After several epic failures to convert an excel file to a html table format, I just uploaded this to google docs
https://docs.google.com/spreadsheet/ccc?key=0AnHlnR_1kjCldGJpdlYwTC1BampVZWZrS3Z6endKTXc
This is a comparison spreadsheet of PAR readings below an e-Shine 50W fixture and a Nova Extreme 1127 T5HO fixture with 2 x 24W 3000K grow lamps (the ones I use).
A few considerations to make:
The e-shine readings were taken with the fixture out of the box and turned on a sum total of less than 5 minutes prior to the test. So there might be some variation in long-term readings.
1) I ran out of new T5HO lamps so I had to use ones I had removed from the scrubber already. So the T5HO lamps are at the end of their useful scrubbing life, 90 days x 18 hours = 1620 hours. I'm not sure how this affects the PAR readings. The Nova Extreme 1127 fixture was brand new out of the box, I just switched the lamps.
2) All readings were taken with an Apogee meter with the fixture approximately 2" from the top of the sensor. The sensor was pointed straight up. I made a stand-off bracket our of Duplo Legos (highly scientific) and laid white graph paper on the table below the fixture and marked each measurement point on 1" increments. I measured along the center axis of the fixture, then along lines 1" and 2" from the center axis.
3) I did the e-Shine fixture first, then the Nova. The Nova fixture has an extra row of data points at the ends nearest the endpoints of the lamps. I didn't realize this until afterwards. Removing these data points (A ans S) raises the sum and lowers the average so that the E-Shine is about 140% of the Nova on both overall.
4) I had to let the Nova fixture warm up for a while before the readings were consistent along the axis. I took one set of readings along half of the center axis, then did 1" and 2" off that half, then went back to the center axis on the other side and the readings did not mirror the first half. When I went back to double-check the first half center axis, the PAR values had dropped 10-15%. I let the fixture run for about 20 minutes, then the readings had stabilized. Perhaps someone can shed some light on what is going on there. I thought T5HO was supposed to get more efficient as they heated up.
As you can see from the results, the e-Shine fixture, even though it has a smaller profile (both the enclosure and with respect to the element exposure, meaning the T5HO are longer and the window area on the fixture is wider), it is higher on every number except for the extreme corner data points.
On the flip side, the max to min ratio on the e-Shine fixture is much higher. Meaning that the readings in the center of almost 700 PAR and 120ish on the edges is a larger swing than the Nova of 460 to 110ish
The PAR meter reads out a little higher under the blue LEDs. Being this close to the fixture, there is little blending effect so the e-Shine fixture has a much higher variance of intensity throughout the sample field. The Nova fixture has a much more consistent peak intensity in the middle of the fixture and the number generally drop off as you get away from the dead center of the fixture.
I messed around with the PAR meter a bit to test a few things. Obviously pointing the sensor straight up all the time did not result in the maximum reading. On the +/-2 lines, if I pointed the meter towards the source, the number would increase, significantly at times. At the center line, I was able to get maximum PAR readings of over 800 on the e-Shine fixture. I was able to get readings of about 500 on the Nova fixture, but barely. +/-2 readings on the Nova fixture would also increase, but not as noticeably as the e-Shine fixture.
So being my first run at doing this, the results are far from scientific, but nonetheless very interesting.
What it tells me is that at the worst case, the e-Shine LED fixture is comparable if not better than the Nova T5HO fixture. Even if you de-rate the e-Shine fixture by, say, 20% for end-of-life after 7 years of running at 18 hours/day, then compensate the Nova fixture to take into effect the lamp intensity drop-off from 1600 hours of use over 3 months (increase output by 20%) then they are equal with the Nova at it's best and the e-Shine at it's worst.
Another factor that seems to be making a big difference is, as predicted, spectrum specific focus. The e-Shine fixture with 660nm LEDs has been shown, at least in a couple of instances, to equal and somewhat outperform T5HO. The intensity readings I measured seem to support the concept that the LED fixtures tuned to a specific output wavelength provide a much higher amount of useable light for the algae than T5HO, which has a lot of 'wasted' bandwidth. I think it's fair to say you can de-rate the T5HO fixture by 25% and maybe as much as 50%, which, at worst case, put the LED fixture at about double the useful light. Experiments performed long ago (meaning more than 6 months ago) have resulted in similar results (real-life results of algal growth on scrubbers). With this taken into consideration, and incorporating the 'double-light' scrubber, you could likely run an LED fixture such as the e-Shine fixture for half the time that you would need to run the Nova T5HO fixture, meaning the 50,000 hour life would make the fixture last for 14 years instead of 7, if the driver doesn't burn out before then (which it probably would).
So, talking life-cycle cost, the equivalency point of the Nova to the e-Shine, not taking energy savings into account, works out to be about 9 months.
The e-shine fixture runs about $70, plus $75 shipping for 2, and add 3.9% + $0.30 paypal fees that they make you pay when you buy from them bring the cost of 2 fixtures to about $220.
The Nova fixture costs $70 with shipping if you shop around. You will need to buy new lamps, cheapest is 8 for $50 with shipping. So 2 fixtures runs about $140 and 12 lamps about $75, for a total of $215. That would give you the fixtures plus lamps for 270 days. After that, it's going to cost you $100/year in materials (4 lamps x 4 lamp changes per year = 16 lamps @ $50 for 8 lamps). If you compare to the e-Shine fixture at 7 year life, you will have saved over $600 in material cost alone.
This also assumes that the non-waterproof e-Shine fixtures don't fail prematurely due to inadequate construction or lack of appropriate moisture protection by the end user.
As far as energy costs go, I know that the Nova pulls about 57 watts each and the e-shine about 47 watts. So there's not a whole lot of savings there. The LEDs likely pull about 30 watts, add the driver and 2 fans and you're at about 47. However, if you run then half the time per day, and you probably could, then you save 50%. In that case, 2x57 = 114 W * 18 hr = 2 kWh for Nova, 2x47 = 94 W * 9 hr = 0.85 kWh. In CA, that's huge. In Iowa, at $0.07-$0.08/KWh, not so huge.
I haven't ran any numbers to compare CFLs to LEDs but I would expect the life-cycle cost to be a little better for CFL as the initial costs are lower, but using comparable CFL to T5HO wattage, the average and max/min will be much worse for CFL, so I would expect LED to reign supreme.
But, it looks like any way you cut it, LED beats the pants off of fluorescent, hands down. Now it's just figuring out exactly how badly shredded the pants are after the beat-down is over.
