On-Demand Escalators Can Cut Energy Use By Up To 52% (Video)
Escalators can be a tricky topic. On the one hand, they're huge energy sucks when no one is using them and they're endlessly looping without a passenger, or when stairs are a perfectly useful option. On the other hand, escalators are a big resource in places like airports or for those of us who aren't able to get up a flight of stairs, so it's not like we could or would want to get rid of them. The solution seems to be escalators that run only when needed -- and that solution can save a ton of electricity. Life As A Healthcare CIO points us to an example of just such an on-demand escalator in use at the Narita airport near Tokyo.
"They run at a very slow speed, just enough to overcome the inertia of starting them up. When a passenger walks near the escalator platform, the rate increases and the escalator runs at full speed until 30 seconds after the passenger leaves the escalator."
There is a similar one in use at an airport in Seoul, but this one appears to be shut off entirely until it senses someone walk up to it:
I've never come across an on-demand escalator -- any escalator I've seen is either on or off, and that's that. So the idea that this (rather "duh) technology is already in place was news to me. However, New York has already has these in place in some locations since 2008, and they're quite popular in various areas of Europe.
HK EE Net elaborates on at least one form of technology used for these energy-saving escalators: voltage with variable amplitude and frequency (i.e. VVVF control).
"In escalator applications, VVVF control can be incorporated with automatic start/stop control or automatic two-speed control to vary the escalator speed according to the passenger flow. The operation of these kinds of escalator is determined by the presence or absence of passengers, hence energy can be saved when the escalator is idle. In lift applications, variable speed drives can reduce peak motor starting currents by as much as 80% compared with conventional motor drives. Further, wear and tear of the equipment can also be reduced during start/stop of the motor by using VVVF motor drive. In escalator applications, the measured energy saving of automatic start/stop and two-speed escalator can be up to 52% and 14% respectively in an office building."
So these airports are definitely seeing some sort of energy savings. It'd be great to see technology like this used in all sorts of locations that have varying flows of passengers, like subways and transit stations, office and convention buildings, and so on.