Analysis of availability and accessibility of hydrogen production: An approach to a sustainable energy system using methane hydrate resources

It is considered that use of hydrogen as an energy source may contribute to environmental improvement and provide an alternative energy system. Moreover, it is anticipated that hydrogen will be in great demand in the near future for use in such vehicles as fuel cell-based cars. Research and development of a number of advanced methods of hydrogen production (OTEC, water photolysis using a semiconductor, a municipal waste gasification—smelting system, etc.) is currently under way.A comparison of different hydrogen-rich fuels in this paper shows that methane is advantageous for hydrogen production from the viewpoint of energy efficiency as measured by thermodynamic analysis. This paper therefore proposes combining existing technology for hydrogen production with an unconventional methane source in order to facilitate the realization of a hydrogen energy system: i.e., this paper proposes combining the process of steam reforming, which is commercialized worldwide, with use of untouched natural gas hydrate (NGH) resources. Gas hydrate deposits, which are distributed worldwide, hold great amounts of methane gas and have hardly been touched. This paper presents the economic parameters of NGH development and discusses the concept of devising useful applications of NGHs, with consideration given to (1) independence from current fossil fuels; (2) energy transport using the hydrate system; (3) CO₂ sequestration — replacement of methane hydrate with CO₂ hydrate in the submarine layer and (4) improvement of current steam reforming of methane by CO₂ reuse and zeolite application. This paper thus proposes a new solution that will make a key contribution to the systematic development of a new sustainable energy structure.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Effects of Alternative Cotton Agriculture on Avian and Arthropod Populations

Abstract:  Among the major agricultural crops in the southeastern United States, cotton ( Gossypium hirsutum L.) generally provides the least suitable habitat for most early successional songbirds. Newer cropping approaches, such as use of conservation tillage and stripcover cropping, offer hope for improving the ecological value of cotton fields. We examined the effects of clover stripcover cropping with conservation tillage versus conventionally grown cotton with either conventional or conservation tillage on avian and arthropod species composition and field use in east-central Georgia. Stripcover fields had higher bird densities and biomass and higher relative abundance of arthropods than both conservation tillage and conventional fields. During migration and breeding periods, total bird densities on stripcover fields were 2–6 times and 7–20 times greater than on conservation and conventional fields, respectively. Abundance and biomass for epigeal arthropods were also greatest on stripcover fields during much of the breeding season. Although the clover treatment attracted the highest avian and arthropod densities, conservation fields still provided more wildlife and agronomic benefits than conventional management. Our findings suggest that both conservation tillage and stripcropping systems will improve conditions for birds in cotton, with stripcropped fields providing superior habitat. The reduction of inputs possible with the clover system could allow farmers to lower costs associated with conventional cotton production by $282–317/ha. This reduction of input, coupled with similar or possibly increased yield over conventional systems makes stripcover cropping not only a good choice for reducing negative impacts on wildlife and surrounding ecosystems, but also an economically desirable one.     

易腐性有机垃圾的产生与处理技术途径比较

我国城市垃圾以易腐性有机垃圾为主.目前有关管理部门提出逐步减少进入填埋场的易腐性有机垃圾量,因此,必须寻求其他填埋替代技术消纳易腐性有机垃圾物流.本文对几种常规技术方案进行了比较.认为应该根据非餐饮业和餐饮业易腐性有机垃圾各自的产生源特点,采取不同的处理方案;但目前这些替代技术用于处理易腐垃圾时均存在各自的缺陷.本文据此提出了相应的技术完善要求和配套管理政策建议.     

THE LOUISIANA ENVIRONMENTAL MANAGEMENT SYSTEM AND ITS UTILITY IN WATER RESOURCE PLANNING1

ABSTRACT: The Louisiana Environmental Management System (LEMS) is a data processing program developed to aid the Louisiana Joint Legislative Committee on Environmental Quality in decisions leading to resources legislation. Serving as a central data collection and retrieval point for various agencies, the LEMS will maintain assembled information on the location of monitoring stations and coordinate the files of user agencies with data on: land use; air and water quality; meteorological, climatological, and hydrological phenomena; vegetation; fish and wildlife conservation; population; and economics. This data is geographically stored in relation to the state plane coordinate system. For decision making, all pertinent hydrologic, topographic, engineering, cadastral, and other information from separate sources can be automatically mapped as a combined overlay to one of three chosen scales. Land-use patterns are the input data for iterative analyses of present conditions and simulated future human activities for assessing the environmental impact of proposed multiple-purpose water resource developments.     

A comparative assessment of alternative approaches to sustainable development

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The transformative power of commoning and alternative food networks

ABSTRACT

A commoning framework offers a critical lens to fully appreciate the scope and impact of alternative food networks (AFNs). Fieldwork from an AFN in southern China is drawn upon to show how commoning enacts changes in how members contextualise and anchor their social relations to one another with regards to sourcing food as a commons. A commoning framework gives a fuller picture of how the constitutive effects of AFNs reside not in their introduction of a new uniformity but in their navigation of the multiplicity of the social through its proposition and co-construction of a new ‘cognitive praxis’.     

