Here's a funny one for ya: The picture above is just one of several billboards that greeted me on my journey to my sister's house in Pittsburgh last weekend. They all extolled the clean and green credentials of coal and some even noted that the dirtiest fuel around had received no bailout money (not true- $3.4 billion in the economic stimulus package was set aside for CCS).

But what I am wondering about here is what exactly do we mean by clean? I ask because as I drove into Pittsburgh, an area dependent on this "cleaner, greener" coal, I drove by another sign- an air quality alert board informing me that the air for that day in the city was unhealthy to breathe. That certainly doesn't jive with my definition of clean but perhaps the coal industry is using a different metric.