Chapter 8, Problem 37ICA

One problem with solar energy is that any given point on the planet is illuminated by the sun for only half of the time at best. It would be helpful, if there were a simple, affordable, and efficient means for storing any excess energy generated on sunny days for use during the night or on cloudy days.

You are investigating the electrodes used in electrolysis cells as part of a three-stage process for solar energy collection and storage.

1. A.    Convert sunlight to electricity with photovoltaic cells.
2. B.     Use the electricity generated in an electrolysis cell to split water into its component elements, hydrogen and oxygen. The hydrogen can be stored indefinitely. The oxygen can simply be released into the atmosphere.
3. C.     Use a fuel cell to recombine the stored hydrogen with oxygen from the atmosphere to generate electricity.

You have obtained an array of new high-efficiency, thin-film photovoltaic cells with an efficiency of 41%. The efficiency of fuel cells varies with the current demands placed on them, but the cells you have obtained yield an overall efficiency of 37% at the anticipated load.

Assume the total solar power on the solar cells is 2000 watts [W]. You conduct four experiments, each with a different alloy of palladium, platinum, gold, copper, and/or silver for the electrodes in the electrolysis cell. The final output power from the fuel cell is measured for each case, and the results are tabulated below. Determine the efficiency of each electrolysis cell and complete the table.

Alloy	Output Power (P0) [W]	Electrolysis Cell Efficiency (η)
(a) Alloy A	137
(b) Alloy B	201
(c) Alloy C	57
(d) Alloy D	177