loosely related: charging electronic cars from street lights
http://www.htwk-leipzig.de/typo3temp/pics/5e8c7a9140.jpg
http://www.elektromobilitaet-verbindet.de/projekte/laternenp...
LED street lighting the newest challenge to old utility business models
41–50 of 59 posts
Re: LED street lighting the newest challenge to old utility business models
#42Won't the blue in the spectrum from these disrupt people's sleep even further? http://www.health.harvard.edu/newsletters/Harvard_Health_Let...
Re: LED street lighting the newest challenge to old utility business models
#43Won't the blue in the spectrum from these disrupt people's sleep even further? http://www.health.harvard.edu/newsletters/Harvard_Health_Let...
If you're sleeping under the streetlights, you have bigger problems.
Re: LED street lighting the newest challenge to old utility business models
#44This doesn't make any sense. A high pressure sodium vapor lamp has an efficiency of around 150 lm/W. An LED has an efficiency of under 100 lm/W. Where is the energy savings? If anything an LED uses more energy, not less.
Under scotopic (night) viewing conditions, it is lower than that. Also when you take into account the losses due to the reflectors to get the light out of a lamp, the nice little lambertian LED emitters require much less optics to do a good job of providing light on a wide road area.
Re: LED street lighting the newest challenge to old utility business models
#45Here's my plan: use street lighting for a wireless mesh and stick camera's in each one so the NSA can keep us all safe.
csmuk's comment says they do just that in the UK (consider this comment as a GOTO statement)
Re: LED street lighting the newest challenge to old utility business models
#46I wonder what percentage of street lights actually have activity below them? What about a motion sensing light that has dual-brightness levels? A lower level when no pedestrian or car activity is detected, and a brighter level when it is. Not only would this save energy, and look very cool when a car drives down a deserted street as lights brighten in advance of it, but it could enhance security as late night prowler…
Most of the lights near my towns exit ramp work off of light sensors (dusk to dawn style). There are a couple where the sensor is either too sensitive or angled incorrectly (so it picks up vehicle headlights). As your car approaches, the light turns off. It's rather disconcerting when it happens.
Re: LED street lighting the newest challenge to old utility business models
#47Our town just voted to buy our street lights back from the utility. It's projected to save us millions even before we upgrade them to LEDs. It's notable that the utility is forced to offer to sell them back by a state law, otherwise they would have no interest in it.
Re: LED street lighting the newest challenge to old utility business models
#48This doesn't make any sense. A high pressure sodium vapor lamp has an efficiency of around 150 lm/W. An LED has an efficiency of under 100 lm/W. Where is the energy savings? If anything an LED uses more energy, not less.
> A high pressure sodium vapor lamp has an efficiency of around 150 lm/W Source? Allegedly, Cree has developed a white LED with up to 254 lm/W. [1] [1] Cree Sets New Record for White LED Efficiency http://techon.nikkeibp.co.jp/english/NEWS_EN/20120423/214494...
> Source?
It's poor form to ask for a source of something that would take you 15 seconds to google.
> Allegedly, Cree has developed a white LED with up to 254 lm/W
Interesting considering that the theoretical maximum is 251 lm/W - so I wonder which law of physics they violated to do that. (Most likely it's not actually white, but reddish.)
And this time I will give you a source since this is a tiny bit harder to google http://physics.ucsd.edu/~tmurphy/papers/lumens-per-watt.pdf
Re: LED street lighting the newest challenge to old utility business models
#49My neighborhood in Los Angeles recently switched over to LED. I am happy that they are trying to save money/energy, but having a bright white light outside my window has been quite obnoxious. The older lights were dimmer with a more natural light color.
Contemporary LED lighting does seem much harsher with very sharp shadows and much less pleasant to the eye than older lights. I believe that lighting need to be assessed on it's overall merits, not just based on brightness / cost ratio.
Agreed. I am sure that they could tint/screen/soften the light to help make them less intrusive. I would even be happy if they dimmed the lights. It doesn't have to so bright for people to get around the streets.
Re: LED street lighting the newest challenge to old utility business models
#50The Lion's Gate Bridge, which I believe is the busiest bridge in Vancouver, BC, relatively recently upgraded their lighting to LED. It reduced power consumption by 90%, and saves the city $30,000/yr in energy and maintenance.
In addition to the power savings, the old bulbs lasted an average of 72 hours between replacements, while the new ones have an estimated lifetime of 12 years, and replacing them is the 'hidden' cost that a lot of people wouldn't normally consider (and replacing bulbs mounted on a bridge is even worse than replacing street lights).