Tuesday, November 9, 2010
The Head of a (Green) Pin...
Sure, we all have some generic understand that "green" means "saving our mother earth from ecological disaster at the hands of man" but, if you want to write articles that quantify the savings, i.e., cloud computing is better than X, or producing a National Geographic Magazine has a carbon footprint of Y you had better have some sort of rational scientific basis.
The problem here is separating the causuistry, which I wrote about a few days ago, from actual causality. If we pretend what we are talking about is a form of causality or exact measurement and it turns out not be then the entire discussion is no more valid than arguing about how many angles can dance on the head of a pin, even if the pin has a green head.
Before delving into something like the "greenness" of publishing a magazine or deciding whether a "cloud computing" facility is "more green" than some other type of computing we need solid foundation on what "green" actually means. The classic definition of "green" in this context is the amount of CO2 put into the atmosphere by some process: driving, heating, generating electricity, and so forth.
Now there isn't such a thing as a "green-o-meter" that you can just punch in some numbers to get the "greenness" of some activity. Sure there are web sites and other things that claim to do this but they really cannot be real (which we'll see in a minute).
So instead we have to use a proxy for the "green-o-meter" - that is something that we can measure easily which can be translated into a measurement of "greenness".
We're going to define green here in a comparative way: We're going to say something is more green than another thing if it uses less measurable energy to do the same task. This is actually a cheat as we will see later but for now, and to keep this article simple, we will assume this. Of course, this assumes we actual want to do the thing we are talking about, i.e., drive, because, I could simply not drive instead which would use zero relative energy.
But even this can be subject to disagreement.
Let's take the example of something everyone can understand and is familiar with: a stove. I had remodeled our house and in the process I planned to move the kitchen into the new addition. In this process we are switching from electricity to gas. However, because of the bad economy we cannot afford to acquire the kitchen appliances we originally wanted so we decided to temporarily acquire some used ones instead. That we could complete the move of the kitchen and replace the used appliances with new ones in the future.
So I ask myself this: which is greener? The electric stove or the gas stove.
This seems like a simple question, doesn't it?
So first off, let's take away the issue of the creation of the stove, its transportation, etc. and just consider the basic function: heating something, like a pot of water.
This limits the question to this: when we turn the knob "on" to heat, say, a pot of water, which type of stove is more green?
First off let's see what we can find out relative to this. Certainly some people seem to think electricity is more "green" than gas (from the link): "Unfortunately, I’m going to have to disappoint everyone who loves to cook on a gas cook top and tell you right now that an electric cooktop is going to be more eco-friendly – hands-down." Yet this site says the exact opposite: "Usually it's more efficient to burn natural gas where it's needed -- in your home -- than to burn it at a power plant, convert the heat to electricity and then send the electricity over wires to your house. "
Well, this isn't much help...
Let's look at the specifications for the stoves then - perhaps that will make it possible to compare.
Some digging reveals that a gas stove might have a 9,500 BTU nat. rating per burner. From more digging apparently nat = natural gas. However, electric stoves are rated in Watts, e.g., 3,200 Watts per burner.
Since there is a direct formula for the conversion: 1 watt = 3.412141633 BTU/Hr you can easily compare the two.
But wait, this just compares the output of the burner on each type of stove. Different stoves have different ratings, e.g., one electric stove might have 1,250W burners and another 3,200W burners.
So let's pick two imaginary stoves that have exactly equivalent rating for their burners - one gas and one electric.
So which of these is more green? Neither, actually, as the burners are rated the same so the stove use the same amount of energy.
But is that a proper comparison? Is a gas stove "as green" as an electric one?
No, actually, because of how you use the stove.
If had two stoves, one gas and one electric, equal BTU/Watt ratings mean that given both stoves are on and the burners heating at full efficiency it would take the same amount of time to heat the same amount of water (in equal amounts in equal pots) the same amount. Not from scratch, mind you, but with the burners already on and placing the pot on the running stove.
But in reality you don't use the stove like this. You start out with a cold pot of water on the stove with the burner off, you turn on the stove, and let the burner heat the water. When you consider this the problem becomes more complicated because now you must consider a time element - how long does it take the stove to reach the full operating temperature? We know that both stoves have the same burner ratings so once each reaches full operating temperature we know they are equivalent.
Though you don't have to believe me the gas stove has a virtually instant startup time: that is once the flame appears its at full temperature. So let's say, just for argument, that it takes 1 second to bring the gas stove up to full temperature.
On my old electric stove it takes about 90 seconds for the burner to reach full temperature.
Bottom line is that while both stoves produce the exact same amount of heat the electric stove takes longer to reach full temperature. Of course, during this warm-up time some heat is transferred to the pot, but not nearly as much as full power.
So, all things being equal, including exactly equal stoves, it would seem that the gas stove is greener because it uses less energy to do the same job as the electric stove.
So does a gas stove cause my "green footprint" to be smaller than the electric stove? Or am I being fooled by causuitry here?
This is a much more complex question since it involves the relative "greenness" of the infrastructure used to provide gas and electricity to my house as well as the efficiency of that infrastructure in delivering this energy to me.
Now, most people of live near a big city probably have both gas and electricity. Generally everyone in the US, at least, has electricity, and some have other technologies like oil if they live in rural areas.
We must now examine the relative greenness of the infrastructure used to deliver the gas and electricity. Which uses more energy? Is one greener than the other?
For example, we could say the the delivery system for each was "equal" in terms of green, i.e., the wires and the pipes use the same amount of energy to build and maintain. But that's not enough either because gas in a pipe is not the same as electricity in a wire. Electricity is lost in the transmission from point A to point B. This is not true with gas.
Similarly something must create the electricity, i.e., a generator, and something must power that device. Where as gas simply comes up out of the ground under pressure in the first place - though a gas well must be dug to reach the gas.
So what is greener for my stove? Gas or electricity.
The actual answer is probably impossible to tell. I can guess that since gas does not involve a conversion to another form (electricity) and does not lose energy during the transmission that its more efficient, but that discounts the discovery and drilling process.
The point of all this discussion is how on earth would it be possible to tell if a physical, printed magazine was "greener" than, say, an electronic version of that magazine shipped via a cloud computer through a WIFI to my iPad.
I have greatly simplified the stove example - virtually anyone you discuss this with might not agree with the cheats and short cuts I took. They might have different ideas about measuring green.
The bottom line is don't write articles and say "X is more green than Y" without some rational, scientific basis.
If you don't believe me check out some of the web sites the "green" ad sponsors offer to see if you can find any rational, scientific basis for their claims.
Posted by John Gault at 7:23 AM