We here at HEXAPOLIS have discussed in details the various potential applications of graphene – the two-dimensional carbon allotrope. And now a group of resourceful researchers over at MIT have found yet another use for the one-atom thick wonder material, with its crucial impact envisioned in most of the world’s electricity-producing power plants. To that end, it has been suggested that applying a graphene coating over power-plant condensers could make them far more energy efficient. In other words, the wonder material could directly aid the output of steam-generated electricity – which in itself accounts for over 80 percent of world’s electricity generation.
In terms of working scope of a thermal power plant, water is heated up to very high temperatures, to be converted into steam – which in turn is used for turning the turbine. The kinetic energy derived from this turning turbine is used for generating electricity, while the steam is condensed back into water for the cyclic procedure. As for the project by MIT, the condensers are the crucial components that are to be utilized for enhancing the effectiveness of the process. In that regard, according to the researchers involved, a coating of graphene can improve the rate of heat transfer (of these condensers) by a factor of four. When translated to overall figures, this could lead to around 3 percent increase in electricity production (as per Electric Power Research Institute’s calculations), thus accounting for savings of “millions of dollars per power plant per year”.
Now the question arises – how does the graphene coating work? Well, in regular scenarios, most condensers consist of metal coils made of copper that interact with the incoming steam during its flow. During the post-condensation phase, there can be two types of occurrences – water droplet formations that are easily collected by the gravitational force or creation of water films that coats the metal surfaces. It is the latter occurrence that can seriously impede the heat transfer; and as such, scientists prefer the first mode where water droplets are created. So, by the usage of graphene – which is also a hydrophobic element – the coating can repel the water films, thus transforming them into water droplets.
Interestingly, a coating of polymer over the metal surfaces also pertains to similar results. But the predicament with polymer is that the material has shown tendencies of degradation over just a short period of time (around 12 hours). And in some cases, it was even found that the thickness of a polymer coating adversely affected the heat transfer quotient of the coil it is supposed to protect. On the other hand, graphene didn’t demonstrate any sign of perceptible degradation in the testing phase (for at least 2 weeks).
Lastly, this advantage is further complemented by the improvement potential of the overall system. To that end, scientists are looking forth to increase the rate of heat transfer to five times more than the currently achieved number (of four-fold improvement), by adjusting the temperature differences of the mechanisms. And the best part is – this technology could be available in less than a year, since the graphene coating can be derived from large scale chemical vapor deposition (CVP) processes.
Source / Image Credit: MIT