Solar Cells – Libby Gibson – 06/02/12

6th February 2012

Solar Panels

Today on The URN Science Show we are going all green and environmentally friendly and we’re chatting to Libby Gibson, a chemist from the University of Nottingham about solar cells.

Libby’s research is on Dye-sensitized solar cells. These are a cheap, chemistry-based way of converting sunlight into electricity. It’s an exciting time in the field and new efficiency records are being broken all the time.

The other exciting part of our work is that we can adapt the device to perform photocatalysis – i.e. drive chemical reactions with light. For energy, we’re aiming to produce hydrogen from water that we can use in fuel cells, or replace steam-reforming of methane (a large contribution to CO2 emissions) for ammonia.

Whiskey in the Student Science Lab

We’ve also got an interview from the people behind the TED series of lectures. They are coming to Nottingham soon, so tune in to hear how you can get hold of tickets for those.

The show today will be hosted by the resident chemist on The Science Show’s production team; Grace. We will also be visiting the student science lab to investigate how to generate your very own whiskey cloud using only a plastic bottle and a pump.

It’s like Whiskey in the Jar. Except it’s whiskey… in a… plastic bottle.

Some might say we have nothing better to do in our spare time.

In science in the news this week, those clever astronomers over at the VLT (Very Large Telescope – how imaginative) in Chile have managed to combine four of their separate telescopes together to create one larger telescope using a technique known as ‘interferometry’. This makes a telescope which is effectively 130m in diameter. Incredible. More about this during the show.

Today. Monday 6th February. 6-7pm. Do it.

The VLT

Crystalline Silicon Solar Cells
Here on the left is an example of crystalline silicon solar cells, but Libby doesn’t use these, she works on dye sensitised solar cells… This is a low-cost solar cell based on a semiconductor formed between a photo-sensitized anode and an electrolyte, a photoelectrochemical system.

The hope is that these solar cells can help bridge the gap between production and projected need by 2050. Currently we estimate that a further 15 terawatts will be needed, taking our total production to around 30 terawatts. If the solar cells can provide 15 terrawatts, that would be the equivalent of 6.5 × our average global power consumption… Just imagine 5 billion kettles being put on to boil at once! That’s nearly enough for everyone on Earth!

Flexible dye sensitizer solar cell

Here on the right is an example of the flexible dye sensitizer solar cells that Libby works on. This one is an example of the mass production outfit by G24 innovation in Cardiff UK (www.g24i.com).

[video:http://www.youtube.com/watch?v=8UX1Vt7681E]
Check out our Student Science about the Whiskey Cloud Experiment..
Have a listen to George and Carl explaining it all here:

A simple PN Junction
Libby has been talking about PN-junctions and here’s an example of a simple one, free electrons on the n-side and free holes on the p-side can initially wander across the junction. When a free electron meets a free hole it can ‘drop into it’. So far as charge movements are concerned this means the hole and electron cancel each other and vanish. You can find out some more here: http://www.st-andrews.ac.uk/~jcgl/Scots_Guide/info/comp/passive/diode/pn_junc/pn_junc.htm

Mitch from Cavendish asked us how much of the Earth we would need to paint to power the rest of the world, well Nathan Lewis, Professor of Chemistry at Caltech has done the work for you!

Solar power world map!
He’s worked out that the USA’s entire energy needs could be met by tiling a 400 × 400 kilometer parcel of land in the sunny Midwest with solar panels.
The rest of the world needs only six similar panels appropriately sited of course… Read a bit more about it here: http://pleiotropy.fieldofscience.com/2009/11/powering-planet-with-solar-energy.html

Grace, Libby and Dave