In the coming Control Age, scientists will be able to design and create entirely new materials and processes with desired properties and outcomes. With such capabilities, we should find solutions to some of the most vexing problems that civilization now faces, including energy, in all of its aspects, and changing global climate patterns.

Injection of CO2 into depleted natural gas reservoirs offers the potential to sequester carbon while simultaneously enhancing CH4 recovery. Enhanced CH4 recovery can partially offset the costs of CO2 injection. With the goal of analyzing the feasibility of carbon sequestration with enhanced gas recovery (CSEGR), we are investigating the physical processes associated with injecting CO2 into natural gas reservoirs. The properties of natural gas reservoirs and CO2 and CH4 appear to favor CSEGR. To simulate the processes of CSEGR, a module for the TOUGH2 reservoir simulator that includes water, brine, CO2, tracer, and CH4 in nonisothermal conditions has been developed. Simulations based on the Rio Vista Gas Field in the Central Valley of California are used to test the feasibility of CSEGR using CO2 separated from flue gas generated by the 680 MW Antioch gas-fired power plant. Model results show that CO2 injection allows additional CH4 to be produced during and after CO2 injection.

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[1] The development and initial application of a mechanistic model (TOUGHREACT-N) designed to characterize soil nitrogen (N) cycling and losses are described. The model couples advective and diffusive nutrient transport, multiple microbial biomass dynamics, and equilibrium and kinetic chemical reactions. TOUGHREACT-N was calibrated and tested against field measurements to assess pathways of N loss as either gas emission or solute leachate following fertilization and irrigation in a Central Valley, California, agricultural field as functions of fertilizer application rate and depth, and irrigation water volume. Our results, relative to the period before plants emerge, show that an increase in fertilizer rate produced a nonlinear response in terms of N losses. An increase of irrigation volume produced NO 2 À and NO 3 À leaching, whereas an increase in fertilization depth mainly increased leaching of all N solutes. In addition, nitrifying bacteria largely increased in mass with increasing fertilizer rate. Increases in water application caused nitrifiers and denitrifiers to decrease and increase their mass, respectively, while nitrifiers and denitrifiers reversed their spatial stratification when fertilizer was applied below 15 cm depth. Coupling aqueous advection and diffusion, and gaseous diffusion with biological processes, closely captured actual conditions and, in the system explored here, significantly clarified interpretation of field measurements.

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