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PNNL researchers drop the cost of capture using amines

In a nice bit of science, researchers at PNNL have outlined a path to drop the cost of capture of CO2 from pulverized coal plants. The incumbent technology for carbon capture from power plants is to use amine towers, where an amine dissolved in water reacts with CO2 in the flue gas stream. When the amines are heated, the CO2 is driven off, and the solvent is regenerated. This technology has existed for decades, and the best estimate today is that it can capture CO2 at a cost of about $47/ton.


The water is necessary in these systems to ensure the amines will flow as a liquid even after the CO2 has been captured. The scientists at PNNL have redesigned the molecules so that they require vastly less water, yet still have good viscosity profiles. Squeezing the water out of these solvents lowers the amount of energy needed to heat them, and specifically lessens the amount of energy wasted on water, which is otherwise inert in these systems. The amount of capital invested in heat exchange is also reduced. In total, the cost of amine capture thus drops to $39/ton.


These costs could get cheaper still. The water-lean amines developed at PNNL are less corrosive than conventional mixtures, which could allow for cheaper materials in construction. The overall plant design is also different enough from convention that it seems there is likely additional opportunity to experiment with and improve plant layout. It's not clear exactly how much cheaper this can get, but maybe $30/ton could be in sight. It will be years, however, before these solvents can be tested at scale, much less iteratively improved.


Also, there is the chance they will not make it to market at all. The molecules are far more complex than conventional triethanolamine, for example, and they will require significant investment in scale-up of manufacturing to move forward. PNNL started on this path a bit ago, but as far as I can tell has not issued an exclusive license for them yet. There are also question marks around long term stability. The path out of the lab is tricky, but enough interest is growing in post-combustion capture for applications such as concrete plants that perhaps a partner will take the plunge. Just not yet.



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