Cheap synthetic fuel - Revision history

Hkhenson: a few changes after a long time

2022-11-24T04:11:57Z

a few changes after a long time

← Older revision		Revision as of 04:11, 24 November 2022
Line 5:		Line 5:
	Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil. (Design-to-cost target of $100/bbl.)		Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil. (Design-to-cost target of $100/bbl.)

	Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace the current use of natural oil. That's a large number, but not impossible.		Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day of synthetic fuel from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace the current use of natural oil. That's a large number, but not impossible.

	'''<big>Chemistry</big>'''		'''<big>Chemistry</big>'''

	The Sasol plant uses reformed natural gas as a ~~feedstock~~, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:		The Sasol plant uses reformed natural gas as a feed stock, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:

	CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O		CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O
Line 17:		Line 17:
	It's possible to electrolyze CO<sub>2</sub> into oxygen and carbon monoxide. Unfortunately, this is more costly in energy than making the extra hydrogen. (161 kWh to 100 kWh) Still, if the CO2 electrolyzers are less expensive than the hydrogen electrolyzers, they may be worth investigating.		It's possible to electrolyze CO<sub>2</sub> into oxygen and carbon monoxide. Unfortunately, this is more costly in energy than making the extra hydrogen. (161 kWh to 100 kWh) Still, if the CO2 electrolyzers are less expensive than the hydrogen electrolyzers, they may be worth investigating.

	'''<big>~~Csrbon~~</big>'''		'''<big>Carbon</big>'''

	34,000 bbl/day is 1417 bbl/hr. At 7.33 bbl/ton, 193 tons of hydrocarbons per hour of which 12/14 or 166 tons per hour is carbon The CO<sub>2</sub> input for an Oryx-sized plant would be 44/12 times this figure or 607 tons per hour.		34,000 bbl/day is 1417 bbl/hr. At 7.33 bbl/ton, 193 tons of hydrocarbons per hour of which 12/14 or 166 tons per hour is carbon The CO<sub>2</sub> input for an Oryx-sized plant would be 44/12 times this figure or 607 tons per hour.

	Air is about 1.2 kg/m^3 at ~~20 deg C~~ and about 418 ppm CO<sub>2</sub>. A cubic meter contains close to half a gram of CO<sub>2</sub>, 1000 cubic meters about half a kg, a million cubic meters half a ton, a billion (a cubic km) 500 tons. Depending on the separation efficiency, upwards of 1,2 cubic km of air will have to be processed per hour to feed an Oryx-sized plant.		Air is about 1.2 kg/m^3 at STP and about 418 ppm CO<sub>2</sub>. A cubic meter contains close to half a gram of CO<sub>2</sub>, 1000 cubic meters about half a kg, a million cubic meters half a ton, a billion (a cubic km) 500 tons. Depending on the separation efficiency, upwards of 1,2 cubic km of air will have to be processed per hour to feed an Oryx-sized plant.

	This is incidentally about 5.3 million tons of CO<sub>2</sub> per year. It would presumably displace oil that put 5.3 million tons per year of CO<sub>2</sub> in the atmosphere. If the X-~~prise~~ people could be talked into crediting this, it would qualify because oil left in the ground would certainly stay there for more than 100 years.		This is incidentally about 5.3 million tons of CO<sub>2</sub> per year. It would presumably displace oil that put 5.3 million tons per year of CO<sub>2</sub> in the atmosphere. If the X-prize people could be talked into crediting this, it would qualify because oil left in the ground would certainly stay there for more than 100 years.

	'''<big>Hydrogen and Energy</big>'''		'''<big>Hydrogen and Energy</big>'''
Line 33:		Line 33:
	'''<big>Waste Heat and a Possible Use</big>'''		'''<big>Waste Heat and a Possible Use</big>'''

	Combining CO and H<sub>2</sub> is exothermic. As above, 27 percent of the energy in the ~~feedstock~~ has to be removed from the reaction vessel as waste heat. Some of this can be recovered with steam turbines, though the temperature is not high enough for good efficiency. However, the waste heat can be used to drive a chimney which sucks this huge volume of air through the CO<sub>2</sub> separators and exhaust it far above the separator intake.		Combining CO and H<sub>2</sub> is exothermic. As above, 27 percent of the energy in the feed stock has to be removed from the reaction vessel as waste heat. Some of this can be recovered with steam turbines, though the temperature is not high enough for good efficiency. However, the waste heat can be used to drive a chimney which sucks this huge volume of air through the CO<sub>2</sub> separators and exhaust it far above the separator intake.

