Southerly by David Haywood

Enjoyed your latest broadcast - I was reading about the NZ research just the other day and was wondering where to buy shares ;-)
A further benefit that I don't think got mentioned is that these cells can be put on all sorts of surfaces - possibly even fabrics. Of course the devils are always in the details when it comes to moving basic research into commercial production (I know only too well - most of my research is in that interface), but hopefully they will have some luck and good support.

Cheers,

Judi

Judi:-

You're quite right! Unfortunately time didn't permit more than a quick overview of this technology.

Some interesting areas where other research groups have had promising results include forming these cells onto flexible surfaces -- which, for example, could be used as a coating for roofing steel.

Others researchers have been able to integrate Grätzel cells into window glass. This means that you could have the north-facing (in our hemisphere) windows of an office block completely covered in semi-transparent low-cost solar cells.

Both the above approaches would reduce the cost of these cells even further, since buildings (obviously) require both roofs and windows anyway -- so you effectively get most of the substrate and all of the mounting structure for free.

The other nice thing about the Grätzel dye cells is that -- unlike silicon solar cells -- they will work in dim light conditions (cloudy days, etc) to a certain extent. This means that in real sunlight conditions they will actually perform better (in comparison to conventional silicon cells) than their raw efficiency would suggest.

My wife, Heather, reckons that eliminating toxicity is the biggest benefit offered by the work reported on here. Established solar technology shares the waste problem familiar from nuclear power - moderately expensive to setup, cheap and very clean to run, but what do you do with your equipment when you're done? Gallium arsenide is nowhere near as nasty as nuclear waste, and hard to build bombs from, but if solar power really took off then there would be be vastly larger volumes and they would likely be dispersed throughout the community.

By contrast, the porphyrin approach leaves you with glass, "a plant chemical, and ground up rock."

All very well to focus on the cells, but don't ignore the balance of plant required so you can use the power...
Batteries, if you are using a storage system, with their metal content require regular replacement that needs managing for toxicity effects.
And don't forget the cost component too - 40% to 60% of the capital with silicon cells is balance of plant, a large reduction in cell cost still won't make it cost effective compared to grid supplied power.

Andrew Stevenson wrote:

Batteries... don't forget the cost component

Fair point. Energy storage is certainly a major issue with all the 'flow type' renewable energy sources e.g. solar, wind, wave, and (perhaps to a lesser extent in NZ) tidal flow.

I was hoping to be able to cover this topic in the current series of PA science, but it might have to wait for next time.

a large reduction in cell cost still won't make it cost effective compared to grid supplied power

Interestingly, with regard to other 'balance of plant': it's anticipated that the price of grid-tied inverters will also drop significantly with larger production volumes. For new installations it looks like the Grätzel cells could be integrated into existing building components (window glass, roofing steel, etc), which would reduce the cost of additional structural items (e.g. mounting frames, etc).

This is very encouraging!
We live with an off-grid system that includes 12 x 80 watt panels, and electricity costs us approx 10 x what you'll pay the power companies. That's partly 'cos we use a lot of petrol or diesel and have to write off generators over 3-5 years; but batteries are also a fairly big cost (approx $20+ a week). It also takes some time to look after them! The inverter was expensive- but hopefully won't cost a lot to replace.
The most encouraging thing I've read about is the possibility of a new generation of capacitors replacing batteries. It's well on the way for electric cars- and the "claim" is that we'll get the same storage as our 16 bulky deep-cycle batteries in a package not much larger than a paperback (perhaps more A Suitable Boy than Mills and Boon :-). There was a bit of a trumpet about this a couple of years ago, which afaik has died down...
But PV "glass" would be terrific- at the same time as putting in double glazing, power the lights!

Yes much is promised by those developing new technologies, but little is delivered in comparison to those claims.
Provided a claim passes the sniff test (does not violate the laws of physics or requires super unobtanium to power it etc); a useful guide I've been told for evaluating a new technology at the laboratory/concept stage is to multiply any stated costs or time to develop by pi...
As Judi said in the first post, "the devils are always in the details"

I wonder why you focus on 'Energy' but fail mention 'Power'.

A babbling brook, a rooftop baking under the sun, a gentle breeze, waves crashing on the shore . All sources of energy but until its harnessed into power its useless to us !

My electricity company calls a low usage customer one who uses less than 8000 kWhr per year.
That is about 20kWhr per day, and at the flick of a switch any time.

Power has to relentless, reliable and preferably come via existing methods of delivery

Steve Curtis wrote:

I wonder why you focus on 'Energy' but fail mention 'Power'.

Thanks for your comment, Steve.

I think your question may arise because you are confused about the terms energy and power.

Power is defined as energy per unit time. It's measured in Joules/second (aka Watts).

Energy is, of course, measured in Joules. A kWh is simply a special unit of energy used by electricity companies (where 1 kWh = 3.6 MJ).

In other words, the examples you give ("babbling brook, a rooftop baking under the sun, a gentle breeze, waves crashing on the shore") are all examples of both energy and power.

The examples that you claim are power ("8000 kWhr per year... 20kWhr per day) are, in fact, examples of energy.

You may be talking about the difference between exergy and energy -- but, even so, your statements are misguided with respect to the output of solar cells, which directly produce energy in the form of electricity (i.e. virtually 'pure' exergy).

Wikipedia may have some useful information for you in terms of energy, power, and exergy:

http://en.wikipedia.org/wiki/Energy
http://en.wikipedia.org/wiki/Power_%28physics%29
http://en.wikipedia.org/wiki/Exergy