Corporate Banner
Satellite Banner
Technology
Networks
Scientific Communities
 
Become a Member | Sign in
Home>News>This Article
  News
Return

MIT Researchers Develop Solar-to-Fuel Roadmap for Crystalline Silicon

Published: Monday, March 18, 2013
Last Updated: Monday, March 18, 2013
Bookmark and Share
New analysis points the way to optimizing efficiency of an integrated system for harvesting sunlight to make storable fuel.

Bringing the concept of an “artificial leaf” closer to reality, a team of researchers at MIT has published a detailed analysis of all the factors that could limit the efficiency of such a system. The new analysis lays out a roadmap for a research program to improve the efficiency of these systems, and could quickly lead to the production of a practical, inexpensive and commercially viable prototype.

Such a system would use sunlight to produce a storable fuel, such as hydrogen, instead of electricity for immediate use. This fuel could then be used on demand to generate electricity through a fuel cell or other device. This process would liberate solar energy for use when the sun isn’t shining, and open up a host of potential new applications.

The new work is described in a paper this week in the Proceedings of the National Academy of Sciences by associate professor of mechanical engineering Tonio Buonassisi, former MIT professor Daniel Nocera (now at Harvard University), MIT postdoc Mark Winkler (now at IBM) and former MIT graduate student Casandra Cox (now at Harvard). It follows up on 2011 research that produced a “proof of concept” of an artificial leaf — a small device that, when placed in a container of water and exposed to sunlight, would produce bubbles of hydrogen and oxygen.

The device combines two technologies: a standard silicon solar cell, which converts sunlight into electricity, and chemical catalysts applied to each side of the cell. Together, these would create an electrochemical device that uses an electric current to split atoms of hydrogen and oxygen from the water molecules surrounding them.

The goal is to produce an inexpensive, self-contained system that could be built from abundant materials. Nocera has long advocated such devices as a means of bringing electricity to billions of people, mostly in the developing world, who now have little or no access to it.

“What’s significant is that this paper really describes all this technology that is known, and what to expect if we put it all together,” Cox says. “It points out all the challenges, and then you can experimentally address each challenge separately.”

Winkler adds that this is a “pretty robust analysis that looked at what’s the best you could do with market-ready technology.”

The original demonstration leaf, in 2011, had low efficiencies, converting less than 4.7 percent of sunlight into fuel, Buonassisi says. But the team’s new analysis shows that efficiencies of 16 percent or more should now be possible using single-bandgap semiconductors, such as crystalline silicon.

“We were surprised, actually,” Winkler says: Conventional wisdom held that the characteristics of silicon solar cells would severely limit their effectiveness in splitting water, but that turned out not to be the case. “You’ve just got to question the conventional wisdom sometimes,” he says.

The key to obtaining high solar-to-fuel efficiencies is to combine the right solar cells and catalyst — a matchmaking activity best guided by a roadmap. The approach presented by the team allows for each component of the artificial leaf to be tested individually, then combined.

The voltage produced by a standard silicon solar cell, about 0.7 volts, is insufficient to power the water-splitting reaction, which needs more than 1.2 volts. One solution is to pair multiple solar cells in series. While this leads to some losses at the interface between the cells, it is a promising direction for the research, Buonassisi says.

An additional source of inefficiency is the water itself — the pathway that the electrons must traverse to complete the electrical circuit — which has resistance to the electrons, Buonassisi says. So another way to improve efficiency would be to lower that resistance, perhaps by reducing the distance that ions must travel through the liquid.

“The solution resistance is challenging,” Cox says. But, she adds, there are “some tricks” that might help to reduce that resistance, such as reducing the distance between the two sides of the reaction by using interleaved plates.

“In our simulations, we have a framework to determine the limits of efficiency” that are possible with such a system, Buonassisi says. For a system based on conventional silicon solar cells, he says, that limit is about 16 percent; for gallium arsenide cells, a widely touted alternative, the limit rises to 18 percent.

Models to determine the theoretical limits of a given system often lead researchers to pursue the development of new systems that approach those limits, Buonassisi says. “It’s usually from these kinds of models that someone gets the courage to go ahead and make the improvements,” he says.

“Some of the most impactful papers are ones that identify a performance limit,” Buonassisi says. But, he adds, there’s a “dose of humility” in looking back at some earlier projections for the limits of solar-cell efficiency: Some of those predicted “limits” have already been exceeded, he says.