	Verdox, the company developing https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 says to assume 5 m/s gas velocity and 200 Pa pressure drop through the CO<sub>2</sub> separators. A square meter of intake at 5 m/s will admit 5*3600 m^3/hr. The input area for one cubic km/hr at 5 m/s would be about 60,000 square meters. At 30 m high, this would be a wall 2000 meters long. Bent in a circle around the chimney, this would be about 640 meters in diameter tapering into a 180 m diameter chimney. The CO<sub>2</sub> separation at a GJ/ton would take about 169 MW, about 4% of the power needed for hydrogen production.		Verdox, the company developing https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 says to assume 5 m/s gas velocity and 200 Pa pressure drop through the CO<sub>2</sub> separators. A square meter of intake at 5 m/s will admit 5*3600 m^3/hr. The input area for one cubic km/hr at 5 m/s would be about 60,000 square meters. At 30 m high, this would be a wall 2000 meters long. Bent in a circle around the chimney, this would be about 640 meters in diameter tapering into a 180 m diameter chimney. The CO<sub>2</sub> separation at a GJ/ton would take about 169 MW, about 4% of the power needed for hydrogen production.
Line 57:		Line 57:
	The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/19009_h2_production_cost_pem_electrolysis_2019.pdf. At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.		The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/19009_h2_production_cost_pem_electrolysis_2019.pdf. At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.

			At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over10 years. If the capital cost is $11 B over ten years the cost is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.
	~~need to fix here. cost per bbl is ok, need better number on capital~~

	At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons ~~over 10~~ years. If the capital cost is $11 B over ten years the cost is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.

	The capital cost for the chimney is unknown at this time. 6/22/21		The capital cost for the chimney is unknown at this time. 6/22/21
Line 86:		Line 83:
	https://en.wikipedia.org/wiki/Hydrogen_production		https://en.wikipedia.org/wiki/Hydrogen_production

	The take-home is that in some places PV has gotten so inexpensive that it would be possible to make carbon-neutral synthetic hydrocarbons to replace natural oil for about the same price.		The take-home is that in some places PV has gotten so inexpensive that it would be possible to make carbon-neutral synthetic hydrocarbons to replace natural oil for about the same price if we can get the cost of electrolyzers down.

	Footnote		Footnote

	The U.S. Internal Revenue Service defines a BOE is equal to 5.8 million BTU.[1] (5.8×106 BTU59°F equals 6.1178632×109 J, about 6.1 GJ [HHV], or about 1.7 MWh		The U.S. Internal Revenue Service defines a BOE is equal to 5.8 million BTU.[1] (5.8×106 BTU59°F equals 6.1178632×109 J, about 6.1 GJ [HHV], or about 1.7 MWh

Hkhenson: notes and minor fixes

2022-05-13T05:44:23Z

notes and minor fixes

← Older revision		Revision as of 05:44, 13 May 2022
Line 51:		Line 51:
	'''<big>Cost</big>'''		'''<big>Cost</big>'''

	PV power in the Mideast has fallen to as low as 1.35 cents per kWh at the 900 MW scale. It may fall to less than a cent. Making 14 tons of fuel takes 6 tons of hydrogen. At $13.50 per MWh and 50 MWh/ton, the hydrogen energy cost for 14 tons of fuel would be $4050. This is a bit less than $40/bbl.		PV power in the Mideast has fallen to as low as 1.35 cents per kWh at the 900 MW scale. It may fall to less than a cent. Making 14 tons of fuel takes 6 tons of hydrogen (2/3rd of it combining with the oxygen from the CO<sub>2_</sub>. At $13.50 per MWh and 50 MWh/ton, the hydrogen energy cost for 14 tons of fuel would be $4050. This is a bit less than $40/bbl.

	If you write the billion-dollar Oryx plant down in ten years, the capital cost is about $8/bbl.		If you write the billion-dollar Oryx plant down in ten years, the capital cost is about $8/bbl.

	The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/19009_h2_production_cost_pem_electrolysis_2019.pdf. At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.		The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/19009_h2_production_cost_pem_electrolysis_2019.pdf. At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.


			need to fix here. cost per bbl is ok, need better number on capital

	At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years. If the capital cost is $11 B over ten years the cost is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.		At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years. If the capital cost is $11 B over ten years the cost is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.

