Calcium Hydride Heat Storage

This is another incremental improvement on the business of operating thermal heat systems driven by solar sources in particular.  We have identified a superior storage medium that is well known and readily available at low cost.  All solar systems need a working fluid to grab the heat energy even it the intent is to shove it immediately into an engine.  Having a working fluid that nicely enters into a chemical reaction giving off a mobile gas avoids reaction reversal and truly stores the energy in a safe form for later convenient consumption.  It can all get cold even.

 

In fact it means that a solar thermal plant can be engineered to be a standby energy source that sells its energy during peak demand and will fit nicely into a photovoltaic system were no such storage may be practical.

 

This is a major advance for solar thermal power and likely makes the high temperature designs presently been deployed economically feasible.  It will possibly work best in the extremes of the desert plants such as the tower system built in Spain.

It might even be possible to divert heat output at an ordinary thermal plant with this method although it is likely an expensive diversion of effort.

 

 EMC Solar Claims Calcium Hydride Has Ten times the density of conventional molten salt solar storage

 

http://nextbigfuture.com/2010/01/emc-solar-claims-calcium-hydride-has.html

 

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A cheap and effective way to store solar power is needed to increase the usability and adoption of solar power. Molten salt storage has been seen as one of the best ways to create solar power storage that is scalable to megawatt hours or more.

EMC Solar and partners are trying to achieve continuous, cost competitive, and modular configuration for large scale solar power production, in GWatt quantities.

Calcium hydride is chosen due to its ability to be broken apart using a thermal heat source, such as the sun. Calcium hydride provides up to 0.90 kW-hr/kg of heat when it converts to calcium and hydrogen.

Hydrogen is stored in a separate low temperature hydride tank. Two heat exchangers are used to extract the thermal energy from the hydrogen before storage in the low temperature hydride. The heat exchangers are required to extract the remaining 20% of the total system energy still in the 1100 C hydrogen before it is cooled to near room temperature.

A central triple walled reaction chamber holds both Calcium and Calcium hydride as liquids between 1000 C and 1100 C. Heat is extracted from the reaction chamber to drive one or multiple 100 kW high temperature Dual Shell Stirling engines operating at 50% conversion efficiency.

The thermal storage costs are substantially lower than a nitrate salt system and reflect both the simplicity of the calcium hydride system and the significant increase in power density. In the calcium hydride system the two liquids, calcium and calcium hydride, remain in the central reaction chamber. Only hydrogen is pumped between tanks

Proposed 100 kW solar system:

* Store 18 hours of thermal energy 

* Down mirror focuses sunlight from heliostat field

* 4,690 kg Calcium

* 234 kg Hydrogen

* Reaction chamber insulated with a quartz window for solar heat input

* Two tank boron oxide high temperature heat exchanger for hydrogen

* Two tank nitrate salt low temperature heat exchanger for hydrogen

* Low temperature Sodium aluminum hydride tank holds 5% hydrogen by weight 

The system uses a new low cost wire braced heliostat field with 50 square metres per panel at $100/metre squared in production. The new heliostat configuration eliminates the cosine effect, common with power tower designs, by utilising a parabolic mirror aligned with the sun throughout the day. The parabolic mirror is integrated with a quartz lens and side mirror which provides a 0.1 metre constant diameter focused light beam. The heliostat design has the added advantage of eliminating the power tower and replacing it with a small down mirror located directly above the reaction chamber.

Sunlight is focused through a quartz window, into the reaction chamber, onto an inverted molybdenum cone submerged in the liquid calcium which absorbs the solar energy. Major cost reductions occur due to the use of a down mirror system which allows the power head to be immersed within the reaction chamber inside the liquid calcium. This allows a significant increase in heat transfer capability. An insulated cover is placed between the quartz window and power head at night minimizing thermal losses.

The advantage of this system is that it is a completely reversible closed cycle. The intermittent sunlight can be chemically stored and released at a controlled rate for electric power production. The system uses materials which are low cost and provide a competitive electrical production facility for very large scale application.

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The storage of thermal energy in the form of sensible and latent heat has become an important aspect of energy management with the emphasis on efficient use and conservation of the waste heat and solar energy in industry and buildings. Latent heat storage is one of the most efficient ways of storing thermal energy. Solar energy is arenewable energy source that can generate electricity, provide hot water, heat and cool a house, and provide lighting for buildings. Paraffin waxes are cheap and have moderate thermal energy storage density but low thermal conductivity and, hence, require a large surface area. Hydrated salts have a larger energy storage density and a higher thermal conductivity. In response to increasing electrical energy costs and the desire for better lad management, thermal storage technology has recently been developed. The storage of thermal energy in the form of sensible and latent heat has become an important aspect ofenergy management with the emphasis on the efficient use and conservation of the waste heat and solar energy in the industry and buildings. Thermal storage has been characterized as a kind of thermal battery.

