Link: https://www.spacedaily.com/reports/Reality_check_on_technologies_to_remove_carbon_dioxide_from_the_air_999.html

• Challenge 1: Scaling up
• Challenge 2: Energy requirement
• Challenge 3: Siting
• Challenge 4: Cost

the world would need to generate billions of tonnes of CO2 credits at an affordable price. That prospect doesn't look likely. The largest DAC plant in operation today removes just 4,000 tonnes of CO2 per year, and the price to buy the company's carbon-removal credits on the market today is $1,500 per tonne.

The researchers recognize that there is room for energy efficiency improvements in the future, but DAC units will always be subject to higher work requirements than CCS applied to power plant or industrial flue gases, and there is not a clear pathway to reducing work requirements much below the levels of current DAC technologies.

"Given the high stakes of climate change, it is foolhardy to rely on DAC to be the hero that comes to our rescue."