ADVANCES IN NEW ENERGY STORAGE

Cost effective storage of wind and solar energies is the holy grail of New Energy.

“He who cannot store will not have energy after 4.” Professor Nate Lewis, California Institute of Technology

Traditional battery technology, just barely reaching the capacity to cost-effectively store enough electricity to move one passenger car 40 or 80 or, maybe, a couple of hundred miles, is utterly inadequate to the scale of energy storage required to turn intermittent New Energies into electricity grid base load.

Engineers have made some progress with compressed air storage but it is only short-term storage and it is expensive.

Fanciful futures of a “hydrogen economy” were concocted on the idea of using New Energies to make electricity and then using the electricity to separate water into oxygen and hydrogen fuel, but nobody ever found a way to do it efficiently. It remains far cheaper to use the electricity or store it in car batteries than to make hydrogen fuel for storage.

Advances in the last few years with “growing” potentially cheap nanomaterials that capture solar energy and release it as electricity have led materials scientists and chemists to a new paradigm. They are searching for a way to mimick nature’s breathtakingly brilliant process of photosynthesis. If they can find the right cheap, abundant, durable materials, they believe they can manipulate them on the nano-scale to transform water into storable hydrogen fuel in one simple step.

In the last year, labs at the California Institute of Technology (Cal Tech), the University of California at Berkeley (Berkeley Labs) and Massachusetts Institute of Technology (MIT) have been conducting a collaborative program and have been reporting they are nearing achievement. A paper published in the recent issue of the journal Science reports another step forward in the process.

MIT researchers Daniel Nocera and Matthew Kanan say they have found the “earth-abundant” material that releases oxygen and hydrogen from water in relatively simple, uncontrolled environments.

The emphasis of the MIT researchers on earth-abundant materials is due to the fact that it has long been known the reaction could be created using platinum. Using platinum to make a hydrogen fuel cell, however, would make the cost of a vehicle that used it prohibitive and certainly would not be practical as grid storage. Platinum is also not durable in common circumstances.

Researchers in Australia have discovered a way to get the same chemical reaction from an inexpensive plastic (polymer).

These scientists are moving closer to the possibility of making cheap hydrogen fuel in large quantities faster than anybody expected. Does it make the “hydrogen economy” more real? The ‘hydrogen highway” probably still remains an expensive and therefore impractical exercise. Incorporating hydrogen storage into a New Energy electricity grid, however, is a step or two closer. The potential for a crucial breakthrough now looms a little more enticingly.

Note: Links are only available to the article abstracts. The journal does not allow access to the full articles without a subscription.

The Nocera Lab website on the storage concept

More on the general state of the research from Nate Lewis.

click to enlarge

2 Reports Raise Hopes on Energy
Matthew L. Wald, August 1, 2008 (NY Times)
and
‘Major discovery’from MIT primed to unleash solar revolution; Scientists mimic essence of plants' energy storage system
Anne Trafton, July 31, 2008 (MIT News Office)

WHO
Matthew W. Kanan and Daniel G. Nocera, Researchers/Co-Authors, MIT; Bjorn Winther-Jensen, Orawan Winther-Jensen, Maria Forsyth & Douglas R. MacFarlane, Researchers/Co-Authors, Australian Centre for Electromaterials Science/Monash University

WHAT
In Situ Formation of an Oxygen-Evolving Catalyst in Neutral Water Containing Phosphate and Co2+ and High Rates of Oxygen Reduction Over a Vapor Phase-Polymerized PEDOT Electrode demonstrate important progress in the cost effective storage of intermittent New Energies.

Frm the MIT lab.

WHEN
Both articles were published in the August 1, 2008, issue of the journal Science.

WHERE
- The MIT (Cambridge, Mass.) researchers are part of a collaborative project also involving Cal Tech (Pasadena, Calif.) and the Berkeley Labs (Berkeley, Calif.).
- Monash University is in the town of Clayton in the state of Victoria in Australia.

WHY
- For the scientists, from the Nocera/Kanan abstract: “[The report is on a] catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing Co2+. A variety of analytical techniques indicates the presence of phosphate in an approximate 1:2 ratio with cobalt in this material. The pH dependence of the catalytic activity also implicates HPO42– as the proton acceptor in the O2-producing reaction. This catalyst not only forms in situ from earth-abundant materials but also operates in neutral water under ambient conditions.”
- For the non-scientists: It is a system that has uses common materials like tin and cobalt and release oxygen and hydrogen from water without having to seal or drastically control the temperature of the system.
- The Nocera/Kanan process recatalyzes (when the process is run backwards) into water.
- It can also use saltwater and release water so may be adaptable to desalination.
- For the scientists, from the Monash abstract: “We describe an air electrode based on a porous material coated with poly(3,4-ethylenedioxythiophene) (PEDOT), which acts as an O2 reduction catalyst. Continuous operation for 1500 hours was demonstrated without material degradation or deterioration in performance. O2 conversion rates were comparable with those of Pt-catalyzed electrodes of the same geometry, and the electrode was not sensitive to CO. Operation was demonstrated as an air electrode and as a dissolved O2 electrode in aqueous solution.”
- For the non-scientists: A special type of plastic (polymer) can be substituted for platinum, is efficient and durable.
- The performance from the plastic is comparable to the performance of platinum at a fraction of the cost.

Cobalt and phospahte in water releasing oxygen. Add another catalyst, release hydrogen, combine the O2 and H2 and, voila, electricity and water. (click to enlarge)

QUOTES
- Nocera/Kanan: “In natural photosynthesis, energy from sunlight is used to rearrange the bonds of water to O2 and H2-equivalents. The realization of artificial systems that perform similar "water splitting" requires catalysts that produce O2 from water without the need for excessive driving potentials. Here, we report such a catalyst…”
- Monash University researchers: The air electrode, which reduces oxygen (O2), is a critical component in energy generation and storage applications such as fuel cells and metal/air batteries. The highest current densities are achieved with platinum (Pt), but in addition to its cost and scarcity, Pt particles in composite electrodes tend to be inactivated…”