“We don’t always get it right,” Buonassisi says, but such an analysis “lays a roadmap for development and identifies a few ‘levers’ that can be worked on.”


Further Information

Join For Free

Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 3,300+ scientific posters on ePosters
  • More Than 4,800+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

New Device can Study Electric Field Cancer Therapy
Microfluidic device allows study of electric field cancer therapy through low-intensity fields, preventing malignant cells spreading.
Friday, July 08, 2016
Programmable RNA Vaccines
Tests in mice show the vaccines work against Ebola, influenza, and a common parasite.
Wednesday, July 06, 2016
Seeing RNA at the Nanoscale
MIT researchers have developed a new way to image proteins and RNA inside neurons of brain tissue.
Wednesday, July 06, 2016
Tough New Hydrogel Hybrid Doesn’t Dry Out
Water-based material could be used to make artificial skin, longer-lasting contact lenses.
Friday, July 01, 2016
Wireless, Wearable Toxic-Gas Detector
Inexpensive sensors could be worn by soldiers to detect hazardous chemical agents.
Friday, July 01, 2016
New System for Detecting Explosives
Spectroscopic system with chip-scale lasers cuts detection time from minutes to microseconds.
Wednesday, June 01, 2016
Illuminating Hidden Gene Regulators
New super-resolution technique visualizes important role of short-lived enzyme clusters.
Friday, May 27, 2016
Controlling RNA in Living Cells
Modular, programmable proteins can be used to track or manipulate gene expression.
Wednesday, April 27, 2016
Long-Term Drug Release
New tablet attaches to the lining of the GI tract, resists being pulled away.
Thursday, April 07, 2016
Pharmacy on Demand
New, portable system can be configured to produce different drugs.
Monday, April 04, 2016
A Programming Language for Living Cells
New language lets researchers design novel biological circuits.
Monday, April 04, 2016
Why Some Tumors Withstand Treatment
Mechanism uncovered that allows cancer cells to evade targeted therapies.
Thursday, March 17, 2016
Cancer Cells Remodel Environments Before Spreading
Researchers at MIT have found that the cancer cells remodel their environment to make it easier to reach nearby blood vessels.
Wednesday, March 16, 2016
Paving the Way for Metastasis
Cancer cells remodel their environment to make it easier to reach nearby blood vessels.
Tuesday, March 15, 2016
A New Way to Discover DNA Modifications
Researchers systematically find molecules that help regulate and protect DNA.
Wednesday, March 02, 2016
Scientific News
Liquid Biopsies: Miracle Diagnostic or Next New Fad?
Thanks to the development of highly specific gene-amplification and sequencing technologies liquid biopsies access more biomarkers relevant to more cancers than ever before.
Core-Shell Columns in HPLC: Food Analysis Applications
Explore the most recent applications of core-shell columns in food analysis.
Review of the Analysis of Haemoglobin A1c for Diabetes Diagnostics
This paper aims to clarify methods, units, quality requirements, reference and cutoff limits for hemoglobin A1c (HbA1c) and ratio of blood glucose/HbA1c on the basis of the results from Finnish quality control surveys by comparing them to the literature.
Colon Cancer Blocked in Mice
Case Western Reserve University Researchers block common type of colon cancer tumour in mice, laying groundwork for human clinical trial.
New Centre Offers Ultra-Speed Protein Analysis
UW-Madison researchers to establish development centre for next-gen protein measurement technologies.
Disrupting Tumour-Promotion in Humans
Researchers have modified an existing protein to represses a specific cancer-promoting ‘message’ within cells.
Protein Nanocages Could Improve Drug Design and Delivery
HHMI scientists have designed and built 10 large protein icosahedra that are similar to viral capsids that carry viral DNA.
Vaccine Strategy Targets Multiple Influenza Viruses
Scientists have identified vaccine-induced antibodies that can neutralize strains of influenza virus that infect humans.
Connectome Map More Than Doubles Human Cortex’s Known Regions
Researchers at NIH have developed software that automatically detects the “fingerprint” of each of these areas in an individual’s brain scans.
Discovered Through ‘Big Data’ Analysis
Researchers at the SBP have identified over 100 new genetic regions that affect the immune response to cancer.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
3,300+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,800+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FOR FREE!