All About Solar | Green Energy News

August 14, 2005 – Vol.10 No.21

All ABOUT SOLAR.

This week’s news...

Has a hydrogen fueling solution been found? Have solar thermal energy and metal fuels come to rescue?

Fuel cell companies and some of the major car companies seem adamant: hydrogen fuel cells will replace the internal combustion engine in the world’s vehicles - eventually.

While fuel cells themselves are improving - fuel cells can now operate in below freezing temperatures for instance - hydrogen supply, fueling, storage and infrastructure still remain big questions. General Motors and technology partners are now considering liquid hydrogen - rocket fuel -for fuel cell vehicles. Somehow it’s hard to imagine a fuel that needs such careful handling in the hands of consumers.

There must be a better way to store hydrogen at atmospheric pressure, ambient temperature and at low cost.

Perhaps there is.

The Weizmann Institute of Science of Israel, along with scientists from the Swiss Federal Institute of Technology, the Paul Scherrer Institute and others have developed an emission-free, all-green method of both producing hydrogen and storing solar energy. Solar thermal energy is used to deoxidize common metal ores, such as zinc, then the metal is allow re-oxidize in water to produce hydrogen gas. The energy from concentrated sunlight is stored in the metal. The metal reacts in water to generate hydrogen. The net equation? Solar makes hydrogen.

Using its solar research facilities in Canada, the Weizmann scientists used concentrated sunlight in a solar reactor to heat zinc ore to 1200 degrees Celsius (2192 F) in the presence of wood charcoal. The process split the ore, releasing oxygen and gaseous zinc which was later condensed to powder. The deoxidized zinc can then be reacted with water yielding hydrogen and a fresh batch of zinc oxide which can be recycled back into the solar reactor to begin the process anew.

Alternatively, the deoxidized zinc from the reactor can be used in zinc batteries or zinc-air fuel cells to generate electricity directly.

The energy needed for the process is, of course, solar energy and energy needed to mine the zinc (or other metals) in the first place. (After the initial mining the zinc is continuously recycled.)

Aside from developing a way to store solar energy they’ve created a method to generate on-demand hydrogen: feed raw zinc powder or pellets into a fuel cell vehicle where it can react with water to generate hydrogen. Refueling would also require fresh water and the removal of zinc oxide.

Sound a little daunting? Perhaps, but less so than storing hydrogen at 10,000 pounds per square inch or as a liquid at 420 degrees F below zero (-250 degrees C).

Does the technology sound a little familiar? Lead acid batteries occasionally explode because of the build-up of hydrogen gas. (Lead metals immersed in electrolyte (partially water) can make electricity, but also hydrogen.) Metal-air fuel cells too have a problem of hydrogen build-up.

And, concentrated solar energy has been used in the past to melt steel. There’s plenty of heat from the sun to melt all kinds of metals - virtually forever and without greenhouse gases.

Though appealing (very appealing) the technology has a major drawback. The companies that supply world’s vehicles with fuel - big oil - would be left out of the loop. Unless of course they got out of the fossil fuel business and into the solar energy to metal fuels to hydrogen business.

But then again, maybe, for them, it’s not a bad idea. Given declining reserves, the geopolitical situation and pressure to reduce greenhouse gas emissions, maybe a new business strategy is in order.

Do they care what they sell as long as it’s something? It’s really about profits, not oil.

Visit the Weizmann Institute of Science http://www.weizmann.ac.il/ and their Solar Research Facilities and the SolarTower of Power at http://www.weizmann.ac.il/ESER/solar_page.html