https://en.wikipedia.org/wiki/Deep_Space_1 This is not exactly new... at all. NASA's ion engines have been in service for several years now. Also a tenth liter of fuel is also willfully misleading: the engines expell a liter of propellant but that is not fuel. It is just the expelled material whose momentum generates the forward thrust.

then Google users would unwittingly create said traffic conditions. It actually presents an interesting problem in optimization. Suppose that car GPS installations begin to feature the Google Maps traffic estimation. Not only would people unfamiliar with an environment be compelled to use the new feature but even those who are regular auto commuters. Those who wish to save time getting home would all be directed along the same main roads which at the time would report lower traffic. These users would, however, in turn create traffic on those same roads that originally looked so appealing. Unless the units could communicate with eachother to distribute drivers evenly along roots with approximately equal favorable traffic conditions, a system like this would present problems if it were to become sufficiently ubiquitous. It is related to the problem with automated trading systems on the stock market. Many systems at holding companies would observe that a stock has crossed some critical threshold and would begin to buy or sell in vast quantities automatically. The resulting change in value does not contribute to the market's ability to allocate capital, but instead is just a fluke resulting from a Boolean algorithm. All I'm saying is... this traffic business may cause unforeseen issues.

Compost is rotting food. There is a reason why it is more tenable in suburban or rural environments. "Composting in most major U.S. cities" means having foot rot in highly densely populated areas. To look at other "successful" composting programs check out Calcutta or Port-au-Prince...