Enabling a Future Based on Electricity Through Non-Equilibrium Plasma Chemistry
Total Page：16
File Type：pdf, Size：1020Kb
Science Challenges in Low-Temperature Plasma Science and Engineering: Enabling a Future Based on Electricity Through Non-Equilibrium Plasma Chemistry Raw Materials Chemicals and Products Healthcare Plasma Lossless Transmission Wind New Technologies Solar Plasma Processor Recovered Resource Green Generation Waste, Contamination Workshop held at the National Science Foundation | Arlington, VA | 22-23 August 2016 Workshop Report Science Challenges in Low Temperature Plasma Science and Engineering: Enabling a Future Based on Electricity through Non-Equilibrium Plasma Chemistry Workshop held at the National Science Foundation Arlington, VA 22-23 August 2016 Workshop Co-Chairs: Selma Mededovic Thagard Department of Chemical and Biomolecular Engineering Clarkson University, Potsdam, NY 13699-5705, [email protected] Mohan Sankaran Department of Chemical and Biomolecular Engineering Case Western Reserve University, Cleveland, OH 44106-7217, [email protected] Mark J. Kushner Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109-2122, [email protected] Report Submitted: Preliminary – February 2017 Final – April 2017 Acknowledgements The attendees and organizers of the workshop, Science Challenges in Low Temperature Plasma Science and Engineering: Enabling a Future Based on Electricity through Non- Equilibrium Plasma Chemistry, gratefully acknowledge the support of the National Science Foundation (CBET-1613074) and the Army Research Office (W911NF-16-1-0562). We are also thankful for the advice and support of Dr. Vyacheslav Lukin (PHY), Prof. JoAnn S. Lighty (CBET), Prof. Triantafillos John Mountziaris (CBET) and Prof. Hao Ling (ECCS) of NSF; and Dr. David Stepp and Dr. Michael P. Bakas of ARO. Dr. Maria Burka (NSF) was instrumental in helping form the vision for the workshop and guiding the organizers through the process. The co- chairs are particularly grateful to Prof. David B. Graves (University of California at Berkeley) for his insightful advice on formulating the agenda of the workshop and in producing this report. Dr. Julia Falkovitch-Khain (University of Michigan) was irreplaceable in helping to organize the workshop. Finally, we thank the University of Michigan College of Engineering and the Michi- gan Institute for Plasma Science and Engineering for their support. Prof. Mark J. Kushner (Uni- versity of Michigan) compiled and edited this report, aided by Ms. Laura Crane for copyediting and Ms. Rose Anderson for cover design. Image credits for report cover: International Thermonuclear Experimental Reactor, www.iter.org. Eindhoven University of Technology, Department of Applied Physics. www.tue.nl/en/university/departments/applied-physics/research/plasma-physics-and-radiation- technology/plasma-and-materials-processing-pmp/facilities/technologies/expanding-thermal-plasma-etp. CeramTech GmbH, www.ceramtec.com/ceramic-materials/biolox/periprosthetic-joint-infection. Engineering Research Consulting, engrrc.com/wp-content/uploads/2016/04/molecules3-1.jpg. Fujifilm Europe B.V., green-plasma.eu/index.php/applications-properties/potential-applications. BBC Learning, www.bbc.co.uk/programmes/p01z2407. The Scientist Magazine, www.the-scientist.com/?articles.view/articleNo/32594/title/A-Win-for-GM-Crops. Bigstockphoto.com. i Table of Contents Page I. Executive Summary 1 II. The Plasma Enabled Sustainable Future .................................................................. 3 II.A. The Role of LTPs in Sustainability.............................................................. 3 II.B Why LTPs? Why Engineering? Why Now?................................................ 5 II.C. The LTP Workshop...................................................................................... 8 II.D. The Unifying Research Challenges.............................................................. 8 III. Scientific Background – The Science of Non-Equilibrium Plasmas Providing Societal Benefit.......................................................................................................... 11 IV. Science Challenges in the Focus Application Areas................................................. 14 IV.A. Multiphase Plasma Systems......................................................................... 14 IV.B. Energy and the Environment........................................................................ 19 IV.C. Biotechnology and the Food Cycle............................................................... 25 IV.D. Synthesis and Modifications of Materials.................................................... 31 V. Concluding Remarks – Looking Ahead.................................................................... 