Enhancing the concentration of CO2 in greenhouses can improve agricultural yields by c30%. It costs $4-60/ton to supply this CO2, while $100-500/ton of value is unlocked. Shell and ABF have already under-taken projects, while industrial gas and monitoring companies can also benefit. But the challenge is scale. Around 50Tpa of CO2 is supplied to each acre of greenhouses. Only c10% is sequestered. So the total CO2 sequestration opportunity may be limited to around 50MTpa globally.