Conventional Natural Gas Research Articles

Discovery and geological significance of high quality hydrocarbon source rocks in interglacial of Neoproterozoic in the eastern part of the southern margin of North China

A conglomerate of glacial deposits from Neoproterozoic Sinian is generally developed in the southern margin of the North China Plate. However, whether the hydrocarbon source rock exists in a conglomerate of glacial deposits is still undeterminable as it has not been studied previously. The developmental characteristics of the conglomerate were systematically observed and measured. The conglomerate was subsequently divided into four sets, and the gray-black shale was discovered in between them. The said shale has the thickness of 36 m, 46 m, and 7 m, respectively from top to bottom. The study presents the highly-abundant organic matter in the shale, which belong to the high-quality hydrocarbon source rock. The organic matters are derived from lower organisms. The discovery of thick and high-quality hydrocarbon source rocks in conglomerates opens up new exploration areas for conventional natural gas, as well as provides a powerful basis for shale gas exploration. The dropstones that appeared in hydrocarbon source rocks and conglomerates are cogent evidence of glaciation. The findings provide an important guiding significance for the genesis of the conglomerate.

Simulation and optimization of a methanol synthesis process from different biogas sources

Abstract Nowadays the exploitation of conventional natural gas resources has been contributing to the problem of increasing CO2 concentrations in the atmosphere and consequently increasing the global warming. The natural gas accounted for a majority of the feedstock used for methanol manufacture. Nevertheless, in the next years, methanol will have to be produced from less polluting sources that release small quantities of CO2 and methane to the atmosphere. In this regard, the use of biogas for producing methanol appears to be a viable alternative. However, few studies have studied the optimization of methanol production plants from renewable sources. Thereby, the main purpose of this paper is to make a comparative analysis, throughout mathematical modeling and simulation, of different methanol production routes, by considering four biogas sources: landfill, palm oil effluent, corn cobs and sorghum fermentation. For all cases, an optimization study was performed, with the goal of maximizing the methanol production. The results evidenced that the biogas from palm oil showed to be the most profitable concerning the other sources. On the other hand, the landfill gas showed to be a very limited capacity for methanol supply. Finally, the process optimization indicate that the operating conditions must be adjusted with respect of the biogas composition, in order to allow the maximum production.

Analysis of Heat Transfer Irreversibility in Processes for Liquefaction of Coalbed Methane with Nitrogen

Liquefaction is considered as one of the best methods for using coalbed methane (CBM). Unlike conventional natural gas, CBM usually contains a high proportion of nitrogen, so the liquefaction system performance, especially the heat transfer characteristics, differs from that of conventional natural gas liquefaction processes and depends on the nitrogen content. Irreversibility is an important aspect of the heat transfer characteristics and reflects the potential for further optimization of the heat exchanger system. In this paper, four liquefaction processes for nitrogen/methane mixtures are evaluated. Heat exchanger irreversibilities in each of these four processes are analyzed and compared for CBM nitrogen contents ranging between 0 and 70% and a methane recovery rate of 95% on the basis of optimization results provided by previous studies. It is revealed that the irreversibility in the heat exchanger system decrease with the increase of nitrogen content, and it is higher for the mixed refrigerant system than for the nitrogen refrigerant system. The results provide a direction for improvement of the liquefaction system performance and a reference for the selection of liquefaction processes for CBMs with different nitrogen contents.

