Archive for the ‘energy’ Category

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More on compact fluorescent lights

July 18, 2009

I compared a new14w CFL designed to replace a 65W incandescent recessed light (Commercial electric, model  EDXR -30-14) and an new 65W incandescent recessed light (GE Reveal 65) by measuring their spectra with a NIST traceable calibrated spectroradiometer.  In each case the bulb pointed down, like a typical recessed light, with the spectroradiometer measurement point 108 cm below the bulb.  The measurement was repeated seven times for each bulb: first with the spectroradiometer directly below the bulb, then with the spectroradiometer moved about 15 cm horizontally, then 30 cm horizontally…out to about 90 cm horizontal shift. 

Note that the GE Reveal 65 had an “enhanced color spectrum that used a neodymium glass filter to reduce the amount of light in the middle part of the visible spectrum to yield more vivid reds and blues.  I would have been better off with a simpler incandescent lamp for this comparison. 

The first graph below shows the spectral irradiance for the CFL.  Note that most of the irradiance is in the visible part of the spectrum.  The seven curves correspond to the seven horizontal positions, with the highest irradiance being directly below the bulb.  The second graph is the same, but zoomed in to the visible part of the spectrum.

setup

CFL irrad 400-1400

CFL irrad 400-750

The following two graphs show the same thing for the incandescent lamp.  Notice the dip in the middle of the visible spectrum.  This is due to the neodymium glass filter.  If that filter were not present the total irradiance of the incandescent lamp would have been higher.  I will repeat this experiment at a later date with the simpler incadescent lamp.

Incan irrad 400-1400

 

Incan irrad 400-750

Irradiance only tells the beginning of the story.  The human eye is more sensitive to some colors than to others.  It is more sensitive to the middle of the visible part of the spectrum than to the red or the blue.  Of course, it is totally blind to the UV and the IR.  So, the irradiance is multiplied by  a Luminosity Function  and a constant to give a measure of how bright a light is.  The following plot shows the typically used Photonic Luminosity function.

Luminosity function

The following two graphs show the products of the Photonic Luminostiy function, a constant (683 lux/W/m2), and the spectral irradiance of the CFL and the incandescent bulbs.  The total area under any curve gives the “brightness” for the lamp at a particular horizontal shift.  I have deliberately left the Y axis the same on both graphs to make them easier to compare.  It is clear that the CFL is very bright over two narrow wavelength bands centered on about 545 nm and 620 nm, while the incandescent light is spread more evenly over the visible spectrum.  This is probably why people feel that colors look less natural under a CFL.CFL photonic

Incan photonicAfter all the graphs and the math, which light is brighter?  It depends on the horizontal position, as shown in the following figure.  The incandescent is brighter directly below the lamp, but the CFL is brighter off to the sides.  This should not be too surprising, because the light from the incandescent comes from a small filament, which is more easily reflected in the same direction than the light from the extended source of the CFL.  But when integrated over all directions, the incandescent and the CFL are probably a very close match, as claimed by the CFL manufacturer.

relative brightness

It would be interesting  to repeat this experiment with bulbs that have accumulated about 1000 hours.  But that is an experiment for another day.

Warm-up time.

I also measured the irradiance of the CFL as a function of time.  This was done for the lamp after it had been off and cool for hours, and again after it had been fully warmed and then allowed to cool for three minutes.   It takes about 4.5 minutes to get to full irradiance for a cold lamp, and about 3 minutes for a warm lamp.  Of course, the warm-up time for the incandescent is essentially zero minutes.

 

 

warm-up time

Conclusions

There are  hundreds of different configurations of CFLs  and incadescent bulbs being used in the world.  My sample is miniscule.  However, some of my numerical results are probably fairly representative, and there are common observations reported by many users. 

As shown above, at least in my case, the 14 Watt CFL was about a bright as the  65 Watt incandescent it was designed to replace.  However, the color quality of the CFL was much poorer.  This poor color quality is a function or the flourescent nature of the lamp, and is likely common to most CFLs. 

The CFL takes a long time to warm up, compared to the instant-on of an incandescent.  The warmup time probably varies from one type of CFL to another.  I have data to indicate that the irradiance vs. time for the warmup minutes can look quite different for a new CFL vs. and an identical CFL with several thousand hours, but that data is not presented here.

As indicated in a previous post, my experience is that a CFL will save money compared to an incandescent that it is designed to replace.  But as shown here, the color quality of the light is worse and there may be an annoying wait for it to warm up.

I will continue to use CFLs where they make sense, but I am also stockpiling some incandescents for the day when they are no longer available by government mandate.  Short duration use of many CFLs reduces their lifetime, and as seen above, it may take several minutes for the CFL to get to full brightness.  So I will use incandescents in closets and storage rooms, etc., and CFLs in the main living areas.

