Formula 1 cars have energy recovery for kinetic energy (regenerative braking) and thermal energy (motor generator unit in turbocharger shaft). Both of these technologies have potential to be used for buses and other heavy vehicles that move in an urban environment.<p>As an example, my regular bus route is 50% highway at 80 km/h and 50% urban start-stop traffic. The city buses have a huge turbo diesel or natural gas engine, and the turbo takes about 3 seconds to spool up. At 80 km/h, drivers tend to be pumping on and off the throttle, purging the turbo pressure repeatedly. This is horrible for fuel efficiency.<p>Ideally, an electric motor should do the initial few seconds acceleration, while the turbo is being spooled up using the electric motor attached. When the turbo is spools up, the internal combustion engine should be slowly introduced by adding fuel according to the correct stoichiometric ratio. At cruise speeds, engine power could be regulated by harvesting energy off the turbine rather than pumping the gas pedal which purges the whole turbo.<p>A city bus should be able to operate at or near optimum stoichiometric conditions at all times, saving a ton of gas and emissions. Currently there's a huge puff of black diesel smoke every time the bus leaves a bus stop.<p>These are very exciting times for anyone who is interested in motor sports technologies applied to efficient transport.
I just pulled numbers from some of the public transit buses that DoubleMap tracks. I see annual usage of 40k-50k miles on a single bus. Given 2013's diesel prices and standard diesel bus efficiency, that might be about $1/mile, so let's say $50k/yr in fuel for a single bus.<p>If they claim to save 20% on fuel, then a single bus would save about $10k/yr, and if the system can pay for itself in three years, then it would cost about $30k.<p>These mileage numbers aren't for London, so that estimate could be off by quite a bit. Still, consider than a standard diesel bus may cost $250k in the US while a hybrid 40' bus could cost $600k,[1] and this looks like a great deal.<p>[1] <a href="http://www.intercitytransit.com/SiteCollectionDocuments/hybrid-fact-sheet.pdf" rel="nofollow">http://www.intercitytransit.com/SiteCollectionDocuments/hybr...</a>
Just a note: the system was never actually used in any Grand Prix. Williams had problems with packaging and weight balance (safety was also a concern). They later followed other teams and settled on battery-based solution. Flywheel had only one significant advantage over these: lower operating costs. That's what makes it feasible for use in public transport, I guess.
Volvo is on a similar path: <a href="http://www.extremetech.com/extreme/154405-volvo-hybrid-drive-60000-rpm-flywheel-25-boost-to-mpg" rel="nofollow">http://www.extremetech.com/extreme/154405-volvo-hybrid-drive...</a>
Why now? Flywheels have been around for a hundred years... meanwhile, batteries have improved a lot.<p>There have been long articles about flywheels every now and then, yet you never see them in buses.<p><a href="http://discovermagazine.com/1996/aug/reinventingthewh842" rel="nofollow">http://discovermagazine.com/1996/aug/reinventingthewh842</a>
<a href="http://en.wikipedia.org/wiki/Gyrobus" rel="nofollow">http://en.wikipedia.org/wiki/Gyrobus</a><p>Motorsport is arguably a latecomer to mechanical batteries, which have been used in vehicular, transport, industrial, and aerospace applications for a long, long time.