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There is concern that mercury (Hg) in coal combustion by-products might be emitted into the environment during processing to other products or after the disposal/landfill of these by-products. This perception may limit the opportunities to use coal combustion by-products in recycle/reuse applications and may result in additional, costly disposal regulations. In this program, CONSOL conducted a comprehensive sampling and analytical program to include ash, flue gas desulfurization (FGD) sludge, and coal combustion by-products. This work is necessary to help identify potential problems and solutions important to energy production from fossil fuels. The program objective was to evaluate the potential for mercury emissions by leaching or volatilization, to determine if mercury enters the water surrounding an active FGD disposal site and an active fly ash slurry impoundment site, and to provide data that will allow a scientific assessment of the issue. Toxicity Characteristic Leaching Procedure (TCLP) test results showed that mercury did not leach from coal, bottom ash, fly ash, spray dryer/fabric filter ash or forced oxidation gypsum (FOG) in amounts leading to concentrations greater than the detection limit of the TCLP method (1.0 ng/mL). Mercury was detected at very low concentrations in acidic leachates from all of the fixated and more than half of the unfixated FGD sludge samples, and one of the synthetic aggregate samples. Mercury was not detected in leachates from any sample when deionized water (DI water) was the leaching solution. Mercury did not leach from electrostatic precipitator (ESP) fly ash samples collected during activated carbon injection for mercury control in amounts greater than the detection limit of the TCLP method (1.0 ng/mL). Volatilization tests could not detect mercury loss from fly ash, spray dryer/fabric filter ash, unfixated FGD sludge, or forced oxidation gypsum; the mercury concentration of these samples all increased, possibly due to absorption from ambient surroundings. Mercury loss of 18-26% was detected after 3 and 6 months at 100 F and 140 F from samples of the fixated FGD sludge. Water samples were collected from existing ground water monitoring wells around an active FGD disposal site (8 wells) and an active fly ash slurry impoundment (14 wells). These were wells that the plants have installed to comply with ground water monitoring requirements of their permits. Mercury was not detected in any of the water samples collected from monitoring wells at either site. A literature review concluded that coal combustion byproducts can be disposed of in properly designed landfills that minimize the potentially negative impacts of water intrusion that carries dissolved organic matter (DOM). Dissolved organic matter and sulfate-reducing bacteria can promote the transformation of elemental or oxidized mercury into methyl mercury. The landfill should be properly designed and capped with clays or similar materials to minimize the wet-dry cycles that promote the release of methylmercury.

This paper describes the economically optimal adoption and operation of distributed energy resources (DER) by a hypothetical California microgrid (μGrid) consisting of a group of commercial buildings over an historical test year, 1999. The optimization is conducted using a customer adoption model developed at Berkeley Lab and implemented in the General Algebraic Modeling System. A μGrid is a semiautonomous grouping of electricity and heat loads interconnected with the existing utility grid (macrogrid) but able to island from it. The μGrid minimizes the cost of meeting its energy requirements (consisting of both electricity and heat loads) by optimizing the installation and operation of DER technologies while purchasing residual energy from the local combined natural gas and electricity utility. The available DER technologies are small-scale generators (<500 kW), such as reciprocating engines, microturbines, and fuel cells, with or without combined heat and power (CHP) equipment, such as water and space heating and/or absorption cooling. By introducing a tax on carbon emissions, it is shown that if the μGrid is allowed to install CHP-enabled DER technologies, its carbon emissions are mitigated more than without CHP, demonstrating the potential benefits of small-scale CHP technology for climate change mitigation. Reciprocating engines with heat recovery and/or absorption cooling tend to be attractive technologies for the mild southern California climate, but the carbon mitigation tends to be modest compared to purchasing utility electricity because of the predominance of relatively clean central station generation in California.