Last comment

I have presented this information as a small part of a large issue.  My endorsement of CFLs, despite some of their drawbacks, is most definitely not support for the government mandate to force us to use CFLs.  I am stockpiling incandescents for certain situations and would suggest that others do the same.  Perhaps the price of LEDs will drop enough to make this issue irrelevant.

Ultimately, I would like to see abundant amounts of energy available to all Americans and to all the people of the world.  Then the issue of light bulb choice would simply be moot.  My fear is that we are moving in the opposite direction.

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Funny numbers from Palm Desert, California

March 20, 2009
Rick and Wendy Clark (NYT photo)

Rick and Wendy Clark (NYT photo)

This New York Times story tells us the tale of Rick Clark and the financial backing he is getting from the Palm Desert, California city government to pay for a home solar PV installation.    Applying some back of the envelope calculations based on this NYT piece leaves me scratching my head.  Mr Clark, who the Times takes pains to assure us is not some global warming fearing greeny, borrowed $62,000 on a twenty year loan from a municipal financing program to pay for his new PV array.  Clark’s monthly payment would be about $400 per month at 4% interest.  This is probably not a great hardship for guy who has “a buggy for racing on sand dunes, and two sleek power boats for pulling water skiers” in his garage.  Clark won’t have to worry about any financial pinch because, as the article explains…

“California residents receive a straight rebate for about 20 percent of the cost of a solar power system. In addition, a federal income tax credit for 30 percent of the cost of installing solar panels was extended to participants in the municipal loan programs as part of the economic stimulus bill passed by Congress.”

 The article doesn’t say, but by my calculations this $62,000 of city money bought about 8,000 watts of installed PV at $8/Watt.  A generous estimate would be that this array will yield about 50 kilowatt-hours per day, or about 1500 kilowatt-hours per month in sunny southern California.  (Insolation at Palm Desert is about 6000 Watt-hours per square meter per day.  Roughly speaking, each installed watt will then yield about 6 Watt-hours per day. So, 8000 installed watts X 6 watt-hours per installed watt per day gives 48,000 watt hours per day or 48 kilowatt-hours per day.) This is important to Clark because

“His monthly energy bill for a 3,400-square-foot home and a guest house routinely surpassed $1,400 in summer months when the air conditioning ran all the time.”

I am forced to conclude one of two things.  Either Mr. Clark is a colossal energy hog, or the cost of electricity is way too high in California.  The average residential cost for electricity in the United States was 11.47 cents per kilowatt-hour in November of 2008.  At that rate Clark’s monthly $1400 would buy 12,000 kilowatt-hours of energy.  That’s more than amount of electrical energy I use in my house every two years!!!!  We’re told by the Energy Information Administration that the average cost per kilowatt-hour in California is 14.76 cents per kilowatt-hour.  In this case Mr. Clark must have been paying for 9500 kilowatt-hours per month.  Still a colossal amount.  But wait a minute, we calculated above that Clark’s PV system would yield about 1500 kilowatt-hours per month, nowhere near 9500.  If 1500 kilowatt-hours is worth $1400, that’s almost $1 per kilowatt-hour!!!  Even the vaunted tiered utility pricing doesn’t come close to this (…yet).

Neither one of these conclusions seems possible.  So maybe the claim that “his monthly energy bill…routinely surpassed $1,400 in summer months” was a wee bit of an exageration to make the story in the NYT more compelling.  The storyline goes something like this:

“See how expensive electricity is in California.  It will soon be that expensive for you to.  But don’t worry, solar PV is a great investment.”

City provided $7.5 million for loans

Mr Clark’s $62,000 came from a $7.5 million pool of city money provided these solar PV loans.  The money is almost tapped out with about 100 borrowers.  With an estimated 2.5 people per household those 100 borrowers represent about 0.5% or Palm Desert’s total population of 50,000.  I would be willing to bet that Mr. Clark (with his house, guest house, dune buggy, two speed boats and $1400 monthly summer electric bill)  and the other 100 borrowers live off incomes far above the average Palm Desert household income of $65,505. 

There is something funny about these numbers. This is just one more gear in the elaborate political/economic/eco-religious Rube Goldberg machine that delivers energy to consumers in California.

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Hypocrites, or simply confused?

March 14, 2009

It should be no surprise that President Obama is pushing for higher fuel economy standards.  I assume if you support Obama then you support government mandated higher fuel standards.   

I believe in voluntary adoption of higher fuel economy standards.  That is why I have driven a Honda Civic for 20 years.  Rising oil prices will insure that others will also opt for better mileage vehicles at time goes on.   And if you are worried about CO2, higher fuel economy standards won’t make any difference.  Because every drop of oil that you don’t burn helps keep the price low enough for somebody in India or China to burn it. 

