Depends on how you define “harder”. Surface-mined low-sulfur coal in Wyoming is anywhere from $4.00 to $6.00 per ton FOB. Even when you throw in delivery costs you can still ship it to most anywhere in the central 2/3 of the nation, from Arizona to Mississippi to New York to Oregon for under $25 a ton. And in the Midwest/Middle US, you can get as low as $11 a ton, delivered.
On a heat basis, the DoE says that the latest 2002 data (Aug 2002 compilation) was that the average cost of coal delivered to all plants in the US was 121.9 cents/MBtu. Comparing to other fuels:
Ah, yes, bioplastics. Of course you’re right that we could use those to make polymers–it’s a combination of research and expense at the moment.
Not to mention the great big fusion reactor in the sky, but how about some nice fission reactors on the ground? I’ll never understand people who are irrationally afraid of nuclear.
By most accounts, the Alberta Tar Sands have a larger oil reserve than Saudi Arabia, but extracting usable oil is at least twice as expensive.
If the Americans are willing to pay as much as $3/gallon (comparable to what Europeans already pay), then it will become profitable to fully exploit inconvenient soucres like the Tar Sands. At that point, there’d be enough oil to last at least a few centuries.
Personally, I’m hoping for controlled fusion within my lifetime.