Global warming? Don’t overlook waste energy
I put the swamp cooler to bed a couple of weeks ago because I was afraid it was going to freeze. Now it turns nice and my wife says the house is too hot and she wants me to hook it back up. Ah, fall in western Colorado.
Humans have a difficult time controlling the temperature. One of the problems we have is that most of our efforts to control temperature use energy, and energy utilization creates heat. And that may be a problem for our current proposed solutions to global warming.
Energy is a complex subject. I seem to have less and less of it these days, so I’m surely no expert.
But we usually measure energy by temperature (although there are numerous other measures). But that’s why the study of energy is sometimes called thermodynamics, which translated means roughly “temperature changes.”
Energy appears to obey a handful of simple rules.
For example, it is thought that energy is neither created nor destroyed — that all the energy in the universe already exists and all that we do is change it into one or another of its basic forms: mechanical, electrical, chemical, thermal, radiant, magnetic, sound, nuclear and elastic.
This apparent fact is known as the first law of thermodynamics.
However, when we change energy from one form to another, it is never completely efficient. When my swamp cooler motor turns the squirrel cage to suck air through the wet cooler pad — the process of turning electrical energy to mechanical energy — it generates heat. We don’t notice this much because the moving air acts to cool the motor.
In our cars, when we burn gas to drive pistons to turn wheels, we are changing thermal energy into mechanical energy.
But the change is not 100 percent efficient, so the motor gets hot and we have to have a cooling system. This loss of heat with every energy transfer is sometimes referred to as the second law of thermodynamics — usually expressed in more concise, but obscure language.
The problem is that humans are making more transfers of energy than ever before simply because we are using more energy. This extra energy, lost mostly as heat, is sometimes called waste heat.
Eric Chaisson of Tufts University estimates that humans have increased energy use by close to 100 percent since the days of simple hunter- gatherer existence. About half the energy that humans use ends up as waste heat, so waste heat becomes a significant source of global warming.
Theories of global warming seem to assume that the major source of heat gain is from the sun and the problem is growing amounts of carbon dioxide that is trapping the heat in.
But waste heat is yet another source of heat that is also trapped by the carbon dioxide layer.
In a recent paper, two researchers from Sweden, Bo Nordell and Bruno Gervet, suggest that even if we lower emissions and stabilize carbon dioxide, the Earth will continue to warm because of greater production of waste heat from greater usage of energy.
This means that even some of the so called “green” technologies may contribute to global warming. When we use nuclear energy, the reactor must be cooled and the excess heat dumped somewhere: waterways or the atmosphere. Even wind energy, sort of like the reverse of my swamp cooler, is converted to mechanical energy, which is then converted to electrical energy. But at each conversion more waste heat is generated.
There is considerable disagreement about how much waste heat is accumulating, how rapidly it will increase, and how much it contributes to global warming at the present time.
Let’s see, if I run my swamp cooler, I contribute to global warming. But that warms the planet, requiring me to run my swamp cooler. Maybe if I just wait awhile, I won’t have to put the swamp cooler away at all.