Abstract: Over 70% of the terrestrial Earth is affected by fire in some way and roughly 50% of terrestrial ecosystems are fire dependent – meaning fire is necessary for these ecosystems to exist including the critical services these ecosystems provide such as carbon storage, and water resources.  Climate change is rapidly changing Earths fire activity – we are now seeing larger and more extreme wildfires that are burning at times we have not seen before.  Moreover, climate change in pushing conditions beyond the validation range of the empirically based models used to predict fire behavior and ecosystem response. This is referred to as the no-analog future, which necessitates a new fire modeling approach. Providing today’s society with the tools necessary to reduce wildfire risk, maintain ecosystem function – including water resources in light of climate change requires state of the art wildfire science that accounts for a rapidly changing landscape.  Here at Los Alamos, we are working on the science necessary to reduce wildfire risk, while maximizing landscape carbon stabilization to mitigate climate change and protecting water resources – often in the form of safely reintroducing necessary fire to a landscape that has on one hand not seen fire in over a century and on the other requires fire for is very existence through the use of prescribed fire. This requires a multi-disciplinary approach that includes ecosystem science, hydrology, wildfire behavior, atmospheric chemistry, and use of physics based mechanistic models to capture a systems response in the no-analog future.  I will be showcasing new wildland fire and ecosystem process-based models developed at LANL to understand how tightly entwine interactions of fire behavior, hydrology, and ecosystem structure drive ecosystem resiliency in a changing climate.

Abstract: Albeit slow and not without its challenges, lead (Pb) emissions and sources in the United States (U.S.) have decreased immensely over the past several decades. Despite the prevalence of childhood Pb poisoning throughout the twentieth century, most U.S. children born in the last two decades are significantly better off than their predecessors in regard to Pb exposure. For example, in the 1970’s virtually every child in the U.S. would be considered Pb affected by today’s regulatory blood Pb standard, which is 5 micrograms/deciliter, with some variations among state health departments as to what level a given state begins case management for children. However, the rate of decline in blood Pb levels is not equal across demographic groups, with urban children and children of color exhibiting disproportionately higher average blood Pb levels than their non-urban and white counterparts. In part to address this disparity and to continue to reduce population and individual blood Pb levels, many U.S. federal agencies are moving quickly in various “Close to Zero” efforts, including newer regulatory guidance to further limit lead exposures.

The current state of lead exposure sources is much different than it was 40 years ago. For example, modern atmospheric emissions of Pb in the U.S. are nearly negligible since the banning of leaded gasoline in vehicles and regulatory controls on Pb smelting plants and refineries. This is evident in the rapid decrease of atmospheric Pb concentrations across the U.S. over the last four decades. One of the most significant remaining contributors to air Pb is aviation gasoline (avgas), which is minor compared to former Pb emissions. However, continual exposure risks to legacy Pb sources exist in older homes and urban centers, where leaded paint and/or historically contaminated soils and dusts can still harm children. Thus, while effective in eliminating nearly all primary sources of Pb in the environment, the slow rate of U.S. Pb regulation has led to still-significant legacy sources of Pb in the environment. Substantially more work is required to identify where legacy Pb sources are actively exposing children to harm, and substantially more resources, and new approaches, are needed to provide mitigation relief to parents. The presentation reviews the progress made in Pb abatement, its status, and discusses urban Pb exposure, and future research and regulatory needs.

Abstract:

Fracture systems and faults control the strength of the Earth’s crust, fluid flow, and heat and mass transport at a wide range of scales. In addition to the significance of fractures to natural crustal-scale and geomorphic processes, natural and induced fractures are of fundamental importance to oil and gas production, geothermal energy extraction, and the subsurface storage of CO₂ and hydrogen. Understanding how fractures form, under what stress conditions, how fast, and how their growth is influenced by chemical reactions is of fundamental importance.

