Energy Perspective

I've been reading a book "The atom and the Apple" by Sebastien Balibar a French Physicist a great book though some things I didn't get he really did clear up the future of energy. I summarize what he wrote.

1. Do  windmills represent a viable source of energy for replacing oil?
A wind mill spreads it's blades 100m produces a maximum of 2million watts(2MW) if run continuously but wind is variable and the best you can hope of is say 1/4 of  this 0.5MW.
In the case of France their are 60 nuclear plants producing a 1GW (1billion watts) to replace all these power plants you would need 63GW / 0.5W = 126,000 windmills 5000km of wind mills would only replace 6 nuclear reactors not practical.

World energy consumption is increasing constantly . In 2000 it was 14000 GW it comes from 32% oil, 26% coal, 19% Gas, make 77% from fossil fuel the rest is 5% nuclear, 6% hydroelectric dams, 10% biomass mostly wood and 1-2% from things like wind and solar.

The problems with nuclear energy include the chance of accidents and the disposal of waste which really adds up to tonnes and tonnes of reactive waste.Work on 4th generation reactors looks promising and further minimizing waste

2. Thermo nuclear fusion is in experimental stages with some huge hurdles to overcome before use.
Like the sun it smashes hydrogen together under heat and pressure creating helium and releasing lots of energy in the process. The problem is putting this mini sun in a box and extracting the energy some serious plumbing problems.

3 .The main available trouble free energy source is savings we could make. Downsizing, heating and lighting efficiencies, eating seasonal produce etc. The problem is not only technical it's political human and global.

4. Solar energy has some potential. France receives 100 to 200 watts per square meter it would take only 30 square meters to supply each persons energy consumption. Easy to use solar to produce hot water by running it through black pipes. Solar to produce electricity is more difficult.
The maximum theoretical output of silicon solar cell is 25%. Semiconductor film incorporated in construction materials have a 5% efficiency. To produce 30GW of power 10% of the total power consumed in France you would need to cover 4,000KM squared that is the same as covering all of Sydney or London.
Further progress in solar cells could see it become a part of the solution.

5. Biomass energy from plants. Photosynthesis on paper does not look efficient as for every on watt of power received from sunlight a field only captures 5 milliwatts or 0.5%. So in order to serve our energy needs we would need to dedicate area 20 to 100 times larger than currently used for agricultural purposes.

6. Fuel Cells: If you submerge 2 electrical wires into water and run a current through it hydrogen will be released on one side and oxygen on the other; you have electrolysed the water. A fuel cell does the opposite it consumes hydrogen  producing water and electricity. They were invented to supply energy to space ships.
The best case would be to produce hydrogen from solar or nuclear energy - could then be used to run cars, buses and planes.