Life cycle greenhouse gas emissions of hydrogen fuel production from chlor-alkali processes in the United States

By-product hydrogen from chlor-alkali processes can help meet the increasing demand for hydrogen fuel in early fuel cell electric vehicle markets (e.g., California) in the U.S. Hydrogen produced from chlor-alkali plants is typically combusted for process heat on site, vented to the atmosphere (i.e., wasted), or sold to the external merchant hydrogen market. Whether it is combusted, vented, or sold as a commodity, relevant information is lacking as to the life-cycle environmental benefits or trade-offs of using by-product hydrogen from chlor-alkali plants. A life-cycle analysis framework was employed to evaluate well-to-gate greenhouse gas (GHG) emissions associated with by-product hydrogen from chlor-alkali processes in comparison with hydrogen from the conventional centralized natural gas steam methane reforming (central SMR) pathway. U.S.-specific, plant-by-plant, and up-to-date chlor-alkali production characteristics were incorporated into the analysis. In addition to the venting and combustion scenarios, to deal with the multi-functionality of the chlor-alkali processes that simultaneously produce chlorine, sodium hydroxide, and hydrogen, two different co-product allocation strategies were adopted—mass allocation and market value allocation. It was estimated that by-product hydrogen production from chlor-alkali processes creates 1.3–9.8 kg CO2e/kg H2 of life-cycle GHG emissions on average, which is 20–90% less than the conventional central SMR pathway. The results vary with co-product treatment scenarios, regional electric grid characteristics, on-site power generation, product prices, and hydrogen yield. Despite the variations in the results, it was concluded that the life-cycle GHG emission reduction benefits of using by-product hydrogen from chlor-alkali processes are robust. With a diverse set of scenario analyses, the study developed a comprehensive and detailed life-cycle GHG emissions inventory of the chlor-alkali by-product hydrogen pathway and quantified sensitivity indices in the context of different assumptions and input parameter values.

Experimental and numerical analysis of turbulent premixed combustion of low calorific value coal gases in a generated premixed burner

This study describes experimental and numerical studies of low-calorific value coal gas combustion under turbulent premixed combustion conditions. Any conventional natural gas burner is not convenient to burn a low calorific value coal gas efficiently and properly. Therefore, a newly generated premixed burner that can burn a low calorific value coal gas has been designed and manufactured in the present study. This burner has also got a hydrogen pipe (as non-premixed) by which hydrogen can be supplied into the flame zone in order to enhance the combustion performances of the low-calorific value coal gases. In the numerical part of this study, the generator gas has been modelled numerically by a computational fluid dynamics code. The predicted temperature distributions of the generator gas have been compared with the experimental data. According to the comparison, it can be said that the predicted temperature profiles are satisfactorily in good agreement with the experimental data in terms of trends and values. In the experimental part of the present study, the blast-furnace gas flame was not observed without hydrogen supply during the experiments as it includes few combustible gases excluding carbon monoxide. However, the maximum flame temperature of the generator gas was measured as of 1220.1 K without hydrogen supply. It has also been concluded that the flame temperatures of the low calorific value syngases were enhanced as the hydrogen was supplied from the center of the newly generated burner into the flame zone. In addition to the temperature measurements, emissions such as nitrogen oxide, carbon monoxide and carbon dioxide were also examined by a gas analyzer inside the combustor. The results show that the nitrogen oxide emission levels increase as the hydrogen is supplied into the flame region because of thermal nitrogen oxide mechanism. It may also be concluded that carbon dioxide levels ascend as hydrogen is supplied because of water gas shift reaction. It can be eventually concluded that the newly generated burner provides more stable flame and hydrogen addition improves the combustion performances of the low calorific value coal gases under premixed combustion conditions.

Potential of direct-injection for the improvement of homogeneous-charge combustion in spark-ignition natural gas engines

The direct-injection has been considered as a way to improve the performance of conventional spark-ignition natural gas engines with the port-fuel-injection by increasing the engine volumetric efficiency. However, insufficient attention has been paid to the potential of direct-injection for the combustion and thermal efficiency improvement of homogeneous-charge combustion in natural gas engines that can be achieved by the spray-induced turbulence enhancement of the in-cylinder fuel–air mixture. The current study investigates the engine thermal efficiency, combustion speed, combustion stability and hydrocarbon emissions of a direct-injection natural gas engine under varied injection timings, and compares the combustion characteristics of the direct-injection with those of port-fuel-injection. Then, a particular engine operation scheme (port-fuel-injection of natural gas and direct-injection of nitrogen) is applied to evaluate the potential of spray-induced turbulence on the thermal efficiency improvement in the homogeneous-charge combustion mode. The results showed that the direct-injection could improve the engine combustion speed, combustion stability and thermal efficiency in low-load conditions as a result of enhanced in-cylinder turbulence at retarded injection timings. Meanwhile, the direct-injection decreased the engine thermal efficiency in high-load conditions and increased the hydrocarbon emissions regardless of the engine load condition due to the deteriorated mixture homogeneity. When the in-cylinder turbulence and mixture homogeneity were both achieved, a few percent of thermal efficiency improvement was obtained by the direct-injection, and the improvement rate increased as the engine load decreased.