An analysis was made of siting issues in the coastal zone, one of the nation's most critical natural resource areas and one which is often the target for energy development proposals. The analysis addressed the changing perceptions of citizens toward energy development in the coastal zone, emphasizing urban communities where access to the waterfront and revitalization of waterfront property are of interest to the citizen. The findings of this analysis are based on an examination of energy development along New Jersey's urban waterfront and along the Texas-Louisiana Gulf Coast, and on redevelopment efforts in Seattle, San Francisco, Boston, and elsewhere. The case studies demonstrate the significance of local attitudes and regional cooperation in the siting process. In highly urbanized areas, air quality has become a predominant concern among citizen groups and an influential factor in development of alternative energy facility siting strategies, such as consideration of inland siting connected by pipeline to a smaller coastal facility. The study addresses the economic impact of the permitting process on the desirability of energy facility investments, and the possible effects of the location selected for the facility on the permitting process and investment economics. The economic analysis demonstrates the importance of viewing energymore » facility investments in a broad perspective that includes the positive or negative impacts of various alternative siting patterns on the permitting process. Conclusions drawn from the studies regarding Federal, state, local, and corporate politics; regulatory, permitting, licensing, environmental assessment, and site selection are summarized. (MCW)« less

The findings of a literature review on the environmental concerns and associated control methods of geothermal energy utilization are presented. The document introduces the environmental problems associated with geothermal energy utilization; assesses the current status of control methods; references appropriate environmental documents; and identifies areas where additional environmental research is needed. The review attempts to consolidate current understanding of the environmental impact of geothermal energy development. Approximately 180 reports written by authors in industry, government and academia have been reviewed in the areas of air emissions, surface and subsurface liquid discharges, solid wastes, noise, subsidence, and induced seismicity.

Due to continuing high demand, depletion of non-renewable resources and increasing concerns about climate change, the use of fossil fuel-derived transportation fuels faces relentless challenges both from a world markets and an environmental perspective. The production of renewable transportation fuel from microalgae continues to attract much attention because of its potential for fast growth rates, high oil content, ability to grow in unconventional scenarios, and inherent carbon neutrality. Moreover, the use of microalgae would minimize “food versus fuel” concerns associated with several biomass strategies, as microalgae do not compete with food crops in the food chain. This paper reviews the progress of recent research on the production of transportation fuels via homogeneous and heterogeneous catalytic conversions of microalgae. This review also describes the development of tools that may allow for a more fundamental understanding of catalyst selection and conversion processes using computational modelling. The catalytic conversion reaction pathways that have been investigated are fully discussed based on both experimental and theoretical approaches. Finally, this work makes several projections for the potential of various thermocatalytic pathways to produce alternative transportation fuels from algae, and identifies key areas where the authors feel that computational modelling should be directed to elucidate key information to optimize the process.

The COVID-19 pandemic caused and still causes unprecedented disruptions in daily lives of billions of people globally. It affects practices and routines across all household consumption domains, including clothing consumption. Drawing on Social Practice Theory, this article explores and compares changes in clothing acquisition practices during COVID-19 across nine countries: the USA, the UK, Finland, Germany, Switzerland, Iran, Czech Republic, India, and Hong Kong SAR. Data was obtained through a standardized survey containing rated and open-ended questions, which were analyzed through descriptive quantitative analysis and inductive qualitative content analysis of open-ended questions. The results of this cross-country research indicate that all forms of fashion consumption, including more sustainable practices, have decreased during the pandemic. The most visible impacts have occurred in the material arrangements associated with fashion acquisition practices (e.g., closed physical shops, shipping disruptions, cancelled events, remote work, etc.). However, changes that result from these disruptions may be shorter-lived that changes that happened as a result of changing meanings associated with fashion consumption and its more sustainable forms and new competencies and skills acquired during the pandemic that could ensure more lasting practicing of more sustainable forms of fashion consumption.

