So, that last little blog, looking at emissions from pet coke.
I\’m getting extremely confused here. And if anyone really knows this stuff then please do tell the rest of us.
Looking around it\’s easy enough to see that lignite produces more CO2 per unit of energy (it\’s usually in BTUs) than does sub-bituminous coal. Sub-bituminous more than bituminous.
This makes logical sense: there\’s more C in the material as you progress. As the C is what your source of energy is a higher concentration of this and a lower concentration of everything else that you\’re heating up at the same time will lead to more useful energy per unit of CO2 produced.
However, the stats that I can see claim that this reverses when we get to anthracite. Which is weird, for anthracite has more C in it than bituminous coal. We would expect (or at least I would) there to be a straight line relationship with C rather than a U shaped one.
So, it\’s possible that this is true: maybe the \”volatiles\” in the lower grade coals more than make up for the higher C in the highest grade one.
It\’s also possible that there\’s something hinky with the numbers. Anthracite isn\’t actually mined in the US any more (and all the stats I\’ve found are US ones). What is used is anthracite culm: that\’s the waste left over in slag piles from previous anthracite mining. And what makes me suspect this is that the numbers for emissions from anthracite culm appear to be the same as those quoted for anthracite. Which really doesn\’t sound right at all.
And then we get pet coke numbers equated to anthracite ones. And I can imagine that that\’s true: high C level after all. But what I can\’t work out is why a higher C level should lead to greater emissions per BTU. Sure, higher emissions per tonne fuel used: but why per useful energy?