Transit operators today have a wide selection of choices with regards to the type of energy to power their fleets; gas, clean diesel, diesel-electric hybrid, CNG, hydrogen fuel-cell, electric (trolley), battery-electric, capacitive-electric, with more to come in the future. One technology absent from that list is “electro-mechanical flywheel storage” – using a large, gyroscopic flywheel to capture, store, and release electricity that then powers an electric motor. One manufacturer and several nations tried that method in the 1950s – let’s take a look at the Gyrobus.
While I’m sure most CC readers understand how flywheel energy storage works, here’s a short video for those that may need a refresher.
The initial origins of the flywheel-electric bus (FEB) began in the late 1940s in Switzerland with the manufacturer Oerlikon. The Swiss were looking for alternatives for their trolley bus routes where due to geography or cost, continual overhead wiring wasn’t viable. With a typical range of between four and six kilometers, Gyrobuses would recharge at overhead stations along the way. Three-poles would extend from the front roof to connect to an overhead gantry which ran three-phased 500 volt AC. The integral electric motor/generator would then spin the flywheel up to 3,000 rpm. The average charging time was 30 seconds to 3 minutes to top off or recharge. Regenerative braking could also return energy to the flywheel. A full recharge from a complete flywheel stop took around 40 minutes, however standard procedure was for the flywheel to never run completely down. A plug-in port allowed for continuous charging at night for quick operation in the morning.
The Gyrobus was built by a consortium of Swiss manufacturers; Oerlikon made the flywheel and drive system, FWB (Franz Brozincevic & Cie, Wetzikon) made the chassis, and coachbuilder CWA (Carrosseriewerke Aarburg) manufactured the aluminum body. Length varied but the typical model was 10.4 meters (34 ft) long and seated 30. The huge flywheel weighed 1.5 metric tonnes (3300 lbs), was 1.6 meters in diameter, and was situated in the middle of the bus, spinning in a horizontal axis. With that much mass spinning, the flywheel needed to be in the exact center of the bus to ensure stable handling. Even then, drivers stated it handled “quirky.”
The first full commercial service began in October 1953, linking the Swiss communities of Yverdon-les-Bains and Grandson using two buses. The concept proved successful technically but less so commercially. Electrical consumption from the grid to power the heavy flywheels was considered excessive and with such limited production, parts were prohibitively expensive. The two Gyrobuses remained in service until 1960, when the route was converted to diesel.
In 1955, the city of Leopoldville in the Belgian Congo (Now Kinshasa, Republic of the Congo) purchased 12 Gyrobuses to use on various routes. They operated for four years before the poor roads took their toll. With war breaking out in 1959, service was ended.
Ghent Belgium was the third location to use Gyrobuses beginning operations in 1956 on a route linking Ghent and Merelbeke. They stayed in service for three years, being withdrawn in 1959. The operator concluded they were unreliable, “spending more time off the road than on.” City officials also noted their weight increased road damage. Fortunately, one Ghent 1955 model Gyrobus G3 was spared from the crusher – it’s on display at the Flemish Tram and Bus Museum in Antwerp, Belgium.
Could flywheel technology be used in buses today? Possibly, but not likely. Today’s ultra-capacitor buses, in use in cities like Shanghai, Tel Aviv, Belgrade and Sofia, have single-charge ranges of up to 40 km (26 miles). But who knows, with today’s much lighter and stronger metals, smaller more powerful motors, and electronic controls, maybe someone will come up with a completely new “spin” on things.
Fun Fact: Though not used in buses, flywheel technology is found today in a variety of applications, from a backup energy tool to an intermediate “smoother” for electric sources that fluctuate such as solar and wind. Further, a flywheel-electric tram is currently in service in the West Midlands of the UK – flywheel-powered “Parry People Movers” (designated as British Rail Class 139 railcars) operate on the Stourbridge Town branch line, running a shuttle service between Stourbridge Junction and Stourbridge Town. A short video for those interested is here.
More recently used in the Chrysler Patriot proposed LeMans car.
I remember when flywheel power kept popping up in more recent decades before lithium ion batteries became viable. But I did not know about this actual production bus, and it is a fascinating footnote to transit history. Like so many promising new technologies, it wasn’t until it was put to the test that its limitations became apparent.
A similar charging strategy was tried (and used) with early battery buses, IIRC.
Wow! Never heard of a flywheel powered bus. Thanks for the article.
Remember reading about this in Pop Science around 1961. The article said the bus was being used in London, but maybe they were over-optimistic.
How interesting. 1.5 tonnes of whirling dervish under the floor surely meant the bus could only run on left (or right) turn routes!
I had no clue that supercapacitor buses could do up to 40kms, as I thought it was maybe 4km. I had to rabbit-hole several to marvel at them. Closest we get here is the new 21 km city of Brisbane “Metro”, which is really made up of rubber-tyred bendy-bus units with lithium-iron-titanium batteries which charge up in 6 minutes either end.
I don’t get the Stourbridge shuttle. It has a reciprocating LPG engine, which runs to spin up the flywheel, to make electricity to make it go: since you cannot create more energy than you put in (from combustion), why not just use the LPG engine? The engine is a 2.3 litre Ford, which you’d normally say isn’t nearly enough to push 12-odd tons, but with the right gearing, surely it could be done – it only goes 0.8 of a mile, and tops out at just 20mph, after all.
Don’t bring the 2nd law of thermodynamics into it, Justy – there’s money to be made from selling these crackpot schemes to the gullible.
There was a recent revival with a 40K rpm carbon fibre flywheel which was just as bats. Even more when it exploded; the containment vessel weighed so much…
PSA were developing a compressed-air regenerative braking system. It appeared to ignore any potential (sorry) of the hydropneumatic system and was thus binned too.
I’m sure Yutong or whoever can now sell you a regular hybrid bus that’s cheaper and less unreliable than the hopeless new London bus was – especially once they ran out of Other People’s Money.
A coworker once told me about it a few years ago and I’ve been intrigued by it since. Necessity breeding innovation.
I remember reading about the concept behind this when I was younger, but if this application was mentioned, I don’t remember that. Like a lot of things, it’s a really cool idea with a lot of downsides. Gyroscopic effects are a big one, but you also have the combination of a ridiculous amount of mechanical energy and Murphy’s law. You *could* have it minimally contained to get the most possible out of it, but that doesn’t meet most standards of safety, and if you do a good job containing it, you end up with a big, heavy lump. So it probably only works in stationary situations, but maybe some day, more exotic materials will increase the “storage capacity” per Lb and offset the limitations enough to change the equation.