Since Fossil Carbon currently costs almost the same, irrespective, which Hydrocarbon’s market price we apportion to the weight percentage of its Carbon Backbone, the differences in price per energy are not even proportionate to their Hydrogen per Carbon contents – suggesting that Hydrogen is unconsidered:

• coal may be sold as low as U$ 1.63/GJ calorific value
• Crude oil at 41.8GJ/toe ( = 7.14bbl at U$ 34/bbl) costs U$ 5.80/GJ calorific value
• Natural Gas with 36MJ/m3   (at U$ 0.16/m³)     costs   U$ 4.40/GJ calorific value

When burned, the disposal of atomic Carbon into the atmosphere per recovered energy is predominantly influenced by the used fuel’s Hydrogen to Carbon Ratio – being a main measure for Carbon Efficiency:

• coal 30kg/GJ
• crude oil 22kg/GJ
• Natural Gas 16.4kg/GJ

So if fuel was priced based on Carbon Efficiency under combustion by U$ 0.32/kg Carbon replacement cost:

• coal should cost U$ 9.60/GJ calorific value             –>  U$ 230.40/tonne (á 24GJ/tonne)
• crude oil U$ 7.04/GJ calorific value                            –>  U$   41.21/bbl
• Natural Gas U$ 5.25/GJ calorific value                       –>  U$     0.19/m³

Of course the same pricing scheme should be applied on Refuse Derived Fuels & Biomass:

• MSW-RDF at ≈ 13GJ/t @ 30%wt Carbon  -> U$ 8.72/GJ    =>  U$ 113.15/tonne
• Biomass  at  ≈  15GJ/t  @ 50%wt Carbon  -> U$ 11.35/GJ   =>   U$ 170.25/tonne

The price difference between current arms’ length market and Carbon Efficiency sensitive pricing would represent a Carbon Tax for the use of fuel in combustion:

• Natural Gas: U$ 14.16/t CO2
• crude oil:       U$ 15.50/t CO2
• Biomass:       U$ 51.38/t CO2  (traded at U$ 4.67/GJ)
• coal:                U$ 72.45/t CO2
• MSW-RDF:     U$ 79,80/t CO2  (traded at U$ 0.75/GJ)

Maybe this looks peculiar to anyone not caring about Carbon Efficiency so far – but it might be a way to push towards the right usage for each of the fuels compared above in terms of what should be best used for combustion and what might rather be used for refining under a maximum Carbon retention in a chemically re-usable form. Under the Carbotopia™ approach, fuels with residual moisture turn out to be more efficiently usable under decomposition into energy rich gases for refining than for burning, as the intrinsic moisture content can contribute towards hydrocracking instead of cannibalizing part of the fuel’s chemical energy for evaporation. Apart thereof its anoxic decomposition allows recoverable separation of fuel contaminants as Nitrogen, Sulfur, Chlorine, etc.