In many regions of the world, flooded mines are a potentially cost-effective option for heating and cooling using geothermal heat pump systems. For example, a single coal seam in Pennsylvania, West Virginia, and Ohio contains 5.1 x 10 12 L of water. The growing volume of water discharging from this one coal seam totals 380,000 L/min, which could theoretically heat and cool 20,000 homes. Using the water stored in the mines would conservatively extend this option to an order of magnitude more sites. Based on current energy prices, geothermal heat pump systems using mine water could reduce annual costs for heating by 67% and cooling by 50% over conventional methods (natural gas or heating oil and standard air conditioning).

Effective storage of CO 2 requires a better understanding of coal and minerals such as clays to develop new sorbent materials and sequestration technologies.The looming global energy and environmental crises underscore a pressing need for the revision of current energy policies. The dominatingsalbeit somewhat optimisticspublic perception is that hundreds of years' worth of coal available for power generation will offset the decline of oil and gas reserves. Although use of coal accounts for half of U.S. electricity generation and for a quarter of world energy consumption, it has been perceived until recently as an unwelcome guest "from the era and pages of Charles Dickens" by environmentalists and legislators (1). For coal power generation to be properly considered, CO 2 and other greenhouse gas (GHG) generation and deposition must be addressed to assuage global climate change concerns. The ongoing development of a "pathway to stabilization" of CO 2 emissions championed by the U.S. Department of Energy (DOE) (2) is an integral part of the global response to these challenges. Capturing and sequestering CO 2 emissions is one of the principal modes of carbon management. The current strategies are geared toward implementation of various sequestration options, including terrestrial (via improved management of forests, range-, wet-, and agricultural lands), geological sequestration, and advanced biological and chemical approaches (2, 3).One of the carbon storage opportunities is sequestration in deep (>1.5 km) coal seams that are not suitable for mining. In this option, CO 2 injected into a coal bed becomes adsorbed onto the coal's surface and is immobilized. The main difficulty of this method is maintaining injectivity as the coal matrix imbibes CO 2 and swells (4). Furthermore, delivery of the captured GHG emission from the point of power generation to the remote sequestration site involves dealing with logistical problems and relatively high transportation costs. However, there are numerous shallow (<300 m deep) active and decommissioned coal mines that have large reservoir capacities. The coal remaining in place after the mining will provide some sequestration capacity. Yet the key question is whether other materials that could be placed in the mined void space underground or on the surface would enhance the CO 2 sorption.Herein we will suggest a novel process that includes capturing GHG in abundant materials, which can be facilitated by controlled sequential heating and cooling of these solids. By taking advantage of the properties of waste materials generated during coal production and the exhaust heat generated by the power plants, such an approach permits the integration of the entire CO 2 cycle, from generation to deposition. Coupling coal extraction/preparation with power generation facilities would improve the economics of "zero-emission" power plants due to the proximity of all the involved facilities (Figure 1). Challenges and opportunitiesTo assess the feasibility of this concept, engineers need to consid...

zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA A study was conducted to evaluate two chemical models of iron oxidation. The first model was proposed by U. S. EPA in 1983 for use in the design of acid mine drainage (AMD) treatment systems. This model expresses the oxidation rate as a function of ferrous iron, oxygen concentrations, and pH. The second model was proposed by the U. S. Bureau of Mines and expresses the oxidation rate as a function of a treatment system's oxygen transfer rate. The findings of the study were that the model based on oxygen transfer was accurate in predicting oxidation rates over a wide range of initial ferrous iron concentrations. The predictions of the EPA model were inaccurate in modeling iron oxidation.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Water Environ. Res., 64, 817 (1992).

The Kettle Creek watershed contains 50–100-year-old surface and underground coal mines that are a continuing source of acid mine drainage (AMD). To characterize the mining-altered hydrology of this watershed, an airborne reconnaissance was conducted in 2002 using airborne thermal infrared imagery (TIR) and helicopter-mounted electromagnetic (HEM) surveys. TIR uses the temperature differential between surface water and groundwater to locate areas where groundwater emerges at the surface. TIR anomalies located in the survey included seeps and springs, as well as mine discharges. In a follow-up ground investigation, hand-held GPS units were used to locate 103 of the TIR anomalies. Of the sites investigated, 26 correlated with known mine discharges, whereas 27 were previously unknown. Seven known mine discharges previously obscured from TIR imagery were documented. HEM surveys were used to delineate the groundwater table and also to locate mine pools, mine discharges, and groundwater recharge zones. These surveys located 12 source regions and flow paths for acidic, metal-containing (conductive) mine drainage; areas containing acid-generating mine spoil; and areas of groundwater recharge and discharge, as well as identifying potential mine discharges previously obscured from TIR imagery by nondeciduous vegetation. Follow-up ground-based electromagnetic surveys verified the results of the HEM survey. Our study suggests that airborne reconnaissance can make the remediation of large watersheds more efficient by focusing expensive ground surveys on small target areas.

No abstract