The formation of rock fractures under upper crustal conditions is conventionally regarded as a primarily brittle mechanical process. This view is now evolving with the recognition of the significance of coupled chemical reactions for fracture growth. This is particularly relevant to systems where the formation is in contact with fluid far out of chemical equilibrium, conditions expected for enhanced oil recovery, hydraulic fracturing, enhanced geothermal systems, CO₂ storage, and hydrogen storage in porous formations.

In combination with field structural observations of fractures in a variety of natural settings, my students and postdocs conducted laboratory fracture mechanics tests of shale and sandstone of varying composition in the presence of aqueous fluid of varying pH and salinity to quantify the effect of chemical reactions on fracture growth. We also synthesized fractures in geomaterials under reactive laboratory conditions to define characteristics of fractures and fracture systems that form in chemically reactive systems and to understand how such reactive fracture systems differ from purely mechanical brittle fracture processes.

We find that chemical reactions can both enhance and inhibit fracture growth depending on the mineral and fluid composition and the reactions involved. Acidic pore water enhances fracture growth in carbonate-rich shale lithologies, whereas high salinity impedes fracture growth in clay-rich shales. Silicification under geothermal or epithermal conditions can lead to significant strengthening with a three-fold increase in fracture toughness, whereas chlorite-clay alteration reduces fracture toughness. Silicified rock is more susceptible to fracture growth under alkaline aqueous conditions.

Fracture growth experiments demonstrate that fractures formed in chemically reactive environments are generally characterized by wider kinematic apertures compared to fractures forming under less reactive conditions, with fracture shapes that deviate from predicted elliptical profiles. Such deviations in fracture profile may enhance or impede fracture growth.

These results apply to natural as well as engineered fracture systems and are thus of direct relevance to the stability of shale caprocks in CO₂ and hydrogen storage systems, and to induced fracture performance in enhanced geothermal systems and unconventional oil and gas reservoirs. Because chemical reactions can both enhance and inhibit fracture growth, these processes provide the opportunity to optimize fracture outcomes under managed fluid chemical conditions.

Abstract:

Bioethanol crops have the potential to meet future energy demands and mitigate climate change by partially replacing fossil fuels. However, the large-scale cultivation of these crops may also impact climate change through changes in land cover, terrestrial water and energy balance, carbon and other nutrient dynamics, and their interactions. This represents a pivotal challenge within the Food-Energy-Water System (FEWS) nexus. Our study estimates potential bioethanol yield across the US based on crop field studies and conversion technology analysis for three crops – corn, Miscanthus, and two cultivars of switchgrass (Cave-in-Rock and Alamo). This presentation will provide a detailed analysis of the implications of growing bioethanol crops on water and energy resources and GHG emissions. Additionally, the presentation will explore how the growing challenges of extreme climate conditions, including droughts and heat waves, are shaping these critical factors across the US.

Abstract: As planetary geology reaches the edges of the solar system and prepares for the leap to exoplanets, we should be ready to encounter igneous processes occurring over a much wider range of T-X space than is familiar to terrestrial petrologists. Volcanism on Earth is typically restricted to compositions that can be generated by partial melting of the Earth’s mantle and/or crust, and through subsequent modifying processes such as magma mixing, assimilation, and fractional crystallization. This leads to the familiar range of terrestrial lava compositions, limited at the present day to foidites (e.g., Nyiragongo, DRC) at the low-SiO2 end, and high-silica rhyolites (e.g. Obsidian Dome, USA) at the other. Carbonatites represent a rare departure from silicate volcanism on Earth. At much lower temperatures, cryovolcanism is the probable mechanism for the extrusion of sodium carbonate-rich domes on Ceres. Sulfate, chloride, and carbonate-rich brines are likely cryovolcanic materials at Europa, Enceladus, and other ocean worlds.

