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It's nearly nightfall now. We're in an African village walking along a sandy path strewn with dry leaves and we're heading towards a house, a hut, where

there's a family with a daughter, a primary school age who has a solar lantern to do her homework just looking round and that's really unusual for this

village everywhere else is in complete darkness now.

The girl is Rachel. This is the mother.

8 minutes to.

1, 2, 3, 4.

So by the light of the little solar lamp Rachel is moving tiny little

dry twigs to do her counter.

8 minus 2 is 6 whatever country you're in.

How much of a difference has this solar lantern made to Rachel's progress at school?

She's saying previously, before this lantern, she couldn't do what she's doing now.

This simple arithmetic, she could fail completely.

But now that this has made a difference, she's now progressing well in class.

I mean that's really quite moving, you know, he's an example of how giving people just the tiniest amount of energy can make a difference to their lives.

It's also an indication of the scale of the global challenge

if this is the only light at night time in a village like this.

Hello, I'm Roger Harabin.

Welcome to the second part of changing climate change in the run-up to the coming UN Climate Conference in Paris.

Last week we looked at climate science, you can get that on the BBC I player.

This week we're asking how the need for energy for a growing population can be met without creating

...