Hkhenson at 20:22, 11 May 2022

2022-05-11T20:22:16Z

← Older revision		Revision as of 20:22, 11 May 2022
Line 9:		Line 9:
	'''<big>Chemistry</big>'''		'''<big>Chemistry</big>'''

	The Sasol plant uses reformed natural gas as a ~~feed stock~~, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:		The Sasol plant uses reformed natural gas as a feedstock, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:

	CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O		CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O

	44 + 6 -> 14 + 36 (mols)		44 + 6 -> 14 + 36 (mols, kg, tons, etc.)

	It's possible to electrolyze CO<sub>2</sub> into oxygen and carbon monoxide. Unfortunately, this is more costly in energy than making the extra hydrogen. (161 kWh to 100 kWh) Still, if the CO2 electrolyzers are less expensive than the hydrogen electrolyzers, they may be worth investigating.		It's possible to electrolyze CO<sub>2</sub> into oxygen and carbon monoxide. Unfortunately, this is more costly in energy than making the extra hydrogen. (161 kWh to 100 kWh) Still, if the CO2 electrolyzers are less expensive than the hydrogen electrolyzers, they may be worth investigating.

Hkhenson at 20:20, 11 May 2022

2022-05-11T20:20:02Z

Hkhenson at 17:20, 25 October 2021

2021-10-25T17:20:08Z

← Older revision		Revision as of 17:20, 25 October 2021
Line 35:		Line 35:
	Combining CO and H<sub>2</sub> is exothermic. As above, 27 percent of the energy in the feed stock has to be removed from the reaction vessel as waste heat. Some of this can be recovered with steam turbines, though the temperature is not high enough for good efficiency. However, the waste heat can be used to drive a chimney which sucks this huge volume of air through the CO<sub>2</sub> separators and exhaust it far above the separator intake.		Combining CO and H<sub>2</sub> is exothermic. As above, 27 percent of the energy in the feed stock has to be removed from the reaction vessel as waste heat. Some of this can be recovered with steam turbines, though the temperature is not high enough for good efficiency. However, the waste heat can be used to drive a chimney which sucks this huge volume of air through the CO<sub>2</sub> separators and exhaust it far above the separator intake.

	Verdox, the company developing https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 says to assume 5 m/s gas velocity and 200 Pa pressure drop through the CO<sub>2</sub> separators. A square meter of intake at 5 m/s will admit 5*3600 m^3/hr. The input area for one cubic km/hr at 5 m/s would be about 60,000 square meters. At 30 m high, this would be a wall 2000 meters long. Bent in a circle around the chimney, this would be about 640 meters in diameter. The CO<sub>2</sub> separation at a GJ/ton would take about 169 MW, about 4% of the power needed for hydrogen production.		Verdox, the company developing https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 says to assume 5 m/s gas velocity and 200 Pa pressure drop through the CO<sub>2</sub> separators. A square meter of intake at 5 m/s will admit 5*3600 m^3/hr. The input area for one cubic km/hr at 5 m/s would be about 60,000 square meters. At 30 m high, this would be a wall 2000 meters long. Bent in a circle around the chimney, this would be about 640 meters in diameter tapering into a 180 m diameter chimney. The CO<sub>2</sub> separation at a GJ/ton would take about 169 MW, about 4% of the power needed for hydrogen production.

	During the day, the waste heat from the electrolysis can be added to the F/T waste heat. The hydrogen production of 82.8 tons per hour has a waste heat of 10 MW per ton. To provide enough hydrogen for the F/T to run full time, the hydrogen production, while the sun is up (an average of 9 hours a day for Qatar), will have to run at 24/9 times this rate or 82.8 * 24/9 * 50 MW or 11 GW. 11 GW is a large block of power, but the Saudis have signed a deal for 300 GW of solar by 2030. That's enough for 27 Oryx-sized plants. That may be what they have in mind.		During the day, the waste heat from the electrolysis can be added to the F/T waste heat. The hydrogen production of 82.8 tons per hour has a waste heat of 10 MW per ton. To provide enough hydrogen for the F/T to run full time, the hydrogen production, while the sun is up (an average of 9 hours a day for Qatar), will have to run at 24/9 times this rate or 82.8 * 24/9 * 50 MW or 11 GW. 11 GW is a large block of power, but the Saudis have signed a deal for 300 GW of solar by 2030. That's enough for 27 Oryx-sized plants. That may be what they have in mind.

