Catalyst: Solar power

DR GRAHAM PHILLIPS:

Power generated by the sun is simply too good to pass up.

DR CHARLES LINEWEAVER:

The sun puts out a lot of energy. In fact, it puts out about 10 to the 23rd kilowatts of power. If the sun is a big ball here, the earth is a tiny speck. It's receiving one millionth of all the power the sun puts out. Now, that one millionth, however, is enough to power all of humanity and all of civilisation for quite a few years into the future. But why would you do it in space? Why not just cover up the houses on every carport and every roof with solar panels? Well, we can do that. However, there's about ten times more energy available up in outer space. There's no rain in outer space. We can see the rain coming in here on Mt Stromlo. And about one tenth of the radiation that's hitting the top of the clouds is getting down here. Not only that, there's no night in space, there's no shade in space and there's no winter in space.

DR GRAHAM PHILLIPS:

Today, photovoltaic cells are almost there times more efficient than they used to be. So a recent Pentagon study has just recommended that US$10 billion be spent to build the very first space solar farm.

DR CHARLES LINEWEAVER:

I think someone at the Pentagon sat down and said, 'Why are we involved in Iraq? Why are spending $7 billion a month on this? Wouldn't it be more useful if we took that money and did something to secure a better energy supply?'

DR GRAHAM PHILLIPS:

The interest shown by the Pentagon seems to have given the idea of space-based solar power a whole new lease of life. So how exactly does the energy captured by the space solar farm get back to Earth? The sunlight is converted into electricity by the solar cells. The electricity is converted into microwaves and beamed down to Earth. On the ground, a rectenna converts the microwaves back into electricity.

DR CHARLES LINEWEAVER:

Now, microwaves have wavelengths of about that long. They can go through clouds, so if it's raining or clouding like it is over there we can still beam down power to some rectenna or microwave receiving antenna without a problem. And so you'd get some satellite go 'boop' and that would recharge the batteries of a city and therefore we'd still have solar power. We wouldn't have to rely on oil.

DR GRAHAM PHILLIPS:

And what about the 'safety factor'? What would happen, for example, if you were to drive or fly through the energy beam?

DR CHARLES LINEWEAVER:

The energy in radio waves or microwaves is not enough to do any damage to your skin. That's why people can talk all day long on mobile phones, which are emitting and receiving microwaves, and nothing is happening to their heads, as far as we know. They're much longer wave lengths and, therefore, kind of benign. No matter how much you turn up the power they still don't have enough energy to get an electron and pop it out of your skin or to mutate your DNA, as far as we know.