LED Lighting: A Case Study

Our company just completed an installation of 4-foot LED fluorescent-replacement tubes for a customer in Pasadena. These tubes use 11.6 watts as opposed to the 32 watts that the most efficient T8 fluorescent tube would use or the 34-40 watts that an inefficient T12 would use.

If LED lighting could save the customer money while providing the same or better light and reducing carbon emissions, it would be one of the best solutions available for going green. So let's use this installation as a case study to see if LEDs can deliver on their promise.

The Economics
The retail price of one LED tube is $59.95. This is much higher than a $2 or $3 fluorescent tube, but if you do the math on the overall cost of the lighting you see that LEDs are an excellent investment.

The 56 LED tubes in this project cost $2,997 more than the cost of fluorescents (not including the fact that you'd have to buy 5 replacement fluorescents by the time one LED tube burns out). But because they use 20.4 fewer watts and are on 24/7, together they will save 10,007 kWh per year which translates to $1,438 in electricity costs EACH YEAR. So even if you exclude savings on maintenance and disposal fees associated with the mercury in fluorescents, the electricity savings will pay for the LED tubes in 2.1 years.

Add to this the fact that the City of Pasadena has a terrific energy efficiency rebate program and our customer will see a payback on this project in 0.6 years. This is an astonishing return on investment for any capital investment.

Another way to look at it is the net present benefit of the project, since the LEDs will save electricity for their entire 50,000 hour lifetime. Over the life of the tubes (approx. 6 years in a 24/7 usage environment) the net present value of the benefit without the rebate is $5,996.

Verdict: the economics are extremely sound.

The Light Quality/Quantity
One obstacle to the adoption of LED technology is customer concern about the amount of light and the light color. This installation allowed us to test these factors in a real-world environment.

Light Color
The before and after photos only tell part of the story. The camera, like the human eye, adjusts to the light color and amount of light. So the 'before' picture, to the right, looks like it's pretty white. But in the 'after' picture on the left below (really a 'during' picture since the installation was half completed at that point) you can see that the LEDs in the center and left aisles look white whereas the fluorescents on the right aisle look yellow/orange. We measured a color temperature of 4200K under the fluorescent fixtures and 6200K under the LED fixtures. Pure daylight is generally in the 5400-5800K range, so the LEDs are putting out a high quality light.

Light Quantity
We took before and after footcandle readings from three locations: directly under the fixture, 3 feet from the narrow edge of the fixture (to the side), and 5 feet from the broad edge of the fixture (near the wall). As expected, the LED lights were about 7% brighter directly under the light, just as bright off to the side, and 8% dimmer near the wall. So the amount of light is the same, but the distribution is more focused.

Verdict: the light quality/quantity is the same if not better.

The Environment
Why do I mention the environment last? Because while I think it's important, not all customers value it the most. And I believe that to make a meaningful impact on climate change or dependence on foreign oil we have to find solutions have a beneficial impact on the environment, but would make sense for the customer on an economic basis alone. To paraphrase Mary Poppins, saving money is the spoonful of sugar that makes the medicine of carbon reduction go down.

In this case, the environmental impact is hugely positive. First, LED tubes have no mercury. But perhaps more important are the carbon emissions prevented. As we mentioned above the lights in this project will use 10,007 fewer kWh per year. Using the US Green Building Council's estimate of 1.771 pounds of CO2 per kWh, this translates into a reduction of 17,723 pounds -- almost nine tons -- of CO2 per year.

Verdict: LED lighting is massively beneficial for the environment.

All in all, the project is a success on all fronts. And this is not science fiction. This is happening right now, today, in a parking garage in Pasadena. People are saving money, helping the environment, and reducing the strain on our electric grids all at the same time.

LED Lighting - Fluorescent Replacements

Sorry for the long delay in my posts, I was on vacation in the green country of Brazil... uhh... researching their sugar ethanol fuel industry. Okay okay, it had more to do with researching their fermented sugarcane, or cachaça, industry.

