricize complex models and methods for linking models across human and natural systems. Illustrative examples from published literature and an ongoing research project focused on timber harvest and carbon sequestration are used throughout the paper. The paper concludes with a brief discussion of remaining challenges to modeling indirect and cross-scale linkages and of the potential utility of complex models of land systems. [Copyright &y& Elsevier]

The purpose of this paper is to develop and apply a new method to assess economic potential for agricultural greenhouse gas mitigation. This method uses secondary economic data and conventional econometric production models, combined with estimates of soil carbon stocks derived from biophysical simulation models such as Century, to construct economic simulation models that estimate economic potential for carbon sequestration. Using this method, simulations for the central United States show that reduction in fallow and conservation tillage adoption in the wheat-pasture system could generate up to about 1.7 million MgC/yr, whereas increased adoption of conservation tillage in the corn--soy--feed system could generate up to about 6.2 million MgC/yr at a price of $200/MgC. About half of this potential could be achieved at relatively low carbon prices (in the range of $50 per ton). The model used in this analysis produced estimates of economic potential for soil carbon sequestration potential similar to results produced by much more data-intensive, field-scale models, suggesting that this simpler, aggregate modeling approach can produce credible estimates of soil carbon sequestration potential. Carbon rates were found to vary substantially over the region. Using average carbon rates for the region, the model produced carbon sequestration estimates within about 10% of those based on county-specific carbon rates, suggesting that effects of spatial heterogeneity in carbon rates may average out over a large region such as the central United States. However, the average carbon rates produced large prediction errors for individual counties, showing that estimates of carbon rates do need to be matched to the spatial scale of analysis. Transaction costs were found to have a potentially important impact on soil carbon supply at low carbon prices, particularly when carbon rates are low, but this effect diminishes as carbon prices increase. [ABSTRACT FROM AUTHOR]

Researchers have been analyzing the costs of carbon sequestration for approximately twelve years. The purpose of this paper is to critically review the carbon sequestration cost studies of the past dozen years that have evaluated the cost-effectiveness of the forestry option. Several conclusions emerge. While carbon sequestration cost studies all contain essentially the same components they are not comparable on their face due to the inconsistent use of terms, geographic scope, assumptions, program definitions, and methods. For example, there are at least three distinct definitions for a `ton of carbon'' that in turn lead to significantly different meanings for the metric `dollars per ton of carbon''. This difference in carbon accounting further complicates comparison of studies. After adjusting for the variation among the studies, it appears that carbon sequestration may play a substantial role in a global greenhouse gas emissions abatement program. In the cost range of 10 to 150 dollars per ton of carbon it may be possible to sequester 250 to 500 million tons per year in the United States, and globally upwards of 2,000 million tons per year, for several decades. However, there are two unresolved issues that may seriously affect the contribution of carbon sequestration to a greenhouse gas mitigation program, and they will likely have counteracting effects. First, the secondary benefits of agricultural land conversion to forests may be as great as the costs. If that is the case, then the unit costs essentially disappear, making carbon sequestration a no-regrets strategy. In the other direction, if leakage is a serious issue at both the national and international levels, as suggested by some studies, then it may occur that governments will expend billions of dollars in subsidies or other forms of incentives, with little or no net gain in carbon, forests or secondary benefits. Preliminary results suggest that market interactions in carbon sequestration program analyses require considerably more attention. This is especially true for interactions between the forest and agricultural land markets and between the wood product sink and the timber markets. [ABSTRACT FROM AUTHOR]

A large body of research suggests that US cropland soils can also sequester significant amounts of C and are a promising source of C credits. This paper presents a framework for assessing the transactions costs associated with per-hectare and per-credit contract types and addresses the potential magnitude of transactions costs associated with measuring soil C credits under a per-credit contract within the dry-land crop region of Montana, USA. In the empirical analysis, we estimate the total measurement costs for soil C credits and investigate how changes in contract (and region) size as well as increases in C credit variability affect total measurement costs. The empirical analyses suggest that increasing the size of the contract and aggregating credits over a larger number of producers can lower measurement costs associated with the per-credit contract, even in the face of increasing C variability. Thus contracts for large quantities of soil credits increase the likelihood that the per-credit contract remains more efficient than the per-hectare contract. However, these empirical results reflect the specific data and conditions present within the case study region. The theoretical expectation is that sample size and measurement costs can either increase or decrease as the population to be sampled increases. Thus the measurement costs associated with a per-credit contract could respond differently from this analysis across the spatial extent of the US. [ABSTRACT FROM AUTHOR]

