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The U.S. Department of Energy is spending $7 billion to demonstrate capturing 6 million tons of CO2 from the atmosphere. Companies are also paid to capture and store CO2 underground with tax credits of $180 per ton. To what end? DOE’s billion ton 2050 goal might cost $180 billion a year, just to remove 3% of global CO2 annual emissions, never mind historical CO2. ETH Zurich estimates direct air-capture of CO2 will cost $230-$540 per ton. Experts at U.S. National Bureau of Economic Research justify high costs by reporting $1,056 per ton Social Cost of Carbon Dioxide. Removing annual CO2 emissions at that price would consume a third of world GDP.
BURIAL. Burial expenses are high. The U.S. offers CO2 burial tax credits of $85 per ton, or $60 if injected into an oil field to push up more oil. That wasn’t economic enough for the shuttered Petra Nova project. Where to store the CO2? Even liquified CO2 occupies three times the volume of oil that creates it, and the world burns four cubic miles of oil per year, plus coal and natural gas.
REVIVAL. Reviving CO2 into fuel requires ample, cheap hydrogen. Hydrogen atoms can replace oxygen atoms in CO2 and chain the resulting -CH2- links into hydrocarbons such as diesel, gasoline, and jet fuel. George Olah’s 1994 Nobel Prize essay previewed this.
“As atmospheric carbon dioxide is available to all people on the Earth this will enable mankind to liberate itself from dependence on fossil fuels … energy could come from safe nuclear power plants … also diminish the danger of global warming by removing and recycling the rising carbon dioxide content of the atmosphere.”
Olah envisioned net-zero hydrocarbon fuel synthesized from CO2 captured from the atmosphere; hydrogenated in refineries; burned in standard internal combustion engines of cars, trucks, and planes; emitting CO2 back to the atmosphere. Such CO2 recycling can cut mining and burning of fossil fuels increasing atmospheric CO2.
EXPENSIVE HYDROGEN. The U.S. DOE is spending $8 billion on hydrogen hubs to demonstrate hydrogen use and production. The industrial steam-reforming process harvests hydrogen from methane (CH4) but produces CO2, which some hub projects will capture and bury to claim clean hydrogen. Even more money will be spent via the Inflation Reduction Act which pays companies a $3 subsidy for each kilogram of low-carbon hydrogen produced.
Some hydrogen hubs will use electrolysis to separate H2O into hydrogen and byproduct oxygen. Low cost electrolyzers and cheap electricity are critical to compete with hydrogen from methane. Intermittent electricity from wind and solar sources reduces the duty cycle for expensive electrolyzers to about a third, raising their depreciation costs. Full time nuclear enables cheaper hydrogen.
CHEAP HYDROGEN. Solid oxide electrolysis cells (SOECs) such as from Bloom Energy and Topsoe can reduce costs by using both nuclear heat and nuclear electricity to separate hydrogen from H2O. New nuclear technology of high temperature gas reactors and molten salt reactors provides heat over 700°C, enabling both SOEC and copper-chlorine cycle production of nuclear hydrogen at $1 per kilogram. Only nuclear power can provide the needed continuous, clean electricity at 3 cents per kilowatt-hour and heat at 1 cent needed to make cheap hydrogen.
Hydrogen itself is not a practical vehicle fuel. It is expensive to compress or chill hydrogen enough to transport to fueling stations and carry in a vehicle. But hydrogen is less expensive if produced and used at a co-located refinery to make CO2 into fuel. Cheap energy from a co-located nuclear power plant cooled with flowing seawater can provide dissolved CO2.
CHEAP CO2. Sea-capture can be less costly than air-capture because the sea already captures a third of mankind’s emitted CO2, which is 130 times more concentrated in seawater than the atmosphere. An electrochemical technology, pH-swing, can remove CO2 from seawater by dividing the flow into two streams, one acidic, one basic. The CO2 can be bubbled out of the acidic stream, which is then combined back with the basic stream, swinging the seawater pH back to normal. Pacific Northwest National Laboratory and MIT studies estimate such CO2 costs at $20-$56 per ton. Captura and Equatic startups are each testing pH-swing systems on the Pacific coast, estimating costs under $100 per ton.
The U.S. Navy Research Lab has developed electrochemical cells that free both CO2 and H2 from seawater. Their jet fuel cost estimates were $3-$6 per gallon. Bosch estimates future synthetic fuel costs of $4-$6 per gallon. Such net zero Seafuel is potentially competitive with fossil fuels.
FUTURE VISION. Net zero Seafuel from revived CO2 will allow the U.S. and the world to continue to use existing internal combustion engine vehicles, while also cutting CO2 emissions. The U.S. can become free of China’s domination of rare earths and metals production for batteries, magnets for electric vehicle motors and wind turbine generators.
For net zero Seafuel to be competitive with fossil fuels, we need hydrogen costing $1 per kilogram and CO2 under $100 per ton. The recent White House announcement of “steps to bolster domestic nuclear industry” will not make electricity and heat costs low enough to synthesize fossil-competitive net zero fuels. The U.S. can reduce nuclear energy costs by overturning NRC regulations that ignore societal benefits in favor of assuaging unfounded fears of radiation harm, exaggerated by a factor of a thousand. ThorCon is bypassing U.S. regulations to build molten salt reactors in Indonesia, which demands cheap, ample power.
More research and development is needed to scale up the lab-scale electrochemical technologies for extracting CO2 and hydrogen. We also need to engage expertise of the refinery and chemical industries, not castigate them. Dow is an exemplary leader building high temperature gas reactors for its Seadrift plant in Texas.
The biggest challenge is gaining access to enough CO2, perhaps from desalination plants or richer seawater sources such as the Humboldt current. Seafinery technology demonstrations could be jumpstarted using pure CO2 from Allam cycle natural gas oxycombustion, reusing the CO2 prior to emission. My Dartmouth course slides and book illustrate more options.
We must look beyond impossibly expensive projects that fail to reduce CO2’s warming effects, and instead rejuvenate the maligned nuclear energy and refining technologies the U.S. originally developed.
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The post Bury CO2 or Revive It? appeared first on Energy News Beat.
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