TNO is part of a consortium working on the technology HotCO2. The aim is to develop a HotCO2 system that produces pure CO2 and heat independently of each other in order to get maximum yield per cubic metre of consumed natural gas.
The productivity of a greenhouse increases rapidly when the CO2 level of the greenhouse air is kept at a high level. This can be done through the addition of CO2 via a flue gas duct. Combined heat and power (CHP) systems are widely used for the production of CO2, electricity and heat, but this approach suffers losses because all three are not required at the same time. TNO is developing the HotCO2 process, which will provide a solution for these losses by completely decoupling CO2 and heat production. HotCO2 is a buffer technology that can produce CO2 and heat separately. Instead of a buffer technology based on water, HotCO2 makes use of a metal bed.
With HotCO2 it is possible to generate CO2 and heat with a single device. Allowing metal particles to oxidize (rust) results in net heat production. Subsequently, through the use of natural gas, the oxidized metal can be converted back into metal, with the release of CO2. Unlike a hot water buffer that slowly loses its heat to the environment. HotCO2 has no buffer losses.
The capacity of HotCO2 is currently more than fifty times higher than the capacity of waterborne buffer technologies. In the summer season or during the day natural gas or biogas can be used to produce pure CO2, which is beneficial to the plants. Heat can be generated in the winter or at night. By means of the HotCO2 process, a single device can generate both heat and CO2 depending on the grower's current needs (see diagram under Downloads). Using HotCO2, growers can produce their own CO2 when they need it, during periods of peak demand for CO2 or during the weekends for example. This will enable growers to reduce their use of natural gas. Moreover, with the HotCO2 process pure CO2 be made (no NOx and ethylene) so the CO2 can be used in the greenhouse directly.
In addition to producing high-grade CO2 for use in the greenhouse, HotCO2 is energy efficient. HotCO2 reduces CO2 emissions and gas consumption by buffering heat or CO2. The process is flexible in terms of production, upscaling and buffering of heat and CO2. HotCO2 can run on natural gas and biogas. The technology for HotCO2 is being developed in collaboration with industry.