Catalyst Cracks Ethanol for Fuel Cells

This obscure item is actually rather good news. Available methods, as mentioned were chemically slow and also likely very inefficient. My own exposure to the problem was to discover that the best chemical method filled the membrane up with chalk. Oh well.

We have already understood that the best available liquid fuel for long term transportation will be ethanol. We can produce it easily today using cattail starch and possibly will also be able to convert the cellulose. This can be accomplished in the volumes necessary without disturbing food production.

The idea of using an ethanol fuel converter to produce hydrogen and to use that hydrogen to produce current through a fuel cell is attractive and likely very efficient.

Most important, it can step into situations where an EEStor style battery based system will likely never be acceptable such as long haul trucking in general.

I particularly draw attention to the following quote:

"The ability to split the carbon-carbon bond and generate CO2 at room temperature is a completely new feature of catalysis," Adzic said. "There are no other catalysts that can achieve this at practical potentials."

If we can extend a similar capability to the conversion of methane and other hydrocarbons and even other organic molecules, then we have an actual shortcut in the production of hydrogen for powering fuel cells. This certainly gives it to us for ethanol which is certainly a giant first step.

Up to this point one was forced to imagine needle forges, pyrolyzing methane perhaps to break out the hydrogen. It would plausibly work for hydrazine but nothing else. Now we have a room temperature process that produces CO2 and hydrogen. Does it get any better?


New Catalyst Paves The Path For Ethanol - Powered Fuel Cells

http://www.biofueldaily.com/reports/New_Catalyst_Paves_The_Path_For_Ethanol_Powered_Fuel_Cells_999.html

http://www.energy-daily.com/images/ternary-electrocatalyst-ethanol-oxidation-sm.jpg

Model of a ternary electrocatalyst for ethanol oxidation consisting of platinum-rhodium clusters on a surface of tin dioxide. This catalyst can split the carbon-carbon bond and oxidize ethanol to carbon dioxide within fuel cells.

by Staff Writers
Upton NY (SPX) Jan 29, 2009

A team of scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, in collaboration with researchers from the University of Delaware and Yeshiva University, has developed a new catalyst that could make ethanol-powered fuel cells feasible.

The highly efficient catalyst performs two crucial, and previously unreachable steps needed to oxidize ethanol and produce clean energy in fuel cell reactions. Their results are published online in the January 25, 2009 edition of Nature Materials.

Like batteries that never die, hydrogen fuel cells convert hydrogen and oxygen into water and, as part of the process, produce electricity.

However, efficient production, storage, and transport of hydrogen for fuel cell use is not easily achieved. As an alternative, researchers are studying the incorporation of hydrogen-rich compounds, for example, the use of liquid ethanol in a system called a direct ethanol fuel cell.

"Ethanol is one of the most ideal reactants for fuel cells," said Brookhaven chemist Radoslav Adzic. "It's easy to produce, renewable, nontoxic, relatively easy to transport, and it has a high energy density. In addition, with some alterations, we could reuse the infrastructure that's currently in place to store and distribute gasoline."

A major hurdle to the commercial use of direct ethanol fuel cells is the molecule's slow, inefficient oxidation, which breaks the compound into hydrogen ions and electrons that are needed to generate electricity. Specifically, scientists have been unable to find a catalyst capable of breaking the bonds between ethanol's carbon atoms.

But at Brookhaven, scientists have found a winner. Made of platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles, the research team's electrocatalyst is capable of breaking carbon bonds at room temperature and efficiently oxidizing ethanol into carbon dioxide as the main reaction product. Other catalysts, by comparison, produce acetalhyde and acetic acid as the main products, which make them unsuitable for power generation.

"The ability to split the carbon-carbon bond and generate CO2 at room temperature is a completely new feature of catalysis," Adzic said. "There are no other catalysts that can achieve this at practical potentials."

Structural and electronic properties of the electrocatalyst were determined using powerful x-ray absorption techniques at Brookhaven's National Synchrotron Light Source, combined with data from transmission electron microscopy analyses at Brookhaven's Center for Functional Nanomaterials.

Based on these studies and calculations, the researchers predict that the high activity of their ternary catalyst results from the synergy between all three constituents - platinum, rhodium, and tin dioxide - knowledge that could be applied to other alternative energy applications.

"These findings can open new possibilities of research not only for electrocatlysts and fuel cells but also for many other catalytic processes," Adzic said.

Next, the researchers will test the new catalyst in a real fuel cell in order to observe its unique characteristics first hand.

This work is supported by the Office of Basic Energy Sciences within DOE's Office of Science.

Energy Storage Breakthrough at MIT

This is the third very important discovery announcement made over the past three months. This one permits the use of electrolysis as an energy storage protocol. The energy cost is not quantified at all but is certainly been cheered in this report. And since the source is hardly uninformed, even a smile is significant. They have done it.
We now have an efficient energy storage protocol to go with our efficient thin film wide temperature band refrigeration discovery and the emerging printed nanosolar film technology. They are all slotted for commercialization over the next four years.

