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New England Electricity Demand

I pulled together a simple GSpreadsheet that pulls 5 minute data of ISO-NE electrical demand (using the useful but clunky importdata function). My interest is the timing of peak demand on days with high demand- like June 20-22, 2012. I’m looking to assess how well local solar PV production lines up with demand on these days. The more they line up, the higher the economic value of solar PV production.

This graph should be dynamic:

Filed under energy data electricity New England

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Cree LED Recessed Light: Ready for Prime Time

I recently bought and installed a Cree Ecosmart GU24 LED down light at Home Depot. It’s listed at $50 but I think I paid $35 (and my electric utility will cut $5 off that if I remember to send them a rebate form).  $35 is still pretty steep for a light bulb, but a) this is more than a light bulb (it includes finishing trim), and b) if it lasts anywhere close to the claimed lifetime, I won’t have to deal with it for 10-20 years.  

Here’s a “before” shot of the fixture (though this is actually the light down the hall; the light I replaced was one of my last incandescent bulbs).

Here’s the installation shot. I removed the old trim, and pulled out the socket (which had been attached to the top of the recessed can), and screwed the bulb into it. The next step was to simply shove the light in the can, and kind of mess with it until the metal clips on the side of the light got a good grip. The main installation difficulty was that the original can itself is a bit loose in the ceiling, so I had to move it around a bit to get it nice and perpendicular to the hole.

But, after a few minutes of messing around, I pushed the light in, and was ready to go. The finish bits of this bulb look good; turned off, it looks better than it did before:

What the light looks like when turned on matters too.  Here are my impressions:

  • The bulb is brighter than the 60W incandescent it replaced, and also brighter than the 15-20W (I’m not sure) CFL downlight down the hall.  The brightness is great.
  • I can’t tell you the light’s CRI, but the quality of the light looks great to me.  Not too harsh, not too yellow.  Perfect.
  • The light turns on instantly, and gets to 100% brightness in less than a second. The ramp up in brightness is noticeable, but not at all a problem. I prefer it to instant brightness- it’s a little easier on the eyes/brain.

I’ve had CFLs that aren’t instant-on, and found the brief lag annoying (I automatically start thinking, “Is it gonna turn on?” even if the lag is only a few tenths of a second).  I’ve had other CFLs where the rampup to full brightness is a problem.  This seems to vary greatly among CFLs, and in my experience has, for whatever reason, been a bigger issue with downlights. I don’t know if it’s the form factor, the bulb orientation, or what. 

I had an incandescent bulb in this fixture before because it was the first light you saw when entering the house, and the CFL I had in there before didn’t get bright enough, quick enough. I have a lot of CFLs in my house, and am generally quite happy with them, except for the downlights.  So, I’m pretty excited to find a better performing, lower power alternative.

People buy stuff for their houses all the time that have no economic payback. I’m happy with this light because it looks great and I probably won’t have to mess with it for at least a decade. That’s enough for me to replace a few more downlights right there.  But, I’m also interested in energy efficiency and conservation, so let’s run the numbers:

This light is on ~4 hours a day. My marginal rate for electricity is about 15 cents (yes, that’s the real retail rate where I live). I’m saving 50W vs. an incandescent bulb, for ($0.15/kWh * 4 hrs/day * 365 days/year * 50W/(1000 W/kW)) = $11 a year. So, my payback is a bit over 3 years, depending on the accuracy of my 4 hours/day estimate.  Even at 2 hours/day, we’re looking at a 6 year payback, which is fine given the claimed life of the light. For those who prefer other measures: I find a positive NPV after 5 years using a 10% interest rate (I’m using a high rate because this is sort of a risky investment; LEDs are still fairly new), and an IRR in the range of 25-30% if this thing lasts 5-10 years. Plus, I neglected the cost of replacement incandescents, so the economics are actually even better than these numbers. I’m not doing a fully loaded accounting (which has to include secondary impacts on heating & cooling, increased use due to lower operating costs, etc.) because I simply wanted to know whether this light comes close to making financial sense. Unless it dies much earlier than expected, it totally does.  

Another question is whether it makes sense to replace a CFL with an LED. In that case, the energy savings are only 5-10 Watts. Without running through all the numbers, which have to include projected lifetimes and costs for both CFLs and LEDs, it seems to me that CFLs still probably offer better economics. Unless the light is on most of the day, in which case I think the LED starts to win. I’ll maybe take a closer look at that later.

Regardless, I like this bulb a lot more than the recessed CFLs I am using. It looks nice. The light quality is great. The ramp-up to full brightness is great. Installation was harder than just screwing in a bulb, but not by much. Barring disaster, I don’t have to mess with it for a long time. It dims better than CFLs (this is unimportant to me, but it’s on a circuit with a dimmer, so I guess it’s a benefit).  And, importantly, the economics (vs. an incandescent) are better than acceptable.

Bottom line: LEDs are ready to go. I will buy more of these. I’ll probably take my time, because I expect prices to drop and the technology to improve, but I won’t wait too long. I want more of these.

Filed under electricity lighting

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California ISO: System Status

The CA ISO system status shows the current demand, wind generation, and solar generation for the CA ISO, in both numerical (current demand/generation) and graphical form.

It also has a “Conserve-O-Meter” which I assume shows how small the gap between capacity and demand is.

I’ve been doing a lot of analysis of the demand for electricity for our local municipal utility. It’s amazing how little time is spent at or near peak loads. The costs associated with those peak loads are significant. Anything (such as publishing capacity/demand data like this) that can encourage people to behave a little differently on the hottest of the hot days is a good thing.

Filed under energy data electricity visualization