CO2 Capture for Commercial Use

Does anyone know of any proven technology that can be used to extract and capture carbon dioxide for future commercial use? I am working with a client that needs CO2 for his greenhouse and buys it now. The client is installing a wood waste fired boiler and would like to extract the CO2 from the exhaust gas and then use it for the greenhouse instead of buying it. There is also the opportunity to sell the captured CO2 to other end users and I am finding it difficult to locate suppliers of equipment that can do this. There are a lot of scrubbing systems out there but we need to extract and capture CO2 in a clean, reusable state.

Any help here would be greatly appreciated!

Mike