By David Jamieson, President of the Australian Institute of Physics.

Submitted to Canberra Times as a guest column for publication Monday 30 October 2006. Views in this opinion piece are those of the author and not necessarily policies of the AIP.

There is a rising energy debate in our community. But what we need is not energy – but power. There is a not so subtle and very important difference, as the difficulties Australia faces today arise from problems associated with power, not energy.

Let me explain.

Australia and the world have an abundance of energy but we have a terrible shortage of power. Energy is measured in Joules. Joules are to energy as litres are to water or dollars are to bank accounts. There are lots of Joules lying around - in sunlight, coal, uranium, hot water, mobile phone batteries.

Power is the rate at which energy is delivered. Power is to energy like flow rate from a tap is to water or the weekly spending rate is to dollars. Power is measured in Joules per second (also known as Watts – after James Watt.)

What we need to run our cities and our civilisation is power, not energy. To run the nation of Australia requires about 45 billion Joules of energy to be delivered every second of the day seven days a week. This is an astonishing amount of power.

And delivery is the challenge. Let me put it another way. Imagine I tell you that you have won the lottery. The prize is 7,682,300 dollars. I give you a cheque. You put it in the bank right away and shortly afterwards pay off your house, buy a car, whatever. You can spend the dollars at whatever rate you want. All at once (on your house) or gradually (several cars over the next few weeks). A pile of dollars in the bank is powerful.

What instead if I said, “Congratulations, you have won the lottery.” “But the dollars are distributed 1 km apart over the surface of Australia. All 7,682,300 square kilometres of this nation of ours.” Same number of dollars as before, but not nearly so powerful. Going to be a problem to spend. Going to cost heaps to collect into a concentrated form so you can pay off your house. That’s the challenge for Australia and the world – delivering the power when and where we want to use it. And we need this power all the time.

Another example. Your mobile phone battery stores about 10 thousand Joules in a fully charged battery – useful. Your bathtub full of water at a temperature of 60 degrees Celsius will release about 80 million Joules of energy when it cools down to room temperature. Useless. There is no way, even in principle, to collect that energy and put it into your phone battery (let alone thousands of phone batteries) so it can be tapped to provide useful power. It is too dilute.

Indeed the second law of thermodynamics says that you cannot obtain more than about one eighth of this energy no matter how clever you are. Roughly speaking the second law accounts for the energy wasted collecting the energy.

How about solar energy? There is plenty of solar energy, but very little power. To power Melbourne (7 billion Joules per second) would take thousands of square kilometres of solar collectors. Very expensive and energy intensive to build. Useless at night! Remember we expect reliable power 24/7.

So you might say, let us conserve! Cut back! Energy efficient light bulbs!

But we can’t sustain twenty million people without electricity. Even if we cut back our power consumption by 50% (which seems unlikely – no more iPods, internet, air conditioners, lifts, cars…just the bare essentials) we will still need to find around 22 billion Joules per second to run our newly austere lives. To say nothing of the fact that in the future, environmental catastrophe may mean we will need to take in millions of refugees from places that have become uninhabitable due to climate change. Or set up vast, power hungry sea water desalination plants to provide water to our ever drier land. Whatever happens, we are going to need more power.

However we can set an example to the world and attempt to arrest that climate change without hideous thinning of our population. It is clear to everyone that human generated CO2 is linked to climate change. But don’t worry! It won’t have much effect on you or your children. We are a rich and powerful nation. We can cope. It is unlikely Australian children will be dying from famines due to crop failures. That will happen in the Third World.

Our power stations mostly use coal to make electric power giving our country one of the highest rates of CO2 emission in proportion to the amount of power generated, especially in Victoria and South Australia which use brown coal.

At the moment it is people living by subsistence agriculture who are paying the price for this. What can give us the power we need to run our civilisation without the greenhouse emissions? Especially as this is an emergency! The climate appears to be changing. We cant’ wait until we are certain, we must do something about it now! We need an alternative power source right now!

We must be sure that the alternatives can provide us with the power we need to run our civilisation. We must look at the numbers. We must judge the down sides of the alternatives against the down sides of our present practices. And we must make that judgment on a global scale. We must take responsibility for the disposal of our own wastes.

Solar, wind, hydro can all play a part but only nuclear power can deliver the power we need to run our civilization without greenhouse emissions today.

We must take responsibility for the downsides of our own lifestyle. It is the only ethical thing to do.