Chicago has ~250,000 street lights, most are sodium vapor (yellow street lights) HED lights that send light basically in every direction
Saturday, 09 April 2011 Time is Energy – Daniel Simon
While most sane people would probably say no…if you live in Chicago you actually say YES!
I am talking about the annual $ value of the wasted energy from our street lights. Chicago has ~250,000 street lights, most are sodium vapor (yellow street lights) HED lights that send light basically in every direction. While the point of street lights is to light the street, the most common model of street light sends as much light up into the night sky as it does down to the street, where we want it. That is waste–pure and simple.
I spent a few minutes researching the question today and ran across this website that runs through the numbers (check out the photo of Chicago from space at the bottom of the website to "see" the waste). The group is called Illinois Coalition for Responsible Lighting…I only ran across their website today, but their math looks right (their homepage shows a map of the whole US lit up).
The bottom line is that Chicago streetlights burn a bit over 300 million kwh each year, and Chicagoans pay ~$18 million/yr–according to the 2008 values/calculation on the website above. This means that if we use LED street lights which direct their light down (plus I've read that they save over 50% of the energy of sodium vapor lights) we would get just as much light, but save $9 million each year (and eliminate 150 million kwh/yr of unnecessary energy demand, carbon emissions etc.). According to the case study linked to above, the payback would be under 5 years (maybe less today since LEDs improve every year and that study is 6 years old).
Since Chicago is nearly 1% of the US population, scaling this to the whole country means we could reduce more than 15 billion kwh of energy waste each year (3% of our total electricity use) and save over $1 billion in electricity costs alone. (Note the $9 million in savings was based on less than $0.06/kwh rate the City of Chicago payed in 2008.)
Actually along the north end of the Lake Shore Drive, some LED lights have been installed just in the last ~6 months and are working great. Hopefully we can roll those out citywide in a hurry!