Basic Research Needs for Geosciences - Energetics Meetings and ...

EXECUTIVE SUMMARYCROSSCUTTING RESEARCH ISSUESThe microscopic basis of macroscopic complexity. Classical continuum mechanics relies on theassumption of a separation between the length scales of microscopic fluctuations andmacroscopic motions. However, in geologic problems this scale separation often does not exist.There are instead fluctuations at all scales, and the resulting macroscopic behavior can then bequite complex. The essential need is to develop a scientific basis of “emergent” phenomenabased on the microscopic phenomena.Highly reactive subsurface materials and environments. The emplacement of energy systembyproducts into geological repositories perturbs temperature and pressure, imposes chemicalgradients, creates intense radiation fields, and can cause reactions that alter the minerals, porefluids, and emplaced materials. Strong interactions between the geochemical environment andemplaced materials are expected. New insight is needed on equilibria in compositionallycomplex systems, reaction kinetics in concentrated aqueous and other solutions, reaction kineticsunder near-equilibrium undersaturated and supersaturated conditions, and transient reactionkinetics.Thermodynamics of the solute-to-solid continuum. Reactions involving solutes, colloids,particles, and surfaces control the transport of chemical constituents in the subsurfaceenvironment. A rigorous structural, kinetic, and thermodynamic description of the complexchemical reality between the molecular and the macroscopic scale is a fundamental scientificchallenge. Advanced techniques are needed for characterizing particles in the nanometer-tomicrometersize range, combined with a new description of chemical thermodynamics that doesnot rely on a sharp distinction between solutes and solids.TECHNICAL AND SCIENTIFIC IMPACTThe Grand Challenges, Priority Research Directions, and Crosscutting Issues described in thisreport define a science-based approach to understanding the long-term behavior of subsurfacegeologic systems in which anthropogenic CO 2 and nuclear materials could be stored. Theresearch areas are rich with opportunities to build fundamental knowledge of the physics,chemistry, and materials science of geologic systems that will have impacts well beyond thespecific applications. The proposed research is based on development of a new level ofunderstanding—physical, chemical, biological, mathematical, and computational—of processesthat happen at the microscopic scale of atoms, molecules and mineral surfaces, and how thoseprocesses translate to material behavior over large length scales and on ultra-long time scales.Addressing the basic science issues described would revolutionize our ability to understand,simulate, and monitor all of the subsurface settings in which transport is critical, including themovement of contaminants, the emplacement of minerals, or the management of aquifers. Theresults of the research will have a wide range of implications from physics and chemistry, tomaterial science, biology and earth science.xiiBasic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems