The most detailed and realistic recent survey on coal that I'm aware of was done last March by the Energy Watch Group. You can download it here.

They claim that in terms of energy content the US peaked in its coal production in 2002, and that "Global coal production to peak around 2025 at 30 percent above present production in the best case."

They also cite somewhat different values for the heating value of different grades of coal (HO: why is your number for anthracite lower than bituminous?):

Anthracite: 30 MJ/kg
Bituminous coal: 18.8–29.3 MJ/kg
Subbituminous coal: 8.3–25 MJ/kg
Lignite: 5.5–14.3 MJ/kg

Here is their summary chart:

At the time I was a bit rushed and couldn't find a site that I could reference with more accurate numbers - what you get for occasionally being in a hurry.

This seems to converge with Kjell Aleklett's analysis:

Global warming exaggerated, insufficient oil, natural gas and coal
by Kjell Aleklett
Published on 18 May 2007 by Dagens Nyheter. Archived on 21 May 2007.

Climate change and global warming has become part of our everyday life, and central to this debate is the emissions of carbon dioxide (CO2). The fossil fuels that we use contain carbon and hydrocarbons, and in the combustion of these fuels, carbon dioxide is released along with energy.

In the present climate debate, however, the amount of available fossil fuels does not appear to be an issue. The problem, as usually perceived, is that we will use excessive amounts in the years ahead. It is not even on the map that the amount of fossil fuels required in order to bring about the feared climate changes may in fact not be available.

Mexico's giant oil field Cantarell is afflicted with problems and the production is in rapid decline. In 2005, the Mexican national oil company Pemex presented two scenarios for the ultimate production; one optimistic in which it was assumed that 50% of the initial oil under ground would ultimately be recoverable, one pessimistic assuming only 30% recoverability. That the trend appears to validate the pessimistic scenario is naturally disastrous for Pemex and the Mexican state, but our climate is the winner.

There is an important decision to be made. Should we regard the oil remaining in the ground as a source that could result in future CO2 emissions, or should we accept that this oil for the time being actually remains in the ground? The Intergovernmental Panel on Climate Change (IPCC) considers it a resource.

...

The third fossil source of CO2 emissions is coal. According to a widely held view, the amount of available coal is virtually endless. However, when we do detailed studies of production profiles in the six countries harboring 85% of the world's coal reserves, we discover clear signs of peaking coal production in certain regions. Moreover, we notice a decline in production of the highest quality coal, that is, the coal with the highest energy content per volume. In the US, the world's second largest coal user, the volume of mined coal is increasing while the total energy content is decreasing. Has US already reached "Peak Coal" in terms of energy.

(more)

http://www.energybulletin.net/29845.html

And the US Energy Information Administration claims - we might say reports - that on an energy-content basis United States coal production peaked in 1998 (at least to date). See

http://www.eia.doe.gov/emeu/aer/overview.html, Table 1.2

My compilation "Who's talking about the peaking of world oil production" compilation also contains some telling quotes on the coal situation as well as noting that the U.S. is rapidly losing its status as a net coal exporter, imports having tripled since 2000, exports having declined markedly. See

http://globalpublicmedia.com/whos_talking_about_peak_oil

The EIA figures show an undulating plateau for the energy derived from coal for over a decade. Their production figures, for the first 11 months of 2007 show a marked decline (in quantity) over the first 11 months of 2006, which, from a quick scan, could be the first decline in recent times. It could be that the Energy Watch group was right. And yet even a lot of peak oilers continue to trot out the "250 years of coal" mantra. I wonder why.