Engineers at Isentropic Ltd, a company in Cambridge UK, have developed a system fo storing large amounts of energy cheaply using gravel.

Currently, the most economically viable way of storing large amounts of energy is through pumped hydro, in which excess electricity is used to pump water up a hill. The water is held back by a dam until the energy is needed and then released to turn turbines and generate electricity.

Isentopic claims that its gravel-based battery would be able to store equivalent amounts of energy but use less space and be cheaper to set up.

The system consists of two silos filled with gravel. Electricity is used to heat and pressurise argon gas that is fed into one of the silos, heating the gravel to 500°C. When the gas leaves the chamber, it has cooled to ambient temperature but is still pressurised. The pressurised argon is fed into the second silo, where it expands back to normal atmospheric pressure. This process acts like a giant refrigerator, causing the temperature inside the second chamber to drop to -160°C.

In effect, electrical energy is stored as a temperature difference between the two rock-filled silos. To release the energy, the cycle is reversed, and as the energy passes from hot to cold it powers a generator that makes electricity.
Click here to read the rest of this entry.

Researchers at the Massachusetts Institute of Technology, led by Associate Professor Yang Shao-Horn, in collaboration with Professor Paula Hammond, have found that using carbon nanotubes for one of the battery’s electrodes produced up to a tenfold increase in the amount of power that a lithiun-ion battery could deliver from a given weight of material.

In the new battery electrode, carbon nanotubes are "electrostatically self-assembled" into a tightly bound structure that is porous at the nanometer scale. The carbon nanotubes have many oxygen groups on their surfaces, which can store a large number of lithium ions. This enables carbon nanotubes to serve as the positive electrode in lithium batteries.

Carbon nanotubes are a form of pure carbon in which sheets of carbon atoms are rolled up into tiny tubes. Normally, carbon nanotubes on a surface tend to clump together in bundles, leaving few exposed surfaces to undergo reactions. The "electrostatic self-assembly" process incorporates organic molecules on the nanotubes and they assemble in a way that has a many exposed surfaces.

The new batteries have some of the advantages of both capacitors and conventional lithium batteries. Like capacitors, they can produce very high power outputs in short bursts – but the energy output for a given weight of the new electrode material is five times greater than for conventional capacitors. Like conventional batteries, they can provide lower power steadily for long periods – but the total power delivery rate with the new batteries is10  times that of lithium-ion batteries

In addition to their high power output, the carbon nanotube electrodes showed very good stability over time. After 1,000 cycles of charging and discharging a test battery, there was no detectable change in the material’s performance.

Researchers at Purdue University have developed a new highly efficient technique for making hydrogen fuel cells suitable for vehicles. The technology has the potential to be twice as effective as current fuel cells at around half the temperature and much lower pressure.

The process uses ammonia borane, a high hydrogen-content powdered chemical and combines two hydrogen generating processes — hydrolysis and thermolysis — to achieve conditions appropriate for use in vehicles.

Currently hydrogen fuel cells run at pressures of aound 5,000 psi. Hydrolysis alone requires a catalyst to turn hydrogen into energy, and thermolysis requires a temperature of 170°C to function. By combining hydrolysis and thermolysis processes, and introducing ammonia borane into the reaction, the required temperature is lowered to about 85°C and the pressure requirements lower to 200 psi.

The researchers believe that, if this technology can be scaled up, it would be the perfect reaction to generate electricity for hydrogen fuel cell vehicles and small appliances. As well as scaling up the process, the researchers are working on ways to recycle the ammonia borane used in the reaction and return it to its original state.

American 60 Minutes has shown this segment on teh Bloom Box, a new fuel cell system that its makers say can cost-effectively generate electricity on the spot, without being connected to the electricity grid. Large corporations are already testing the device; the manufacturer foresees one in every home.

(The segment begins with an advertisement.)

Watch CBS News Videos Online

Researchers at Uppsala University in Sweden have designed a battery that exploits the unique cellulose structure of the Cladophora algae, which is characterized by a very large surface area.

By coating this structure with an extremely thin layer of conducting polymer, the team produced a battery that weighs very little and can be fully charged in as little as 11.3 seconds. The battery has been able to retain its charge after 1,000 charging cycles.

According to Professor  Maria Strømme, who led the research team, "We are talking about a battery that mainly consists of paper and salt water and that can theoretically be made in your own kitchen (if you have a strong mixer) without the major energy input needed to create today’s batteries".

The battery has a storage capacity of 25 watt-hours per kilogram which is relativley low compared to current lithium ion batteries which can store 100 to 160 watt-hours per kilogram.

One of the main factors in the high cost of fuels cells is the use of platinum as a catalyst. Platinum is scarce and costs around $1,200 an ounce – and that price is likely to skyrocket if fuel cells with platinum catalysts become widely used.