Of course everyone is been coy as to actual efficiencies at this time but would not be talking unless they are expecting a vast improvement over past alternatives. We know that the nanosolar crowd has started their pricing at $1.00 per watt. This will displace all the competition and also indicates that a further order of magnitude price decline is a possibility. Making the separation of hydrogen and oxygen efficient suggests that the swing between storage and utilization is perhaps dropping under twenty percent which is sufficient to make hydrogen the energy storage medium of choice.

Future solar energy conversion efficiencies can be expected to approach and surpass the thirty percent mark and achieve this by harvesting infrared energy also. The efficiency of the refrigeration material is driven by the available temperature range. This was dogged until recently by a ten to twenty degree spread but this has now opened up to one hundred degrees. A lot of things have just become possible and not just cheaper.

Arthur C. Clark missed seeing these announcements by mere months. He predicted these developments forty years ago, in particular the access to solar energy at costs under $1.00 per installed watt.

You must understand. This all means that a home can be clad in a nanosolar skin that supplies all power while storing surplus for the nighttime and will also cool the inside with another interior skin. The house will be a net exporter of energy, perhaps sufficient to supply a hydrogen based vehicle or two. Fuel cells just became important again.

There is still a couple of years of development to grind through, but after seeing how quickly nanosolar has been launched, I am been conservative.

MIT develops way to bank solar energy at home

/energy/article/37841CAMBRIDGE, Massachusetts (Reuters) - A U.S. scientist has developed a new way of powering fuel cells that could make it practical for home owners to store solar energy and produce electricity to run lights and appliances at night.

A new catalyst produces the oxygen and hydrogen that fuel cells use to generate electricity, while using far less energy than current methods.

With this catalyst, users could rely on electricity produced by photovoltaic solar cells to power the process that produces the fuel, said the Massachusetts Institute of Technology professor who developed the new material.

"If you can only have energy when the sun is shining, you're in deep trouble. And that's why, in my opinion, photovoltaics haven't penetrated the market," Daniel Nocera, an MIT professor of energy, said in an interview at his Cambridge, Massachusetts, office. "If I could provide a storage mechanism, then I make energy 24/7 and then we can start talking about solar."

Solar has been growing as a power source in the United States -- last year the nation's solar capacity rose 45 percent to 750 megawatts. But it is still a tiny power source, producing enough energy to meet the needs of about 600,000 typical homes, and only while the sun is shining, according to data from the Solar Energy Industries Association.

Most U.S. homes with solar panels feed electricity into the power grid during the day, but have to draw back from the grid at night. Nocera said his development would allow homeowners to bank solar energy as hydrogen and oxygen, which a fuel cell could use to produce electricity when the sun was not shining.

"I can turn sunlight into a chemical fuel, now I can use photovoltaics at night," said Nocera, who explained the discovery in a paper written with Matthew Kanan published on Thursday in the journal Science.

Companies including United Technologies Corp produce fuel cells for use in industrial sites and on buses.

Automakers including General Motors Corp and Honda Motor Co are testing small fleets of fuel-cell powered vehicles.

POTENTIAL FOR CLEAN ENERGY

Fuel cells are appealing because they produce electricity without generating the greenhouse gases associated with global climate change. But producing the hydrogen and oxygen they run on typically requires burning fossil fuels.

That has prompted researchers to look into cleaner ways of powering fuel cells. Another researcher working at Princeton University last year developed a way of using bacteria that feed on vinegar and waste water to generate hydrogen, with minimal electrical input.

James Barber, a biochemistry professor at London's Imperial College, said in a statement Nocera's work "opens up the door for developing new technologies for energy production, thus reducing our dependence on fossil fuels and addressing the global climate change problem."

Nocera's catalyst is made from cobalt, phosphate and an electrode that produces oxygen from water by using 90 percent less electricity than current methods, which use the costly metal platinum.

The system still relies on platinum to produce hydrogen -- the other element that makes up water.

"On the hydrogen side, platinum works well," Nocera said. "On the oxygen side ... it doesn't work well and you have to put way more energy in than needed to get the (oxygen) out."

Current methods of producing hydrogen and oxygen for fuel cells operate in a highly corrosive environment, Nocera said, meaning the entire reaction must be carried out in an expensive highly-engineered container.

But at MIT this week, the reaction was going on in an open glass container about the size of two shot glasses that researchers manipulated with their bare hands, with no heavy safety gloves or goggles.

"It's cheap, it's efficient, it's highly manufacturable, it's incredibly tolerant of impurity and it's from earth-abundant stuff," Nocera explained.

Nocera has not tried to construct a full-sized version of the system, but suggested that the technologies to bring this into a typical home could be ready in less than a decade.

The idea, which he has been working on for 25 years, came from reflecting on the way plants store the sun's energy.

"For the last six months, driving home, I've been looking at leaves, and saying, 'I own you guys now,'" Nocera said.

(Editing by Vicki Allen)