Increase in the use of conservation practices by agriculture in the United States will enhance soil organic carbon and potentially increase carbon sequestration. This, in turn, will decrease the net emission of carbon dioxide. A number of studies exist that calibrate the contribution of various individual, site-specific conservation practices on changes in soil organic carbon. There is a general absence, however, of a comprehensive effort to measure objectively the contribution of these practices including conservation tillage, the Conservation Reserve Program, and conservation buffer strips to an change in soil organic carbon. This paper fills that void. After recounting the evolution of the use of the various conservation practices, it is estimated that organic carbon in the soil in 1998 in the United States attributable to these practices was about 12.2 million metric tons. By 2008, there will be an increase of about 25%. Given that there is a significant potential for conservation practices to lead to an increase in carbon sequestration, there are a number of policy options that can be pursued. [ABSTRACT FROM AUTHOR]

Increase in the use of conservation practices by agriculture in the United States will enhance soil organic carbon and potentially increase carbon sequestration. This, in turn, will decrease the net emission of carbon dioxide. A number of studies exist that calibrate the contribution of various individual, site-specific conservation practices on changes in soil organic carbon. There is a general absence, however, of a comprehensive effort to measure objectively the contribution of these practices including conservation tillage, the Conservation Reserve Program, and conservation buffer strips to change in soil organic carbon. This paper fills that void. After recounting the evolution of the use of the various conservation practices, it is estimated that organic carbon in the soil in 1998 in the United States attributable to these practices was about 12.2 million metric tons. By 2008, there will be an increase of about 25 percent. Given that there is a significant potential for conservation practices to lead to an increase in carbon sequestration, there are a number of policy options that can be pursued. [ABSTRACT FROM AUTHOR]

Climate change mitigation efforts to achieve net-zero emissions require not only decreasing current greenhouse gas emissions, but also the deployment of negative emissions technologies. Soil organic carbon sequestration in agricultural lands is one such negative emissions strategy, currently being incentivized predominantly through voluntary carbon offset markets. Through semi-structured interviews, we assess both conventional and organic farmer perspectives on soil carbon offset programs that have been created in the United States since 2017. The perspectives of farmers both participating and not participating in agricultural soil carbon markets were similar and consistent. Farmers in both groups expressed concerns about the convoluted, burdensome and unpredictable nature of receiving offset credits and emphasized that they were implementing practices for their own business interests and sustainability concerns, not the financial incentive of the generation of carbon credits. Based on our research, carbon offset credit payments for agricultural soil carbon sequestration are largely reaching farmers who were already implementing these beneficial practices or were already strongly interested in implementing these practices, and the payments for the offset credits are seen as a 'gravy on top', suggesting that these offset markets face strong challenges of ensuring true additionality essential to effective climate mitigation. [ABSTRACT FROM AUTHOR]

This paper evaluates how changes in economic market and policy conditions, including the establishment of a per-unit tax on unabated emissions of carbon dioxide (CO2) set equal to estimates of the social cost of carbon (SCC), influence the economics of carbon capture and storage (CCS) for two hypothetical power generation facilities located in the United States. Data are provided from modified versions of models and resources created and managed by the National Energy Technology Laboratory. Changes in economic market and policy conditions are evaluated over a series of scenarios in which differences in the levelized cost of electricity (LCOE) provide estimates of the financial gap necessary to overcome for CCS to be considered the cost-minimizing choice for each power generation facility type considered. Results suggest that for the coal and natural gas power generation facilities considered, a per-unit tax set equal to an SCC exceeding $123 per metric ton of CO2 (/tCO2) emitted (2018 dollars) and $167/tCO2 emitted, respectively, in combination with current Section 45Q tax credits, yields investment in CCS as the cost-minimizing choice; SCC values as low as $58/tCO2 and $98/tCO2 can make CCS the cost-minimizing choice with additional support policies (e.g., free transportation and storage options). [ABSTRACT FROM AUTHOR]

Carbon capture (CC) technology is receiving increasing attention as a critical technology for climate change mitigation. Most previous studies focus on the application of CC technology in the power generation sector, while fewer studies have analyzed applications in the refining industry, which is one of the largest greenhouse gas (GHG) emissions sources in the U.S. industrial sector. Unlike the power generation sector, the refining industry has highly distributed CO 2 emission sources. In this paper, bottom-up modeling and techno-economic analysis approaches are integrated to quantify the national CO 2 emission reduction potential and costs of three types of CC technologies applied to U.S. refineries: (1) pre-combustion, (2) post-combustion, and (3) oxyfuel-combustion. Two scenarios are developed to compare different design strategies for CC systems; one is a distributed design scenario for post-combustion technology, the other is a centralized design scenario for pre-combustion and oxyfuel-combustion technology. The results of the two scenarios are compared, and the trade-offs between different design strategies are highlighted. The results shown in this study provide an intuitive and quantitative understanding of the potential of CC technology to reduce CO 2 emissions from the U.S. refining industry. Such information is helpful to policymakers, oil companies, and energy/environmental analysts for strategic planning and systems design to manage future CO 2 emissions of refineries. [ABSTRACT FROM AUTHOR]