So, are the owners of these vehicles hypocrites or just confused? 

cadillac-dts-2
Cadillac Deville DTS. 15 mpg city

Ford Exposition
Ford Expedition.   11 MPG city.

Cadillac Escalade
Cadillac Escalade.  About 14 mpg city.

Ford Yukon FlexFuel
GMC Yukon 11 mpg city. (Don’t worry about the terrible mileage, the owners have a dispensation directly from Gaia because it is a “flexfuel” vehicle.)

Chevy Trailblazer.  12 mpg city.
Chevy Trailblazer 12 mpg city.

Chevy Silverado.  14 mpg city.
Chevy Silverado 14 mpg city.

Lexus SUV
Lexus SUV. About 17 mpg city.  This picture is my favorite.  It was taken by my son on a school field trip to the Colorado state capitol.  I have not blocked out the license plate because I do not think that senate district 28 State Senator Suzanne Williams should enjoy an expectation of privacy. I would think that a state senator who resides on the Transportation Legislative Regulatory Commission (TLRC), is the vice-chair of the state Transportation Committee, and who supports a president that wants to have government mandated higher fuel standards would find something other than a Lexus SUV to drive around town.

 

Hummer

Hummer H1. About 10 mpg. This picture is from the Hummer Guy website.

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Volcanos in Gakkel Ridge NOT responsible melting the Arctic ice

July 10, 2008

I am not only a global warming skeptic, but a skeptic in general.  I call ’em as I see ’em.

There have been some attempts to link the arctic sea ice loss of the last several years to reports of volcanoes under thousands of feet of water in the Gakkel Ridge,

The truth is that all the energy from a volcano the size of Mount St. Helens could only melt 100 square kilometers of three meter thick ice.  This is a trivial amount of ice for the arctic region, which typically oscillates between about 4 million and 14 million square kilometers every year.  100 square kilometers is only one hundred thousandth of the yearly change in Arctic sea ice extent

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Arctic region showing the location of the Gekkal ridge.  This Google Earthimage, with annotation by Moriarty, obviously does not show the arctic sea ice.

Let’s do some simple math to work this out:

First, how much energy is released by a volcano?  Of course, if varies greatly, but we just need an order of magnitude approximation for now.  A common estimate  for the energy released by the Mount St. Helens explosion is 24 megatons, where a megaton is supposed to be equivalent to the energy released by a million tons of TNT.  A joule is the basic SI unit for energy, and one megaton is equal to 4.2 million billion joules (4.2e+15 joules).  Therefore the 24 megatons released by Mount St. Helens translates into about 100 million billion joules (1.0E+17 joules).  That is:

(4.2E+15 joules/megaton  X  24 megatons  = 1.0E+17 joules).

So now the question is: how much ice could be melted by 100 million billion joules of energy?  It takes about 4 joules to heat one gram of water by 1 degree C.  But it takes many more joules to melt a gram of ice.  The amount of energy needed to melt a gram of a solid to a liquid is called the “heat of fusion.”  The heat of fusion for water is 334 joules per gram.   If we divide the total energy of the volcano by the heat off fusion of water, we will get the number of grams of ice that could be melted.  Doing the math:

1.0E+17 joules   /   334 joules per gram   =   3.0E+14 grams

OK, the energy released by Mount St. Helens would melt about 3.0E+14 (three hundred million million) grams of ice.  A gram of ice is about 1.1 cubic centimeters (1.1 cc), so we can round it to 1 cc just to make things simple.  That means that Mount St Helens released enough energy to melt 3.0E+14 cubic centimeters of ice. 

Let’s get a handle on what “3.0E+14 cubic centimeters of ice” means.  A cubic meter of ice is the same as 1,000,000 cubic centimeters of ice.   So, 3.0E+14 cubic centimeters of ice are the same as 3.0E+8 cubic meters of ice.  Still a pretty big number to grasp.  A sheet of ice that is one meter thick and one square kilometer would have a volume of 1 million cubic meters (1.0E+6 m3).  In this case, 3.0E+8 cubic meters of ice would be the same as 300 square kilometers of ice that is 1 meter thick.

Now we have a number that is easier to deal with.  That is, the energy of Mount St. Helens would be enough to melt 300 square kilometers or ice that is 1 meter thick.  Finally, we’ll make the estimate that the ice is about 3 meters thick in the arctic.  (Of course, it is much thicker some places and much thinner in others.)  Then the energy of Mount St. Helens would melt about 100 square kilometers of ice in the Arctic.