Life cycle greenhouse gas assessment of hydrogen production via chemical looping combustion thermally coupled steam reforming

Abstract Chemical looping combustion thermally coupled steam reforming (CLC-SR) emerges as a new alternative to achieving hydrogen production simultaneously with inherent CO2 capture. To evaluate the environmental performances of any competing technology, it is of necessity to consider total emissions in association with the technology over its entire lifetime. In this study, a life cycle greenhouse gas emission (LCE) assessment of the CLC-SR is conducted, together with a comparison with the conventional natural gas steam reforming (SR). The energy efficiency of 75.2% for achieving 97.0% inherent CO2 capture is obtained in the CLC-SR, with the LCEs of 3009 g CO2 eq./kg H2, approximately accounting for one third in those of conventional natural gas SR. The main LCE contributors in the CLC-SR are plant operation and natural gas losses from the natural gas production and transport. To further meet the emission reduction potential, several key parameters are varied to illustrate their influence on LCE performances of the CLC-SR, including reformer operation temperature, different types of oxygen carriers (OCs) and the lifetime of OCs. The results of this investigation demonstrate the CLC-SR is a promising alternative to conventional SR for cleaner hydrogen production from a LCE perspective.

Death by a Thousand Cuts? Western Canadaas Oil and Natural Gas Policy Competitiveness Scorecard

Pipelines face delays or are not built at all. Governments are adding greenhouse gas emissions prices. Provinces have introduced higher corporate income taxes. Property and other municipal taxes on energy producers have also been on the rise. Taken together, what are the costs of these recent policies for the western Canadian energy sector? And how does each compare in its effect on the competitiveness of Canadian provinces, both in relation to each other and to US energy-producing states? To assess the effect of policy-induced competitiveness costs on energy producers, this Commentary calculates the cumulative change in profitability that energy producers would face for an otherwise identical well because of government policies that affect taxes and pipeline access. In the first of what will be an annual series – updated as policymakers change the policy-induced costs on conventional oil and natural gas producers – this Commentary finds that: • pipeline constraints have greatly reduced the price that oil producers receive. This effect is by far the largest competitiveness cost on energy producers; • corporate taxes and provincial royalties are major policy costs for producers. Canadian provinces have historically been competitive with the US on taxes, but recent changes in the US highlight the need to examine the cost of taxation – the outcome of Alberta’s recent royalty review was a step in the right direction; • greenhouse gas emission taxes have been big news politically and publicly, but so far have not been economically important for energy producers. Further, the Alberta (and similar federal) system gives companies a strong incentive to reduce their emissions with little competitiveness cost. Indeed, companies with below-average emissions are better off under the current system; and • finally, property and municipal taxes have enormous variation across Canada and the US. There is room for provinces to reduce the cost of both provincial and municipal property taxes on energy producers. Policymakers now need to take steps to ensure that approved new pipelines get built and to reduce the burden of corporate income, royalty, property and greenhouse gas emissions taxes.

