[ExI] Cheap fuel from coal and solar

Keith Henson hkeithhenson at gmail.com
Wed Oct 18 21:41:32 UTC 2023


The Oryx plant in Qatar makes 34,000 bbl of diesel per day.


On Wed, Oct 18, 2023 at 12:08 PM David Gluss <dgluss at gmail.com> wrote:
> What's F/T?
> On Wed, Oct 18, 2023 at 10:41 AM Keith Henson <hkeithhenson at gmail.com> wrote:
>> --------- Forwarded message ---------
>> From: Keith Henson <hkeithhenson at gmail.com>
>> Date: Mon, Oct 16, 2023 at 2:17 PM
>> Subject: Cheap fuel from coal and sola
>> We are going to need fuel for a considerable time.
>> From the dawn of the industrial revolution,
>> H2O + C → H2 + CO (ΔH = +131 kJ/mol)
>> The reaction is endothermic, so the fuel must be continually re-heated
>> to maintain the reaction. (Wikipedia)
>> Carbon is 12 gm/mol. 83 mol/kg and a kg would soak up 10900 kJ. A
>> metric ton of carbon evaporated in steam would need 10900000 kJ or
>> 3.03 MW hours.
>> This would produce 1/6th of a ton of hydrogen with a combustion energy
>> content of 50 MWh/ton, about 8.3 MWh. CO combustion is 10.1 MJ/kg. We
>> have 2800 kg or about 7.85 MWh. So we make about 16 MWh of gas from a
>> ton of coal and 3 MWh of renewable electric power. Most of the energy
>> in the gas is from the coal.
>> A few years ago a 900 MW solar PV project in the Mideast signed a
>> power purchase for 1.35 cents per kWh so I think $20/MWh works for a
>> rough economic analysis.
>> Following a ton of coal, the syngas from a ton would cost ~$20 for the
>> coal (plus shipping) and $60 or less for the intermittent power.  Call
>> it ~$80/ton.
>> Half a ton of carbon would be pulled out in the water gas shift
>> reaction to get the hydrogen ratio up to where you need it for F/T
>> input.  500 kg of carbon and 1/6 of that in hydrogen should show up in
>> the product.  The F/T energy loss is about 25%, not sure about the
>> material loss or where it might go.  .583 ton x 7.3 bbl/ton is 4.26
>> bbl. or $18.80 /bbl.
>> That's down near or below the production cost for oil.  Of course, the
>> F/T capital cost has to be added to this plus the completely unknown
>> cost of the arc gasifiers.  The Orxy plant cost is ~$8/bbl (ten-year
>> write-off) but that was in 2007 dollars.  What comes out of an Oryx
>> plant is a refined product rather than crude oil making it more
>> valuable than crude
>> Most big energy projects when you analyze them are just silly.  This
>> is not something you can reject out of hand.
>> This does not help with the build-up of carbon in the atmosphere, but
>> we will have to do air capture anyway.
>> Please check the math.  Age is making this harder and harder.
>> Keith
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