The Economist has an interesting article on train technology. A representative paragraph:
H/t Tyler Cowen.Accelerating a passenger train to 300kph and holding that speed for 100km costs only about €155 ($200) in Italy, says Valerio Recagno of D’Appolonia, an Italian engineering consultancy. Moreover, regenerative brakes can recover much of a slowing train’s kinetic energy and convert it back into electrical energy. This is hard to store, but can be transmitted across the grid if there is another train needing to accelerate within about 30km. And if there is not, Siemens has designed “static frequency converters” that turn electrical energy from braking trains into a sort that can be fed into the public grid and used to power homes and factories. This is now done in more than 20 locations in Germany, with a conversion loss of just 2%. Dr Gruber reckons that this is Siemens’s most significant electrical innovation of the past decade.