Monday, June 28, 2010

Greenhouse Gases and the Ozone Layer:

A Lesson for the Future

Recent reports about environmental problems caused by chemicals introduced in the 1990s to protect the ozone layer struck me as having a message for those of us in the energy business .

The ozone issue relates to the hydrochlorofluorocarbons (HCFCs) that replaced the chlorofluorocarbons (CFCs) once used in aerosol spray cans, air conditioners, and refrigerators. Over the years since they were introduced, they have been found to have several problems.

First, HCFCs may break down in the atomosphere to form oxalic acid, one of the components of acid rain. (The Wikimedia photograph accompanying this posting shows trees damaged by acid rain.) Second, they themselves are greenhouse gases, and are much more potent than carbon dioxide as greenhouse gases. (Articles report they are 4,500 times more potent.)

So why am I commenting on this issue in a blog that is focused on energy in general, and nuclear energy in particular?

I write about this because it is yet another example of our failure to understand fully the implications of any new chemical or technology before we implement it on a large scale. I write about this because it sounds a lot like dumping chemicals into the Gulf of Mexico to disperse oil without fully understanding the environmental effects of these chemicals. I write about this because I continue to find reports of unexpected effects from the so-called benign, environmentally-friendly, renewable solar and wind energy sources.

I am not saying that we should not have replaced CFCs with HCFCs, and I'm not saying that we should have waited for the perfect solution before we did anything. When this change was made, I'm not sure how much people understood about greenhouse gases.

I am just observing that, as we try to correct one problem, we often end up creating another. It sometimes seems that we treat Planet Earth as one large science experiment. I would hope that we can step back and learn from mistakes like these. While we may never be able to anticipate every consequence of a new technology or activity, one would hope that we would learn to analyze things more thoroughly, and perhaps implement new measures differently than we have in the past.

Now that the world is struggling to reduce greenhouse gases, I have to wonder how much the HCFCs have contributed and how much harder the problems of the energy industry are because of them and how much the greenhouse gas reduction measures being developed are considering this component of the problem.

This brings me to the most important reason to comment on this issue in a nuclear blog. I see lessons that can transferred to other fields from the nuclear field. First, there is the use probabilistic risk assessment (PRA) in the nuclear field. PRA has forced engineers to think systematically about possible sequences of events that can lead to accidents. Second, there are measures like defense in depth in nuclear reactors. While chemicals in the environment are very different than systems in a reactor, it seems to me that some greater diversity of solutions might have reduced the unexpected negative consequences of HCFCs.

Recently, the Gulf oil spill has had people commenting on how the oil industry could benefit by adopting measures from the nuclear field. It appears that the nuclear field may have useful models in other cases as well.


1 comment:

  1. Gail - I remain curious about CFC's based on my experience with several leaks on board submarines while I was the engineer officer.

    Inevitably, the heavy gases tended to accumulate in low lying areas of the boat - the bilges and the battery well. There was a certain amount that went airborne, but the difference in measured concentration between a few inches above the bottom of the bilge and above the deckplates was a factor of 100 or more.

    I wrote an article about this observation for my Questioning Attitude blog, but the responses still do not make much sense to me.

    Can you help me understand how heavy gases preferentially rise to the stratosphere?