Media Releases

Nature offers key lessons on harvesting solar power, says U of T chemistry professor

September 23, 2011

TORONTO, ON — Clean solu­tions to human ener­gy demands are essen­tial to our future. While sun­light is the most abun­dant source of ener­gy at our dis­pos­al, we have yet to learn how to cap­ture, trans­fer and store solar ener­gy effi­cient­ly.  Accord­ing to Uni­ver­si­ty of Toron­to chem­istry pro­fes­sor Greg Scholes, the answers can be found in the com­plex sys­tems at work in nature.

“Solar fuel pro­duc­tion often starts with the ener­gy from light being absorbed by an assem­bly of mol­e­cules,” said Scholes, the D.J. LeRoy Dis­tin­guished Pro­fes­sor at U of T.  “The ener­gy is stored fleet­ing­ly as vibrat­ing elec­trons and then trans­ferred to a suit­able reac­tor.  It is the same in bio­log­i­cal sys­tems.  In pho­to­syn­the­sis, for exam­ple, anten­na com­plex­es com­prised of chloro­phyll cap­ture sun­light and direct the ener­gy to spe­cial pro­teins called reac­tion cen­tres that help make oxy­gen and sug­ars. It is like plug­ging those pro­teins into a solar pow­er sock­et.”

In an arti­cle in Nature Chem­istry to be pub­lished on Sep­tem­ber 23, Scholes and col­leagues from sev­er­al oth­er uni­ver­si­ties exam­ine the lat­est research in var­i­ous nat­ur­al anten­na com­plex­es.  Using lessons learned from these nat­ur­al phe­nom­e­na, they pro­vide a frame­work for how to design light har­vest­ing sys­tems that will route the flow of ener­gy in sophis­ti­cat­ed ways and over long dis­tances, pro­vid­ing a micro­scop­ic “ener­gy grid” to reg­u­late solar ener­gy con­ver­sion.

A key chal­lenge is that the ener­gy from sun­light is cap­tured by coloured mol­e­cules called dyes or pig­ments, but is stored for only a bil­lionth of a sec­ond.  This leaves lit­tle time to route the ener­gy from pig­ments to mol­e­c­u­lar machin­ery that pro­duces fuel or elec­tric­i­ty.  How can we har­vest sun­light and uti­lize its ener­gy before it is lost?

“This is why nat­ur­al pho­to­syn­the­sis is so inspir­ing,” said Scholes.  “More than 10 mil­lion bil­lion pho­tons of light strike a leaf each sec­ond.  Of these, almost every red-coloured pho­ton is cap­tured by chloro­phyll pig­ments which feed plant growth.”  Learn­ing the work­ings of these nat­ur­al light-har­vest­ing sys­tems fos­tered a vision, pro­posed by Scholes and his co-authors, to design and demon­strate mol­e­c­u­lar “cir­cuit­ry” that is 10 times small­er than the thinnest elec­tri­cal wire in com­put­er proces­sors.  These ener­gy cir­cuits could con­trol, reg­u­late, direct and ampli­fy raw solar ener­gy which has been cap­tured by human-made pig­ments, thus pre­vent­ing the loss of pre­cious ener­gy before it is uti­lized.

Last year, Scholes led a team that showed that marine algae, a nor­mal­ly func­tion­ing bio­log­i­cal sys­tem, uses quan­tum mechan­ics in order to opti­mize pho­to­syn­the­sis, a process essen­tial to its sur­vival.  These and oth­er insights from the nat­ur­al world promise to rev­o­lu­tion­ize our abil­i­ty to har­ness the pow­er of the sun.

“Lessons from nature about solar light har­vest­ing” was writ­ten by Scholes, Gra­ham Flem­ing of the Uni­ver­si­ty of Cal­i­for­nia, Berke­ley, Alexan­dra Olaya-Cas­tro of Uni­ver­si­ty Col­lege, Lon­don UK and Rienk van Gron­delle of VU Uni­ver­si­ty in Ams­ter­dam, The Nether­lands.

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For more infor­ma­tion, please con­tact:

Greg Scholes
D.J. LeRoy Dis­tin­guished Pro­fes­sor
Depart­ment of Chem­istry
Uni­ver­si­ty of Toron­to

Kim Luke
Fac­ul­ty of Arts & Sci­ence
Uni­ver­si­ty of Toron­to