CO2 Irrigation

The CO2 Irrigation process could reduce the amount of water required for the production of biomass by over 99% when compared to conventional agriculture.Paradoxically, we are irrigating crops with the wrong material - water. Plants give away water in order to obtain an even scarcer commodity that they require for photosynthesis - carbon dioxide. If we give them CO2, they do not need to give away as nearly as much water in the first place.If crops are grown in a sealed greenhouse it prevents the loss of moisture by evaporation, but plants soon use up the carbon dioxide that they need to grow and there is a need to replenish the air. However, when you pump fresh air into the greenhouse to replenish the supply of carbon dioxide, it is also necessary to vent old air out - and when this happens moisture is lost from the system.If, however, a high concentration of carbon dioxide is added to the greenhouse then far less moisture is lost from the system in the vented air. Benchtop experiments on two model crops have demonstrated this at a small scale. The amount of water lost from the system per mass of dry biomass produced was less than 1:1 - a greater than 99% improvement in the efficiency of water use compared to conventional agriculture.If successfully scaled up, this process could enable the production of food and energy crops in areas currently considered too arid for conventional agriculture. Operating in a sealed system would prevent the loss of not only water, but also macro- and micro-nutrients. This would decrease the amount of fertiliser required and help prevent eutrophication from run-off.This concept addresses all three of the subject matters of the Greenius competition - it would increase the land area on which food could be grown, it would reduce substantially the amount of water required for food production and it would address the energy dimension in two ways - firstly by enabling the production of biofuels in areas which cannot currently support their production and secondly by consuming carbon dioxide from power generation and industrial processes.