Process Simulation, Economic and Environmental Sustainability Assessment of a Gas-To-Liquids Process

Natural gas is recognized as one of the cleanest and most abundant fossil fuels. In the past decades, the price ratio of crude oil to natural gas has continuously fluctuated. The gas-to-liquid industry has received continuous interest due to the abundant supply of conventional and unconventional natural gas (shale gas, etc.), as well as the environmental advantages of FT technology. The GTL process chemically converts natural gas to long chain hydrocarbons (naphtha, diesel, wax, etc.) through three main steps, i.e., natural gas reforming, Fischer-Tropsch synthesis (FTS), and products upgrading. In this work, a rigorous simulation model including gas sweetening, syngas production, FTS, and product fractionation is provided. Among different routes for natural gas reforming and different reactors for FTS in a GTL process, autothermal reforming (ATR) and slurry bubble column reactor (SBCR) were chosen respectively, due to their advantages over other solutions. Meanwhile, the economic and environmental analyses were also conducted for the sustainability assessment of provided GTL process using Aspen Icarus and WAR software.

Henry's law and accumulation of weak source for crust-derived helium: A case study of Weihe Basin, China

Crust-derived helium is generated from the radioactive decay of uranium, thorium and other radioactive elements in geological bodies. Compared with conventional natural gas, helium is a typical weak source gas as a result of extremely slow generation rate and absence of helium-generating peak. It is associated with methane or carbon dioxide reservoirs frequently and related to groundwater closely. Helium can meet the industry standard with 0.1% in volume fraction. In order to study the accumulation mechanism of helium, the previous research on Henry's coefficient and solubility of helium, nitrogen and methane are summarized and the key roles of Henry's Law in the helium migration, accumulation and preservation are discussed by simulating calculation taking Weihe Basin as an example. According to the Law, the gas solubility in dilute solution is controlled by the gas partial pressure and the Henry's coefficient. Compared with the carrier gases, the Henry's constant of helium is high, with striking difference at low and high temperature. In addition, the helium partial pressure is greatly different in helium source rocks and gas reservoirs, resulting in the great differences of helium solubility in the two places. The accumulation progresses are as follows. Firstly, helium can dissolve into water and migrate out of helium source rocks due to the high helium solubility, which is caused by high helium partial pressure and high temperature in source rock. Secondly, when dissolved helium is transported to the shallow gas reservoir, it is prone to be out of solution and into reservoir due to the extremely low partial pressure and low temperature. Meanwhile part of carrier gases dissolves into water, as if helium is “replaced” out. Furthermore, the low concentration funnel of dissolved helium is formed near the gas reservoir, then other dissolved helium continues to migrate towards the gas reservoir, which greatly improves the helium accumulation coefficient. Finally, after entering the gas reservoir, helium is difficult to dissolve into the water in cap layers due to its low partial pressure, resulting in the preservation of helium in reservoir. The results show that the helium enrichment mechanism in the aspects of migration, accumulation and preservation, providing theoretical basis for helium resource exploration.

Sustainability of UK shale gas in comparison with other electricity options: Current situation and future scenarios

Many countries are considering exploitation of shale gas but its overall sustainability is currently unclear. Previous studies focused mainly on environmental aspects of shale gas, largely in the US, with scant information on socio-economic aspects. To address this knowledge gap, this paper integrates for the first time environmental, economic and social aspects of shale gas to evaluate its overall sustainability. The focus is on the UK which is on the cusp of developing a shale gas industry. Shale gas is compared to other electricity options for the current situation and future scenarios up to the year 2030 to investigate whether it can contribute towards a more sustainable electricity mix in the UK. The results obtained through multi-criteria decision analysis suggest that, when equal importance is assumed for each of the three sustainability aspects shale gas ranks seventh out of nine electricity options, with wind and solar PV being the best and coal the worst options. However, it outranks biomass and hydropower. Changing the importance of the sustainability aspects widely, the ranking of shale gas ranges between fourth and eighth. For shale gas to become the most sustainable option of those assessed, large improvements would be needed, including a 329-fold reduction in environmental impacts and 16 times higher employment, along with simultaneous large changes (up to 10,000 times) in the importance assigned to each criterion. Similar changes would be needed if it were to be comparable to conventional or liquefied natural gas, biomass, nuclear or hydropower. The results also suggest that a future electricity mix (2030) would be more sustainable with a lower rather than a higher share of shale gas. These results serve to inform UK policy makers, industry and non-governmental organisations. They will also be of interest to other countries considering exploitation of shale gas.

