82 comments on CO2 capture and storage: The economic costs
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82 comments on CO2 capture and storage: The economic costs
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The energy costs of CCS are covered in the previous article: CO2 Capture and Storage: The Energy Costs
Thanks for the reply, but what Im asking is:
How much ff produces the volume of CO2 that is envisaged being stuffed down the wellpipe to squeeze out oil? Is it 1000 draxes or 1/1000 drax?
As some inspiration I offer this useful site:
http://www.cockeyed.com/inside/howmuchinside.html
OK I did it myself, because none of the propaganda 'lifestyle' sites which appear on a google search of Carbon give any facts:
I reckon that coal~graphite therefore:
2267kg per m3/1.98kg per m3 = 1144.95
1144.95 x 44/12 [allows for the weight of O2 in CO2]
= 4198.15
So for example 1 km3 of coal gives 4198.15 km3 of CO2
Of course this may be wrong because I am supposed to be doing other things now anyone else?
I think you've got too much carbon per m3 there.
There's some good information from the EIA on CO2 and coal here: Carbon Dioxide Emission Factors for Coal
Which includes this:
Seems the CO2 emissions are just over 200 pounds of CO2 per million BTU. Which is absolutely meaningless to me but it also corresponds to just over 90kg per 300kWh or 0.3kg/kWh. That's kWh of heat not kWh of electricity. This also ties in with the0.43kg CO2 / kWh UK grid average for generated electricity (considering the thermal efficiency of the plant and the mix of nuclear and natural gas).
Anyway - one tonne of coal produces 2.86 tonnes of CO2. The density of a coal is between 1.1 and 1.5 tonnes per m3, lets assume 1.4 as we're working with good stuff here. The density of CO2 at standard temperature and pressure is 1.98 kg/m3 so coal is 707 times denser.
In volume terms then 1 m3 of coal will produce 2.86 x 707 = ~2000 m3 of CO2. I guess the trick is not to store at standard temperature and pressure?
2000m3 sounds feasible - especially if Graphite =~4000m3 CO2
So..if we burn 1km3 of oil per year and [x]km3 of other ff that's... what? 10000km3 of CO2 per year?? bloody big hole that is...per year..
What's your pressure assumption?
CO2 liquifies under pressure.
Fair enough, the volume may be 1000 times less [made up number] at depth, but mother nature gave you oil/gas at 10000 psi because of plate tectonics. You have millions of tonnes of rock crushing the impervious dome that squirts out oil when you make the hole. You have to remake that pressure to inflate the void. And its not lined with rubber - it has collapsed once, so now it has fissures and leaks. I skimmed a bit of the IPCC report [Chap 5]. I havent turned google furlongs and terrapascals into meaningful units but I dont have to..Look at their diagram of a well head with huge flanges and gaskets, and their diagram of how to cap old wells - welded steel dome and 3 concrete plugs. You think there is much energy from ff left after we have compressed CO2 to those pressures? It talks about dissolving CO2 in water etc, so now we have acid groundwater, carbonate erosion..
Sorry to be argumentative, but I think focussing on 'capture technology' misses the flaw in the plan
ref your comments on CO2 storage options
There are basically two options out there, re-use of depleted oil / gas fields and injection into aquifers.
Both have merits, there is far more volume available in aquifers, but oil fields may be most practical in the first place. Aquifer storage is the longer term best but there are more uncertainties regarding the long term fate of CO2 and its migration will need to be more carefully monitored. Statoil are doing this in the Ut Sira formation in Norway today and it is not treated as such a big deal to be honest.
The comments made on oil reservoirs collapsing as the oil is produced is only semi correct, it depends on
a) the strength of the rock matrix (may not collapse)
b) the mechanism by which pressure is maintained as oil is produced
A lot of fields have compacted to some extent, particularly chalk fields, and non-consolidates sandstones etc. This does not mean that all the pore volume is gone.
There will be an energy requirement to compress CO2 to a high enough pressure to pump it subsurface. This is however still quite a bit less than the energy consumed in the capture processes (today).
A lot of the reasons we have high focus on caåpture technology today is that it is rather inefficient and as the biggest energy consumer, has the most potential for improvement as technology is developed.
Storage is important though - and probably underfocussed by the power / energy industry as it is not such known teritory. Research in this area is also going on, and real tests are being done (eg. Zerogen in Aus.)