38 List of Figures.................................................................................................................... 39 Appendix A: Workshop Agenda........................................................................................ 40 Appendix B: Workshop Attendees.................................................................................... 42 References......................................................................................................................... 44 ii I. Executive Summary The National Academies describe global challenges as society-level priorities requiring in- ternational collaboration to innovate solutions [1]. Perhaps the greatest challenges are centered on energy and environment – collectively called sustainability. A rapidly converging vision of the future portrays societies sustained by green electricity generated by renewable resources. To enact this vision of a future based on renewable electricity (FBRE), sustainable power must be harnessed at large enough scales to produce the essential chemical reactivity that fuels modern society. This goal aligns with the National Science Foundation (NSF) vision in which these grand challenges are described, in part, as “protecting human health; understanding the food, en- ergy, water nexus” [2]. The NSF rightly cites the importance of convergent research in achieving these goals. This report summarizes the role of low temperature plasmas (LTPs) and the LTP science challenges that must be met to achieve the goal of the FBRE. LTPs are partially ionized gases composed of neutral particles, radicals, excited states, ions, and electrons, the latter of which have temperatures of a few to 10 eV (1 eV = 11,600 K). Low temperature means that while the electrons are at high temperatures, the atoms, molecules and ions of the plasma are typically close to room temperature. In LTPs, power transfer from elec- trons to atoms and molecules efficiently produces activated species (e.g., radicals, excited states, photons) and chemical reactivity. With such properties, LTPs are essential to technologies rang- ing from microelectronics to surgical tools. The science and technology of LTPs harbor dynamic and versatile methods of converting the potential energy of electricity to chemical reactivity, thereby enabling the FBRE. Research on LTPs connects fields as diverse as engineering, plasma physics, biology and medicine, and so LTPs embody the definition of convergent research. This research will give rise to sustainable products, carbon neutral chemicals, medical advances, recovered resources, advanced materials, improved food and water security, and environmental stewardship. LTP science, if properly stewarded, has the potential to develop technologies capable of convert- ing electricity into chemical reactivity and new materials at the scale, efficiency, and selectivity required to meet the needs of a rapidly changing society in a sustainable way. To achieve these goals, significant scientific challenges must be addressed and a program- matic home for LTPs established. The workshop, Science Challenges in Low Temperature Plas- ma Science and Engineering: Enabling a Future Based on Electricity through Non-Equilibrium Plasma Chemistry, was held at the NSF in August 2016. The attendees developed a roadmap re- flecting the highest impact, highest return scientific challenges in LTPs in the context of control- ling chemical reactivity for a sustainable future. This report summarizes their findings. Empha- sis was on four focus application areas: Multiphase Plasma Systems Energy and the Environment, Biotechnology and the Food Cycle Synthesis and Modification of Materials The field of LTPs is perhaps unique in being able to impact the broad intellectual diversity repre- sented by these areas, and this diversity represents the convergent nature of the field. This same intellectual diversity makes it difficult to condense the science challenges of the field into a few sentences. However, there are unifying themes which transcend the field in the context of the FBRE: 1 Plasma Produced Selectivity in Reaction Mechanisms in the Volume and on Surfaces: Se- lectivity is the basis of the chemical and materials industries. The scientific challenge that unites the field is devising methodologies whereby plasma produced chemical selectivity can be improved based on knowing the molecular properties of the feedstocks and the desired products. Meeting this goal requires improving our fundamental understanding of plasma particle distributions, plasma-surface interactions and plasma-wave interactions. Interfacial Plasma Phenomena – Surfaces, Interfaces and Nanostructures: LTP applica- tions often involve interaction of plasmas at multiphase boundaries (e.g., gas-liquid) and the transport of activated species