Solar energy

[learnin to learn]

I was wondering, is a space elevator logical? Our satilites orbit around the earth at thousands of miles per hour, how are we going to build a space elevator to a satilite that is orbiting around the earth?

[ronthepon]

A geosynchronous satellite.

[Michaelangelica]

Originally Posted by learnin to learn

I was wondering, is a space elevator logical? Our satilites orbit around the earth at thousands of miles per hour, how are we going to build a space elevator to a satilite that is orbiting around the earth?

I have never really "got" this idea either.
I think it was first proposed by Fred Hoyle?

[Kayra]

This page has a nice animation of it

http://www2.jpl.nasa.gov/basics/bsf5-1.html

[learnin to learn]

dang now that is interesting!!!

[Michaelangelica]

some interesting new solar/energy/water developments
(for Sale - Of course!)
http://www.export.gov.il/Eng/_Articl...ArticleID=2520

[CraigD]

Originally Posted by Michaelangelica

some interesting new solar/energy/water developments
(for Sale - Of course!)
http://www.export.gov.il/Eng/_Articl...ArticleID=2520

The Engineuity company’s idea and development of a device that creates hydrogen and heat from the high-temperature transfer of oxygen from water to a light metal such as aluminum or magnesium is intriguing indeed, potentially lending new meaning to an old automotive term. The system collects spent or , to be removed “by vacuum suction” during refueling. I can think of no better term for the place where the oxide collects than “the rust bucket”.

In the case of aluminum, which is refined from (also known as alumina) extracted from bauxite ore, the system can be viewed as a means of recovering a fraction of the considerable energy required to convert alumina to aluminum metal. After the aluminum wire is oxidized back into alumina, all one need do is re-convert the alumina back into aluminum and draw it into wire to complete the recycling process.

The only fault I can find Amnon Yogev’s description (brief audio recording available here) of the technology’s potential, is that I suspect he is dramatically underestimating the cost of the aluminum. Currently, the cost of aluminum can be reduced by about 95% by recycling. To recycle aluminum metal, one need only melt it, skim off non-metal impurities, and reform it as desired. If the aluminum is oxidized back into alumina, as it must be to generate power using Engineuity’s system, it must be re-refined, a much more energy and facility-costly process.

Still, the technology appears very promising, and better still, sounds as if it would lend itself to hobbyist experimentation. I’m already thinking about where to get a really hot, water-proof heater, and what gauge wire to use to duplicate Engineuity’s system!

Like batteries, hydrogen, and similar approaches, however, this one only stores energy – it doesn’t extract it from a freely occurring natural source, such as solar, nuclear, coal, or oil, so it’s not in the same category of solutions as solar power.

[tarak]

Energy perse is universal but the way we harvest it and the methodologies adopted to deliver it and more essentially the renewability of the original resource arein a process of scientific evolution and one day we will solve our problems

[Kayra]

One issue not taken into account is the true cost of aluminum.

The process is HIGHLY subsidized. Mining is so cheap, and processing so expensive that the companies that make it will only set up factories where the local government will guarantee LONG term subsidized electricity.

If we start using aluminum en-mass, it will likely not be very long before the true cost rears it's ugly head.

Is this also true for Magnesium?

[CraigD]

Originally Posted by Kayra

One issue not taken into account is the true cost of aluminum.
…
Is this also true for Magnesium?

From the perspective of the energy required for recycling of metal oxide back to pure metal, aluminum and magnesium appear very similar. Aluminum and Magnesium metal have similar market prices, about $2/kg. Both are tightly bound to electricity cost.

As best I can estimate, metal oxide-metal systems are currently about 20% energy efficient, compared to 50-95% for H2O-hydrogen systems.

From the perspective of material input and output, oxide-to-pure metal recycling for aluminum requires carbon, and generates CO2. The best and most common magnesium process requires silicon, and generates CaSiO3 (Wollastonite).

Since CaSiO3 is benign and useful, while CO2 is a problematic waste, there appears to be some basis to favor magnesium over aluminum in Engineuity’s energy storage scheme. However, world production of aluminum is about 40 times that of magnesium, so medium-term, supply limitations force the use of aluminum

Despite looking less energetically efficient than H2O-hydrogen systems, metal oxide-metal has the attractive quality of engineering practicality: as a fuel, metal wire is inert and can’t leak. It has a storage life better even than gas or diesel – practically forever. Hydrogen is one of the most reactive elements, and the hardest stuff to keep from leaking existent.

I’m very enthused by this technology.

The wikipedia articles for aluminum separation, the Hall-Heroult process, magnesium sources, and the Pidgeon process seem good research entrypoints.