Coexistence of Fisheries with River Dolphin Conservation

Abstract: Freshwater biodiversity conservation is generally perceived to conflict with human use and extraction (e.g., fisheries). Overexploited fisheries upset the balance between local economic needs and endangered species’ conservation. We investigated resource competition between fisheries and Ganges river dolphins (Platanista gangetica gangetica) in a human‐dominated river system in India to assess the potential for their coexistence. We surveyed a 65‐km stretch of the lower Ganga River to assess habitat use by dolphins (encounter rates) and fishing activity (habitat preferences of fishers, intensity of net and boat use). Dolphin abundance in the main channel increased from 179 (SE 7) (mid dry season) to 270 (SE 8) (peak dry season), probably as a result of immigration from upstream tributaries. Dolphins preferred river channels with muddy, rocky substrates, and deep midchannel waters. These areas overlapped considerably with fishing areas. Sites with 2–6 boats/km (moderately fished) were more preferred by dolphins than sites with 8–55 boats/km (heavily fished). Estimated spatial (85%) and prey–resource overlap (75%) between fisheries and dolphins (chiefly predators of small fish) suggests a high level of competition between the two groups. A decrease in abundance of larger fish, indicated by the fact that small fish comprised 74% of the total caught, may have intensified the present competition. Dolphins seem resilient to changes in fish community structure and may persist in overfished rivers. Regulated fishing in dolphin hotspots and maintenance of adequate dry season flows can sustain dolphins in tributaries and reduce competition in the main river. Fish‐stock restoration and management, effective monitoring, curbing destructive fishing practices, secure tenure rights, and provision of alternative livelihoods for fishers may help reconcile conservation and local needs in overexploited river systems.     

Leaching toxicity characteristics of municipal solid waste incineration bottom ash

The continuously increasing production of municipal solid waste incineration bottom ash (MSWIBA) has promoted its utilization as construction material and raised environmental concern. The physico-chemical properties and leaching behavior of MSWIBA were studied, and ecotoxicological testing using a luminescent bacterium bioassay was performed to assess the ecological pollution risks associated with its leached constituents. The MSWIBA was leached by two types of leachants, H₂SO₄/HNO₃ and HAc solution, at different liquid to solid ratios and contact times. The concentrations of heavy metals and anions in the leachates were analyzed. Multivariate statistical analyses, including principle component analysis, Pearson's correlation analysis and hierarchical cluster analysis, were used to evaluate the contributions of the constituents to the toxicity (EC₅₀) of the MSWIBA leachate. The statistical analyses of the ecotoxicological results showed that the Ba, Cr, Cu, Pb, F⁻ and total organic carbon (TOC) concentrations were closely correlated with the EC₅₀ value, and these substances were the main contributors to the ecotoxicity of the MSWIBA leachate. In addition, the cluster of these variables indicated similar leaching behaviors. Overall, the research demonstrated that the ecotoxicological risks resulting from MSWIBA leaching could be assessed before its utilization, which provides crucial information for the adaptation of MSWIBA as alternative materials.     

The interaction between seaweed farming as an alternative occupation and fisher numbers in the central Philippines

Alternative occupations are frequently promoted as a means to reduce the number of people exploiting declining fisheries. However, there is little evidence that alternative occupations reduce fisher numbers. Seaweed farming is frequently promoted as a lucrative alternative occupation for artisanal fishers in Southeast Asia. We examined how the introduction of seaweed farming has affected village-level changes in the number of fishers on Danajon Bank, central Philippines, where unsustainable fishing has led to declining fishery yields. To determine how fisher numbers had changed since seaweed farming started, we interviewed the heads of household from 300 households in 10 villages to examine their perceptions of how fisher numbers had changed in their village and the reasons they associated with these changes. We then asked key informants (people with detailed knowledge of village members) to estimate fisher numbers in these villages before seaweed farming began and at the time of the survey. We compared the results of how fisher numbers had changed in each village with the wealth, education, seaweed farm sizes, and other attributes of households in these villages, which we collected through interviews, and with village-level factors such as distance to markets. We also asked people why they either continued to engage in or ceased fishing. In four villages, respondents thought seaweed farming and low fish catches had reduced fisher numbers, at least temporarily. In one of these villages, there was a recent return to fishing due to declines in the price of seaweed and increased theft of seaweed. In another four villages, fisher numbers increased as human population increased, despite the widespread uptake of seaweed farming. Seaweed farming failed for technical reasons in two other villages. Our results suggest seaweed farming has reduced fisher numbers in some villages, a result that may be correlated with socioeconomic status, but the heterogeneity of outcomes is consistent with suggestions that alternative occupations are not a substitute for more direct forms of resource management.     

Bioenergy recovery from landfill gas: A case study in China

Landfill gas (LFG) utilization which means a synergy between environmental protection and bioenergy recovery was investigated in this study. Pressure swing adsorption technology was used in LFG purification, and laboratory experiment, pilot-scale test, and on-site demonstration were carried out in Shenzhen, China. In the laboratory experiment, A-type carbon molecular sieve was selected as the adsorbent by comparison of several other adsorbents. The optimal adsorption pressure and adsorption time were 0.25 MPa and 2 min, respectively, under which the product generation rate was 4.5 m³/h and the methane concentration was above 90%. The process and optimization of the pilot-scale test were also reported in the paper. The product gas was of high quality compared with the National Standard of Compressed Natural Gas as Vehicle Fuel (GB18047-2000), when the air concentration in feed gas was under 10.96%. The demonstration project was composed of a collection system, production system, and utilization system. The drive performance, environmental protection performance, and economic feasibility of the product gas — as alternative fuel in passenger car, truck, and bulldozer—were tested, showing the feasibility technology for LFG utilization.