If you haven’t seen the amazing time-lapse video generated from footage shot by residents of the International Space Station, you should do so now. I’ve embedded it here. It’s undeniably beautiful. But there’s something about it that’s incredibly disturbing. Watch it first, then let’s talk.
What jumps out at you first? Possibly the amazing auroras, a near-solid layer in the atmosphere that fluoresces like a raver’s plastic jewelry. Or maybe it’s the flashes of lightning dancing across whole regions of the dark side of the Earth.
But I’m guessing the amazing degree to which we’ve made our mark on the night-side of our planet is in the top three. Perhaps you even picked out a place you know at night by the patterns of the lights, as I did with the area around Chicago, Cleveland, Toronto and Buffalo at time 00:20-00:21.
Twinkly lights at night can be pretty, though the objections of astronomers and others concerned about the loss of our dark skies are gaining increasing support. When you spend as much time out in the desert as I do, the tiny vestiges of dark sky become increasingly precious. One of the things I’ll miss about where we live: you can actually see more than a handful of stars in the sky from downtown.
There’s a bigger problem, though.
Light is energy. Every single artificial light you see shining from the night-time side of the earth means we are broadcasting a staggering amount of energy out into space, enough energy that the light can be seen shining brightly from 220 miles up, which is approximately the distance between the ISS and the Earth’s surface. Imagine how powerful a light would have to be for you to see it from 220 miles away, and then imagine the energy used by continents full of those lights. To a first approximation, all of that light is generated with electrical power — though open flames here and there may add a few lumens to the total, it wouldn’t be much. Assuming figures from a couple of years ago are still accurate, half that electricity in the United States comes from burning coal, another fifth from burning natural gas, with nukes, hydro, diesel and a few other sources making up the remainder.
Those lights you see, in other words, come mainly from burning fossil fuels.
This isn’t news, really. But think about what we use those lights for: safety and security, comfort, productivity, reading at night and deterring crime and reading the street number of the house to which you’re delivering the pizza, and a thousand other things.
None of those arguably worthwhile goals are accomplished by shining light into space, but that’s what we’re doing. We want to fill our local, nighttime environments with enough light to be comfortable and secure, but aside from those lights intended to direct aircraft, we end up wasting every single photon directed skyward. That’s about 30 percent of a typical unshielded outdoor lightsource.
Tracking down the source of that glare of light being seen from the ISS is complex. There’s stationary outdoor lighting such as streetlamps, traffic signals and other such fixtures, which accounts for about eight percent of the energy used in lighting. There are household and industrial exterior lights, generally not tracked as a distinct subsection of each location’s total lighting budget. There’s glare through windows from brightly lit building interiors. There’s vehicular lighting. But just that first category — streetlights, stoplights, etc. — consumes the output of more than 15 gigawatts of electrical generating capacity in the US, which means the energy just that category of outdoor lighting wastes into space is a little more than 5 gigawatts’ worth of generating capacity. Half that mix comes from coal, which works out to 7 million tons of coal burned to illuminate the underside of the ISS as it flies over the US each year.
According to my back-of-the-envelope calculations, there’s a low-tech way around this issue:
If 30 percent or more of the light from a typical outdoor source is wasted into space, as shown on the left side of the above envelope, then simply putting a reflective cover over that bulb (as seen on right) would bounce those ISS_bound photons back down onto the sidewalk where we could use them. This would mean that we could swap out that 100W bulb on left for a 30 percent dimmer one, keep our sidewalks just as well illuminated, and burn less coal and oil while keeping our night skies darker.
For perspective, that 5 gigawatts of generating capacity wasted just by stationary outdoor lights and not counting private homes’ and businesses’ outdoor lighting, fugitive indoor lighting, or lighting from vehicles? That’s about 40 times the generating capacity of the Ivanpah Solar Electric Generating System. Not that Ivanpah will power streetlights: they go on at night when solar doesn’t work. But still. We could retire that much fossil fuel burning by killing 148,000 acres of desert, or we could put hats on streetlights and cut down their wattage a bit. And like I said, that’s not counting the 1000-watt floodlight over your neighbor’s deck that shines into your bedroom window.
So when I look at the video here, my glee at seeing aurorae in the Van Allen Belt is tempered a bit by the reminder of just how profligately we waste electrical power. If it’s such a scarce and dangerous commodity, threatening to bake our planet, so that we have to kill native deserts for industrial solar and wind, why are we flinging terawatts of it into space where we’ll never get it back?
... and you’ve touched only on the visible light energy waste by “broadcasting” it uselessly to space. We are profligate in the radio, as well. Omni-directional radio doesn’t have to be so omni, for example, and I believe that the brightest radio source at some frequencies in our solar system—so bright, in fact, that it would probably be the first thing noticed by an alien version of SETI—is defense radar systems.
“Losing the Night” a phrase coined by Dr. Larry Buell, has been around since the 1960’s. Originally a concept lost on all but a few, many now realize the intrinsic value of the night sky. For those of us who live in areas where ambient light does not destroy the beauty of a star lit night, this is a daily right of passage. For others who cannot, it is an occasional wonder.
The fact is that we can reduce our energy use by nearly 40% simply through energy conservation. Given this has not happened it should be mandated. This would stem the tide of new energy production an allow us to develop a sensible “master plan” that would guide our energy future for the next 100 years. Hard to believe this has not been the top priority in reducing our dependence on fossil fuels. Thanks for the stimulating write!
Alas, its worse than you think, and your low tech solution will not solve the problem.
More than 75% of the energy used by incandescent lights is emitted as
non-visible light: Infrared light.
If we switched to both fluorescent light bulbs AND made the lighting directional
as you suggest, that will help ALOT
Fluorescent bulbs convert wattage MUCH more efficiently to visible light.
As much as 80% of the wattage comes out as visible light.
All the above will save $$ as well.
Check out this link at Anza Borrego—they have tried both of the above techniques.
Its an international Dark Sky certified site.
http://palomarskies.blogspot.com/2009/08/borrego-springs-ca-worldss-2nd-dark-sky.html
Husband and I are building a retirement home in rural Mono County, California, and one of the county rules is that outside lights must shine DOWN. Not sure of the reason for the rule, but it certainly saves energy; it doesn’t take nearly as big a bulb to just light the walkway near the house, as it would to light up the whole yard. Big bonus: turn off that outside light, go outside, and see STARS, unmuddied by neighbor’s lights.
Those arrows you drew above the words “70 WATTS USEFUL” bounce off the ground and go ... well ... guess where?
Well sure, or at least them as aren’t absorbed by the earth and objects thereon. But in the meantime, they’ve illuminated the area we meant to illuminate, which is sort of the whole reason we were theoretically putting a light source there, as opposed to just going directly into space without reflecting off our retinas first.
Also, Elisha’s right, as evidenced by this NASA infrared image (hat tip to Sherwood.) Fortunately, the switch from incandescent bulbs is pretty much inevitable.
Looking again at that IR image of the Bay Area, Chris, there’s something else that jumps out at me: how clearly delineated the Hayward fault is (and, to a slightly lesser extent, the San Andreas): very bright on one side, dark on the other. It reminds me of something a geology colleague said to me once a long time ago: if you draw a map of the East Bay indicating where the most significant public buildings are—police stations, schools, fire stations, etc.—you’d have a pretty good map of the Hayward fault.
Looks as though the Calaveras Fault shines out pretty bright too.
Yes, it does. We can be pretty dumb critters.