Hkhenson: cleanup

2021-09-11T02:59:16Z

cleanup

← Older revision		Revision as of 02:59, 11 September 2021
Line 57:		Line 57:
	The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/20004-cost-electrolytic-hydrogen-production.pdf At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.		The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/20004-cost-electrolytic-hydrogen-production.pdf At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.

	At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years.		At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years. If the capital cost is $11 B over ten years the cost is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.
	If the capital cost is $11 B ~~the capital cost~~ over ten years is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.

	The capital cost for the chimney is unknown at this time. 6/22/21		The capital cost for the chimney is unknown at this time. 6/22/21
Line 66:		Line 65:
	The CO<sub>2</sub> separator can run all the time, but there must be storage for hydrogen while the sun is not shining. 3/4 of a day at 83 tons per hour is almost 1500 tons of hydrogen.		The CO<sub>2</sub> separator can run all the time, but there must be storage for hydrogen while the sun is not shining. 3/4 of a day at 83 tons per hour is almost 1500 tons of hydrogen.

	An above ground tank would mass as much as an aircraft carrier.		An above ground tank for the hydrogen would mass as much as an aircraft carrier.

	Another solution such as an empty gas field would be much more economical. If there is excess CO<sub>2</sub>, it could be mixed with the hydrogen and the feed to the F/T reactor modulated to get the correct ratio.		Another solution such as an empty gas field would be much more economical. If there is excess CO<sub>2</sub>, it could be mixed with the hydrogen and the feed to the F/T reactor modulated to get the correct ratio.

Hkhenson: Cleanup

2021-09-11T02:53:08Z

Cleanup

← Older revision		Revision as of 02:53, 11 September 2021
Line 66:		Line 66:
	The CO<sub>2</sub> separator can run all the time, but there must be storage for hydrogen while the sun is not shining. 3/4 of a day at 83 tons per hour is almost 1500 tons of hydrogen.		The CO<sub>2</sub> separator can run all the time, but there must be storage for hydrogen while the sun is not shining. 3/4 of a day at 83 tons per hour is almost 1500 tons of hydrogen.

	~~At 50 bar hydrogen is about 5 kg/m^3 or 200 cubic meters per ton. 1500 tons of hydrogen at this pressure~~ would take 300,000 cubic meters. As a sphere that's 83 m in diameter. The bisected area would be 5410 m^2 and the force would be area * 100,000 Ps * 50 or ~27 billion newtons. That's spread along the circumference of ~260 m. Per meter, it would be 104 million newtons. For steel stressed at 200 million Pa, the shell would be half a meter thick and with an area of 21642 square meters would mass around 86,000 tons, close to the mass of an aircraft carrier.		An above ground tank would mass as much as an aircraft carrier.

	~~This is not impossible. Some steels can be stressed 5 times as much, but another~~ solution such as an empty gas field would be much more economical. If there is excess CO<sub>2</sub>, it could be mixed with the hydrogen and the feed to the F/T reactor modulated to get the correct ratio.		Another solution such as an empty gas field would be much more economical. If there is excess CO<sub>2</sub>, it could be mixed with the hydrogen and the feed to the F/T reactor modulated to get the correct ratio.

	A PV farm producing hydrogen for an Oryx-sized plant would be big. At a GW/km^2, 4 GW would take 4 square km. This has to be increased by about 5 for the PV efficiency and another factor of 4-5 for the peak to average. This means the PV farm would cover around 90 square km of land.		A PV farm producing hydrogen for an Oryx-sized plant would be big. At a GW/km^2, 4 GW would take 4 square km. This has to be increased by about 5 for the PV efficiency and another factor of 4-5 for the peak to average. This means the PV farm would cover around 90 square km of land.

Hkhenson: ckeanup

2021-09-10T21:40:50Z

ckeanup

← Older revision		Revision as of 21:40, 10 September 2021
Line 2:		Line 2:


	Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil. (Design-to-cost target of #100/bbl.)
			Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil. (Design-to-cost target of $100/bbl.)

	Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace current use of natural oil. That's a large number, but not impossible.		Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace current use of natural oil. That's a large number, but not impossible.
Line 8:		Line 9:
	'''<big>Chemistry</big>'''		'''<big>Chemistry</big>'''

	The Sasol plant uses reformed natural gas as a ~~feedstock~~, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:		The Sasol plant uses reformed natural gas as a feed stock, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:

	CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O		CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O
Line 57:		Line 58:

	At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years.		At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years.
	If the capital cost is $11 B the capital cost over ten years is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the capital for the F/T plant. At this scale, such a cost reduction seems possible.		If the capital cost is $11 B the capital cost over ten years is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.

	The capital cost for the chimney is unknown at this time. 6/22/21		The capital cost for the chimney is unknown at this time. 6/22/21

Hkhenson: added space

2021-09-09T15:46:06Z

added space

← Older revision		Revision as of 15:46, 9 September 2021
Line 20:		Line 20:
	34,000 bbl/day is 1417 bbl/hr. At 7.33 bbl/ton, 193 tons of hydrocarbons per hour of which 12/14 or 166 tons per hour is carbon The CO<sub>2</sub> input for an Oryx-sized plant would be 44/12 times this figure or 607 tons per hour.		34,000 bbl/day is 1417 bbl/hr. At 7.33 bbl/ton, 193 tons of hydrocarbons per hour of which 12/14 or 166 tons per hour is carbon The CO<sub>2</sub> input for an Oryx-sized plant would be 44/12 times this figure or 607 tons per hour.

	Air is about 1.2 kg/m^3 at 20 deg C and about 418 ppm CO<sub>2</sub>. A cubic meter contains close to half a gram of CO<sub>2</sub>, 1000 cubic meters about half a kg, a million cubic meters half a ton, a billion (a cubic km)500 tons. Depending on the separation efficiency, upwards of 1,2 cubic km of air will have to be processed per hour to feed an Oryx-sized plant.		Air is about 1.2 kg/m^3 at 20 deg C and about 418 ppm CO<sub>2</sub>. A cubic meter contains close to half a gram of CO<sub>2</sub>, 1000 cubic meters about half a kg, a million cubic meters half a ton, a billion (a cubic km) 500 tons. Depending on the separation efficiency, upwards of 1,2 cubic km of air will have to be processed per hour to feed an Oryx-sized plant.

	This is incidentally about 5.3 million tons of CO<sub>2</sub> per year. It would presumably displace oil that put 5.3 million tons per year of CO<sub>2</sub> in the atmosphere. If the X-prise people could be talked into crediting this, it would qualify because oil left in the ground would certainly stay there for more than 100 years.		This is incidentally about 5.3 million tons of CO<sub>2</sub> per year. It would presumably displace oil that put 5.3 million tons per year of CO<sub>2</sub> in the atmosphere. If the X-prise people could be talked into crediting this, it would qualify because oil left in the ground would certainly stay there for more than 100 years.

Hkhenson at 17:15, 6 September 2021

2021-09-06T17:15:06Z

← Older revision		Revision as of 17:15, 6 September 2021
Line 2:		Line 2:


	Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil.		Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil. (Design-to-cost target of #100/bbl.)

	Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace current use of natural oil. That's a large number, but not impossible.		Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace current use of natural oil. That's a large number, but not impossible.
Line 8:		Line 8:
	'''<big>Chemistry</big>'''		'''<big>Chemistry</big>'''

	The Sasol plant uses reformed natural gas as a ~~feed stock~~, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:		The Sasol plant uses reformed natural gas as a feedstock, made into carbon monoxide and hydrogen. Synthetic fuel is roughly CH<sub>2</sub>. If you incorporate the step of reducing CO<sub>2</sub> to CO, the overall reaction is:

	CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O		CO<sub>2</sub> + 3H<sub>2</sub> yields CH<sub>2</sub> + 2H<sub>2</sub>O
Line 50:		Line 50:
	'''<big>Cost</big>'''		'''<big>Cost</big>'''

	PV power in the Mideast has fallen to as low as 1.35 cents per kWh at the 900 MW scale. It may fall to less than a cent. Making 14 tons of fuel takes 6 tons of hydrogen. At $13.50 per MW and 50 MWh/ton, the hydrogen energy cost for 14 tons of fuel would be $4050. This is a bit less than $40/bbl.		PV power in the Mideast has fallen to as low as 1.35 cents per kWh at the 900 MW scale. It may fall to less than a cent. Making 14 tons of fuel takes 6 tons of hydrogen. At $13.50 per MWh and 50 MWh/ton, the hydrogen energy cost for 14 tons of fuel would be $4050. This is a bit less than $40/bbl.

