This is not correct.
Coal prices are certainly sensitive to Chinese demand and exports are going up at a fairly good clip, but they were still only 10% of our entire production in 2011 and while it will be significantly higher this year (12-15% or so probably) it isn't making up for the loss in domestic demand.
With most U.S. coal production going to domestic consumption, mostly power generation, coal prices and NG prices are going to remain heavily correlated just as they have in the past.
So, no, coal prices are not being driven by Chinese demand. They are certainly sensitive to Chinese demand (and other countries such as Japan), but it would be a mistake to assume that Chinese demand can dictate the price. http://www.eia.gov/coal/data.cfm#imports
Quarterly coal exports from the U.S., IN TOTAL, for the first three months of this year were 28 million tons. Last year for Q1 it was 26 million tons. Our quarterly coal production is somewhere around 266 million tons. You can do the math. Our export to China is around 2 million tons per quarter.
So even if our exports to China increase 2x or even 4x it will not necessarily have that big an effect on coal prices.
I don't want to discount the importance of coal exports to the coal industry... it has become vital, but it also has to be looked at in the proper context. And, also, this puts the coal industry more at the whim of world markets while the NG industry has virtually no exposure to world markets.