Advantages And Disadvantages Of PEM Water Electrolysis

PEM water electrolysis

Introduction
It is now well understood that use of fossil fuels as energy sources is unsustainable and damaging to the environment. The world is now moving in the direction of using renewable energy sources that are better for the environment and mitigate some of the damage that has been done. While this is virtuous it is not without its challenges. One of the biggest problems is that renewable energy sources have fluctuating outputs. It is therefore of the utmost importance that energy storage methodology is introduced. To this end, we are introduced to the hydrogen economy. This is used to describe the quintessential role hydrogen has yet to play in the worlds energy supply. Hydrogen is a clean and flexible energy

Advantages disadvantages The membrane acts as a solid electrolyte which reduces resistance by reducing the distance travelled by protons.
The membranous electrolyte is more expensive than the liquid one.
The electro-catalysts used are platinum group metals which allow for high efficiency and fast reaction rates.
The membrane can easily be damaged if mishandled
The solid nature of the electrolyte means that there is no possibility of leaching and thus product contamination.
There possible chemical degradation depending on the material used as a membrane.
The membrane provides gas tightness.
This technology requires the use of expensive platinum group metals.
The cell is compact and thus is easily heated up and cooled off. In combination with fast kinetics thanks to electro-catalysts, the cell has highly responsive even at ambient

This is commonly prepared using the Adams fusion method. Iridic acid (H2IrCL6.xH2O) NaNO3 is mixed with a solvent such as ethanol at 70oC for about 6 hours and then heated to 500oC for an hour [2]. This process should produce pure iridium oxide. The problem, however, is that iridium is expensive, according to one source the current price of iridium is 970 USD/troy ounces. this has led to the use of catalyst supports to reduce the amount of iridium oxide to be used. According to Polonsky et al 2012, this support needs to be cheap and easily accessible. He goes on to explain that using a support is beneficial in crystalline size is reduced and homogeneity of the catalyst is improved, the catalytic activity is improved and that the catalyst supported particles are larger and hence have more active sites. The author also summarises that the three most important aspects to look at when choosing an electrocatalyst should be long-term stability, high specific surface area and decent electron conductivity. To this end, many supports are being examined such as TaC (tantalum carbide) and TiO2 just to name a few. The Adams fusion method is modified to include the support chosen [3]. In the works on Polonsky et al, 2012 it is observed that the Adams fusion method is altered such that different weight percentages of the support and the iridium oxide electrocatalyst are synthesized