This report presents and discusses results from the project 'Fate of Mercury in Synthetic Gypsum Used for Wallboard Production', performed at five different full-scale commercial wallboard plants. Synthetic gypsum produced by wet flue gas desulfurization (FGD) systems on coal-fired power plants is commonly used in the manufacture of wallboard. This practice has long benefited the environment by recycling the FGD gypsum byproduct, which is becoming available in increasing quantities, decreasing the need to landfill this material, and increasing the sustainable design of the wallboard product. However, new concerns have arisen as recent mercury control strategies involve the capture of mercury in FGD systems. The objective of this study has been to determine whether any mercury is released into the atmosphere at wallboard manufacturing plants when the synthetic gypsum material is used as a feedstock for wallboard production. The project has been co-funded by the U.S. DOE National Energy Technology Laboratory (Cooperative Agreement DE-FC26-04NT42080), USG Corporation, and EPRI. USG Corporation is the prime contractor, and URS Group is a subcontractor. The project scope included seven discrete tasks, each including a test conducted at various USG wallboard plants using synthetic gypsum from different wet FGD systems. The project was originally composed ofmore » five tasks, which were to include (1) a base-case test, then variations representing differing power plant: (2) emissions control configurations, (3) treatment of fine gypsum particles, (4) coal types, and (5) FGD reagent types. However, Task 5,could not be conducted as planned and instead was conducted at conditions similar to Task 3. Subsequently an opportunity arose to test gypsum produced from the Task 5 FGD system, but with an additive expected to impact the stability of mercury, so Task 6 was added to the project. Finally, Task 7 was added to evaluate synthetic gypsum produced at a power plant from an additional coal type. In the project, process stacks in the wallboard plant were sampled using the Ontario Hydro method. In every task, the stack locations sampled included a gypsum dryer and a gypsum calciner. In Tasks 1 and 4 through 7, the stack of the dryer for the wet wallboard product was also tested. Also at each site, in-stream process samples were collected and analyzed for mercury concentration before and after each significant step in wallboard production. These results and process data were used to construct mercury mass balances across the wallboard plants. The results from the project showed a wide range of percentage mercury losses from the synthetic gypsum feedstocks as measured by the Ontario Hydro method at the process stacks, ranging from 2% to 55% of the mercury in the gypsum feedstock. For the tasks exceeding 10% mercury loss across the wallboard plant, most of the loss occurred across the gypsum calciner. When total wallboard emissions remained below 10%, the primary emission location varied with a much less pronounced difference in emission between the gypsum dryer, calciner and board dryer. For all seven tasks, the majority of the mercury emissions were measured to be in the elemental form (Hg{sup 0}). Overall, the measured mercury loss mass rates ranged from 0.01 to 0.17 grams of mercury per dry ton of synthetic gypsum processed, or 0.01 to 0.4 pounds of mercury released per million square feet of wallboard produced from synthetic gypsum. The Coal Combustion Product Production and Use Survey from the American Coal Ash Association (ACAA) indicate that 7,579,187 short tons of synthetic gypsum were used for wallboard production in 2006. Extrapolating the results of this study to the ACAA industry usage rate, we estimate that mercury releases from wallboard production plants in 2006 ranged between 150 to 3000 pounds for the entire U.S. wallboard industry. With only seven sets of wallboard plant measurements, it is difficult to draw firm conclusions about what variables impact the mercury loss percentages across the wallboard plants. One significant observation from this study was that higher purge rates of chlorides and fine solid particles from the wet FGD systems appear to produce gypsum with lower mercury concentrations. Any chemical interaction between mercury and chlorides is not well understood; however, based on the information available the lower mercury content in the gypsum product is likely due to the blow down of fine, mercury-rich particles as opposed to a decreased chloride concentration. One possible explanation is that a decrease of fine particles in the FGD slurry allows for less adsorption of mercury onto those particles, thus the mercury remains with the FGD liquor rather than the gypsum product. A more detailed discussion on synthetic gypsum sources and FGD chemistry data can be found in the Experimental section of this report and Table 4.« less