{"id":7163,"date":"2014-01-14T13:39:01","date_gmt":"2014-01-14T18:39:01","guid":{"rendered":"https:\/\/college.unc.edu\/?p=7163"},"modified":"2024-07-02T14:35:15","modified_gmt":"2024-07-02T14:35:15","slug":"solar","status":"publish","type":"post","link":"https:\/\/collegearchive.unc.edu\/?p=7163","title":{"rendered":"Researchers harness energy during day for use at night"},"content":{"rendered":"
\"Tom<\/a>
Tom Meyer’s new system generates hydrogen fuel by using the sun’s energy to split water into its component parts. After the split, hydrogen is stored, while the byproduct, oxygen, is released into the air. (Image courtesy of Yan Liang)<\/figcaption><\/figure>\n

Solar energy has long been used as a clean alternative to fossil fuels such as coal and oil, but it could only be harnessed during the day when the sun\u2019s rays were strongest. Now researchers led by Tom Meyer at the Energy Frontier Research Center at UNC-Chapel Hill have built a system that converts the sun\u2019s energy not into electricity but hydrogen fuel and stores it for later use, allowing us to power our devices long after the sun goes down.<\/p>\n

\u201cSo called \u2018solar fuels\u2019 like hydrogen offer a solution to how to store energy for nighttime use by taking a cue from natural photosynthesis\u201d said Meyer, Arey Distinguished Professor of Chemistry at UNC\u2019s College of Arts and Sciences. \u201cOur new findings may provide a last major piece of a puzzle for a new way to store the sun\u2019s energy \u2013 it could be a tipping point for a solar energy future.\u201d<\/p>\n

In one hour, the sun puts out enough energy to power every vehicle, factory and device on the planet for an entire year. Solar panels can harness that energy to generate electricity during the day. But the problem with the sun is that it goes down at night\u2014and with it the ability to power our homes and cars. If solar energy is going to have a shot at being a clean source of powering the planet, scientists had to figure out how to store it for night-time use.<\/p>\n

The new system designed by Meyer and colleagues at UNC and with Greg Parson\u2019s group at NC State University does exactly that. It is known as a dye-sensitized photoelectrosynthesis cell, or DSPEC, and it generates hydrogen fuel by using the sun\u2019s energy to split water into its component parts. After the split, hydrogen is sequestered and stored, while the byproduct, oxygen, is released into the air.<\/p>\n

\"UNC<\/a>
UNC chemist Tom Meyer (photo by Dan Sears)<\/figcaption><\/figure>\n

\u201cBut splitting water is extremely difficult to do,\u201d said Meyer. \u201cYou need to take four electrons away from two water molecules, transfer them somewhere else, and make hydrogen, and, once you have done that, keep the hydrogen and oxygen separated. How to design molecules capable of doing that is a really big challenge that we\u2019ve begun to overcome.\u201d<\/p>\n

Meyer had been investigating DSPECs for years both at the Energy Frontier Research Center at UNC and before. His design has two basic components: a molecule and a nanoparticle. The molecule, called a chromophore-catalyst assembly, absorbs sunlight and then kick starts the catalyst to rip electrons away from water. The nanoparticle, to which thousands of chromophore-catalyst assemblies are tethered, is part of a film of nanoparticles which shuttles the electrons away to make the hydrogen fuel.<\/p>\n

However, even with the best of attempts, the system always crashed because either the chromophore-catalyst assembly kept breaking away from the nanoparticles or because the electrons couldn\u2019t be shuttled away quickly enough to make hydrogen.<\/p>\n

To solve both of these problems, Meyer turned to the Parsons group at NCSU to use a technique that coated the nanoparticle, atom by atom, with a thin layer of a material called titanium dioxide. By using ultra-thin layers, the researchers found that the nanoparticle could carry away electrons far more rapidly than before, with the freed electrons available to make hydrogen. They also figured out how to build a protective coating that keeps the chromophore-catalyst assembly tethered firmly to the nanoparticle, ensuring that the assembly stayed on the surface.<\/p>\n

With electrons flowing freely through the nanoparticle and the tether stabilized, Meyer\u2019s new system can turn the sun\u2019s energy into fuel while needing almost no external power to operate and releasing no greenhouse gases. What\u2019s more, the infrastructure to install these sunlight-to-fuel converters is in sight based on existing technology. A next target is to use the same approach to reduce carbon dioxide, a greenhouse gas, to a carbon-based fuel such as formate or methanol.<\/p>\n

\u201cWhen you talk about powering a planet with energy stored in batteries, it\u2019s just not practical,\u201d said Meyer. \u201cIt turns out that the most energy dense way to store energy is in the chemical bonds of molecules. And that\u2019s what we did \u2013 we found an answer through chemistry.\u201d<\/p>\n

[ By Thania Benios, UNC News Services]<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Researchers led by UNC chemist Tom Meyer have built a system that converts the sun\u2019s energy not into electricity but hydrogen fuel and stores it for later use, allowing us to power devices long after the sun goes down.<\/p>\n","protected":false},"author":4,"featured_media":7166,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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