Innovative Hybrid CHP systems for high temperature heating plant in existing buildings

This paper deals with the potential role of new hybrid CHP systems application providing both electricity and heat which are compatible with the building architectural and landscape limitations. In detail, three different plant layout options for high temperature heat production along with the electricity generation were investigated and compared each other. To do so, conventional natural gas CHPs and back up boiler, two-stage Electric Heat Pumps (EHPs) and trans-critical CO2 electric heat pump (CO2-HP) have been considered as reference technologies to build hybrid systems. In addition, hybrid solar collectors (PV/T) thermal output, along with the recovered low-grade heat from CHP exhaust gas, flowing to the stack, have been used as the CO2-HP low temperature driving source.

Supercritical methane adsorption on shale gas: Mechanism and model

Shale gas is different from conventional natural gas stored in sandstone and carbonate formations because the shale formation is often both the source and the reservoir of the natural gas itself. The adsorbed gas accounts for 20%–85% of the total amount based on current studies in five major shale formations in the United States. Studying on the mechanism and model of shale gas adsorption is of great importance for reserve evaluation and making development plan. The micropore structure and isothermal adsorption curves of Longmaxi shales were analyzed by low-temperature N2 adsorption and high-pressure CH4 adsorption experiments. The results show that its specific surface area and pore volume are mainly controlled by mesopores (2–200 nm). The excess adsorption capacity ( n ex) increases to a maximum value at the pressure of approximate 10 MPa, and then begins to decline with pressure. This abnormal phenomenon has also been observed in some previous studies, but most researchers stated that the adsorption isotherm of methane in shale monotonically increased with pressure and reached a constant value at a high pressure (i.e., type I isotherm). The main reason for these two different types of adsorption isotherms is whether the volume of the adsorbed phase is assumed to be negligible. To simulate the enrichment and production of methane in shale gas reservoirs, an accurate model of gas adsorption is needed. The most commonly used adsorption model for shale gas reservoirs is the classic Langmuir equation and its extended Langmuir-Freundlich (L-F) equation, which assumes that methane is a monolayer adsorbate and the surface of the solid adsorbent is homogeneous with constant adsorption heat. Many physical adsorption phenomena can be described by the Langmuir model, including coalbed methane adsorption, but the assumptions are too ideal to match the complicated situation of shale gas reservoir. Several multilayer adsorption theories also have been proposed and applied, such as the Dubinin-Radushkevich (D-R) and the Dubinin-Astakhov (D-A) equations based on micropore filling mechanism. The D-R and D-A adsorption model have been widely used in methane adsorption on shale because of its quite good fitting quality. The comparative analysis of the four commonly used adsorption models shows that the fitting effect of D-A model is better than D-R model for micropore filling mode, and the fitting effect of L-F model is better than Langmuir model for monolayer adsorption mode. Further through the two hypotheses, it is proved that the adsorption mode of methane is neither single micropore filling nor single monolayer adsorption, and the adsorption mechanism is the coexistence of micropore filling and monolayer adsorption. Based on the adsorption mechanism, a new model of supercritical adsorption of shale gas—DA-LF model was proposed. The new model has better fitting effect than the commonly used models, and can calculate the adsorption amount of micropores and mesopores, respectively. The results show that the adsorption capacity of micropore filling is larger than that of monolayer adsorption, which accounts for about 76% of the total adsorption capacity, indicating that the supercritical adsorption mechanism is mainly micropore filling and monolayer adsorption coexists.