Many irreversible long-run capital investments entail opportunities for managers to respond flexibly to changes in the economic environment. However, common levelized cost measures used to guide decision-making, such as the levelized cost of electricity, implicitly assume that the values of random economic variables are known with certainty when investment decisions are made. This assumption implies, often incorrectly, that managerial flexibility carries zero value. This paper improves levelized cost measures by deriving an expansion that accounts for both uncertainties in relevant variables and the value of managerial flexibility in responding to them. This method is applied to quantify the value of flexibility in two example decision problems. In one, an operator of a natural gas electricity generation facility evaluates whether to invest in carbon capture capabilities. Another considers retirement decisions for U.S. nuclear plants. These examples illustrate that simplified cost metrics can inaccurately guide decision-making by inflating cost estimates relative to the proposed levelized cost measure that accounts for uncertainty and flexibility. [ABSTRACT FROM AUTHOR]

Background: Carbon storage potential has become an important consideration for land management and planning in the United States. The ability to assess ecosystem carbon balance can help land managers understand the benefits and tradeoffs between different management strategies. This paper demonstrates an application of the Land Use and Carbon Scenario Simulator (LUCAS) model developed for local-scale land management at the Great Dismal Swamp National Wildlife Refuge. We estimate the net ecosystem carbon balance by considering past ecosystem disturbances resulting from storm damage, fire, and land management actions including hydrologic inundation, vegetation clearing, and replanting. Results: We modeled the annual ecosystem carbon stock and flow rates for the 30-year historic time period of 1985-2015, using age-structured forest growth curves and known data for disturbance events and management activities. The 30-year total net ecosystem production was estimated to be a net sink of 0.97 Tg C. When a hurricane and six historic fire events were considered in the simulation, the Great Dismal Swamp became a net source of 0.89 Tg C. The cumulative above and below-ground carbon loss estimated from the South One and Lateral West fire events totaled 1.70 Tg C, while management activities removed an additional 0.01 Tg C. The carbon loss in below-ground biomass alone totaled 1.38 Tg C, with the balance (0.31 Tg C) coming from above-ground biomass and detritus. Conclusions: Natural disturbances substantially impact net ecosystem carbon balance in the Great Dismal Swamp. Through alternative management actions such as re-wetting, below-ground biomass loss may have been avoided, resulting in the added carbon storage capacity of 1.38 Tg. Based on two model assumptions used to simulate the peat system, (a burn scar totaling 70 cm in depth, and the soil carbon accumulation rate of 0.36 t C/ha/year for Atlantic white cedar), the total soil carbon loss from the South One and Lateral West fires would take approximately 1740 years to re-amass. Due to the impractical time horizon this presents for land managers, this particular loss is considered permanent. Going forward, the baseline carbon stock and flow parameters presented here will be used as reference conditions to model future scenarios of land management and disturbance. [ABSTRACT FROM AUTHOR]

Extracted water—water brought to the surface of the ground during carbon capture and sequestration (CCS) projects to create additional room for carbon dioxide injection—exists in a murky legal environment. As part of a broader attempt to identify the complex interactions between water resource policies and CCS, an analysis was undertaken at both the state and the federal level to scope the policy environments surrounding extracted water policies and laws. Six states (California, Illinois, Mississippi, Montana, North Dakota, and Texas) were chosen for this analysis because either active CCS work is currently underway, or the potential exists for future work. Although regulation of extracted waters could potentially occur at many points along the CCS life cycle, this paper focuses on regulation that may apply when the water is withdrawn—that is, accessed and removed from the saline aquifer—and when it is re-injected in a close but unconnected aquifer. It was found that no regulations exist for this source specifically. In addition, greater input is needed from regulators and policy makers in terms of defining this resource. In particular, regulation of extracted waters (and CCS activities broadly) often overlaps with the management of fluids produced during oil and gas development. Many regulations would apply to extracted waters if they were classified as such. Therefore, correct categorization is key as the industry in this space continues to grow. [ABSTRACT FROM AUTHOR]

