The photo is sourced from drax.com
The project’s distinctive feature is the use of metal-organicframeworks – crystalline porous materials consisting of metal ions bound together by organic molecules – in CO2 capture. Representing a crystalline structure, in which metals and organics form a mesh, metal-organic frameworks can change the size of their pores under the impact of temperature, liquids and electromagnetic radiation. Due to this, molecules of foreign compounds can be ‘placed’ inside a metal-organic framework and extracted when the external conditions have changed.
This property of metal-organic frameworks was adopted by Drax, which previously converted the coal-fired power units in North Yorkshire into a biomass power plant. A two-month CO2 capture experiment will take place here. Carbon will be captured in several stages, with the use of two industrial columns lined from the inside with metal-organic frameworks. First, the flue gas generated during power generation and containing CO2 will be pumped into the first column: the pores of the frameworks will absorb CO2, and the flue gas, depleted in carbon dioxide, will be released into the atmosphere. After that, to remove CO2 and send it to storage, the first of the columns will start to heat up to the temperature sufficient to change the properties of the metal-organic frameworks while the second column will receive the flue gas from the bioenergy power plant. After the CO2 has been completely removed, the first column will begin to accept the flue gas again, and the second one will be heated for removal of the carbon dioxide and its subsequent transportation.
The Drax’s technology will be an alternative to the solvent-based carbon capture used in production of liquefied natural gas (LNG). The produced natural gas is pumped into a CO2 absorber containing monoethanolamine, which is a colourless liquid absorbing carbon dioxide and sulfur-containing elements. Methane, purified from the impurities, is fed from the top of the absorber to the gas liquefaction unit, and the liquid settling at the bottom is sent to the CO2 stripping column where carbon dioxide is separated from foreign substances with the use of thermal energy. The Drax’s innovation can make CO2 capture less energy-intensive.