Impact melts are composed primarily of target material, whose composition is dictated by surface processes that extend beyond the realm of igneous petrology. Consequently, they span a much wider range. On terrestrial bodies with primary crusts, such as the anorthositic lunar highlands, impact melts can resemble monomineralic melts, which could never form by any other mechanism. Where impacts remelt secondary crusts, for example the lunar maria, the same magma could be reborn but at a much higher temperature than during initial formation and emplacement. These superheated sheets of lava have tremendous erosive power, both thermal and mechanical, until they cool below their liquidus.

Finally, in situ resource utilization (ISRU) on the Moon or Mars will likely require melting to produce glass and ceramics for construction and technical applications. Energy requirements can be minimized by using starting materials with a glassy component, sourced from volcanic or impact melt deposits (including micron-scale agglutinates). The tendency for finer grained lunar regolith to also be more feldspathic and glassier raises the possibility that physical sorting by size can also sort for composition and crystallinity, facilitating brick/ ceramic production in locations where the bulk regolith is less suitable.

Not your grandfather’s petroleum system: The Goldrush for CO₂ Storage and the Underrated Role of Pressure

Abstract: The Gulf of Mexico is a petroleum super-basin, a maker of fortunes and a major driver of American industry.  Early indications are that it may be similarly spectacular for Carbon Capture and Storage (CCS), a key climate change mitigation technology.  It has some of the densest clusters of point-source CO₂ emissions in the US and proven reservoirs at every stratigraphic level from Jurassic to Pleistocene.  Application of petroleum-inspired volumetric analysis suggests that the Texas coast Miocene section alone could offer 125Gt in storage capacity, enough to store ~2 decades of emissions for the entire US. Recent reforms to the tax code and passage of the Inflation Reduction Act have transformed the incentives for CCS, raising the reward from $10/ton of CO₂ stored to $85/ton.  As of November 2023, at least 49 new storage projects have been announced on the US Gulf Coast, with a total claimed storage capacity greater than 7Gt.  A new gold rush is on.

However, CO₂ injection is not petroleum production and application of petroleum-inspired volumetrics can yield dazzling but wholly unrealistic numbers.  Both petroleum accumulation and CO₂ injection require displacing pre-existing pore fluids (brines), but the similarity ends there.  Petroleum accumulates on geologic time, pushing the native brines out slowly, at pressure equilibrium, and reliably saturating a predictable reservoir volume.  Not so for injected CO₂.  Injection at industrial rates favors the highest permeabilities.  Sweep efficiency is often poor and always hard to predict. More significantly, brine displacement is limited by faults, depositional edges and the same confining zones required to retain CO₂.  Most of the storage space for injected CO₂ must come from compression of rock and preexisting brines, neither of which is very compressible. Pressure build-up is inevitable and it, not saturation, is the key limitation on storage capacity.  Combined with the exponential growth of announced storage projects, that realization raises new questions: What is realistically achievable? What is the potential for interference between projects? What is the value of the storage resource? And how much space is required between projects to avoid interference?

To address these questions, we introduce the concept of pressure space, which we define as pore volume times allowable pressure increase, similar to a gas storage tank whose capacity is defined by volume and pressure rating.  Using new algorithms on the grids developed for the original Miocene static capacity assessment, we find that the Texas coastal Miocene section offers ~10Gt in pressure-based capacity, if all reservoirs within it are pressured up to the statutory limit of 90% of frac pressure.  While still substantial (and only a small fraction of the total Gulf of Mexico), that is an order of magnitude less than the original estimate and equates to less than 0.5% pore volume occupancy (storage efficiency), on average.  For comparison, the 200+ saline storage projects in the global OGCI Storage Resource Catalog claim storage efficiencies from <1% up to 25%.  While some may get these numbers, our work makes clear that they can only be achieved by producing brine and/or consuming pressure space beyond the project boundaries.  Gigaton-scale storage is clearly possible, but it may require more acreage than current project developers are calculating.  Competition for pressure space is predictable and like all gold rushes, this one is likely to yield benefit for society at large, but uneven fortunes for the project developers.