We estimate the carbon sequestration supply curve at the stand level based on the optimal rotation decision and conduct a marginal analysis for payments necessary for postponing harvest for additional 1-year increments of two commercially important species in the United States, loblolly pine and Douglas-fir. Under certain costs, production and timber prices assumptions, payments ranged from $62.23 ($26.97–$105.87) ac/yr. for loblolly pine plantations and $399.17 ($189.80–$628.72) ac/yr. for Douglas-fir plantations. Our results indicate that higher carbon sequestration occurs with higher site index, higher trees per acre, and in unthinned stands. Significant variability within and between species was heavily dependent on the number of years that final harvest was postponed. In addition, we show the effect of prices on the quantity supplied under multiple silvicultural treatments. The study should assist willing forest landowners and potential partners to determine initial reservation prices for carbon sequestration and temporary provision for a 1-year period in line with programs offering this contracting mechanism. [ABSTRACT FROM AUTHOR]

Great hope is being placed in the ability of forest ecosystems to contribute to greenhouse gas (GHG) emission reduction targets to limit global warming. Many nations plan to rely on forest-based climate mitigation activities to create additional and long-term carbon sequestration. Here, we take a critical look at the state of the policy and ecology surrounding forest-based natural climate solutions (NCS), with a focus on temperate forests of the United States (US). We first provide a high-level overview of carbon accounting, including key concepts used in the monitoring, reporting and verification of forest-based NCS. Second, we provide a high-level overview of forest carbon dynamics, including pools and fluxes, and drivers of their change. We then identify gaps in the current systems of GHG accounting, and between current ambitions and basic forest ecology. Improved use of data in models provides a path forward to better assessment and anticipation of forest-based climate mitigation. We illustrate this with the creation of a climate-sensitive forestry model, using tree-ring time series data. This climate-sensitive forest simulator will improve planning of site-level climate mitigation activities in the US by providing more realistic expectations of the carbon sequestration potential of forests undergoing climate change. Our review highlights the sobering complexity and uncertainty surrounding forest carbon dynamics, along with the need to improve carbon accounting. If we are to expect forests to play the significant emissions reduction role that is currently planned, we should view immediate emissions reductions as critical to preserve the climate mitigation capacity of forest ecosystems. [ABSTRACT FROM AUTHOR]

Coalbed methane is a worthwhile potential energy source, because methane gas is eco-friendly and a huge amount of coalbed methane has been buried in the United States, China, Australia, etc. This paper introduces a new simulation model of a vacuum pressure swing adsorption process that has been widely used to purify unconventional gases such as coalbed methane and landfill gas. The developed mathematical model includes a novel interstitial gas velocity equation derived by using a mole balance concept and an overall mass balance equation. The model is verified by comparing with three sets of laboratory-scale (about 0.5 Nm³h-1) experimental data and one set of pilot-scale (100 Nm³h-1) design data. Because the differences between the simulation results and the data are reasonably small, one can conclude that the 200 times scale-up design through the new simulation model is successful. [ABSTRACT FROM AUTHOR]

The continuing development of the organic-rich and extremely low permeability shale reservoirs in the United States has the potential to positively impact the future of carbon storage. Due to the unique characteristics of shale reservoirs, not only can CO 2 be safely stored, it also can be preferentially adsorbed and displace methane, leading to enhanced gas recovery. However, CO 2 storage in depleted or nearly depleted shale formations is not completely risk free. Thus, prior to making the economic commitment to a full-field CO 2 sequestration project, a systematic analysis of the complete set of variables must be considered in the planning of a shale-CO 2 storage initiative. Numerical modeling and simulation is a robust tool that can provide an insight into how the system may operate in order to further understand the feasibility and assist in the design and operation of such a project, and to predict changes that may occur. In order to perform a comprehensive uncertainty analysis, a large number of simulation runs are required. Designing and running simulation cases to model enhanced gas recovery and storage in shale by applying the Explicit Hydraulic Fracture modeling technique (EHF) is long and laborious, and its implementation is computationally expensive. In this paper, a data-driven approach with pattern recognition algorithms is used to develop a new generation of a shale proxy model at the hydraulic fracture cluster level, as a replica of a reservoir simulation model. For more accurate analysis, instead of commonly used mechanistic models, a history-matched hydraulic fractured Marcellus shale pad with multiple stages/clusters is used as a base case to perform the analysis. The detailed procedure for development of the Data-driven proxy model is explained and the model is validated using blind simulation runs. The developed Data-driven proxy model is capable of accurately reproducing the calculated CO 2 injection, CO 2 /CH 4 production profiles, and CO 2 breakthrough time from the numerical simulation model, for each cluster/stage and horizontal lateral. Joint use of the deterministic reservoir model with the Data-driven proxy model can serve as a novel screening and optimization tool for the techno-economic evaluation of the CO 2 -Enhanced Gas Recovery (EGR) and Storage process in shale systems. [ABSTRACT FROM AUTHOR]