A U.K. company, ACAL Energy, has developed a new fuel cell design that reduces the amount of platinum used by 80 percent.

In a conventional fuel cell, platinum is embedded in porous carbon electrodes. ACAL’s design replaces this with a solution containing molybdenum and vanadium as the catalyst. The company says that the resulting fuel cell works as well as a conventional one but should cost 40 percent less.

The company has already made a one-kilowatt system that it intends to sell in limited quantities next year. The new fuel cells should be widely available by 2011. ACAL plans to target the market for diesel generators first, then move on to larger volume applications such as home power generation and electric cars.

The American utility company, Pacific Gas and Electric, is to build an underground compressed air storage facility that would deliver as much electricity as a medium-sized power plant.

The company intends to use wind turbines to pump air into natural underground caverns. The air will then be released as needed to power turbines and meet demand for electricity.

The planned installation will be able to deliver 500 megawatts of electricity for a period of ten hours.  In contrast, utility-scale batteries can store only one or two megawatts.

Smaller compressed air storage plants are already in operation in McIntosh, Alabama and Huntorf, Germany.

Michael Nakhamkin, who designed the compressed air-storage facility in Alabama for Energy Storage and Power has said that "We have learned a lot since building the McIntosh plant in Alabama, and I believe the time is right technically, environmentally and economically for a large-scale deployment of CAES (compressed air energy storage) technology."

Researchers at Ceramatec Inc, a Utah company, have created a small ceramic disk battery which they say will deliver a continuous flow of five kilowatts of electricity over four hours and can be recharged daily for more than ten years.

The new battery runs on sodium-sulphur – a composition that normally operates as a battery at temperatures greater than 300°C. Ceramatec’s new battery runs at less than 90°C. The secret is a thin ceramic membrane that is sandwiched between the sodium and sulfur. Only positive sodium ions can pass through, leaving electrons to create a useful electrical current.

Ceramatec says that batteries will be ready for market testing in 2011, and will sell for about $US2,000.

According to Daniel Nocera, Professor of Energy at the Massachusetts Institute of Technology, who sits on Ceramatec’s advisory board, “These batteries switch the whole dialogue to renewables, They will turn us away from dumb technology, circa 1900 – a 110-year-old approach – and turn us forward.”

Professor Nocera sees the new battery technology as making local power generation and storage, from sources such as solar and wind, practical. He believes that this could take the pressure off the power grid and save tens of billions of dollars needed to upgrade the grid and make it "smart".

Researchers in the UK are developing a rechargeable lithium-air battery that could deliver a ten-fold increase in energy capacity compared to that of currently available lithium-ion cells. The research at the University of St Andrews, with partners at Strathclyde and Newcastle, is funded by the Engineering and Physical Sciences Research Council,

Lithium-air batteries use a catalytic air cathode in combination with an electrolyte and a lithium anode. Oxygen from the air is the active material for the cathode and is reduced at the cathode surface.

According to Professor Peter Bruce of the Chemistry Department at the University of St Andrews, "The key is to use oxygen in the air as a re-agent, rather than carry the necessary chemicals around inside the battery. Our target is to get a five to ten fold increase in storage capacity, which is beyond the horizon of current lithium batteries. Our results so far are very encouraging and have far exceeded our expectations."

Professor Bruce estimates that it will be at least five years before the batteries are commercially available.

Donald Sadoway, a professor at MIT, has developed a prototype of a novel battery that he says could potentially store enough energy for a city the size of New York.

The electrodes in the unique battery are molten metals and the electrolyte, that conducts current between them, is a molten salt. The result is a battery that can quickly absorb large amounts of electricity with electrodes that can operate at electrical currents "tens of times higher than any [battery] that’s ever been measured," according to Professor Sadow­ay. What’s more, the materials are cheap, the design allows for simple manufacturing and the batteries are expected to have a very long life. 

Professor Sadoway envisions wiring together large cells to form enormous battery packs – big enough to meet the peak electricity demand in New York City (about 13,000 megawatts).

The first prototypes consisted of an insulated container. Molten antimony is added at the bottom, an electrolyte such as sodium sulfide in the middle, and magnesium at the top. Since each material has a different density, they remain in distinct layers. As power flows into the battery, magnesium and antimony metal are generated from magnesium antimonide dissolved in the electrolyte. When the cell discharges, the metals of the two electrodes dissolve to again form magnesium antimonide, which dissolves in the electrolyte, causing the electrolyte to grow larger and the electrodes to shrink

Since creating the initial prototypes, the researchers have switched the metals and salts used; because the prototypes were too big to be practical. Professor Sadowa­y won’t identify the new materials but says they work along the same principles. He hopes that a commercial version of the battery will be available in five years.

Click here to see a video in which Professor Sadoway explains how his liquid battery works.