	If you write the billion-dollar Oryx plant down in ten years, the capital cost is about $8/bbl.		If you write the billion-dollar Oryx plant down in ten years, the capital cost is about $8/bbl.

← Older revision		Revision as of 20:20, 11 May 2022
Line 5:		Line 5:
	Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil. (Design-to-cost target of $100/bbl.)		Hydrocarbon fuels are just too useful as portable energy sources not to mention being the basis for plastics and lubricants. All serious energy proposals (such as StratoSolar or power satellites) include making some synthetic hydrocarbons. Even without considering climate problems, natural oil will eventually run out. The problem is making synthetic fuel for a cost close to the current price of oil. (Design-to-cost target of $100/bbl.)

	Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace current use of natural oil. That's a large number, but not impossible.		Making synthetic fuel via the Fischer–Tropsch (F/T) reaction is well developed. Sasol has a plant in Qatar (Oryx GTL) that makes 34,000 bbl/day from reformed natural gas. It has been running since 2007 and cost a billion dollars to build. World consumption of oil is around 100 million bbl/day so it would take around 3000 of these plants to replace the current use of natural oil. That's a large number, but not impossible.

	'''<big>Chemistry</big>'''		'''<big>Chemistry</big>'''
Line 33:		Line 33:
	'''<big>Waste Heat and a Possible Use</big>'''		'''<big>Waste Heat and a Possible Use</big>'''

	Combining CO and H<sub>2</sub> is exothermic. As above, 27 percent of the energy in the ~~feed stock~~ has to be removed from the reaction vessel as waste heat. Some of this can be recovered with steam turbines, though the temperature is not high enough for good efficiency. However, the waste heat can be used to drive a chimney which sucks this huge volume of air through the CO<sub>2</sub> separators and exhaust it far above the separator intake.		Combining CO and H<sub>2</sub> is exothermic. As above, 27 percent of the energy in the feedstock has to be removed from the reaction vessel as waste heat. Some of this can be recovered with steam turbines, though the temperature is not high enough for good efficiency. However, the waste heat can be used to drive a chimney which sucks this huge volume of air through the CO<sub>2</sub> separators and exhaust it far above the separator intake.

	Verdox, the company developing https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 says to assume 5 m/s gas velocity and 200 Pa pressure drop through the CO<sub>2</sub> separators. A square meter of intake at 5 m/s will admit 5*3600 m^3/hr. The input area for one cubic km/hr at 5 m/s would be about 60,000 square meters. At 30 m high, this would be a wall 2000 meters long. Bent in a circle around the chimney, this would be about 640 meters in diameter tapering into a 180 m diameter chimney. The CO<sub>2</sub> separation at a GJ/ton would take about 169 MW, about 4% of the power needed for hydrogen production.		Verdox, the company developing https://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 says to assume 5 m/s gas velocity and 200 Pa pressure drop through the CO<sub>2</sub> separators. A square meter of intake at 5 m/s will admit 5*3600 m^3/hr. The input area for one cubic km/hr at 5 m/s would be about 60,000 square meters. At 30 m high, this would be a wall 2000 meters long. Bent in a circle around the chimney, this would be about 640 meters in diameter tapering into a 180 m diameter chimney. The CO<sub>2</sub> separation at a GJ/ton would take about 169 MW, about 4% of the power needed for hydrogen production.
Line 45:		Line 45:
	How much will 3.1 GW heat the air going up the stack? At 300 K (27 C), the specific heat of air is 1.005 kJ/kg⋅K. I.e., a kW-s (kJ) will heat a kg of air close to a deg K. A GWh is 3.6 billion kW-s, a cubic km of air has a mass of 1.2 billion kg. Thus, a GW will heat 1.2 cubic km of air per hour by 2.5 deg K and 3.1 GW will heat a 1.2 cubic km of air per hour by about 7.75 deg K. Nighttime heating will be much lower at around 2.3 deg or the flow could be reduced and most CO<sub>2</sub> extracted during the day.		How much will 3.1 GW heat the air going up the stack? At 300 K (27 C), the specific heat of air is 1.005 kJ/kg⋅K. I.e., a kW-s (kJ) will heat a kg of air close to a deg K. A GWh is 3.6 billion kW-s, a cubic km of air has a mass of 1.2 billion kg. Thus, a GW will heat 1.2 cubic km of air per hour by 2.5 deg K and 3.1 GW will heat a 1.2 cubic km of air per hour by about 7.75 deg K. Nighttime heating will be much lower at around 2.3 deg or the flow could be reduced and most CO<sub>2</sub> extracted during the day.