In this paper we describe potential impacts to groundwater quality due to CO 2 and brine leakage, discuss an approach to calculate thresholds under which “no impact” to groundwater occurs, describe the time scale for impact on groundwater, and discuss the probability of detecting a groundwater plume should leakage occur. To facilitate this, multi-phase flow and reactive transport simulations and reduced-order models were developed for two classes of aquifers, considering uncertainty in leakage source terms and aquifer hydrogeology. We targeted an unconfined fractured carbonate aquifer based on the Edwards Aquifer in Texas and a confined alluvium aquifer based on the High Plains Aquifer in Kansas, which share characteristics typical of many drinking water aquifers in the United States. The hypothetical leakage scenarios centered on the notion that wellbores are the most likely conduits for brine and CO 2 leaks. Leakage uncertainty was based on hypothetical injection of CO 2 for 50 years at a rate of 5 million tons per year into a depleted oil/gas reservoir with high permeability and, one or more wells provided leakage pathways from the storage reservoir to the overlying aquifer. This scenario corresponds to a storage site with historical oil/gas production and some poorly completed legacy wells that went undetected through site evaluation, operations, and post-closure. For the aquifer systems and leakage scenarios studied here, CO 2 and brine leakage are likely to drive pH below and increase total dissolved solids (TDS) above the “no-impact thresholds”; and the subsequent plumes, although small, are likely to persist for long periods of time in the absence of remediation. In these scenarios, however, risk to human health may not be significant for two reasons. First, our simulated plume volumes are much smaller than the average inter-well spacing (1–2.6 wells/km 2 ) for these representative aquifers, so the impacted groundwater would be unlikely to be pumped for drinking water. Second, even within the impacted plume volumes little water exceeds the primary maximum contamination levels. These observations point to: • The potential utility of uncertainty quantification methods to evaluate the risk of leakage and inform monitoring and corrective action plans of a potential site for long-term CO 2 storage by capturing storage reservoir, leakage pathway, and aquifer heterogeneity. • The importance of establishing baseline groundwater chemistry that captures the pre-injection variability of underground sources of drinking water (USDW) above the reservoir because the EPA has adopted a “no net degradation” policy toward the protection of groundwater resources. • The need to test and develop spatially diverse monitoring techniques capable of detecting leakage early to employ effective mitigation strategies, and more importantly to add confidence to assessments used to evaluate the length of the post-injection site care. In our study, the probability of detecting plumes using existing wells to sample the groundwater chemistry was very low, because the plumes were relatively small in both aquifers. • The need to develop methodologies that prevent and/or directly detect leakage prior to reaching USDWs, because our simulations predict that even small amounts of CO 2 and brine, when left unmitigated, can change USDW pH and TDS concentrations for long periods of time. [ABSTRACT FROM AUTHOR]

Nature-based Climate Solutions (NbCS) are managed alterations to ecosystems designed to increase carbon sequestration or reduce greenhouse gas emissions. While they have growing public and private support, the realizable benefits and unintended consequences of NbCS are not well understood. At regional scales where policy decisions are often made, NbCS benefits are estimated from soil and tree survey data that can miss important carbon sources and sinks within an ecosystem, and do not reveal the biophysical impacts of NbCS for local water and energy cycles. The only direct observations of ecosystem-scale carbon fluxes, for example, by eddy covariance flux towers, have not yet been systematically assessed for what they can tell us about NbCS potentials, and state-of-the-art remote sensing products and land-surface models are not yet being widely used to inform NbCS policymaking or implementation. As a result, there is a critical mismatch between the point-and tree-scale data most often used to assess NbCS benefits and impacts, the ecosystem and landscape scales where NbCS projects are implemented, and the regional to continental scales most relevant to policymaking. Here, we propose a research agenda to confront these gaps using data and tools that have long been used to understand the mechanisms driving ecosystem carbon and energy cycling, but have not yet been widely applied to NbCS. We outline steps for creating robust NbCS assessments at both local to regional scales that are informed by ecosystem-scale observations, and which consider concurrent biophysical impacts, future climate feedbacks, and the need for equitable and inclusive NbCS implementation strategies. We contend that these research goals can largely be accomplished by shifting the scales at which pre-existing tools are applied and blended together, although we also highlight some opportunities for more radical shifts in approach. [ABSTRACT FROM AUTHOR]

The article presents a science lesson plan designed to teach U.S. students about biofuels by research efforts to turn wood from trees into jet fuel as a means to reduce carbon emissions and slow climate change.