Q$1*$

The most prevalent type of electrolyzers and fuel cells currently in use are Alkaline Electrolyzers, which typically operate at $0\mathrm{.}2-0\mathrm{.}3m\frac{A}{c}{m}^2.$ Please use Fig. $1$ as a reference for this type of cell in this assignment.

a$)$ What is the approximate range of Cell Potentials for this interval of Current Densities?

b$)$ What is the associated range of electrolyzer efficiency? Refer to the Lower Heating value of Hydrogen as its purpose is to be used as a fuel.

Q$2*$

To convert the chemical energy in the Hydrogen, produced in Q$1,$ back to electrical energy, the hydrogen is passed through an Alkaline Fuel Cell. Refer to the polarization curve given in Fig. $2.$ Typical operation range is for Current Densities between $0\mathrm{.}2$ to $0\mathrm{.}3\frac{A}{c}m2.$

a$)$ What is the expected Cell Voltage interval for the operational Current Density range?

b$)$ What is the Fuel Cell efficiency for that range, referring to Lower Heating Value of Hydrogen?

c$)$ What is the range of roundtrip efficiencies for the combination of Electrolysis and Fuel Cell?

d$)$ What other inefficiencies will occur for this overall process, and how will those inefficiencies affect the total roundtrip efficiency of the system, if taken into account?

Figure $2.$ Polarization Curve for an Alkaline Electrolyzer, adapted from Brauns

et$.$al $[1].$

Fig $2.$ Polarization curve for an Alkaline Fuel Cell, published in Gutru et$.$ al$.[2].$