Greenhouse CO₂ generators do exist and are used in greenhouses. A cogenerator (also known as: combined heat and power (CHP) (in Dutch: “warmtekrachtkoppeling” (WKK)) in a greenhouse produces CO₂ as a by-product through the combustion of fuel, such as natural gas or biomass, to generate electricity.

The exhaust gases containing CO₂ are strategically released into the greenhouse environment, enhancing photosynthesis and promoting accelerated plant growth.

Another way to obtain CO₂ in greenhouses is to get CO₂ from nearby industrial facilities, where CO₂ is captured and supplied as a by-product of industrial processes. In the Netherlands, there is a pipeline transporting CO₂ from the Rotterdam harbour to the greenhouses located in Westland.

Another way to supply CO₂ in the greenhouses is with external CO₂ tanks. Liquid CO₂ is transported to greenhouses in specialized tanks. This source of CO₂ is then released into the greenhouse atmosphere to support photosynthesis. This source of CO₂ could be relatively expensive to use.