Rsstuart;
When I said car batteries I did not mean the usual meaning
of the term. I meant whatever batteries were in electric cars.

A friend of mine has lead acid cells in his car.
He does about a 40 Km trip to work each day and recharges at work.
He normally only lets them discharge to about 50%.
He does that to increase the lifetime of the cells.
That is two discharge recharge cycles a day.
My question is does two half cycles = one full cycle ?
When they pack it in he is going to replace them with lithium.

The thin film cells sound promising, they would be life of vehicle cells.
I believe the Mitsubishi car will be on the market here next year.

Bazz: "My question is does two half cycles = one full cycle?"

I don't know, Bazz. The question depends very much on the chemistry. Batteries seem to like spending the bulk of the their time at a particular charge level. Lead Acid likes to be kept at 100%. A good solar installation never takes them below 80%, and under those conditions they last 20 years. Definitely in their case 2 x 0.5 doesn't equal 1. Li-Ion prefers 50%. Store them at 100% or 0% and you reduce their shelf life by a factor of 5 or so, from memory (look it up on Wikipedia). The closer you take Li-Ion to the limits, the more damage you do the electrodes. The stress the lithium ions entering the anode and cathode literally tears the crystalline structure apart. Cars extend the lifetime of Ni MH to 10 years by similarly careful management.

By the by, we often here of the effect nano particles and nano engineering will have on us. Nowhere does this appear to be more true than batteries. If you look at the recent breakthroughs in batteries they all appear to be ultimately be brought about by designing the electrodes so they are not torn apart by the ions as they move about while the battery is charged and discharged. Silicon wires, carbon nano-tubes, tiny particles coated with single atom layers - these are all weird mechanical structures that can take the strain of ions entering and leaving without breaking up.

There seems to be a lot of these being discovered, and each year brings more. We are finally moving engineering to the level nature does it - molecule by molecule, and the payback as in thin film Li batteries that have basically unlimited charge cycles and three times the capacity of normal Li-Ion batteries is enormous. As in they are the magic bullet that will solve our energy problems.

However, we can't mass produce cheaply them. Yet. It seems inevitable we will be able to one day. But I have absolutely no idea when that day will come.

By the by, someone posted this site:

http://www.withouthotair.com/

Maybe it was someone here. If so sorry for the repitition.

It is a free online book that is just a whole pile of back-of-the-envelop calculations - that I am so fond of, but he canvases the entire energy outlook. With references to every figure he uses, and he makes the error limits clear.

Like my calculations here it is not particular useful for seeing where we will end up, but is a very useful sanity check - pointing out what is just an absolute waste of time. After reading it, I can't but think Australia is uniquely placed to take advantage of looming energy shortages. We are indeed the lucky country.

I would like to thank all the people who contributed to this topic so far for enlightening a lesser electronics/engineering based individual like me it was utterly fascinating.. Rusty, bazz, grim, raw and others Thank you all

For those like me had only an armchair understanding I think the general issues were:

The real problem impediment seems to be as many alluded to but was finally stated by rstuart the question is simply how do we store the energy to use when and how we need it.

I'm a little despondent as a result of some of the realities of storage methods set out in the detail submitted

In varying forms including but not exclusively Jewely, Fractelle and others“if the answer(s) did exist the powers that be or wanna be would fight it until they can figure out to profit most from the solution”. This of course raised even more questions but are off topic and maybe subject to other discussion topics.
I thank ALL who contributed for helping to clear up a lot of questions.

BTW This discussion thus far has been conducted the way ALL should be conducted and thanks for that too.

An appreciative examinator.

Foxy I'm always impressed

Rusty Catheter: "Sources of suitable silicon for producing semiconductors are becoming scarcer"

Not as far as I am aware. Some of the rare earth materials used for doping are running short, but there are less efficient substitutes.

The point I was trying to make is that this means they should be subject to the "Experience curve". This curve is based on the long standing observation that very roughly, every time the manufactured volume of an item doubles, the price drops by 20%. The price of solar cells show every sign of being subject to this experience curve, just like just about every other mass produced item on the planet. See http://www.iea-pvps.org/products/download/rep1_16.pdf figure 8, page 27, or http://hdgc.epp.cmu.edu/mailinglists/hdgcctml/mail/ppt00010.ppt slide 39.

Production of solar cells is growing by 15%/yr, or 35%/yr depending on who you believe. At 15%/yr (http://www.iea-pvps.org/products/download/rep1_16.pdf page 4 para 1) production doubles every 5 years, which means that after 30 years production we will be producing 64 times more solar cells each year than we do now. At that production level price will have dropped by a factor of 3. Sanity check: PV electricity generation worldwide is now 5.7GW, (page 3 para 1 http://www.iea-pvps.org/products/download/rep1_16.pdf ), world wide electricity production is now 20,000 GW (and growing) http://www.cia.gov/library/publications/the-world-factbook/print/xx.html, so there does seem to be room for such growth. There are no obvious resource limitations (silicon being the 2nd most common element on the planet), so hitting that price seems pretty likely.

So after 30 years solar at the cell should be cheaper than fossil fuels are now. Storage costs may well blow that out of the water - but the electricity itself could end up too cheap to meter here in Oz, by the end of this century. Batteries are subject to resource limitations (Lithium), and we don't know how to mass produce a battery that can withstand a lot of cycles, so the Experience curve doesn't apply to them, yet.

rstuart, my understanding is that most silicon production is from high purity silica or quartzite. The West Australian plant trucks theirs more than 300km to the plant. They don't just shovel in any old sand. While there are no doubt many large deposits, not all are likely to be economical at current low prices. The preparation of metallurgical silicon from this source consumes about 12Mwh per tonne of production. The output of this process is not suitable for semiconductors, but must be digested by organic acids, distilled and crystallised by a variety of means. The energetics of this whole process are not conveniently reduced. Though innovation will no doubt shave a few percent here or there, the chemical state of a bulk material must be changed and said material must be purified considerably.

Were the basic raw material to be available in any volume, and if energy costs were to remain static, plus the availablity of high grade wood chip used in the primary reduction process, then maybe the cost scaling you propose is reasonable. It was for steel in an era of stable energy prices.

I suggest that as suitable silica deposits are depleted, then smaller, more remote ones will be exploited at greater cost and processed using much the same energy expenditure as present at greater cost per unit of energy, using an increasingly depleted supply of high quality woodchip itself shipped further, or dirtier alternatives that result in greater costs in production of chemical grade silicon.

I fully expect the "experience curve" to change for a number of items depending on increasingly expensive raw materials, intractably high energy inputs and a market that hopes to install an order of magnitude more units than presently stretch production.

New types of PV cells may not endure these constraints, of course, so let us hope that that is what the curve predicts.