London’s tube system is literally heating up the city – and that’s a problem. A hundred years ago their subway stations were places to cool down during hot summer days and people had to wear sweaters while commuting. Today, this is no longer the case. The trains are heating the earth which in turn makes the entire tube too hot.
Cooling the tube is now a pressing issue and nifty ideas are being tried. New systems being tested tend to be green and benefit other parts of the city. Basically they are trying to transfer the heat to places that want it to save costs.
An experiment in Islington is trying that very thing using heat from the tube tunnels to warm up a municipal heating service provided to a housing estate. The advantage of this scheme is that it can remove heat in winter when it’s needed above ground. It may seem mildly annoying that surface users don’t want heat in summer when you’d think the tunnels are at their most oppressive, but in fact removing heat in winter helps during the summer.
If the clay surrounding the tunnel can be cooled in winter, it has more capacity to absorb heat in the summer.
As it happens, at this particular trial, the fans can also be reversed so that during the summer months, they can suck cool night time air down into the tunnels as well.
Most hybrid cars capture energy excerpted while braking and use it to help refill the battery. A company that makes flywheels will be working with New York City to apply the same kinetic energy capture concept to subway cars, meaning that the subways will become an even more efficient way to travel. Every time a subway car enters a station and applies the brakes its capturing kinetic energy to get it started again.
The difference is that the power generated would reach into the megawatts. A 10-car subway train in New York’s system might require a jolt of three to four megawatts of power for 30 seconds to get up to cruising speed, according to Louis Romo, vice president of sales at Vycon. That’s enough to power 1,300 average U.S. homes.
And when one train leaves the station, another one comes in right on its heels. While delivering walloping surges in power like that to downtown stations is feasible, remote stations can experience drops in power. Train departures have to literally be staggered to accommodate the availability of power.
“Almost every rail company in the U.S. has a station where voltage sag is a problem,” said Romo.
Vycon claims it can help smooth out this problem by effectively getting the trains to act like Priuses. When drivers hit the brakes on their hybrids, the kinetic energy of the moving car gets transformed into electric power that then gets stored in the battery.
Read more at Green Tech Media.