Having seen all the alternative energy posts here,
I just came across an interesting well illustrated online magazine
(Chinese wheelbarrows etc! as well as "gasbag" vehicles, solar power, pedal power with unusual takes...)
done by someone in Barcelona, Spain
Also with long articles and more illustrations, topic examples
"Wood gas cars were not the only answer to the limited supply of gasoline in World War One and Two....
....an even more cumbersome alternative came in the form of the gas bag vehicle.
The old-timers on these pictures are not moving furniture or an oversized load. What can be seen on the roof is the fuel tank of the vehicle - a balloon filled with uncompressed gas."
Solar power, use in factories, the concentation of solar power etc...