In theory, there is no difference between theory and practice. But, in practice, there is.
—Jan L. A. van de Snepscheut
Michael Walsh has a post over at PJ Media about a Sunday afternoon in Paris with no cars on the streets. I’m sure it was a lovely, peaceful day. When I was in Zurich during the 1973 oil embargo, all traffic was shut down (except for public transport and emergency vehicles) on a Sunday to save fuel, and the city was amazingly quiet.
OTOH, the people of Paris should be thankful for the internal combustion engines that move people and goods around their city. Food, for instance, does not walk by itself from farms to inner city grocery stores. Imagine what Paris would be like if the city’s food were transported as it was a bit more a century ago by horse-drawn wagons. There would be a great deal of dung to be removed from the streets every day.
The Laws of Thermodynamics require that whenever work is done, there will be some inefficiency. Changing the technology used to do work may improve the efficiency and reduce pollution, but it will never do away with losses and the resulting pollution all together. In the case of cars and trucks replacing horses for transport, the amount of pollution resulting from a given amount of work done is less—and there has been a real public heath benefit.