has been a Professor at Caltech since 1988, an active leader in the solar fuels / solar chemical field for over 40 years. Prof. Lewis has published over 600 papers, presented hundreds of public and technical lectures and has worked with researchers from across the world in exploring the development of solar fuels.

Nate presented the inaugural 2022 Nozik Lecture on Monday August 29, 2022. The turnout was fantastic, both in person and online, with a full, but socially distant room. Making an afternoon of the proceedings Nate gave two talks, one looking at big picture methods for the decarbonization of the U.S Electricity Grid, the second taking a very technical deep dive into chemical materials that can 鈥渟ee鈥� light.

Reliable Decarbonized U.S. Electricity Systems

Prof. Nathan Lewis | Caltech

Monday August 29, 2022 | 1:30 PM

SEEC Auditorium C120

Using a data-driven approach based on 39 years of hourly weather data to derive the variability of the wind and solar resource across the contiguous U.S., we analyze the gaps between supply and historical demand that would be present in an electricity system in which generation was provided by variable wind and solar resources. 听We then assess the dynamical relationships and in an idealized system assess the cost-effectiveness of various approaches to satisfy resource adequacy planning requirements, including overbuilding and extensive curtailment of variable renewable generation assets, short and long term storage embodied by batteries, flow batteries and power-to-gas-to-power, flexible nuclear generation, and flexible loads such as generation of hydrogen or electrofuels. 听We additionally have assessed the implications of regionalization of generation assets and load-balancing regions such as California or the Western Interconnect on the needs for flexibility and storage in view of the increased variability and frequency and duration of resource droughts that occurs as the generation and load-balancing regions are confined geographically. 听In California, we additionally show that addition of existing hydroelectric generation slightly increases the need for long-duration storage as opposed to decreasing it, due to the seasonal mismatch between hydroelectric generation and electricity demand. 听The analyses moreover emphasize the need for multi-year planning to ensure resource adequacy in systems that have large contributions of generation from variable renewables.

Inorganic Phototropic Growth of Materials that See the Light

Prof. Nathan Lewis | Caltech

Monday August 29, 2022 | 4:00 PM

SEEC Auditorium C120

We have discovered a materials phenomenon, which we term inorganic phototropic growth, in which materials grow in real time, in 3-D space, towards a uniform intensity, uncorrelated beam of low intensity听light, as occurs in for example palm trees, sunflowers, and corals.听听The听growth results in听the听rapid,听light-directed formation of anisotropic complex, three-dimensional mesoscale morphologies of materials over macroscopic areas, providing access to nanostructures and morphologies that can not readily be made by any other method. 听The听phenomenon transcends traditional chemical and engineering disciplines: no lasers, no physical masks, no lithographic processing, no direct-write technology, no far-field modulation, no templates, and no chemical agents (ligands, surfactants) are used to direct听the听patterning, but full 3-D control is obtainable over听the听resulting morphology of听the听structure by manipulation听the听properties of听the听incident听lightstimuli during growth.听The听nanostructures are created in a single-step synthesis and are determined both by听the听inherent response of听the听electronic processes within semiconductors to听the听presence of听light, and by听thetunable properties (e.g. wavelength, polarization, and direction) of听light听present during听the听electrodeposition. We have experimentally explored this emergent phenomenon by determining how specific optical inputs encode for specific morphologies, and have developed a model that accurately reproduces听the听experimentally observed nanostructures for听the听optical inputs and material systems explored thus far. Our work to date has been focused on听the听growth of Group II-VI materials (i.e. Se-Te alloys and PbSe); however, we expect that听theemerging phenomenon underlying听the听growth process will prove general for听the听electrodeposition of semiconductors in听the听presence of听light. We provide a brief overview of our work to date, and outline research directions designed to provide听the听further scientific insight into听the听processes behind this novel route to nanoscale and mesoscale materials design and synthesis that will be essential to听the听development of future technologies that exploit听the听phenomenon.

Published: Aug. 29, 2022
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