Flutterby™! : Less light, for safety 2013-02-26 21:58:58.720184+00

Less light, for safety

2013-02-26 21:58:58.720184+00 by Dan Lyke 5 comments

Bloomberg: Turn Down the City Lights and Make Streets Safer:

The research bears this out. In 2008, PG&E Corp. (PCG), the San Francisco-based energy company, reviewed the research and found “either that there is no link between lighting and crime, or that any link is too subtle or complex to have been evident in the data.”

Yes. Light pollution is a real thing.

I'm trying to figure out how we might make a bunch of little informed calculator tools that'd help citizens answer questions like these with their own assumptions. Most of my brain cycles are headed towards transportation issues, but since the system is a cycle (and electric vehicles are part of that cycle)...

Cycling a coal plant off and back on takes time and causes increased failures, particularly in the boiler tubes. Unless you rebuild your plant for it, it is likely an expensive mistake to do this daily. Cycling a 500MW plant off and back on costs about $100,000, mostly in damage to the boiler. You will not save this in a night's coal.

Coal fired plants have a lower limit at which they can operate. Typically this is about 30% of capacity, though there is work to reduce this to 20%. Turning them down near the lower limits also damages them. Turning that 500MW plant back to 180MW (36%) costs about $13,000, again mostly in damage.

At 500MW the plant probably burns about 40kg of coal per second. If we consider turning down to 36% capacity for 8 hours at night, that saves about 750 tons of coal which might cost about $22,000, or a net saving of $9,000 after you pay for the damage the load cycling incurs.

The end result appears to be complicated optimization problem that is different for each installed power plant, but the summary might be that a traditional, base load, coal fired power plant is only comfortable operating between 40% and 100% capacity, and they'd much rather sell at a discount or store at an efficiency loss but keep the plant above damage levels.

Andy, it takes too long to cycle coal and nuclear plants for base load to scale them back for late nights. Gas Turbines pick up peaks well, but are expensive

As to "light pollution", I see much of it as wasted, misdirected energy.i do light street lights at otherwse dark intersections.

We lived in an area of older and newer development on adjacent streets. The older had above ground utilities and street lighting and higher incidence of break ins than the newer section that had below ground utilities and no street lights.

Something I learned in an earlier vocation is that lighting makes shadows and if you're doing nefarious things, shadows are your friends.

There's no need to provide load without purpose. shutdown machines, lower the excitation, everybody's happy. It's nice to store energy a la Raccoon mountain, but that's done to take advantage of low cost base generation like hydro in low load times and move that energy to high load periods.

#Comment Re: made: 2013-02-26 22:23:48.57137+00 by: meuon [edit history]

In most places in the USA, late night lighting is just a sink for extra fixed load capacity that has nowhere to go. The best storage medium for that scale is "pumped water" like Raccoon Mountain, but there is eco-controversy involved in more of that.