I am not a huge fan of the U in CCUS, because the synthesis of synthetic chemicals from CO2 is expensive. Whether the CO2 comes from point source or direct air capture is somewhat irrelevant. The energy and capital cost of reducing CO2 to methanol, to take the simplest chemical product, is simply very large.
How expensive? A recent analysis took a careful look a using solar thermal power to underpin methanol production and came up with a price of about $3.00/liter, about 10X the current cost of petrochemically-produced methanol. Of that price, a third of the cost went towards capex for the chemical facility, a third towards capex for the solar thermal power, and the remainder was split between opex, DAC, and taxes. DAC was the smallest of the costs.
Some of this high cost may stem from a lack of aggressiveness in scaling assumptions. Other work calculates costs below $2/liter by imagining aggressive reductions in the cost of capital and renewable electricity. But even a 5X cost premium for synthetic methanol leaves it unlikely to compete with bio-derived sources, much less fossil fuels.
The cheapest alternative for fuel and petrochemicals seems likely to be to start with fossil fuels, and then capture the carbon and re-inject it after the fact. Which one society chooses is a policy question that requires consideration of a host of factors. But we should be realistic about the costs associated with each choice.
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