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12Over the last decade, there has been a growing interest in large-scale use of hydrogen in the transportation and 13 renewable energy sectors. Relatively cost-effective storage options at scale are essential to realize the full potential 14 of hydrogen as an energy carrier. Underground geologic storage of hydrogen could offer substantial storage cost 15 reductions as well as buffer capacity to meet possible disruptions in supply or changing seasonal demands. Several 16 geologic storage site options are being considered including salt caverns, depleted oil and/or gas reservoirs, aquifers, 17and hard rock caverns. This paper describes an economic analysis that addresses the costs entailed in developing 18and operating a geologic storage facility. The analysis focuses on salt caverns to illustrate potential city demand for 19 hydrogen using geostorage options because (1) salt caverns are known to successfully contain hydrogen, and (2) 20 there is more geotechnical certainty involved with salt storage as compared to the other three storage options. The 21 main findings illustrate that geologic limitations rather than city demand cause a larger disparity between costs from 22 one city to the next. For example Detroit hydrogen storage within salt caverns will cost approximately three times 23 more than Los Angeles with its larger population. Detroit is located near thinly bedded salt formations, whereas Los 24Angeles has access to more massive salt formations. Los Angeles requires the development of larger and fewer 25 caverns and therefore has lower costs. 26 27

Desert varnish is a coating of ferromanganese oxides and clays that develops on rock surfaces in arid to semi-arid regions. Active respiration but not photosynthesis was detected on varnished rock surfaces from the Sonoran Desert. Light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, and cultivation experiments indicate that both fungi, primarily dematiaceous hyphomycetes, and bacteria are found on and within desert varnish coatings from the arid regions studied. Some fungi grow as microcolonial fungi (MCF) on rocks, and microscopic observations suggest MCF become incorporated in the varnish coating. SEM-EDAX (energy dispersive X-ray systems) analyses indicate the MCF contain 3 of the characteristic elements of varnish: iron, aluminum, and silicon. In some locations, MCF are also enriched in manganese relative to the rock substratum. Furthermore, some of the dematiaceous hyphomycetes that have been cultivated are able to oxidize manganese under laboratory conditions. It is possible that manganese-oxidizing bacteria, which are found in varnish, also play an important role in varnish formation.

The Delaware Basin is a broad asymmetric sedimentary trough in southeastern New Mexico and west Texas. Basin subsidence occurred from the Pennsylvanian into the Triassic. The basin also underwent tilting since the early Cenozoic. Layered evaporite units of Ochoan age in the basin are 1000 m thick. These evaporites are divided into three stratigraphic units (listed in order of increasing age): the Rustler Formation, the Salado Formation, the Castile Formation. These units, especially the Castile, are deformed along portions of the margin of the Delaware Basin and in some areas internal to the basin. In the northern Delaware Basin adjacent to the WIPP site, the term "Disturbed Zone" (DZ) has been applied to an area in which deformation structures are found in boreholes and from which chaotic seismig reflection data were obtained. The origin and timing of this deformation is considered important for the determination of This docunlent is PUBLI&'L%7 RELEASABLE Authorizing Official Date: 81/31 / W O d

a b s t r a c tResearch involving management of carbon dioxide has increased markedly over the last decade as it relates to concerns over climate change. Capturing and storing carbon dioxide (CO 2 ) in geological formations is one of many proposed methods to manage, and likely reduce, CO 2 emissions from burning fossil fuels in the electricity sector. Saline formations represent a vast storage resource, and the waters they contain could be managed for beneficial use. To address this issue, a methodology was developed to test the feasibility of linking coal-fired power plants, deep saline formations for CO 2 storage, and extracting and treating saline waters for use as power plant cooling water.An illustrative hypothetical case study examines a representative power plant and saline formation in the south-western United States. A regional assessment methodology includes analysis of injectioninduced changes in subsurface groundwater chemistry and fate and transport of supercritical CO 2 . Initial water-CO 2 -formation reactions include dissolution of carbonate minerals as expected, and suggest that very little CO 2 will be stored in mineral form within the first few centuries. Reservoir simulations provide direct input into a systems-level economic model, and demonstrate how water extraction can help manage injection-induced overpressure. Options for treatment of extracted water vary depending upon site specific chemistry. A high efficiency reverse osmosis system (HERO TM ) shows promise for economical desalination at the volumes of recovered water under consideration. Results indicate a coupled use CO 2 storage and water extraction and treatment system may be feasible for tens to hundreds of years.