Energy Sciences

Chronic groundwater overdraft threatens agricultural sustainability in California's Central Valley. Diverting flood flows onto farmland for groundwater recharge offers an opportunity to help address this challenge. We studied the infiltration rate of floodwater diverted from the Kings River at a turnout upstream of the James Weir onto adjoining cropland; and calculated how much land would be necessary to capture the available floodwater, how much recharge of groundwater might be achieved, and the costs. The 1,000-acre pilot study included fields growing tomatoes, wine grapes, alfalfa and pistachios. Flood flows diverted onto vineyards infiltrated at an average rate of 2.5 inches per day under sustained flooding. At that relatively high infiltration rate, 10 acres are needed to capture one CFS of diverted flood flow. We considered these findings in the context of regional expansion. Based upon a 30-year record of Kings Basin surplus flood flows, we estimate 30,000 acres operated for on-farm flood recharge would have had the capacity to capture 80% of available flood flows and potentially offset overdraft rates in the Kings Basin. Costs of on-farm flood capture for this study were estimated at $36 per acre-foot, less than the cost for surface water storage and dedicated recharge basins.

Field research and grower interviews were used to evaluate the potential of minimum tillage for California rice systems. We found that by tilling only in the fall (instead of both the fall and spring), rice farmers can control herbicide-resistant weeds when combined with a stale rice seedbed, which entails spring flooding to germinate weeds followed by a glyphosate application to kill them. Our results indicated that yield potentials are comparable between water-seeded minimum- and conventional-till systems. We also found that rice growers can reduce fuel costs and plant early. However, minimum tillage may require more nitrogen fertilizer to achieve these yields.

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New gene editing technologies give us the potential ability to bring back extinct species, help control the spread of invasive ones, and genetically modify those that spread diseases. They allows us to not only influence the evolutionary path of entire species, but entire ecosystems as well. Furthermore, gene editing has the potential to help us live healthier and longer lives. We have moved past rudimentary macroscopic methods of DNA manipulation and can now remove individual genes from a strand of DNA. However, due to the complexity of this technology, and given that there are few who can use it to its full effect, people have largely failed to respond to its development, particularly regulators. It is not within the scope of this paper to explore the full implications of these various emerging technologies, so instead I will focus on CRISPR, a specific new gene editing complex first used in 2012, and the major developments that have taken place since then.

Water treatment technologies separate relevant solutes from water resources for water reuse, valuable resource recovery, and increasing the equity and availability of clean water worldwide. Although a variety of treatment methods exist, their performance needs to be improved to enable selective separation with increased durability and fouling resistance. To achieve this, we need to gain a better understanding of how molecular-level physics and chemistry impact integrated systems. Regarding current research on water treatment techniques, there is a clear need to study such systems under realistic environmental conditions. In this review, we aim to show that X-ray spectroscopic techniques are uniquely positioned to provide such information by obtaining detailed molecular insight into phenomena relevant to water research. By doing so, we hope to accelerate the rational design of novel treatment materials and processes. Specifically, a deeper understanding of the complex and interconnected phenomena that impact multilevel water treatment processes will lead to the successful development of next-generation water purification technologies.

Sodium-ion batteries have the potential to meet the growing demand for energy storage due to their low costs stemming from natural resource abundances, but their cathode energy densities must be improved to be comparable to those of lithium-ion batteries. One strategy is accessing high voltage capacity through high-valent redox reactions. Such reactions usually cause instability in cathode materials, but Na2Mn3O7 (NMO) has demonstrated excellent performance and reversibility in the high-valent regime due to its unique lattice structure with ordered Mn vacancies. This work expands the universality of the ordered vacancy as a design principle and increases the material candidates with such exceptional electrochemical behavior. Our approach involves synergizing cationic ordered vacancies with tunable metal-ligand hybridization through partial metal substitution. In particular, we successfully incorporated Fe3+ for Mn4+ in NMO to make Na2.25Mn2.75Fe0.25O7 and achieved improved high-valent redox behavior. Fe substitution leads to larger specific capacities (171 vs. 159 mA h g−1 first cycle), enhanced cycle stability (97 vs. 60 mA h g−1 after 50 cycles), and superior rate performance. This study lays the foundation for developing new cathode materials with stable high-valent redox through substitution of redox-active transition metals by employing cationic ordered vacancies and partial transition metal substitution as design principles in tandem.

As an emerging technology, polymer electrolyte fuel cells (PEFCs) powered by clean hydrogen can be a great source of renewable power generation with flexible utilization because of high gravimetric energy density of hydrogen. To be used in real-life applications, PEFCs need to maintain their performance for long-term use under a wide range of conditions. Therefore, it's important to understand the degradation of the PEFC under protocols that are closely related to the catalyst lifetime. Alloying Pt with transitional metal improves catalyst activity. It is also crucial to understand Pt alloys degradation mechanisms to improve their durability. To study durability of Pt alloys, accelerated stress tests (ASTs) are performed on Pt−Co catalyst supported on two types of carbon. Two different AST protocols were being studied: Membrane Electrolyte Assembly (MEA) AST based on the protocol introduced by the Million Mile Fuel Cell Truck consortium in 2023 and Catalyst AST, adopted from the U.S. Department of Energy (DoE).