We have fusion power already... with gravitational confinement and a Mean Time to Failure (MTTF) of 5 billion years. It's called the Sun.

The problem with using solar power to supply the needs of an industrial society is concentration and environmental conflict. The energy flux density is low by industrial standards, but HUGE compared to our total needs. To gather enough of it to supply industrial needs would require covering ever growing square miles of land.

Indirectly we already to this on an industrial scale though agraculture. But agraculture is already diverting every growing square miles of land to feed our growing population. This has already severely distorted the natural ecosystems of much of the world. If we further burden it with 'bio-fuels' (which we have been using since we became proto-human... in the form of firewood), we are making a choice between food, fuel, or nature. The recent trendiness of calling bio-fuels "green energy", as in ecologically sound, it a lie.

Biofuels are simply not the answer for an industrial society... or even a pre-industrial society of more than a few hundred thousand people. The Middle-East was once forested, before the need for firewood consumed them.

Even direct solar to electrical conversion via solar cells on the ground is an illusion in the long run. Although I strongly support using them where possible, they won't supply enough energy for our industrial needs. To bring the entire human population up to the standard of living of the US, would require paving thousands of square miles of land with solar cells. This would spell environmental catastrophy.

Going into space would solve the environmental problem. Orbital solar mirrors, kilometers wide, but thinner than plastic wrap, would concentrate the energy onto solar cells or a heat engine to generate the electricity... then beam the power down via microwaves. A bit expensive to start-up, but doable. Freeman Dyson predicted that this would be the way that an advanced civilization would proceed, with the ultimate result that they/we would eventually build a sphere around the star, called a "Dyson Sphere" to capture all of the star's energy output.

Alternatively, we can gather energy through other means. We already gather solar energy indirectly through water power. The energy to deliver the water to the mountains that give us the water head to power turbines was originally solar. But there are only so many rivers to dam (and damn) and that has its own environmental costs.

Wind power is also really solar... but there are only so many places where local geography creates the funnel effect needed to concentrate the wind for surface mounted turbines. There is however, large wind resources higher up in the atmosphere. Geostrophic winds, commonly called the "jet-stream" has much more energy available and is presently accessable with current technology using tethered auto-gyro wind turbines. In the short run, this is a very viable option for generating electricity.

But, it won't be enough in the long run. The world economy is growing at 2% per annum. Interestingly, so is our demand for energy. The two are linked. At that rate, we will need far greater resources than even geostrophic winds can provide. So where else can we get energy?

One source is the earth itself. Ah... you're thinking I'm refering to geothermal... no... that isn't very useful, save for a few lucky spots on the world, which we should indeed be taking advantage of, especially for heating our cities. No, I was refering to the kinetic energy stored in the earth's rotation. Already some places on the earth allow for capture of some of this energy through tidal flow. One can dam or simply use a wind-mill like turbine to capture the energy in the flowing water. Actually, that geostrophic wind I mentioned above gets part of its energy from the earth's rotation... as does a hurricane or typhoon. But what if we could directly, industrially, tap the earth's rotation?

This isn't as nuts as it sounds. The possiblity exists using the same momentum transfer that helps a hurricane speed up its rotation. Any rapidly spinning object that is forced to change is axis transfers the energy used to force the change of axis into speeding up its rotation. There is an excersize "toy" available that can demonstrate this effect. Some even have generators and LED lights to demonstrate that it can convert external rotation to electrical power. Imagine the possibilies of engineering giant, high speed, artificial hurricanes, perhaps using liquid helium in cryogenically cooled pipes, kilometers in diameter... converting the earth's rotation into electrical energy directly.

-- Candice H. Brown Elliott