The bottom line

The Arctic goes through some serious changes in sea ice extent every year as the season change.  The sea ice extent changes by about 10 million square kilometers every year.  100 square kilometers is about one hundred thousandth of that.  It would take a thousand volcanos the size of Mount St. Helens every year to account for just 1% of the yearly Arctic ice loss.

I am not only a global warming sceptic, but a skeptic in general.  I call ’em as I see ’em.

Mount St Helens explosion, May 18th, 1980.

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Energy cost for shipping food is minor

July 4, 2008

Criticism of our great system of food delivery because of a slavish adherence to a “green” lifestyle is simply unfair.

Ellen Goodman’s syndicated column for July 3rd introduced us to Roger Doiron.  Doiron belongs to a group called “Kitchen Gardeners.”  According to their web site:

“Kitchen Gardeners are a special breed. They are self-reliant seekers of “the Good Life” who have understood the central role that home-grown and home-cooked food plays in one’s well-being. By seeking an active role in their own sustenance, they are modern-day participants in humankind’s oldest and most basic activity, offering a critical link to our past and positive vision for our future.”

Dorian, also works with the Eat Local Foods Coalition of Maine, a group of…

organizations and individuals interested in creating a shift towards a locally-based food system that is economically vibrant, environmentally sustainable, and healthy.  To some, food system reform may not seem like a pressing social need. But food issues play a dominant role in a range of critical social issues, including poverty, hunger, corporate power, misuse of workers, loss of community, and environmental degradation. With each food purchase decision, consumers are — wittingly or not —making powerful choices that will determine the kind of future we live in.”

Kitchen Gardeners and the Eat Local Foods Coalition seem to have several laudable goals, but saving energy by avoiding the burden of shipping foods over long distances to consumers is a dubious one.  Goodman tells us of the lawn sign, shown below, in Doiron’s lawn that expresses their concern.

I have heard frequently from people promoting farmer’s markets, local agriculural, and those opposed to large scale agribusiness, that food shipments are a significant energy drain and a major source of those pesky greenhouse gases.  Therefore, the argument goes, we should all be eating locally grown food.  Let’s put this argument to the test.

First, let’s accept Doiron’s claim that “in Maine the average person’s food travels about 1,500 miles from field to grocery store using up about 400 gallons of gas.”  1,500 miles and 400 gallons of gas would be a lot to have a single pizza or head of lettuce delivered.  I assume what Doiron really means is that produce, meat, canned foods, etc. usually travel by loaded semitrailers, which get about 4 miles to the gallon  when loaded.  So Doiron is correct, 1,500 miles would take somewhat less than 400 gallons (1,500 miles / 4 miles per gallon = 375 gallons).

A typical maximum weight of a semitrailer on a US highway is 80,000 pounds.  Being conservative, we can say that 60,000 pounds represents the net weight of the product being shipped.  60,000 pounds is a lot of pizza or lettuce.  If the typical person eats 2 pounds of shipped food per day, then that 400 gallons of gas has brought food to 30,000 people! Or, each gallon of gas has brought food to 75 people.  (60,000 pounds / 2 pounds per person / 400 gallons  =  75 people per gallon)

I like to think in terms of kilowatt-hours.  The energy content of one gallon of diesel fuel is equivalent to about 40 kilowatt-hours.  So, if a gallon of gas brings food to 75 people, that is about a half of a kilowatt-hour per person.  The total energy consumed per person per day in the US is about 250 kilowatt-hours (see calculation, below*).  Consequently, the half kilowatt-hour used to ship food 1500 miles to one person is about 1/500th of that person’s total daily energy consumption.

Put another way, if a single $5 gallon of gas delivers 2 pounds of food 1500 miles to 75 people, then the shipping cost per person is a puny 7 cents.  That sounds like a bargain to me.

Let’s not forget the huge social benefits to having enough to eat, the variety of fresh foods available to us outside the local growing season, and the ability to smooth out the effects of local weather extremes on agriculture that are all due to the shipping industry.  I am sure gardening has many benefits, but saving the energy and cost of shipping is not one of them.  Criticism of our great system of food delivery because of a slavish adherence to a “green” lifestyle is simply unfair.

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* The total energy consumed per person per day in the US is about 250 kilowatt-hours.  This may surprise many people.  This number is derived by dividing the total yearly energy consumption of the United States by 365 days and dividing again by the population (300,000,000 or 3e+8 people).

According to Lawrance Livermoor National Laboratory, the total energy consumed in the US in 2002 was 97 Quads.  One Quad is 293,000,000,000 kilowatt-hours, or 2.93e+11 kWh

97 Quads  X  (2.93e+11 kWh/Quad) / 365 days / 3e+8 people = 259 kWh/day/person

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