Global Inventory of Gas Geochemistry Data from Fossil Fuel, Microbial and Burning Sources, version 2017

Abstract. The concentration of atmospheric methane (CH4) has more than doubled over the industrial era. To help constrain global and regional CH4 budgets, inverse (top-down) models incorporate data on the concentration and stable carbon (δ13C) and hydrogen (δ2H) isotopic ratios of atmospheric CH4. These models depend on accurate δ13C and δ2H end-member source signatures for each of the main emissions categories. Compared with meticulous measurement and calibration of isotopic CH4 in the atmosphere, there has been relatively less effort to characterize globally representative isotopic source signatures, particularly for fossil fuel sources. Most global CH4 budget models have so far relied on outdated source signature values derived from globally nonrepresentative data. To correct this deficiency, we present a comprehensive, globally representative end-member database of the δ13C and δ2H of CH4 from fossil fuel (conventional natural gas, shale gas, and coal), modern microbial (wetlands, rice paddies, ruminants, termites, and landfills and/or waste) and biomass burning sources. Gas molecular compositional data for fossil fuel categories are also included with the database. The database comprises 10 706 samples (8734 fossil fuel, 1972 non-fossil) from 190 published references. Mean (unweighted) δ13C signatures for fossil fuel CH4 are significantly lighter than values commonly used in CH4 budget models, thus highlighting potential underestimation of fossil fuel CH4 emissions in previous CH4 budget models. This living database will be updated every 2–3 years to provide the atmospheric modeling community with the most complete CH4 source signature data possible. Database digital object identifier (DOI): https://doi.org/10.15138/G3201T.

Analysis of the Potential Economic Viability of Shale Gas Resources in Europe

European countries are currently exploring strategies to ensure a strong level of security of energy supply while decreasing its reliance on natural gas imports. With the strong surge in shale gas developments in the USA, similar ambitions have been the ongoing subject of inquiry in Europe. Detailed knowledge about extraction costs is a key issue in determining future shale gas investments in Europe. The paper at hand analyses the potential of European shale gas resources, highlighting their competitiveness against conventional natural gas. It examines the current volume of shale gas resources in Europe and performs a detailed cost calculation to provide an estimation of shale gas production costs. The results indicate that under current market conditions the repetition of the US shale gas boom is by all measures improbable in Europe. Furthermore, in the case that natural prices were to return to historically higher levels, only a few highly productive shale gas formations would be economically competitive.

A method for assessing infrastructure for [formula omitted] utilization: A case study of Finland

Synthetic hydrocarbons can be produced sustainably with power-to-gas processes, resulting in a net reduction of greenhouse gas emissions due to the substitution of conventional natural gas and other fossil fuels with carbon-neutral alternatives. Acquisition of the CO2 for the synthetic fuel production can be implemented in multiple ways. This work introduces a node-based model to assess different implementation strategies of CO2 utilization systems, taking into account temporal effects, regional variation, and economies of scale for CO2 capture. Intermediate storage volumes, capture costs, transport quantities, and other relevant infrastructural aspects of the CCU system can be estimated with the model. Finland is used as a case study, focusing specifically on the national and regional scale. CO2 capture costs are significant, being nearly four times larger than the cost of storage in the baseline scenario (354M€, 85M€). CO2 sources with smaller annual emissions increases capture costs by 14% compared to baseline. This increase in cost is comparable to the cost of transporting over a quarter of all captured CO2 to off-site processing (varying distance, 100–400km). Seasonal storage of CO2 is found to be beneficial for the cost-efficient production of synthetic fuels, owing to the temporal disparity between CO2 emissions and utilization, as well as the overall cost structure of the components. Five key decision categories are proposed for a carbon utilization system: scale, type, units, location, and technological decisions. These may be applied to describe any carbon utilization system, helping to form a more comprehensive picture of a future energy system, where carbon is widely used as a raw material.