	From https://en.wikipedia.org/wiki/Flue-gas_stack the stack will need to be about 180 m in diameter and a km tall to get a flow of a cubic km per hour. The velocity up the stack will be 11.5 m/s and the delta pressure 171 Pa. Wall friction for this size turns out to be about 0.2 Pa for a 1000 meter stack. The air going up the stack has been stripped of CO<sub>2</sub>, making it slightly lighter. The stripped CO<sub>2</sub> at half a gr/cubic meter or half a kg in 1000 m would lower the pressure by 5 newtons per square meter or 5 Pa.		From https://en.wikipedia.org/wiki/Flue-gas_stack the stack will need to be about 180 m in diameter and a km tall to get a flow of a cubic km per hour. The velocity up the stack will be 11.5 m/s and the delta pressure 171 Pa. Wall friction for this size turns out to be about 0.2 Pa for a 1000-meter stack. The air going up the stack has been stripped of CO<sub>2</sub>, making it slightly lighter. The stripped CO<sub>2</sub> at half a gr/cubic meter or half a kg in 1000 m would lower the pressure by 5 newtons per square meter or 5 Pa.

	The flow up the stack would be restricted by the pressure drop of 200 Pa in the CO<sub>2</sub> separators. An extra 1000 meters of the stack would about compensate. The lower stack flow at night might require fans to provide the pressure.		The flow up the stack would be restricted by the pressure drop of 200 Pa in the CO<sub>2</sub> separators. An extra 1000 meters of the stack would about compensate. The lower stack flow at night might require fans to provide the pressure.
Line 55:		Line 55:
	If you write the billion-dollar Oryx plant down in ten years, the capital cost is about $8/bbl.		If you write the billion-dollar Oryx plant down in ten years, the capital cost is about $8/bbl.

	The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/~~20004-cost-electrolytic-hydrogen-production~~.pdf At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.		The current electrolyzer cost can be found here https://www.hydrogen.energy.gov/pdfs/19009_h2_production_cost_pem_electrolysis_2019.pdf. At the cited, $1000/kW, that is a billion dollars per GW. It would be 4 billion if the power was on all the time, but (since it is intermittent PV) it is more like 11 billion dollars when you are making hydrogen only in the daytime.

	At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years. If the capital cost is $11 B over ten years the cost is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.		At 82.8 tons per hour, the production of hydrogen would be about 725,000 tons per year, 7.25 million tons over 10 years. If the capital cost is $11 B over ten years the cost is about 88 dollars per bbl. This is over twice the cost of energy consumption. The cost of electrolyzers will have to drop by a factor of ten for the per bbl capital cost of the hydrogen plant to reach the same as the per bbl capital for the F/T plant. At this scale, such a cost reduction seems possible.
Line 65:		Line 65:
	The CO<sub>2</sub> separator can run all the time, but there must be storage for hydrogen while the sun is not shining. 3/4 of a day at 83 tons per hour is almost 1500 tons of hydrogen.		The CO<sub>2</sub> separator can run all the time, but there must be storage for hydrogen while the sun is not shining. 3/4 of a day at 83 tons per hour is almost 1500 tons of hydrogen.

	An above ground tank for the hydrogen would mass as much as an aircraft carrier.		An above-ground tank for the hydrogen would mass as much as an aircraft carrier.

	Another solution such as an empty gas field would be much more economical. If there is excess CO<sub>2</sub>, it could be mixed with the hydrogen and the feed to the F/T reactor modulated to get the correct ratio.		Another solution such as an empty gas field would be much more economical. If there is excess CO<sub>2</sub>, it could be mixed with the hydrogen and the feed to the F/T reactor modulated to get the correct ratio.
Line 87:		Line 87:
	Footnote		Footnote

	The U.S. Internal Revenue Service defines a BOE as equal to 5.8 million BTU.[1] (5.8×106 BTU59°F equals 6.1178632×109 J, about 6.1 GJ [HHV], or about 1.7 MWh		The U.S. Internal Revenue Service defines a BOE is equal to 5.8 million BTU.[1] (5.8×106 BTU59°F equals 6.1178632×109 J, about 6.1 GJ [HHV], or about 1.7 MWh