No Clear Cut Winner
In the past few years, the "conventional wisdom" has been that switching from coal to natural gas for power production would benefit the environment. Not only does burning gas reduce particulate emissions, it also reduces CO2 emissions. Most sources acknowledge that natural gas is not as clean as nuclear power and renewables in terms of CO2 emissions, but having been promoting that option as an interim step, allowing the faster draw down of coal power plants.
Now, a report has come out that says "it ain't necessarily so"--switching from coal to natural gas would actually do very little to reduce global climate change. This report takes me back to a point of view I've expressed several times in this blog and elsewhere--the chemical and physical interactions involved in all our power sources and their interactions with the environment are incredibly complicated, and we cannot make long-term policy decisions based on simplistic models of the world.
I'm not a climatologist, so I can't say for sure if someone is going to come along in the next day, or week, or year and debunk this entire analysis. However, my point remains the same. Simply measuring the amount of CO2 generated in a bench-scale test of coal versus natural gas doesn't take into account all the emissions of both energy sources and all their interactions with the environment.
In a similar vein, I just ran across a letter in a recent issue of Science that challenged claims that electric-powered automobiles wouldn't reduce emissions because of the need to generate more power from electric power plants. The letter claimed that there was still a net savings because electric motors are more efficient than internal combustion engines and because electric vehicles obtain some of their power from regenerative braking. Again, I haven't done the math, but it makes sense to me that one can't project the net emissions without taking such factors into account.
So, what does this mean for energy policy and planning? I think we need to keep pointing out the following:
• There are no perfect solutions. Every option has some benefits and some drawbacks.
• Simple comparisons are apt to miss important factors.
• What your mother told you at the dinner table is right--"Everything in moderation."
In short, we need a mix of energy sources. We can't simply replace coal with natural gas so we can wait it out for renewables to be perfected, as some recommend.