Influence of gaseous components and pressures on hydrogen embrittlement of natural gas pipeline

Hydrogen usually penetrates metals through defects such as dislocations, vacancies, and crystalline imperfections and causes embrittlement, leading to cleavage fracture and intergranular fracture. Synthetic natural gas produced by coal gasification, biogas, and landfill gas inevitably contain hydrogen. Therefore, hydrogen embrittlement of pipeline materials should be considered when they are mixed with conventional natural gas and supplied to customers. To analyze hydrogen embrittlement of base metals and girth weld metals of API 5L X70 and X65 gas pipelines, a specimen was treated in 100 % hydrogen environment at 10 MPa to determine the hydrogen concentration in it. Small punch (SP) tests were performed under various gaseous components and pressures. When SP tests were performed at very low speed, hydrogen embrittlement could be observed. Specimens became very susceptible to hydrogen embrittlement with increasing hydrogen partial pressure in the hydrogen/methane gas mixture, and the SP energy also decreased dramatically.

Scenarios to decarbonize residential water heating in California

This paper presents the first detailed long-term stock turnover model to investigate scenarios to decarbonize the residential water heating sector in California, which is currently dominated by natural gas. We model a mix of water heating (WH) technologies including conventional and on-demand (tank-less) natural gas heating, electric resistance, existing electric heat pumps, advanced heat pumps with low global warming refrigerants and solar thermal water heaters. Technically feasible policy scenarios are developed by considering combinations of WH technologies with efficiency gains within each technology, lowering global warming potential of refrigerants and decreasing grid carbon intensity. We then evaluate energy demand, emissions and equipment replacement costs of the pathways. We develop multiple scenarios by which the annual greenhouse gas emissions from residential water heaters in California can be reduced by over 80% from 1990 levels resulting in an annual savings of over 10 Million Metric Tons by 2050. The overall cost of transition will depend on future cost reductions in heat pump and solar thermal water heating equipment, energy costs, and hot water consumption.

Conventional oil and natural gas infrastructure increases brown-headed cowbird (Molothrus ater) relative abundance and parasitism in mixed-grass prairie.

The rapid expansion of oil and natural gas development across the Northern Great Plains has contributed to habitat fragmentation, which may facilitate brood parasitism of ground-nesting grassland songbird nests by brown-headed cowbirds (Molothrus ater), an obligate brood parasite, through the introduction of perches and anthropogenic edges. We tested this hypothesis by measuring brown-headed cowbird relative abundance and brood parasitism rates of Savannah sparrow (Passerculus sandwichensis) nests in relation to the presence of infrastructure features and proximity to potential perches and edge habitat. The presence of oil and natural gas infrastructure increased brown-headed cowbird relative abundance by a magnitude of four times, which resulted in four times greater brood parasitism rates at infrastructure sites. While the presence of infrastructure and the proximity to roads were influential in predicting brood parasitism rates, the proximity of perch sites was not. This suggests that brood parasitism associated with oil and natural gas infrastructure may result in additional pressures that reduce productivity of this declining grassland songbird.

Comparative Life-cycle Assessment of Slurry and Wet Accelerated Carbonation of BOF Slag

This work reports the results of the life cycle assessment (LCA) of two carbonation processes aimed at permanent CO2 storage, employing Basic Oxygen Furnace (BOF) slag from steel manufacturing as alkalinity source. Specifically, the performance of the slurry phase and wet carbonation routes were compared assuming to store the CO2 emitted from a 10 MW conventional natural gas power plant. The LCA was based on the material and energy requirements for each of the involved process steps, i.e. pre-treatment and transport of raw materials, CO2 compression, carbonation, post treatments and management of the obtained products. The slurry and wet route resulted in a net avoided greenhouse warming potential (GWP) of 473 and 384kg CO2/MWhel, respectively. Nevertheless, both routes affected the other environmental impact categories. In general, the wet route had approximately two times higher impact than the slurry route, due in particular to the higher material and energy requirements. An exception was the abiotic resource depletion which resulted higher for the slurry route due to greater water requirement with respect to the wet route. The contributions to all mid-point impact categories were mainly due to energy requirements. A sensitivity analysis showed that the environmental impacts are affected by the energy mix and by the transport distance of slags and carbonation products.