Zero-emissions transport system
Because many canals have locks and thus artificial height differences between water surfaces, renewable energy could be generated on the spot. The required electricity to power the barges could also be generated by wind turbines or solar panels, which would make a zero-emissions transport system also possible in flat countries. Because of the very low energy requirements, the investment in renewable energy would be relatively small (contrary to, for instance, the plans to charge electric cars using solar panels). And as always, obsolete systems can be substantially improved with today's technology and materials.
Low-tech canals
Of course, canal barges are much slower than trucks or trains. But, if they could haul cargo for almost nothing, it would still be an economical choice for many goods. This advantage would grow if oil prices would rise. Many abandoned canals could be put in use again, and even new ones could be built.
Almost all methods above were designed for use on very shallow, trapezoidal "low-tech" canals, which were only 2 metres (6.5 feet) deep at the centre, and much less on the sides (see picture below). These are not public works like the Panama Canal which would take decades and require thousands of workers (or energy-guzzling machines) to build. This is something that might even be done on a community level.
