Throughout this past football season, we Chicago Bears fans have wondered whether ‘good’ Rex or ‘bad’ Rex would show up for each game. We were referring to quarterback Rex Grossman, who one week would throw pinpoint passes, run the offense beautifully, and end up with a lofty quarterback rating in the 100s; and then the next game would overthrow or underthrow most all receivers, run a “three and out” offense, and actually end up with a negative rating.

For an even longer time another ‘good and bad’ issue has lodged in the back of my mind. It concerns carbon dioxide (CO2). It is being touted as a viable refrigerant in HVACR, is being looked at in a wide range of applications by dozens of manufacturers and researchers, and is showing up more and more in installations throughout the world.

At the same time, when I shift my mind outside the world of HVACR I hear about CO2 in another light. It might be summed up in one document sent to me that said in part, “Carbon dioxide is without doubt the most well-known greenhouse gas. It is also the greenhouse gas man contributes to most, primarily through burning fossil fuels. Since the industrial revolution, concentrations of carbon dioxide in our atmosphere have increased at an ever-faster rate. The impact this new concentration of carbon dioxide will have on our climate and on the sea level could be severe.”

Yipes, I thought. Concerns about climates were causing worries over HFC refrigerants when it comes to global warming. In fact, some folks want our industry to move to CO2 to get away from a global warming gas. And here is CO2 labeled a greenhouse gas.

To clarify things, I made a few calls to some folks in the industry who are involved with explaining the viability of CO2 as an HVACR refrigerant. The answers are a bit complex (which may make a good feature story down the road). But for now here’s the basic reasoning:

Yes, our industry uses that same CO2 that some are concerned about because it is a greenhouse gas. But our industry has a way of pulling CO2 from the environment (where it is not wanted) and storing it in containers and eventually tight systems (where it won’t hurt the environment).

As it was explained to me, the process is truly a “good” thing, for it takes a so-called “bad” refrigerant when floating in the environment and makes it a “good-good” refrigerant since it is out of the environment and it can be used to create cooling.

Along the way there is a bit of irony when it comes to the possibility of a leak. If you think back to CFCs and HCFCs, they were refrigerants created by our industry, and when they leaked out they were in effect “new” chemicals being released to the atmosphere. Because they were ozone depletion potential gases, they came under Environmental Protection Agency (EPA) regulations with fines for venting.

But the CO2 our industry uses is being taken from the environment. If a CO2 system leaks, the CO2 is just going back into the atmosphere from where it originally was floating long before our industry had anything to do with it.

That would make for some real interesting issues when it comes to any possible EPA regulations on venting CO2. “Hey, we did a good thing getting that stuff out of the environment. Now you’re going to punish us for a little bit of it going back?”

Again, this is pretty much an overview and a simplification both of the topic itself and the process involved in collecting CO2. For example, there is a range of purity levels for captured CO2. The CO2 used in many of the recent projects involving CO2 and HFC-404A in secondary loop applications has an extremely high purity level, called Coleman Grade 99.99 percent.

But the point is that we in HVACR can consider ourselves as using good CO2 in a good way.

Now if there was only a way to have only good Rex come out onto the football field each week.

Publication date:02/05/2007