Today I'm going to do the math on something I've been quite excited about for a while but is now officially here: LED lighting for offices. [Disclaimer: I know it's here because our company, Go Green Solutions, is selling these]



Why am I so excited? Simply put, LEDs are the future. The ones I'm talking about specifically today are fluorescent tube replacements, which will be especially important since these tubes are almost omnipresent in our office buildings. So much so that 500-600 million fluorescent tubes are replaced each year.

OK, first let's look at the qualitative differences:
-LED lighting has no mercury. Fluorescents do, and have to be disposed of as hazardous waste
-The LED tubes we've tested use 1/4 the wattage (more on this later)
-Under LED tubes you get twice the footcandles at 6 feet!
-The LED tubes last ~6 times as long: 50,000 hours vs. 8,000
-No flicker
-No hum or buzz
-More full spectrum light. Honestly, we've set these tubes up side by side with fluorescents and it's just no contest. The LED light looks like real light. The fluorescent looks like the light they'd give you in an insane asylum.

Of course there is a hurdle: price. And it sure seems like a sizable hurdle right now. Our LED tubes are retailing for $59.95 which seems steep when compared to a cool white fluorescent that may cost $4 or $5. But let's factor in the energy costs. Our LED tube uses 10 watts. The cool white fluorescent T8 four foot tube uses 40 watts. At 10 hours a day, 260 days a year (standard office usage, assuming they turn the lights off at night) that's a difference of about 75 kWh per year, or $11 in energy costs per tube per year!

As you can see from the chart below, the bulbs will break even after four years, and over the course of their lifetime end up saving you over $360. And that's not even including the cost of labor for replacing the ~5 extra fluorescents that burned out in between, or the costs of disposing of them as hazardous waste.



That's pretty significant, and pretty much a no-brainer already. But what about locations such as supermarkets and manufacturing facilities that are running 20-24 hours per day? I did another calculation at 22 hours per day, 365 days per year. The LED tubes break even in 1.5 years.



And of course, financial considerations aren't the only ones. Each tube you replace will save 2,625 pounds of carbon dioxide emissions over its lifetime. Just imagine if instead of those 500-600 million fluorescent tubes that are bought each year, we were installing these LED tubes. That'd remove close to 14 million tons of CO2 from the air per year.



As I said, the future is here, and it's... [resists urge to say "bright"]... promising.

Ocean Iron Fertilization - Doing the Math

I wanted to revisit the Ocean Iron Fertilization idea I mentioned in my last blog post, to run the numbers and see if it's worth the controversy. I found out some interesting things.

I compared three approaches for reducing CO2: (1) OIF, (2) replacing 100 million incandescent bulbs with compact fluorescent or LED bulbs, and (3) replacing 1 million gas-guzzling cars with electric vehicles. The results are surprising. 1,000 tons of iron seeded into oceans beats both other options combined. And that's a small amount considering scientists are thinking about seeding 200,000 tons of iron into the oceans.

How do these compare to the size of the problem at hand. Consider that in 2030 the U.S. will emit 3.3 billion tons of CO2 into the air. So 40 million tons is barely over 1%. Now think that it would take 159,000 tons of iron to sequester 100% of the U.S.'s 2030 CO2 levels, and ocean iron fertilization begins to sound very intriguing, maybe even worth the risks.

Here are the rough calculations I did:

First off, 1,000 tons of iron seeded into algae blooms could sequester roughly 21 million tons of CO2.



Replacing 100 million light bulbs with more efficient compact fluorescent or LED bulbs could save 15 million tons of CO2.



A shocking finding for me was how little CO2 would be prevented by putting a million EVs on the road. Granted, part of this is because right now a big chunk of electricity comes from burning coal. If we moved more of our electricity generation to renewables, this number might increase. But right now a million EVs would remove less than 4 million tons of CO2, the same as 200 tons of iron fertilization.



