Best so far is 1 gigajoule per ton of CO2: http://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 http://news.mit.edu/2019/mit-en

Best so far is 1 gigajoule per ton of CO2: http://news.mit.edu/2019/mit-engineers-develop-new-way-remove-carbon-dioxide-air-1025 http://news.mit.edu/2019/mit-engineers-develop-new-way-remov... Which is pretty much only going to happen if you invest a lot of money into nuclear facilities dedicated to this. 1GJ is about 280 kilowatt-hours.