On this rough evidence, OIF is definitely worth further investigation.

Forget Iron Man, How About Iron Algae?

The Ocean Iron Fertilization (OIF) Controversy

Algae, that wonder-plant that could be the biofuel of the future, could now also help solve the energy crunch problem from another angle: carbon sequestration. Simply put: there are many areas of ocean that have all the requisite elements for algae growth except iron. From time to time dust storms blow iron-rich soil into these oceans, just enough to satisfy the algae's 106:16:1:0.001 Carbon-Nitrogen-Phosphorous-Iron ratio, and huge algae blooms spring up (like the one pictured at right). This ratio means that for every atom of iron, 106,000 carbon atoms are bound into the algae. Or 83,000 pounds of CO2 for 1 pound of iron. The idea is that then 20-30% of the algae biomass sinks below the thermocline (100-200 meters) effectively sequestering the carbon from the atmosphere for hundreds of thousands of years.

I think the idea is a wonderful one in theory. But I would urge some caution when messing around with Mother Nature. A couple of anecdotes come to mind (although I'm sure you could find your own examples by throwing a rock in the air).

First is the story of saltcedar in New Mexico. In the early 20th century they brought in this non-native, deep-rooted species to solve the erosion problems they were having near the Pecos and Rio Grande rivers. The problem was that saltcedar was so successful, and so deep-rooted, that it spread like wildfire and began drinking the rivers dry. Now New Mexico spends millions of dollars a year in a near-futile effort to remove the plants and preserve water (if they're hard for nature to erode, then they're hard for us to remove).

Another story comes from my girlfriend's hometown of Medicine Lake, Montana. In the 30s and 40s they planted crested wheatgrass, a non-native prairie grass, in the Medicine Lake Wildlife Refuge thinking that it would provide a better shelter for wildlife. It proved too successful, growing so thick and so widespread that it's preventing wildlife from nesting there, opposite of the intended effect.

Maybe ocean iron fertilization would also prove too successful, pouring billions of tons of CO2 into the oceans and poisoning fish, replacing one set of problems with another.

In the next post I'll do the math to see whether it's worth exploring.

Biofuels: Algae

I've mentioned biofuels before and how they've been mandated to replace 25-55% of the oil we use for transportation. Today I came across an interesting company that has an innovative way to grow biofuels from my preferred liquid fuel source of the future: algae.

Valcent has developed a closed loop vertical bioreactor (right) which grows algae extremely efficiently. It's really quite clever as it allows the algae to get access to light by funneling it through vertically hanging curtains. The system is closed and therefore conserves water as it avoids the evaporation that occurs in open pond growth systems. Here's a video.

BIOFUEL USAGE
Algae could be the future of biofuels because it's extremely efficient. As much as 50% of its body weight is a high-grade vegetable oil. Different types can also be selected to produce different carbon chains, some better for jet fuel, some better for diesel, etc. The key measure of efficiency for biofuels is gallons per acre. As you can see from the chart on the left, algae crushes the competition.

CO2 SEQUESTERING
Algae is the fastest-growing plant on earth and sequesters the most carbon dioxide as well. So what does this mean about algae's ability to slow global warming by taking CO2 out of the air? Well, it sequesters a whole bunch of CO2, but when we burn it that CO2 is released. The net effect is that it's pretty close to being a carbon-neutral fuel source (not including the fuel involved in transporting it to its destination, i.e. your fuel tank). A U.S. Department of Energy study has shown that the production and use of biodiesel, compared to petroleum diesel, resulted in a 78.5% reduction in carbon dioxide emissions.

COST TO PRODUCE
I found this quote interesting: a Feb. 2007 article on biofuels in MIT's Technology Review said that "today's higher oil prices will make it easier for algae to compete." Note: oil was trading at roughly $60/barrel at that time. Today it's around $135/barrel. Algae is coming fast.